1. An independent power supply system comprising: a natural energy power generation device; a load device including an adjustment load and 5 operated by power from the natural energy power generation device; and a power storage device including a storage battery connected to the natural energy power generation device and the load device to perform charging and discharging, 10 wherein the independent power supply system calculates demand prediction data of the load device and power output prediction data of the natural energy power generation device by using weather forecast data, wherein the independent power supply system reduces 15 power output from the natural energy power generation device when it is predicted that the storage battery will be charged to a level above a maximum charge power of the storage battery based on the demand prediction data and the power output prediction data, and 20 wherein the independent power supply system reduces power consumption of the adjustment load when it is predicted that the storage battery will be discharged to a level above a maximum discharge power of the storage battery based on the demand prediction data and the power 25 output data. 67

2. The independent power supply system according to claim 1, wherein the independent power supply system predictively calculates a state of charge of the storage 5 battery for a predetermined future period by using the demand prediction data, the power output prediction data, and a rated capacity of the storage battery, wherein the independent power supply system reduces power output from the natural energy power generation 10 device when it is predicted that the state of charge for the predetermined future period will exceed the maximum charge power of the storage battery, and wherein the independent power supply system reduces power consumption of the adjustment load when it is 15 predicted that the state of charge for the predetermined future period will fall below a minimum charge power of the storage battery.

3. The independent power supply system according to claim 2, 20 further comprising a controller, wherein the controller calculates the demand prediction data of the load device and the power output prediction data of the natural energy power generation device, and outputs a command to reduce the power output 25 from the natural energy power generation device and a 68 command to reduce the power consumption of the adjustment load.

4. The independent power supply system according to claim 3, 5 wherein the controller is provided outside the natural energy power generation device, the load device, or the power storage device, and outputs control commands to the natural energy power generation device, the load device, and the power storage device through a line. 10

5. The independent power supply system according to claim 2, wherein the controller is provided in the power storage device, wherein the independent power supply system further 15 comprises another controller, wherein the controller calculates the demand prediction data of the load device and the power output prediction data of the natural energy power generation device, and controls a target voltage in the independent 20 power supply system, wherein the control of the target voltage is performed by temporarily setting the target voltage to a value greater than a rated voltage when it is predicted that the state of charge for the predetermined future 25 period will exceed the maximum charge power of the storage 69 battery, and by temporarily setting the target voltage to a value smaller than the rated voltage when it is predicted that the state of charge for the predetermined future period will fall below the minimum charge power of the 5 storage battery, wherein the controller reduces the power output from the natural energy power generation device when the target voltage exceeds the rated voltage for a predetermined time in the natural energy power generation device, and 10 wherein the controller reduces the power consumption of the adjustment load when the target voltage falls below the rated voltage for a predetermined time in the load device. 15 6. The independent power supply system according to any one of claims 2 to 4, wherein the independent power supply system determines whether measurement values of a charge/discharge power of the storage battery or an average value of the 20 measurement values is within a predetermined range, and wherein if the measurement values or the average value is out of the predetermined range, the independent power supply system sets a command value of a power factor of the natural energy power generation device to a value 70 determined by an impedance of a power system in the independent power supply system.

7. The independent power supply system according to claim 6, wherein if the measurement values 5 or the average value is within the predetermined range, the independent power supply system sets the command value of the power factor of the natural energy power generation device to 1. 10 8. The independent power supply system according to claim 5, wherein the independent power supply system determines whether the measurement values of a charge/discharge power of the storage battery or an average value of the measurement values is within a predetermined 15 range, wherein if the measurement values or the average value is within the predetermined range, the independent power supply system sets a command value of a power factor of the natural energy power generation device to 1, and 20 wherein if the measurement values or the average value is out of the predetermined range, the independent power supply system sets the command value of the power factor of the natural energy power generation device to a value determined by an impedance of a power system in the 25 independent power supply system. 71

9. The independent power supply system according to any one of claims 2 to 4, 6 and 7, wherein the independent power supply system reduces an output of the natural 5 energy power generation device when notice information of stopping start-up is received, the notice information of stopping start-up indicating that the load will stop start-up, and wherein the independent power supply system reduces 10 the power consumption of the adjustment load when notice information of starting up is received, the notice information of starting up indicating that the load will start up. 15 10. The independent power supply system according to any one of claims 1 to 9, wherein the natural energy power generation device is a solar power generation device including solar power panels. Dated this 20th 20 day of August 2014

SPECIFICATION
TITLE OF INVENTION
INDEPENDENT POWER SUPPLY SYSTEM
FIELD 5 OF THE INVENTION
[0001]
The present invention relates to an independent power
supply system, and more particularly, to the reduction of
the capacity of a power storage device.
10
BACKGROUND OF THE INVENTION
[0002]
As measures for the emerging environmental problems
such as global warming and acid rain, the depletion of
15 fossil resources, and ensuring energy security, the
installation of power generation facilities using natural
energy, such as wind and sunlight, is becoming more and
more popular.
[0003]
20 Currently, power is typically supplied mainly by
diesel engine generators and the like particularly in
isolated and depopulated areas in the tropical regions
where the system is inadequate. However, these regions
have high solar insolation and are suitable for solar
25 power generation, leading to a high need for a power
3
supply system that can improve economic efficiency through
effective use of renewable energy and, at the same time,
can contribute to the realization of a low carbon society.
Further, also in areas where the power system
infrastructure has 5 been established, there are growing
expectations for the system that allows autonomous
operation by separating the solar power generation system
installed in the demander facility from the system when
the power system is stopped due to a natural disaster or
10 other reasons, to stably and continuously supply power to
the load in the case of stopping of the power system.
[0004]
With respect to power generation facilities using
natural energy, an example of an independent power supply
15 system particularly using a solar power generation device
is described in Document 1. Document 1 describes a
technique for indirectly controlling the output reduction
state of the solar power generation device by changing the
target frequency according to the state of charge (SOC)
20 when performing automatic frequency control in a power
storage device, to prevent the system from stopping due to
over-charge of the power storage device.
DOCUMENTS ON RELATED ARTS
25 PATENT DOCUMENTS
4
[0005]
Document 1: Japanese Patent Application Laid-Open No. 2008-
17652
DISCLOSURE 5 OF THE INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
[0006]
In relation to a power supply system including a
natural energy power generation device, such as a solar or
10 wind power generation device, and a power storage device,
which are operated independent of the power system, it is
necessary to prevent not only over-charge of the power
storage device but also over-discharge of the power
storage device during night and rain when the solar power
15 generation device does not generate power, in order to
stably and continuously supply power to the load with
maintaining the frequency and voltage of the independent
system at appropriate values.
[0007]
20 In the technique disclosed in Document 1, it is
possible to prevent operation stop due to over-charge of
the power storage device. However, in order to prevent
operation stop due to over-discharge of the power storage
device, including night time when the output of the solar
25 power generation is zero, it is necessary to separately
5
provide an adjustment power source such as a diesel engine
or to increase the capacity of the power storage device,
which would lead to an increase in installation costs.
[0008]
5 Accordingly, an object of the present invention is
to provide an independent power supply system capable of
reducing installation costs.
MEANS FOR SOLVING THE PROBLEM
10 [0009]
In order to solve the above problem, an independent
power supply system of the present invention includes a
natural energy power generation device, a load device
including an adjustment load and operated by power from
15 the natural energy power generation device, and a power
storage device including a storage battery connected to
the natural energy power generation device and the load
device to perform charging and discharging. The
independent power supply system calculates demand
20 prediction data of the load device and power output
prediction data of the natural energy power generation
device by using weather forecast data. The independent
power supply system reduces power output from the natural
energy power generation device when it is predicted that
25 the storage battery will be charged to a level above a
6
maximum charge power of the storage battery based on the
demand prediction data and the power output prediction
data. The independent power supply system reduces power
consumption of the adjustment load when it is predicted
5 that the storage battery will be discharged to a level
above a maximum discharge power of the storage battery
based on the demand prediction data and the power output
data.
10 ADVANTAGEOUS EFFECTS OF THE INVENTION
[0010]
According to the present invention, it is possible
to provide an independent power supply system capable of
reducing installation costs.
15
BRIEF DESCRIPTION OF THE DRAWINGS
[0011]
FIG. 1 is a configuration example of an independent
power supply system according to a first embodiment;
20 FIG. 2 is a view schematically showing an example of
the output shift operation of a solar power generation
device and a power storage device, which are included in
the independent power supply system according to the first
embodiment;
25 FIG. 3 is a block diagram showing a functional
7
configuration of a controller of the independent power
supply system according to the first embodiment;
FIG. 4 is a control flow chart of the independent
power supply system according to the first embodiment;
FIG. 5 is a view of a 5 control operation of the
independent power supply system according to the first
embodiment;
FIG. 6 is a configuration example of an independent
power supply system according to a second embodiment;
10 FIG. 7 is a block diagram showing a functional
configuration of a controller provided in a power storage
device according to the second embodiment;
FIG. 8 is a block diagram showing a functional
configuration of a controller provided in a solar power
15 generation device according to the second embodiment;
FIG. 9 is a block diagram showing a functional
configuration of a controller provided in a load device
according to the second embodiment;
FIG. 10 is a control flow chart of the controller
20 provided in the power storage device according to the
second embodiment;
FIG. 11 is a control flow chart of the controller
provided in the solar power generation device according to
the second embodiment;
25 FIG. 12 is a control flow chart of the controller
8
provided in the load device according to the second
embodiment;
FIG. 13 is a view of a control operation of the
independent power supply system according to the second
embodiment5 ;
FIG. 14 is a control flow chart when power factor
adjustment operation is performed in a solar power
generation device according to a third embodiment;
FIG. 15 is a view of a control operation when the
10 power factor adjustment operation is performed in the
solar power generation device according to the third
embodiment;
FIG. 16 is a control flow chart when power factor
adjustment operation is performed in a solar power
15 generation device according to a fourth embodiment;
FIG. 17 is a control flow chart using a notice
signal of stopping start-up of a load device according to
a fifth embodiment; and
FIG. 18 is a view of a control operation using the
20 notice signal of stopping start-up of the load device
according to the fifth embodiment.
DESCRIPTION OF EMBODIMENTS
[0012]
25 Hereinafter, preferred embodiments for carrying out
9
the present invention will be described with reference to
the drawings. The following description is merely
exemplary in nature and the present invention is not
limited to the specific embodiments described below, and
5 various embodiments can be made to meet the description of
the scope of claims. In particular, in the description of
the following embodiments, solar power generation is used
as an example of natural energy power generation. The
present invention is not intended to be limited to the
10 solar power generation, and of course, other types of
natural energy power generation, such as wind power
generation, can be applied as well.

15 [0013]
With reference to FIGS. 1 to 5, a first embodiment
will be described.
FIG. 1 is a diagram illustrating an outline of an
independent power supply system to which centralized
20 control is applied. As shown in FIG. 1, an independent
power supply system 10 is schematically configured so that
a solar power generation device 2 in which the power
output varies depending on the solar insolation, a power
storage device 3 including a secondary battery such as
25 lead storage battery and lithium-ion battery, and a load
10
device 4 are connected to a power line 1 through power
receiving devices for grid-connection 25, 35, and 45,
respectively. Each of the solar power generation device 2,
the power storage device 3, and the load device 4 is
5 operated based on a control command transmitted from a
controller 5 through a line. The controller 5 has a
function to transmit control commands, such as reduction
amount of power output, charge/discharge power, and load
adjustment amount, to each device based on the weather
10 forecast information transmitted through a public line 6
and based on the operation state signals of the electrical
quantities, such as power, voltage, and power factor, and
the state of charge (SOC), which are transmitted from the
solar power generation device 2, the power storage device
15 3, and the load device 4. Then, the independent power
supply system 10 according to the present embodiment is
not provided with a power generation device for adjusting
the output of a rotary machine system with inertia, such
as a diesel engine power generator. For this reason, the
20 power storage device 3 plays a role in performing the
operation to maintain the voltage and frequency as a
reference source of the independent power supply system 10.
Thus, the power storage device 3 performs automatic
voltage regulation (AVR). On the other hand, the solar
25 power generation device 2 and the load device 4 play a
11
role in performing operations, such as temporary power
output reduction and load adjustment, in order to assist
the automatic voltage regulation of the power storage
device 3.
[5 0014]
The solar power generation device 2 includes solar
power panels 21, a power converter for grid-connection 22
which has a grid-connection protective function for
converting DC power generated by the solar power panels 21
10 into AC power, controlling the output, and connecting to
the power line 1, a power receiving device for gridconnection
25 including a transformer, a switch and the
like, and an own terminal voltage/current detector (not
shown in FIG. 1) that is used for control and protection
15 performed by the power converter for grid-connection 22.
Further, although not shown in FIG. 1, the power converter
for grid-connection 22 includes a controller 220 having a
communication function with the outside.
[0015]
20 The power storage device 3 is a device for adjusting
the balance between supply and demand of power of the
independent power supply system 10 by charging or
discharging. The power storage device 3 includes storage
batteries 31A and 31B, power converters for grid25
connection 32A and 32B each having a protective function
12
for converting DC power generated by the storage batteries
31A and 31B into AC power, controlling the output, and
connecting to the power line 1, a power receiving device
for grid-connection 35 including a transformer, a switch
and the like, 5 an own terminal voltage/current detector
(not shown in FIG. 1) that is used for control and
protection performed by the power converters for gridconnection
32A and 32B, a controller 33 for determining
control commands, such as charge/discharge power and
10 operation/stop information, which are transmitted to the
power converters for grid-connection to control the
storage batteries, and an auxiliary 34 of the storage
batteries 31A and 31B. Each of the power converters for
grid-connection 32A and 32B has a function for controlling
15 active/reactive power to maintain the frequency and
voltage of the independent power supply system 10 within
the proper range, based on the control commands from the
controller 33 and on the voltage/current information of
the own terminal. For the storage batteries 31A and 31B,
20 it is possible to use secondary batteries such as lead
storage battery, lithium-ion battery, sodium-sulfur
battery, and redox flow battery. Further, these batteries
should be subjected to refresh charging regularly, so that
it is desirable to provide at least two pairs of storage
25 batteries to allow independent operation so that the power
13
supply system can supply power stably during refresh
charging.
[0016]
The load device 4 includes an adjustment load 41
that can adjust power consumption, a load 42 that has 5 the
function to notify start or stop at predetermined timing,
and a controller 43 for transmitting a load adjustment
command transmitted from the controller 5 to the
adjustment load 41, receiving a notice signal of starting
10 up or stopping transmitted from the load 42, and
transmitting the received notice signal of starting up or
stopping to the controller 5. Further, although not shown
in FIG. 1, the load device 4 also includes an own terminal
voltage/current detector and a load which is a general
15 load with no special functions.
[0017]
FIG. 2 schematically shows the operation pattern
when the output of the solar power generation device 2 is
shifted during night time, which is the basic operation
20 method of the independent power supply system. Basically,
it is assumed that the solar power generation device 2
supplies generated power that is determined by the amount
of solar radiation, and does not perform any particular
output reduction in general. FIG. 2 shows an example in
25 which the power output reaches the rated capacity in fine
14
weather. The power storage device 3 performs a so-called
peak-shift operation to charge the generated power of the
solar power generation device 2 during daytime and
discharge during night time. Then, as shown in FIG. 2,
5 the power storage device 3 supplies the combined output of
the solar power generation device 2 and the power storage
device 3 to the load device 4.
[0018]
FIG. 3 is a block diagram showing the functional
10 configuration of the controller 5 of the independent power
supply system according to the present embodiment. The
controller 5 includes a control calculation unit 51 for
calculating a control command such as power output
reduction/release command, charge/discharge power command,
15 or load adjustment command, which is transmitted to the
solar power generation device 2, the power storage device
3, or the load device 4, a weather data storage unit 52
for storing weather forecast data such as the amount of
solar radiation and temperature, a measurement data
20 storage unit 53 for storing measurement data such as
electrical quantities and operation state information,
which are transmitted from the solar power generation
device 2, the power storage device 3, and the load device
4, a signal input/output interface unit 54 for controlling
25 transmission and reception of the control commands and the
15
measurement information to be transmitted to the solar
power generation device 2, the power storage device 3, and
the load device 4, an input unit 55 in which the operator
corrects the control command and inputs an operation
command for maintenance, 5 and a display unit 56 for
checking the operation state or other information by the
operator.
[0019]
The control calculation unit 51 includes a
10 prediction calculation function 511, an output sift
operation pattern generation function 512, and an output
shift operation pattern correction function 513.
[0020]
The prediction calculation function 511 includes a
15 solar power output prediction calculation part 5111 for
predicting the power output of the solar power generation
device 2 by using the weather forecast data such as
whether, amount of solar radiation, and temperature, which
are stored in the weather data storage unit 52 in advance,
20 and a demand power prediction calculation part 5112 for
predicting the demand power of the load device 4.
[0021]
The output shift operation pattern generation
function 512 includes a storage battery charge/discharge
25 pattern calculation part 5121 for calculating the default
16
value of the charge/discharge pattern of the power storage
device 3 by using the prediction results of the solar
power output and the demand power, a charge/discharge
level determination part 5122 for determining whether each
5 of the charge and discharge levels is in the proper range
with respect to the default setting of the
charge/discharge pattern, a solar-power-output-reductionamount
and load-adjustment-amount calculation part 5123
for calculating the reduction amount of the power output
10 of the solar power generation device 2 or the adjustment
amount of the load device 4, based on the determination
result in the charge/discharge level determination part
5122, and an output shift operation pattern generation
part 5124 for generating output shift operation patterns
15 of the solar power generation device 2, the power storage
device 3, and the load device 4, based on the default
value of the charge/discharge pattern, the reduction
amount of the solar power output, and the adjustment
amount of the load.
20 [0022]
Further, the output shift operation pattern
correction function 513 includes an SOC evaluation
calculation part 5131 for calculating the time transition
of the state of charge (SOC) of the power storage device 3,
25 an SOC level determination part 5132 for determining
17
whether the SOC level is in the proper range, a solarpower-
output-reduction-amount and load-adjustment-amount
correction calculation part 5133 for calculating to
correct the reduction amount of the power output of the
solar power generation 5 device 2 or the adjustment amount
of the load device 4, based on the determination result,
and an output shift operation pattern correction part 5134
for correcting the output shift operation pattern of the
solar power generation device 2, the power storage device
10 3, and the load device 4, based on the correction
calculation results of the reduction amount of the solar
power output and the adjustment amount of the load. Here,
the SOC (State of Charge) is an index indicating the
remaining amount (the quantity of charged electricity) of
15 the storage battery, which is expressed as a percentage
relative to the rated charge capacity.
[0023]
Next, with reference to FIG. 4, the flow of the
control process of the controller 5 of the independent
20 power supply system 10 will be described. The process
described below shows the process of the control
calculation unit 51, in which the control cycle is set to
the range of several minutes to thirty minutes in terms of
the time resolution of the output shift operation pattern
25 data. Further, in the following description, it is
18
assumed that the control cycle is 10 minutes.
[0024]
First, in S41, the controller 5 reads the weather
forecast data, such as the amount of solar radiation Sr
(W/m2) and the external air temperature To 5 (C), which are
collected and stored in the weather data storage unit 52
through the public line 6. In the present embodiment, as
an example, it is assumed that the stored weather forecast
data is the data measured every 30 minutes for 24 hours
10 in the future(for 48 points). In the process S42, the
controller 5 reads the most recent measurement data of the
power output Ppv_m (W) and power factor Pf_m of the solar
power generation device 2, the charge/discharge power
PBATT_m (W) and state of charge SOC (%) of the power
15 storage device 3, and the demand power Pd (W) of the load
device 4, each of which is regularly measured and
processed as the average value for 10 minutes. Here, the
discharge power is defined as positive, and the charge
power is defined as negative.
20 [0025]
In S43, the controller 5 performs a prediction
calculation of the power output Ppv(t) (t=1 to 48), which
is the power output data of the solar power generation
device 2 for 24 hours in the future, by using the
25 prediction data of the amount of solar radiation and
19
temperature read in S42. More specifically, the
controller 5 predicts the power output for each time
division based on the product of each factor by the
following equation (1), using the solar radiation amount
prediction value Sr(t) (W/m5 2) and the external air
temperature To (C) for each time division, and using the
ratio K(t) of the previous prediction value to the most
recent measurement value.
[0026]
Ppv(t)=Sr(t)･Ks･Kpv･Kt(T0)･Kb･Kc･Kpcs･Kα(t)10-310 (kW)
(1)
where
Ks: solar radiation amount correction factor
Kt(To): temperature correction factor
15 Kc: cable efficiency factor
K(t): most recent measurement value/previous
prediction value
Kpv: panel capacity conversion factor
Kb: fouling factor
20 Kpcs: power converter efficiency factor
[0027]
In S44, the controller 5 predicts the demand power
of the load device 4. As the prediction method used in
the present invention, it is possible to use a statistical
25 method, a meta-heuristic method, or other methods. For
20
example, the statistical method performs prediction
calculation with the weather forecast data as parameters
on the basis of the statistically processed data of the
past demand power patterns stored in the measurement data
storage unit 53. It is possible to predict 5 the demand
power with relatively high accuracy on the basis of the
algorithm that repeats a process to gradually correct the
impacts of each of the parameters so that the difference
between the prediction value and the actual value is small.
10 More specifically, this is performed as follows. First,
the controller 5 extracts multiple demand power patterns
with conditions close to those of the target date for
prediction, such as season, day, and weather, from the
data stored in the measurement data storage unit. Next,
15 the controller 5 takes the average of the extracted demand
power patterns to determine the basic predicted demand
power pattern Pd0(t). Finally, the controller 5 adds the
correction factors G1(t) and G2(t) to the basic predicted
demand power pattern Pd0(t) according to the weather and
20 temperature of the day. Thus, the controller 5 calculates
the prediction value Pd(t) of the demand power, which is
the prediction data of the demand power, by the equation
(2).
[0028]
25 Pd(t)=Pd0(t)+G1(t)+G2(t) (2)
21
where
G1(t): demand power correction factor according to
weather
G2(t): demand power correction factor according to
5 temperature
[0029]
The correction factors G1(t) and G2(t) are
sequentially corrected so that the difference between the
prediction value and the actual value is small.
10 [0030]
S45 shows the process of the output shift operation
pattern generation function 512 shown in FIG. 3. In S451,
the controller 5 calculates the charge/discharge power
PBATT(t) of the power storage device 3 from the difference
15 between Pd(t) and Ppv(t) by the equation (3), using the
prediction value Ppv(t) of the power output of the solar
power generation device 2 and the prediction value Pd(t)
of the demand power of the load device 4, which are
predicted by the equations (1) and (2). Then, the
20 controller 5 sets the charge/discharge power PBATT(t) to
the default value.
[0031]
PBATT(t)=Pd(t)-Ppv(t) (3)
Next, in S452, the controller 5 determines whether
25 each of the charge and discharge levels is in the proper
22
range with respect to the default value PBATT(t) of the
charge/discharge pattern of the power storage device 3, as
shown in the equations (4) to (6).
[0032]
If PBATT(t)Pdmax, go to S454 (5)
If PcmaxPBATT(t)Pdmax, go to S455 (6)
where
Pcmax: maximum charge power (W)
10 Pdmax: maximum discharge power (W)
[0033]
As shown in the equation (4), if PBATT(t) exceeds the
maximum charge power Pcmax (as an absolute value, which is
the charge power whose sign is negative, so that the
15 magnitude relationship is reversed), the generated power
is greater than the demand power within the independent
power supply system 10. Thus, in S453, the controller 5
calculates the output reduction amount Ppv(t) of the
solar power generation device 2 by the equation (7). Then,
20 the controller 5 sets the output reduction amount Ppv(t)
(to reduce by the output reduction amount Ppv(t)).
[0034]
Ppv(t)=PBATT(t)-Pcmax (7)
Further, as shown in the equation (5), if PBATT(t)
25 exceeds the maximum discharge power Pdmax, the demand
23
power is greater than the generated power within the
independent power supply system 10. Thus, in S454, the
controller 5 calculates the adjustment amount Pd(t) of
the adjustment load 41 capable of adjusting the power
5 consumption of the load device 4 by the equation (8).
Then, the controller 5 sets the adjustment amount Pd(t)
(to reduce by the adjustment amount Pd(t)).
[0035]
Pd(t)=PBATT(t)-Pdmax (8)
10 As shown in the equation (6), if the discharge power
PBATT(t) is within the proper range, the controller 5 sets
Ppv(t) and Pd(t) to zero.
[0036]
In S455, the controller 5 generates the solar power
15 output Ppv(t)*, the load power consumption Pd(t)*, and the
power storage charge/discharge pattern PBATT(t)*, as output
shift operation patterns by using the output reduction
amount Ppv(t) and the load adjustment amount Pd(t) that
are obtained in S452 to 454.
20 [0037]
Ppv(t)*=Ppv(t)+Ppv(t) (9)
Pd(t)*=Pd(t)+Pd(t) (10)
PBATT(t)*=PBATT(t)-Ppv(t)+Pd(t) (11)
It is also possible to reduce the capacity of the
25 power storage device to a certain extent with the output
24
shift operation patterns generated based on the method
described above. The following will describe the
correction of the output shift operation patterns in order
to further improve the accuracy.
[5 0038]
S46 shows the process of the output shift operation
pattern correction function 513 shown in FIG. 3. In S461,
the controller 5 calculates the state of charge SOC(t) for
24 hours in the future from the current time (every 30
10 minutes for 48 points) by the equation (12), using the
charge/discharge power PBATT(t)* of the power storage
device 3 that is calculated by the equation (11). The
time length in the future for the calculation and the
predetermined time length, which divides the time length
15 in the future for the calculation, will vary depending on
the installation environment or other conditions. Here,
it is assumed that the time length in the future for the
calculation is 24 hours and the predetermined time length
to divide the time length in the future for the
20 calculation is 30 minutes.
[0039]
SOC(t)=SOC(t-1)+((PBATT(t)*0.5)/Ph_rated)100(%)
(12)
Here, Ph_rated is the rated capacity (Wh) of the
25 power storage device 3.
25
[0040]
Next, in 462, with respect to the state of charge
SOC(t) of the power storage device 3, the controller 5
determines whether the state of charge is within the
proper range as shown 5 in the equations (13) to (15).
[0041]
If SminSOC(t)Smax, go to S465 (13)
If SOC>Smax, go to S463 (14)
If SOC(t)
[0052]
With reference to FIGS. 6 to 13, an independent
power supply system of another embodiment of the present
invention will be described, to 5 which autonomous control
is applied. While an application of centralized control
is described in the first embodiment, an application of
autonomous control will be described in the present
embodiment.
10 [0053]
FIG. 6 is a schematic configuration example of an
independent power supply system to which autonomous
control is applied. FIG. 6 is significantly different
from FIG. 1 in that there is no controller for controlling
15 the entire system of an independent power supply system
110 and that means for measuring the combined output of a
solar power generation device 102 and a power storage
device 103 is provided in each of them.
[0054]
20 The independent power supply system 110 is
schematically configured so that the solar power
generation device 102 in which the power output varies
depending on the solar insolation, the power storage
device 103 including a secondary battery such as lead
25 storage battery and lithium-ion battery, and a load device
31
104 are connected to a power line 1 through power
receiving devices for grid-connection 25, 35, and 45,
respectively. Each of the solar power generation device
102, the storage power device 103, and the load device 104
5 is operated based on a control command from the controller
105. The controller 105 has a function to transmit
control commands, such as power output reduction amount,
charge/discharge power, and load adjustment amount, to
each device based on the weather forecast information
10 transmitted through the public line 6 and based on the
operation state signals of the electrical quantities, such
as power, voltage, and power factor, and the state of
charge (SOC), which are transmitted from the solar power
generation device 102, the power storage device 103, and
15 the load device 104. Then, the independent power supply
system 110 according to the present embodiment is not
provided with a power generation device for adjusting the
output of the rotary machine system with inertia, such as
a diesel engine power generator. For this reason, the
20 power storage device 103 has a role in performing the
operation to maintain the voltage and frequency as a
reference source of the independent power supply system
110. Thus, the power storage device 103 performs
automatic voltage regulation (AVR). On the other hand,
25 the solar power generation device 102 and the load device
32
104 play a role in performing operations, such as
temporary power output reduction and load adjustment, in
order to assist the automatic voltage regulation of the
power storage device 103. Then, in the present embodiment,
5 the solar power generation device 102, the power storage
device 103, and the load device 104 are autonomously
operated by controllers included in each of the devices.
[0055]
The solar power generation device 102 includes solar
10 power panels 21, a power converter for grid-connection 122
which has a grid-connection protective function for
converting DC power generated by the solar power panels 21
into AC power, controlling the output, and connecting to
the power line 1, a power receiving device for grid15
connection 25 including a transformer, a switch and the
like, and an own terminal voltage/current detector (not
shown in FIG. 6) that is used for control and protection
performed by the power converter for grid-connection 122.
Further, although not shown in FIG. 6, the power converter
20 for grid-connection 122 includes a controller 320 having a
communication function with the outside. The measurement
values of the combined output of the solar power
generation device 102 and the power storage device 103 are
transmitted to the controller 320 of the power converter
25 for grid-connection 122. Then, controller 320 reduces the
33
power output based on the voltage information of the own
terminal.
[0056]
The power storage device 103 is a device for
5 adjusting the balance between supply and demand of power
of the independent power supply system 110 by charging or
discharging. The power storage device 103 includes
storage batteries 31A and 31B, power converters for gridconnection
32A and 32B having a protective function for
10 converting DC power generated by the storage batteries 31A
and 31B into AC power, controlling the output, and
connecting to the power line 1, an own terminal
voltage/current detector (not shown in FIG. 6) that is
used for control/protection performed by the power
15 converters for grid-connection 32A and 32B, a controller
105 for determining control commands, such as
charge/discharge power and operation/stop information,
which are transmitted to the power converts for gridconnection
to control the storage batteries, and an
20 auxiliary 34 for the storage batteries 31A and 31B. Each
of the power converters for grid-connection 32A and 32B
has a function for controlling active/reactive power to
maintain the frequency and voltage within the proper range,
based on the control commands from the controller 105 and
25 on the voltage/current information of the own terminal.
34
The measurement value of the combined output of the solar
power generation device 102 and the power storage device
103 is transmitted to the controller 105. The weather
forecast information is also transmitted to the controller
105 through the public line 6. For the storage 5 batteries
31A and 31B, it is possible to use secondary batteries
such as lead storage batteries, lithium-ion batteries,
sodium-sulfur batteries, and redox flow batteries.
Further, these batteries should be subjected to refresh
10 charging regularly, so that it is desirable to provide at
least two pairs of storage batteries to allow independent
operation so that the power supply system can supply power
stably during refresh charging. Then, the power storage
device 103 is connected to the power line 1 through a
15 power receiving device for grid-connection 35 including a
transformer, a switch and the like.
[0057]
The load device 104 includes an adjustment load 41
that can adjust power consumption, a load 42 which is a
20 general load with no special functions, and a controller
143 having a function for calculating the load adjustment
amount from the voltage information of the own terminal.
Further, although not shown in FIG. 6, an own terminal
voltage/current detector is also provided.
25 [0058]
35
FIGS. 7 to 9 are diagrams showing functional
configurations of the controllers of the power storage
device 103, the solar power generation device 102, and the
load device 104, which are included in the independent
power supply system to which autonomous control is applied5 .
FIG. 7 corresponds to the controller 105 in the storage
device 103, FIG. 8 corresponds to the controller 320 in
the solar power generation device 2, and FIG. 9
corresponds to the controller 143 in the load device 104.
10 [0059]
In FIG. 7, the controller 105 includes a control
calculation unit 51 for calculating a charge/discharge
power command to be transmitted to the power converters
for grid-connection 32A and 32B in the power storage
15 device 103 and a voltage target command in the independent
power supply system 110, a weather data storage unit 52
for storing weather forecast data such as the amount of
solar radiation and temperature, a measurement data
storage unit 53 for storing measurement data such as the
20 electrical quantities of the own terminal and the combined
output of the solar power generation device 102 and the
power storage device 103, a signal input/output interface
unit 54 for controlling transmission and reception of the
control commands to be transmitted to the power converts
25 for grid-connection 32A and 32B and the measurement
36
information, an input unit 55 in which the operator
corrects the control command and inputs an operation
command for maintenance, and a display device 56 for
checking the operation state or other information by the
5 operator.
[0060]
The control calculation unit 51 includes a
prediction calculation function 511, an output shift
operation pattern generation function 512, and an output
10 shift operation pattern correction function 513.
[0061]
The prediction calculation function 511 includes a
solar power output prediction calculation part 5111 for
predicting the power output of the solar power generation
15 device 102 by using the weather forecast data such as
weather, amount of solar radiation, and temperature, which
are stored in the weather data storage unit 52 in advance,
and a demand power prediction calculation part 5112 for
predicting the demand power of the load device 104.
20 [0062]
The output shift operation pattern generation
function 512 includes a storage battery charge/discharge
pattern calculation part 5121 for calculating the default
value of the charge/discharge pattern of the power storage
25 device 103 by using the prediction results of the solar
37
power output and the demand power, a charge/discharge
level determination part 5122 for determining whether each
of the charge and discharge levels is within the proper
range with respect to the default value of the
charge/discharge pattern, a solar-power-output-5 reductionamount
and load-adjustment-amount calculation part 5123
for calculating the reduction amount of the power output
of the solar power generation device 102 or the adjustment
amount of the load device 104, based on the determination
10 result in the charge/discharge level determination part
5122, and an output shift operation pattern generation
part 5124 for generating output shift operation patterns
of the solar power generation device 102, the power
storage device 103, and the load device 104, based on the
15 default value of the charge/discharge pattern, the
reduction amount of the solar power output, and the
adjustment amount of the load. Further, the output shift
operation pattern correction function 513 includes an SOC
evaluation calculation part 5131 for calculating the time
20 transition of the state of charge (SOC) of the power
storage device 103, an SOC level determination part 5132
for determining whether the SOC level is within the proper
range, a target voltage setting part 5133 for estimating
the correction amount of the output reduction amount of
25 the solar power generation device 2 and the load
38
adjustment amount based on the determination result of the
SOC level determination part 5132, and setting the voltage
target value of the independent system, and an output
shift operation pattern correction part 5134 for
correcting 5 the charge/discharge pattern of the storage
device 103 and the target voltage based on the correction
calculation results of the reduction amount of the solar
power output and the adjustment amount of the load.
[0063]
10 In FIG. 8, the controller 320 of the power converter
for grid-connection 122 of the solar power generation
device 102 includes an output reduction calculation
function 321 and a power control function 322. The output
reduction calculation function 321 includes an own
15 terminal voltage determination part 3211 for reading the
measurement value of the own terminal voltage to determine
the level of the voltage, a battery charge/discharge power
calculation part 3212 for calculating the charge/discharge
power of the storage batteries by using the measurement
20 values of the own terminal power output and the combined
power, a state-of-charge determination part 3213 for
determining the state of charge from the charge/discharge
power of the storage battery, a solar power output
reduction control calculation part 3214 for calculating
25 the reduction amount of the power output by using the
39
determination result of the own terminal voltage and the
charging/discharging determination result of the storage
battery, and a delay timer 3215 for holding the output
limit command only for a predetermined time. The power
5 control function 322 generates a gate pulse signal for
controlling the output power of the power converter for
grid-connection 122 by using the measurement values of the
own terminal voltage and current.
[0064]
10 In FIG. 9, the controller 143 of the load device 104
includes an own terminal voltage determination part 431
for reading the measurement value of the own terminal
voltage to determine the level of the voltage, a load
limit control calculation part 432 for calculating the
15 load limit value from the own terminal voltage
determination result, and a delay timer 433 for holding
the load reduction command for a predetermined time.
[0065]
Next, with reference to FIG. 10, the flow of the
20 control process will be described for each device of the
independent power supply system in autonomous control
operation. FIG. 10 corresponds to the controller 105 of
the power storage device 103, FIG. 11 corresponds to the
controller 320 of the solar power generation device 102,
25 and FIG. 12 corresponds to the controller 143 of the load
40
device 104. The following is an example in which the
control cycle is set to the range of several minutes to
thirty minutes, similarly to FIG. 4. Here, it is assumed
that the control cycle is 10 minutes.
[5 0066]
First, in S81 in FIG. 10, the controller 105 reads
the weather forecast data such as the amount of solar
radiation Sr (W/m2) and the external air temperature To
(C), which are collected and stored in the weather data
10 storage unit 52 through the public line 6. Here, for
example, it is assumed that the weather forecast data is
stored every 30 minutes. In S82, the controller 105 reads
the combined output Psum(W) of the solar power generation
device 2 and the power storage device 103, the power
15 factor Pf, the charge/discharge power PBATT(W) of the own
terminal, and the state of charge SOC(%), each of which is
regularly measured and processed as the average value for
10 minutes. In the present embodiment, similarly to the
first embodiment, the discharge power is defined as
20 positive and the charge power is defined as negative with
respect to the charge/discharge power PBATT.
[0067]
In S83, S84, and S85, the controller 105 calculates
the prediction value of the power output of the solar
25 power generation device 102, the prediction value of the
41
demand power of the load device 104, and the output shift
operation pattern, respectively. The calculation method
of these values is the same as the method described with
reference to FIG. 4, and the description thereof will be
omitted 5 here.
[0068]
S86 shows the process of the output shift operation
pattern correction function 513 shown in FIG. 7. In S861,
the controller 105 calculates the state of charge SOC(t)
10 for 24 hours in the future from the current time (every 30
minutes for 48 points) by the equation (12), by using the
charge/discharge power PBATT(t)* of the power storage
device 103 calculated by the equation (11).
[0069]
15 Next, in S862, with respect to the state of charge
SOC(t) of the power storage device 103, the controller 105
determines whether the state of charge is within the
proper range as shown in the equations (13) to (15).
[0070]
20 In the case of the equation (13), the state of
charge SOC(t) is within the proper range as shown in FIG.
5(a). Thus, there is no need to further correct the
output shift operation patterns Ppv(t)*, Pd(t)*, and
PBATT(t)* obtained in S45.
25 [0071]
42
When SOC(t) exceeds the maximum charge power Smax as
shown in the equation (14), namely, as shown in FIG. 5(b),
when the prediction value of the demand power is less than
the previous prediction value at the time division Tb and
when 5 the output of solar power generation is excessive,
for example, the controller 105 reduces the output Ppv of
the solar power generation device 102 to limit the charge
amount of the power storage device 103 as shown in the
dotted lines in FIG. 5(b) in order to prevent the state of
10 charge SOC(t) from being excessive. Thus, in the process
S863, the controller 105 calculates and sets the output
reduction amount Ppv(t)* of the solar power generation
device 102 by the equation (16). Incidentally, in the
case of the centralized control in the first embodiment,
15 the command is directly transmitted to each device from
the controller 105, but in the case of the autonomous
control, the output reduction command may not be directly
transmitted to the solar power generation device 102 from
the controller 105 located within the power storage device
20 103. Thus, it is designed to allow the controller 105 to
reduce the power output indirectly by controlling the
target voltage Vref of the independent power supply system
110. In other words, in S864, the controller 105
temporarily sets the target voltage Vref to a value Va
25 that is greater than the rated voltage Vo. In this way,
43
the controller 105 controls to reduce the power output
when the target voltage continues to exceed Va for a
predetermined time or more in the solar power generation
device 102.
[5 0072]
Further, when SOC(t) falls below the minimum charge
power Smin as shown in the equation (15), namely, as shown
in FIG. 5(c), when the prediction value of the solar power
output is less than the previous prediction value at the
10 time division Tc and when the power generation amount runs
short, for example, the controller 105 limits the demand
power Pd of the load device 4 to increase the charge
amount of the power storage device 103 in order to prevent
the state of charge SOC(t) from being deficient as shown
15 in the dotted lines in FIG. 5(c). Thus, in S866, the
controller 105 calculates and sets the adjustment amount
Pd(t)* of the load device 104 by the equation (17). In
the case of the autonomous control, similarly to the case
described above, the adjustment command of the demand
20 power may not be directly transmitted to the load device
104 from the controller 105. Thus, it is designed to
allow the controller 105 to adjust the demand power
indirectly by controlling the target voltage in the
independent system. In other words, in S867, the
25 controller 105 temporarily sets the target voltage Vref to
44
a value Vb that is smaller than the rated voltage Vo. In
this way, the controller 105 controls to reduce the demand
power when the target voltage continues to fall below Vb
for a predetermined time or more in the load device 104.
[5 0073]
In S868, the controller 105 corrects the
charge/discharge power PBATT(t) by the equation (20) by
using the charge/discharge pattern output reduction
correction amount Ppv* and the load adjustment correction
10 amount Pd*, which are obtained in S862 to S867. Further,
the controller 105 sets the target voltage Vref to Va
(>Vo) or Vb (
[0081]
20 Next, referring to FIGS. 14 and 15, a description
will be given of an independent power supply system of a
third embodiment to which a solar power generation device
is applied to perform reactive power control based on
centralized control.
25 [0082]
49
FIG. 14 is a view showing a flow of the controller 5
when the solar power generation device 2 for performing
reactive power control is applied to the independent power
supply system 10 operated by using centralized control.
In the present embodiment, a process that is added 5 to the
first embodiment is performed in the control calculation
unit 51 in FIG. 3 used in the description of the first
embodiment. The configuration of the independent power
supply system 10 and the functional configuration of the
10 controller 5 are the same as those described in FIGS. 3
and 4, respectively, and the description thereof will be
omitted here.
[0083]
Here, the control cycle of the control calculation
15 unit 51 is set to a range of several minutes to 30 minutes
in terms of the time resolution of output shift operation
pattern data. In this embodiment, it is assumed that the
control cycle is 10 minutes, for example. In FIG. 14, the
process from S101 to S106 is the same as the process from
20 S41 to S46, and the description thereof will be omitted
here. In S107, the controller 5 calculates the power
factor to be transmitted to the power converter for gridconnection
22 of the solar power generation device 2.
First, in S1071, the controller 5 calculates the
25 charge/discharge level PBATT_ave of the power storage
50
device 3 by averaging the measurement values of the
charge/discharge power of the power storage device by a
moving average, for example. Then, in S1072, the
controller 5 compares the charge/discharge level PBATT_ave
to a threshold. When the charge/discharge level PBATT_5 _ave
is within a predetermined range, for example, within 50%
of the rated output, the controller 5 sets the command
value of the power factor to 1 (S1073). When the
charge/discharge level PBATT_ave is out of the
10 predetermined range, the controller 5 sets the command
value of the power factor Pf to the optimum power factor
PfOPT, which is determined by the impedance of the premise
system (S1074). Here, the optimum power factor PfOPT can
be approximately calculated in advance by the equation
15 (21), as the ratio of the resistance component R of the
system impedance to the reactance component X from the
output terminal of the solar power generation device 2 to
the connection point of the load device 4.
[0084]
PfOPT20 ≒R/X (21)
Next, with reference to FIG. 15, a description will
be given of the control when power factor adjustment
operation is performed by the solar power generation
device of the independent power supply system to which
25 centralized control is applied. FIG. 15(a) is a case when
51
the solar power generation device 2 constantly operates
with power factor 1 without performing reactive power
control. FIG. 15(b) is an example of the operation
results when the possible output compensation amount is
less 5 than the proper range and when the solar power
generation device 2 performs an optimum power factor
operation. In the independent power supply system 10, in
addition to the voltage variation caused by the imbalance
between supply and demand as described in each of the
10 above embodiments, there also occurs a combined voltage
variation which is the superposition of voltage variations
that occur when the consumption power variation of the
load device 4 and the output variation of the solar power
generation device 2 act on the impedance as shown in FIG.
15 15(a). Also in the description in each of the embodiments,
the charge/discharge power is adjusted by the automatic
voltage regulation of the power storage device 3 so that
the charge/discharge power, including the voltage
variation, is regulated to the target voltage. However,
20 if the power variations in the load device 4 and the solar
power generation device 2 are large, the compensation
amount of the power storage device 3 is increased. On the
other hand, as shown in FIG. 15(b), the voltage variation
caused by the output variation of the solar power
25 generation device 2 is reduced when the solar power
52
generation device 2 is operated with an optimum power
factor determined by the equation (21). Thus, the
combined voltage variation to be compensated by the power
storage device 3 is only the voltage variation of the load
device 4. As 5 a result, the compensation amount can be
reduced. Of course, other methods can be used to
calculate the power factor as well.
[0085]
In the present embodiment, the controller 5
10 determines whether the average value of the measurement
values of the charge/discharge power of the storage
battery is within a predetermined range. If the average
value exceeds the threshold and is out of the
predetermined range, the controller 5 operates by setting
15 the command value of the power factor of the solar power
generation device 2 to a value determined using the
impedance of the power system in the independent power
supply system. In this way, it is possible to reduce the
load of the automatic voltage regulation (AVR) of the
20 power storage device by reducing the combined voltage
variation which is the superposition of the voltage
variations that occur when the consumption power variation
of the load device 4 and the output variation of the solar
power generation device 2 act on the impedance. In
25 addition, as long as the average value is within the
53
predetermined range, it is possible to perform power
generation operation without wasting producible power
output by setting the command value of the power factor of
the solar power generation device 2 to 1.
[5 0086]
Note that, in the present embodiment, it is assumed
that the process is applied in combination with the first
embodiment. When the process is applied in this way, it
is possible to complement the component of the
10 compensation that can be achieved by the first embodiment,
(so that the process has good compatibility,) resulting in
a more effective combination. However, of course it is
also possible to perform the control in a way described in
the present embodiment without combining the first
15 embodiment. In this case, it is also possible to reduce
the voltage variation and thus contribute to the reduction
of the capacity of the power storage device.
[0087]
Further, in the present embodiment, it is focused on
20 the average value of the measurement values of the
charge/discharge power of the storage battery to change
the control by determining whether the average value is
within the predetermined range. However, the value used
in the present invention is not limited to the average
25 value of the measurement values. The same control can be
54
achieved if a value that changes in correlation with a
measurement value, including the measurement value itself,
is set along with a predetermined value. If the method to
employ the average value of the measurement values is used,
the determination can 5 be performed accurately without
influence of instantaneous variation. Thus, the
reliability is increased and the method is effective.
This advantageous effect in the present embodiment is also
obtained in the fourth embodiment.
10

[0088]
In the third embodiment, there has been described
the independent power supply system using the solar power
15 generation device for performing reactive power control by
using centralized control. In the present embodiment, a
case will be described with reference to FIG. 16 in which
the solar power generation device for performing reactive
power control is applied to an independent power supply
20 system operated by autonomous control. The entire
configuration of an independent power supply system 110
according to the present embodiment is the same as the
configuration described in FIG. 6. The description
thereof will be omitted here.
25 [0089]
55
FIG. 16 shows a flow of the process of the
controller of the solar power generation device 102
according to the present embodiment. Note that the
control flow of the power storage device 103 and the
5 control flow of the load device 104 are the same as those
described in FIGS. 10 and 12, respectively. Further, the
process from S121 to S127 in FIG. 12 is the same as the
process from S81b to S87b in FIG. 11. Thus, the
description of these processes is omitted in this
10 embodiment.
[0090]
In S128, similarly to the process described in S107
in FIG. 14, the controller calculates the operation power
factor of the power converter for grid-connection 122 of
15 the solar power generation device 102. First, in S1281,
the controller calculates the charge/discharge level
PBATT_ave of the power storage device 103 by averaging the
measurement values of the charge/discharge power of the
storage battery by a moving average, for example. Next,
20 in S1282, the controller compares the charge/discharge
level PBATT_ave to a threshold. When PBATT_ave is within a
predetermined range, for example, within 50% of the rated
output, the controller sets the command value of the power
factor to 1 (S1283). When PBATT_ave is out of the
25 predetermined range, the controller sets the command value
56
of the power factor Pf to the optimum power factor PfOPT
that is determined by the impedance of the premise system
(S1284). Here, the optimum power factor PfOPT can be
calculated in advance by the equation (21) as the ratio of
5 the resistance component R of the system impedance to the
reactance component X from the output terminal of the
solar power generation device 102 to the connection point
of the load device 104.
[0091]
10 According to the present embodiment, the solar power
generation device 102 determines whether the average value
of the measurement values of the charge/discharge power of
the storage batteries 31A and 31B is within the
predetermined range. When the average value is out of the
15 predetermined range, the solar power generation device 102
sets the command value of the power factor of the solar
power generation device 102 to a value determined by the
impedance of the power system in the independent power
supply system. In this way, the same operation as in the
20 third embodiment can be achieved in the independent power
supply system as a whole, even when autonomous control is
performed, not centralized control. As a result, the same
effects can be obtained as in the third embodiment. In
addition, as long as the average value is within the
25 predetermined range, it is possible to perform power
57
generation operation without wasting producible power
output by setting the command value of the power factor of
the solar power generation device 2 to 1.
[0092]
Note that, in the present 5 ent embodiment, it is assumed
that the process is applied in combination with the second
embodiment. When the process is applied in this way, it
is possible to complement the component of the
compensation that can be achieved by the second embodiment,
10 (so that the process has good compatibility,) resulting in
a more effective combination. However, of course it is
also possible to perform the control in a way described in
the present embodiment without combining the second
embodiment. In this case, it is also possible to reduce
15 the voltage variation and thus contribute to the reduction
of the capacity of the power storage device.

[0093]
20 As a fifth embodiment, an independent power supply
system using information of starting or stopping of the
load will be described with reference to FIGS. 17 and 18.
Note that the configuration of the independent power
supply system 10 and the functional configuration of the
25 controller 5 according to the present embodiment are the
58
same as those described in FIGS. 3 and 4, respectively.
Thus the description thereof will be omitted here.
[0094]
FIG. 17 shows a flow of the process of the
controller 5 when notice information of stopping start-5 up
of the load is used in the independent power supply system
operated by using centralized control. The process
described below shows the process of the control
calculation unit 51 in FIG. 3. It is desirable that the
10 control cycle of the control calculation unit 51 is set to
the range of several minutes to 30 minutes in terms of the
time resolution of the output shift operation pattern data.
For example, it is assumed that the control cycle is 10
minutes here.
15 [0095]
In FIG. 17, the processes from S131 to S136 are the
same as the processes from S41 to S46 shown in FIG. 4, so
that the description thereof is omitted. In S137, the
controller 5 calculates the control command based on the
20 notice information of stopping start-up of the load.
First, in S1371, the controller 5 determines the presence
of the notice signal of stopping start-up transmitted from
the power storage device 3. When the notice signal of
stopping of the load is received, the controller 5
25 calculates the output reduction amount of the solar power
59
generation device 2 and the charging/discharging
adjustment amount of the power storage device 3 by the
method described below in S1372.
[0096]
As shown in FIG. 18(5 a), when the notice signal of
stopping is received at time T1, the load is stopped at
time T2 after a predetermined time elapsed. Thus, the
controller 5 calculates the output reduction amount of the
solar power generation device 2 in preparation for the
10 load stop. Then, the controller 5 performs the power
factor control calculation in S138 and then issues a
command of reduction output to the solar power generation
device 2 in S139. The power generation amount is reduced
because of this command, and the charge/discharge power of
15 the power storage device 3 shifts in the discharge
direction (positive direction) to prevent the imbalance
between supply and demand. In this state, when the load
is stopped at time T2, the power storage device 3 is
shifted in the discharge direction to ensure a sufficient
20 amount of compensation in the charge direction. Thus,
rapid reduction of power consumption can be absorbed by
charging.
[0097]
When the notice signal of starting up of the load is
25 received, the controller 5 calculates the adjustment
60
amount of the load device 4 and the charge/discharge power
adjustment amount of the power storage device 3 in S1373
by the method described below. As shown in FIG. 18(b),
when the notice signal of starting up is received at time
5 T5, the load is started at time T6 after a predetermined
time elapsed. Thus, the controller 5 calculates the
adjustment amount of the adjustment load 41 of the load
device 4 in preparation for the load start. Then, the
controller 5 performs the power factor control calculation
10 in S138, and then issues a command of the adjustment
amount of power consumption to the load device 4 in S139.
The power consumption amount is reduced because of this
command, and the charge/discharge power of the power
storage device 3 is shifted in the charge direction
15 (negative direction) to prevent the imbalance between
supply and demand. In this state, when the load is
started up at time T2, the power storage device 3 is
shifted in the charge direction to ensure a sufficient
amount of compensation in the discharge direction. Thus,
20 a rapid increase in power consumption can be absorbed by
discharging. Then, when the adjustment command of power
consumption of the load device 4 is released at time 7
after a predetermined time elapsed, the charge/discharge
power of the power storage device 3 moves in the discharge
25 direction so as to maintain the balance between supply and
61
demand.
[0098]
In the present embodiment, when the notice
information of stopping start-up, which indicates that the
load will stop start-up, is received, the controller 5 5
reduces the output of the solar power generation device 2.
When the notice information of starting up, which
indicates that the load will start up, is received, the
controller 5 reduces the power consumption of the
10 adjustment load 41. In this way, it is possible to
maintain the supply-demand balance of the independent
power supply system 10 without increasing the capacity of
the power storage device 3, even if a significant power
change occurs due to a steep change in the starting or
15 stopping of the load.
[0099]
In the present embodiment, the charge/discharge
level of the power storage device 3 is adjusted in advance,
by reducing the power output of the solar power generation
20 device 2 and by adjusting the power consumption of the
load device 4 based on the notice information of stopping
start-up of the load, in order to ensure the required
compensation amount.
[0100]
25 In the present embodiment, it is assumed that the
62
process is applied in combination with the first
embodiment. When the process is applied in this way, it
is possible to complement the component of the
compensation that can be achieved by the first embodiment,
(so that the process has good compatibility,) 5 resulting in
a more effective combination. However, of course it is
also possible to perform the control in a way described in
the present embodiment without combining the first
embodiment. In this case, it is also possible to reduce
10 the voltage variation and thus contribute to the reduction
of the capacity of the power storage device. In addition,
the process described in the present embodiment can also
be applied in combination with the third embodiment. This
case will contribute the most to the reduction of the
15 capacity of the power storage device. As a result, the
installation costs can be significantly reduced.
[0101]
As for the contents described in the above
embodiments, it is possible to achieve stable power supply
20 by preventing over-charge and over-discharge of the
storage battery, including night hours, while maintaining
the frequency and voltage against steep power changes in
the solar power generation and the load, only by using
multiple solar power generation devices and power storage
25 devices, without grid-connection with the power system of
63
the electric power company.
[0102]
Note that the equations and parameters described in
the embodiments are merely examples, and applying methods
5 that are not described in this specification to the
embodiments is not excluded from the present invention.
EXPLANATION OF REFERENCE CHARACTERS
[0103]
10 1...power line
2, 102...solar power generation device
3, 103...power storage device
4, 104...load device
5, 33, 43, 143, 320...controller
15 6...public line
10, 110...independent power supply system
21...solar power panels
22, 32A, 32B, 122... power converter for gridconnection
20 25, 35, 45... power receiving device for gridconnection
31A, 31B...storage battery
34...auxiliary
41...adjustment load
25 42...load
64
44...system unit for grid-connection
51...control calculation unit
52...weather data storage unit
53...measurement data storage unit
54...signal 5 nal input/output interface unit
55...input unit
56...display unit
321...output reduction amount calculation function
322...power control function
10 431, 3211...own terminal voltage determination part
432...load limit control calculation part
433, 3215...delay timer
511...prediction calculation function
512...output shift operation pattern generation
15 function
513...output shift operation pattern correction
function
3212...storage battery charge/discharge power
calculation part
20 3213...state-of-charge determination part
3214...solar power output reduction control
calculation part
5111...solar power output prediction calculation part
5112...demand power prediction calculation part
65
5121...storage battery charge/discharge pattern
calculation part
5122...charge/discharge level determination part
5123...solar-power-output-reduction-amount and loadadjustment-
5 amount calculation part
5124...output shift operation pattern generation part
5131...SOC evaluation calculation part
5132...SOC level determination part
5133...solar-power-output-reduction-amount and load10
adjustment-amount correction calculation part
5134...output shift operation pattern correction part
66

WE CLAIM:
1. An independent power supply system comprising:
a natural energy power generation device;
a load device including an adjustment load and
5 operated by power from the natural energy power generation
device; and
a power storage device including a storage battery
connected to the natural energy power generation device and
the load device to perform charging and discharging,
10 wherein the independent power supply system
calculates demand prediction data of the load device and
power output prediction data of the natural energy power
generation device by using weather forecast data,
wherein the independent power supply system reduces
15 power output from the natural energy power generation
device when it is predicted that the storage battery will
be charged to a level above a maximum charge power of the
storage battery based on the demand prediction data and the
power output prediction data, and
20 wherein the independent power supply system reduces
power consumption of the adjustment load when it is
predicted that the storage battery will be discharged to a
level above a maximum discharge power of the storage
battery based on the demand prediction data and the power
25 output data.
67
2. The independent power supply system according to claim 1,
wherein the independent power supply system
predictively calculates a state of charge of the storage
5 battery for a predetermined future period by using the
demand prediction data, the power output prediction data,
and a rated capacity of the storage battery,
wherein the independent power supply system reduces
power output from the natural energy power generation
10 device when it is predicted that the state of charge for
the predetermined future period will exceed the maximum
charge power of the storage battery, and
wherein the independent power supply system reduces
power consumption of the adjustment load when it is
15 predicted that the state of charge for the predetermined
future period will fall below a minimum charge power of the
storage battery.
3. The independent power supply system according to claim 2,
20 further comprising a controller,
wherein the controller calculates the demand
prediction data of the load device and the power output
prediction data of the natural energy power generation
device, and outputs a command to reduce the power output
25 from the natural energy power generation device and a
68
command to reduce the power consumption of the adjustment
load.
4. The independent power supply system according to claim 3,
5 wherein the controller is provided outside the
natural energy power generation device, the load device, or
the power storage device, and outputs control commands to
the natural energy power generation device, the load device,
and the power storage device through a line.
10
5. The independent power supply system according to claim 2,
wherein the controller is provided in the power
storage device,
wherein the independent power supply system further
15 comprises another controller,
wherein the controller calculates the demand
prediction data of the load device and the power output
prediction data of the natural energy power generation
device, and controls a target voltage in the independent
20 power supply system,
wherein the control of the target voltage is
performed by temporarily setting the target voltage to a
value greater than a rated voltage when it is predicted
that the state of charge for the predetermined future
25 period will exceed the maximum charge power of the storage
69
battery, and by temporarily setting the target voltage to a
value smaller than the rated voltage when it is predicted
that the state of charge for the predetermined future
period will fall below the minimum charge power of the
5 storage battery,
wherein the controller reduces the power output from
the natural energy power generation device when the target
voltage exceeds the rated voltage for a predetermined time
in the natural energy power generation device, and
10 wherein the controller reduces the power consumption
of the adjustment load when the target voltage falls below
the rated voltage for a predetermined time in the load
device.
15 6. The independent power supply system according to any one
of claims 2 to 4,
wherein the independent power supply system
determines whether measurement values of a charge/discharge
power of the storage battery or an average value of the
20 measurement values is within a predetermined range, and
wherein if the measurement values or the average
value is out of the predetermined range, the independent
power supply system sets a command value of a power factor
of the natural energy power generation device to a value
70
determined by an impedance of a power system in the
independent power supply system.
7. The independent power supply system according to claim 6,
wherein if the measurement values 5 or the average
value is within the predetermined range, the independent
power supply system sets the command value of the power
factor of the natural energy power generation device to 1.
10 8. The independent power supply system according to claim 5,
wherein the independent power supply system
determines whether the measurement values of a
charge/discharge power of the storage battery or an average
value of the measurement values is within a predetermined
15 range,
wherein if the measurement values or the average
value is within the predetermined range, the independent
power supply system sets a command value of a power factor
of the natural energy power generation device to 1, and
20 wherein if the measurement values or the average
value is out of the predetermined range, the independent
power supply system sets the command value of the power
factor of the natural energy power generation device to a
value determined by an impedance of a power system in the
25 independent power supply system.
71
9. The independent power supply system according to any one
of claims 2 to 4, 6 and 7,
wherein the independent power supply system reduces
an output of the natural 5 energy power generation device
when notice information of stopping start-up is received,
the notice information of stopping start-up indicating that
the load will stop start-up, and
wherein the independent power supply system reduces
10 the power consumption of the adjustment load when notice
information of starting up is received, the notice
information of starting up indicating that the load will
start up.
15 10. The independent power supply system according to any
one of claims 1 to 9,
wherein the natural energy power generation device is
a solar power generation device including solar power
panels.
Dated this 20th 20 day of August 2014