I
!
DESCRIPTION
POWER CONVERSION DEVICE, CONTROL DEVICE FOR POWER CONVERSION
DEVICE, AND CONTROL METHOD FOR POWER CONVERSION DEVICE
TECHNICAL FIELD
[0001]
The present invention relates to power conversion devices or power conditioning
systems, control devices or control equipments for a power conditioning system, and control
5 methods for a power conditioning system.
BACKGROUND ART
[0002]
An electric power system is controlled so that an electric power supplied to this
electric power system balances with a power consumption of a load coupled to this electric
10 power system. However, when a system failure of the electric power system occurs and for
example an isolated power system is generated in the electric power system, the supply and
demand are temporarily unbalanced and thereby the frequency of the electric power system will
deviate from a predetermined frequency.
[0003]
15 Therefore, as described in JP-A-57-211940, a technique has been invented for
adjusting the supply-and-demand unbalance within an isolated power system by shutting off a
power source or a load by online control and thus maintaining the frequency.
CITATION LIST
PATENT LITERATURE
20 [0004]
Patent Literature 1 JP-A-57-211940
SUMMARY OF INVENTION
TECHNICAL PROBLEM
[0005]
25 On the other hand, power sources, such as a photovoltaic generation device and a
wind power generation device, via a power conditioning system are assumed to be introduced in
>
large numbers. The power conditioning system coupled to a photovoltaic generation device or
a wind power generation device is supposed to be shut off in the event of a system failure and
return in a predetermined time, for the purpose of protecting the devices.
[0006]
5 This return timing usually occurs in a fixed time from the occurrence of a system
failure. In the case where the power sources, such as a photovoltaic generation device and a
wind power generation device, via a power conditioning system are introduced in large numbers,
when the power sources are shut off for the purpose of protecting devices and return in a certain
time, the power sources will return intensively at a predetermined timing. Accordingly, an
10 influence on the electric power system related to the return will increase, and therefore a sharp
change might be caused in the frequency of an isolated power system and depart from the
upper/lower limits.
[0007]
The present invention has been made in view of the above circumstances, and
15 provides: a power conditioning system coupled to a photovoltaic generation device, a wind
power generation device, or the like, the power conditioning system being capable of introducing
a photovoltaic generation device, a wind power generation device, or the like so as not to affect a
system fluctuation in the frequency or the like in the event of a system failure; a control
equipment for the power conditioning system; and a control method for the power conditioning
20 system.
SOLUTION TO PROBLEM
[0008]
In order to achieve the above-described purpose, the power conditioning system
according to the present invention includes: an output suppression control section that reduces an
25 output based on fluctuation information of an electric power system; and a return control section
that increases the output in a predetermined return pattern after the output decreases, wherein the
return pattern is formed so as to be variable by external instruction information.
[0009]
Alternatively, the power conditioning system according to the present invention
30 includes: a return pattern generation section that prepares the return pattern information so as to
increase the output of the power conditioning system in a predetermined return pattern after a
decrease in the output of the power conditioning system associated with the fluctuation
information of the electric power system; and a transmitter transmitting the return pattern
information.
ADVANTAGEOUS EFFECTS OF INVENTION
[0010]
According to the present invention, a fluctuation amount due to a supply-and-
5 demand unbalance of an electric power system can be reduced.
The other purposes, features, and advantages of the present invention will become
clear from the description of the following embodiments of the present invention related to the
accompanying drawings.
BRIEF DESCRIPTION OF DRAWINGS
10 [0011]
FIG 1 shows a return pattern command system in a power conditioning system
according to a first embodiment of the present invention, the return pattern command system
receiving return pattern information from a planning server, transmitting an output command
value, and controlling the power conditioning system.
15 FIG 2 is an overall view of the planning server calculating the return pattern
information and an electric power system, according to the first embodiment of the present
invention.
FIG 3 is a flow chart showing a return pattern information generation and
transmission algorithm of the power conditioning system in the first embodiment of the present
20 invention.
FIG 4 is a flow chart showing an algorithm for calculating a return pattern of the
power conditioning system in the first embodiment of the present invention.
FIG 5 A shows an example of a time-series waveform of a frequency deviation
calculated in the first embodiment of the present invention.
25 FIG 5B shows an example of a time-series waveform of the output of the power
conditioning system calculated in the first embodiment of the present invention.
FIG 6 is a flow chart showing an output control processing algorithm of a return
pattern command system in the first embodiment of the present invention.
FIG 7A shows an example of a display screen that is a simple example of an
30 effect of normal input data in the first embodiment of the present invention.
FIG 7B shows an example of a display screen that is a simple example of the
effect of the normal input data in the first embodiment of the present invention.
I
FIG 8 A shows an example of a display screen that is a simple example of an
effect of abnormal input data in the first embodiment of the present invention.
FIG 8B shows an example of a display screen that is a simple example of the
effect of the abnormal input data in the first embodiment of the present invention.
5 FIG 9A shows an example of the display screen that is a screen interface of the
device in the first embodiment of the present invention.
FIG 9B shows an example of the display screen that is a screen interface of the
device in the first embodiment of the present invention.
FIG 9B shows an example of the display screen that is a screen interface of the
10 device in the first embodiment of the present invention.
FIG 9D shows an example of the display screen that is a screen interface of the
device in the first embodiment of the present invention.
FIG 10 shows a return pattern command system in a second embodiment of the
present invention.
15 FIG 11A shows an example of the display screen that is an example of the return
pattern in a third embodiment of the present invention.
FIG 11B shows an example of the display screen that is an example of the return
pattern in the third embodiment of the present invention.
DESCRIPTION OF EMBODIMENTS
20 [0012]
Hereinafter, the embodiments of the present invention will be described.
[0013]
FIG 1 is a view showing a first embodiment of the present invention. A return
pattern command system 200 is described using FIG 1. FIG 1 is a view showing a
25 configuration of a planning server 10, a communication network 300, the return pattern
command system 200, a node 150, and a distributed power source 210. The distributed power
source 210 is a power generation device utilizing natural energy of a photovoltaic generation
device, a wind power generation device, or the like, and such energy is hereinafter referred to as
renewable energy. The return pattern command system 200 includes a power conditioning
30 system output control section 34 and a power conditioning system 50 coupled to a
communication section 30 via a communication network 300. The power conditioning system
50 is coupled to the distributed power source (generator) 210 via a node (bus) 150 and a line
coupling these, and to the communication section 30 of the power conditioning system output
control section 34 via the communication network. In the return pattern command system 200,
there is a sensor 190 in the vicinity of the node 150, and the sensor 190 is coupled to the
communication section 29 of the power conditioning system output control section 34 via the
communication network 300. Return pattern information 340 prepared by the planning server
5 10 is sent to the return pattern command system 200 via the communication network 300.
[0014]
Next, the configuration of the power conditioning system output control section
34 is described. An input section 25, such as a keyboard or a mouse, a display device 26, a
computer or computer server (CPU) 27, a memory (RAM) 28, a communication section 29, a
10 communication section 30, and various databases (a normal input database 31, an emergency
input database 32, a program database 33, and a log database 35) are coupled to a bus 40. The
computer or computer server (CPU) 27 carries out an indication of image data to be displayed, a
search of data within the various databases, and the like by executing a calculation program read
from the program database 33 to the RAM 28. The RAM 28 is a memory for temporarily
15 storing: input/output data, such as image data for display, return pattern information, emergency
return pattern information, and return pattern information log data; and record data. Here,
necessary image data is generated by CPU 27 and is displayed on the display device 26 (e.g., on
a display screen).
[0015]
20 Into the memory in the power conditioning system output control section 34, five
main databases are stored. Input data, such as time series data of a gate block time, a gate
deblock time, and an output limiter command value of the power conditioning system 50, is
stored into the normal input database 31. The input data is transmitted via the communication
network 300, a communication section 13 (illustrates in FIG 2) of the planning server 10, and
25 the communication section 29 of the power conditioning system output control section 34. Into
the emergency input database 32, input data, such as time series data of a gate block time, a gate
deblock time, and an output limiter command value of the power conditioning system, as default
return pattern information of the power conditioning system 50, is stored when the return pattern
information from the planning server 10 cannot be obtained due to a communication failure or an
30 unexpected failure. Into the program database 33, a power conditioning system output control
program and a log data recording program that are analysis programs are stored. These
programs are read to CPU 27 as required and are executed for analysis or calculation. Into the
log database 35, information (node voltage V) and return pattern information from the sensor
190 are stored when the log data recording program is executed.
[0016]
Next, FIG 2 is a view showing the configuration of the communication network
300 that links an electric power system 100 comprising a bulk power system 110 and an isolated
power system 120, the planning server 10, a breaker 180, and the return pattern command system
5 200. The electric power system 100 comprises a power generator 130, the node (bus) 150. a
line 170 coupling these, the distributed power source 210 coupled to the node 150 via the return
pattern command system 200, a load 160, and the breaker 180 coupled between the lines
between the nodes 150 of the bulk power system 110 and the nodes 150 of the isolated power
system 120. The breaker 180 sends opening/closing information 320 to the planning server 10
10 via the communication network 300. The return pattern command system 200 has the sensor
190 at its own node 150, and receives the return pattern information 340 from the planning
server 10 via the communication network 300. The sensor 190 measures a node voltage V310.
and sends this information to the return pattern command system 200 via the communication
network.
15 [0017]
Next, the configuration of the planning server 10 is described. The display
device 11, the input sections 12, such as a keyboard or a mouse, the communication section 13.
the computer or computer server (CPU) 14, the memory (RAM) 15, and various databases (a
system database 21, a calculated-result database 22, and the power conditioning system return
20 pattern database 23, a program database 24, and a measurement database 36) are coupled to the
bus 41. The computer or computer server (CPU) 14 executes the analysis programs (a transient
stability analysis program and a power conditioning system return pattern calculation program)
read from the program database 24 to the RAM 15, and carries out an indication of image data to
be displayed, a search of data within various databases, and the like. The RAM 15 is a memory
25 for temporarily storing calculated temporary data and calculation result data, such as image data
for display, a transient stability analysis result, and the return pattern information of the power
conditioning system. Here, necessary image data is generated by CPU 14 and is displayed on
the display device 11 (e.g., on a display screen).
[0018]
30 Into the planning server 10, five main databases are stored. In the system
database 21, there are stored information, such as a node voltage V, a current I of a line, an active
power P, a reactive power Q for each planned time cross section of the electric power system
100, an active power P and reactive power Q of a load or a power generation device, a line
constant Z(=R+jX) indicative of an impedance of the line 170, a load/amount of electrical
generation, system configuration data representing the connection status of lines and/or nodes of
the system, a power generator model/constants, a control system model/constants, and an
assumed fault condition. The opening/closing information 320 detected by the breaker 180 is
stored into the measurement database 36. The opening/closing information 320 is transmitted
5 to the communication section 13 of the planning server 10 via the communication network 300.
In the calculated-result database 22, there are stored a node voltage V, the current I, active power
P, and reactive power Q of a line, the active power P and reactive power Q of a load, line
constants, which are the results of power flow analysis and transient stability analysis; and
calculation results, such as an internal phase angle 5, angular velocity deviation ACQ, active power
10 P, reactive power Q of a power generator; a frequency f of a node, time series data of the output
P of the power conditioning system. The calculation results of return pattern information (a
gate block time, a gate deblock time, and the output time-series waveform data of the power
conditioning system) of the power conditioning system are stored into the power conditioning
system return pattern database 23. Into the program database 24, a power flow analysis
15 programs, a state estimation analysis program, a transient stability analysis program, and a power
conditioning system return pattern analysis program that are analysis program are stored.
These programs are read to CPU 14 as required and are executed for analysis or calculation.
[0019]
Next, the contents of a calculation process of the planning server 10 are described.
20 FIG 3 is a flow chart showing a return pattern information generation and transmission
algorithm of the power conditioning system. Here, a processing flow is described, including:
with the use of system data and planning data, a step of calculating an power flow; a step of
estimating a state; with regard to an assumed failure case set in the database, a step of calculating
transient stability and a step of calculating a return pattern of the power conditioning system; a
25 step of storing calculation results; and assuming a case where an isolated power system failure
occurred at a certain time, a step of transmitting return pattern information.
[0020]
First in Step S2, system conditions are set. Here, a line impedance Z(=R+jX)
and the initial values of a planned load/amount of electrical generation P, Q required for the
30 power flow analysis and the generator model/constants and control-system model/constants
required for the transient stability analysis are read from system data 21 or from a user input of
the input section 12 to the RAM 15. In Step S3, power flow analysis is performed using the
data set in Step S2, the voltage and line flow (active/reactive power flow, a line current, etc.) of
each node are calculated, and the calculation results are stored into the RAM 15. In Step S4,
the data for each time cross section stored in the system data 21 is read to the RAM 15, and state
estimation analysis is performed using the results of the power flow analysis calculated in Step
S3. This state estimation analysis is performed assuming that associated with the occurrence of
a failure at a time instance to as shown in a dotted line of FIG 5B, the output [p.u] of each
5 power conditioning system generally controlled by the system becomes 0.00. and returns like a
point C at a time instance tA, and then at a time instance tB the output [p.u] becomes 0.10 like a
point D.
[0021]
Note that, for the data serving as the base of the state estimation analysis, each
10 sensor output value when the occurrence of a failure is detected (at tc of FIG 5 A) is used.
[0022]
The state estimation analysis refers to a calculation function to, based on the
observational data of power transmission/distribution devices, including a substation, a power
station, and a power transmission line, and on the connection data, determine whether or not
15 there is abnormal data in the observation data, remove the abnormal data if there is any, and
estimate a plausible system state in a specific time cross section.
[0023]
Here, the state estimation analysis and the power flow analysis differs as follows.
In the power flow analysis, assuming there is no error in input data, the redundancy is 1.0,
20 abnormal data is not removed, input data includes facility constants (r, x, y/2, tap ratio), power
generator P, V, and load P, Q, and the Newton-Raphson method is used as the calculation
algorithm, while in the state estimation, for the error in input data, assuming there is an error (an
error of a measuring instrument, an error due to a communication delay) in observation data (PQ:
equal to or less than ±3%, V: equal to or less than ±1%), the redundancy is desirably equal to or
25 greater than 1.2, abnormal data is removed, input data includes facility constants (r, x, y/2, tap
ratio), power generator P, V, load P, Q, and a weighting factor of an observed value, and the least
square method is used as the calculation algorithm.
[0024]
With regard to an error in input data, the followings are assumed, for example.
30 In a model system, for a variable to be calculated, in the power flow analysis, there is no "error"
in data, while in the state estimation, because data is a "measured value", the measured value
includes a "measurement error" (hereinafter, a measured value is referred to as a "observed
value").
[0025]
The state estimation analysis is performed in accordance with the various
methods, e.g., Lars Holten, Anders Gjelsvlk, Sverre Adam, F. F. Wu, and Wen-Hs lung E. Liu,
and Comparison of Different Methods for State Estimation. IEEE Trans. Power Syst., 3(1988),
1798-1806, and the like. Here, a result of the state estimation analysis is obtained, for example.
5 by calculating each time cross section for each 100 msec from a time instance 0.0 sec to a time
instance 10.0 sec, as a frequency deviation [Hz], as shown by a dotted line of FIG 5A, In Step
S5, the state estimation result calculated in Step S4, the power generator model/constants, and
the control-system model/constants are read to the RAM 15, and transient stability analysis is
performed. In Step S6, the transient stability analysis result calculated in Step S5 is read to the
10 RAM 15, and power conditioning system return pattern calculation is performed. The detail of
the calculation method is described later. In Step S7, the transient stability analysis result
calculated in Step S5 and Step S6 are stored into the calculation result database 22, and the return
pattern calculation result of the power conditioning system is stored into the power conditioning
system return pattern database 23. In Step S8, it is determined using break information of the
15 breaker 180 whether an isolated power system failure has occurred, and if the isolated power
system failure has not occurred, the flow returns to Step 1, while if the isolated power system
failure has occurred, the flow proceeds to Step S9. In Step S9, the time series data of the gate
block time and gate deblock time and an output limiter command value stored in the power
conditioning system return pattern database 23 are transmitted to the communication section 29
20 via the communication section 13 and the communication network 300, and the flow is
complete.
[0026]
Next, Step S6 is described using FIG 4 and FIGS. 5A, 5B. FIG 4 is a flow chart
showing an algorithm for calculating the return pattern of the power conditioning system.
25 [0027]
First, in Step S10, a time-series waveform of the frequency f among the transient
stability analysis results calculated in Step S5 is caused to pass through a low pass filter to
remove a short-period oscillating noise, and a resulting frequency time-series waveform is read
to the RAM 15. In Step Sll, a frequency change rate is calculated from the frequency time-
30 series waveform calculated in Step S10. In Step S12, a point where the frequency change rate
becomes zero is searched, and its time instance is stored. For example, the time instance tA of a
point A and the time instance tB of a point B of FIG 5 A are stored. In Step S13, return pattern
information is prepared for causing the output of the power conditioning system to increase in a
primary straight line from a return start time to a return end time. For example, the return
^ pattern information is prepared for causing the output of the power conditioning system from the
time instance tA of the point A and the time instance tn of the point B of FIG 5B to increase in a
primary straight line from a point C to a point D (a solid line of FIG. 5B).
[0028]
5 Next, the contents of the calculation process of the power conditioning system
output control section 34 are described. FIG 6 is a flow chart showing an output control
processing algorithm of the return pattern command system. Here, a processing flow is
described, including: a step of receiving the voltage V310 of the (its own) node 150 of the power
conditioning system 50 and the return pattern information 340 transmitted via the
10 communication network 300 from the planning server; a step of determining whether or not the
power conditioning system has been shut off; a step of determining whether or not there is
abnormality in receipt information; and a step of changing the return pattern depending on the
presence or absence of abnormality in the receipt information.
[0029]
15 First, in Step S50, the information on the node 150 of the power conditioning
system is collected. Here, the voltage V310 of the node 150 required to determine that a
voltage drop has occurred at the node 150 of the power conditioning system as a result of the
occurrence of a failure is measured using the sensor 190, and is collected by the communication
section 29 via the communication network and stored into the RAM 28. In Step S51, it is
20 determined whether or not the power conditioning system 50 has been shut off due to a failure.
Here, it is determined, by the voltage V310 of the node 150 held in the RAM 28 in Step S50,
whether or not the power conditioning system has been shut off for the purpose of protecting
various devices. Here, the power conditioning system output control section 34, upon detection
a decrease of the voltage V310 of the node 150 down to less than 30 V (60 V) that is 30% of a
25 normal voltage 100 V (or 200 V), outputs to the power conditioning system 50 a command for
stopping the operation (setting the power conditioning system output [p.u.] to 0.00).
[0030]
That is, when a terminal voltage [%] shown in FIG. 9D decrease due to the
occurrence of a failure, then as shown at points E and F at the time instance tc of FIGS. 5 A, 5B,
30 the power conditioning system 50 stops to operate (the power conditioning system output
[p.u,]=0.00) and will maintain this stop state until a command to return is given. If the power
conditioning system 50 has been shut off, the flow proceeds to Step S52, while if not, the flow
returns to Step S50. In Step S52, the return pattern information 340 transmitted by the
communication section 29 via the communication network 300 from the planning server 10 is
12
^ received, and stored into the normal input database 31. In Step S53, it is determined whether or
not there is no abnormality in the received information received in Step S52. Here, the
abnormality in the receipt information refers to a case where the return pattern information
cannot be received due to a transmission delay or the like although it is determined in Step S51
5 that the power conditioning system has been shut off, or a case where the gate block time of the
return pattern information does not match the shut-off time of the power conditioning system.
If there is no abnormality, the flow proceeds to Step S54, a gate block limiter command value of
the power conditioning system is prepared from the return pattern information 340 received in
Step S52, and is held in the RAM 28. In Step S55, the gate block limiter command value of the
10 power conditioning system held in the RAM 28 is transmitted to the power conditioning system
50 by the communication section 30 by using the power conditioning system output control
program. Moreover, if there is any abnormality, the flow proceeds to Step S56, the gate block
limiter command value of the power conditioning system is prepared from the emergency return
pattern information, which is stored in advance into the emergency input database 32 by a user
15 using the input section 25, and is held in the RAM 28. In Step S57, the gate block limiter
command value of the power conditioning system held in the RAM 28 is transmitted to the
power conditioning system 50 by the communication section 30 by using the power conditioning
system output control program. In Step S58, the return pattern information log data held in the
RAM 28 and transmitted to the power conditioning system 50 is stored into the log database 35,
20 and then the flow is complete.
[0031]
Next, an example of the return pattern display of the power conditioning system is
described using FIGS. 7A, 7B, FIGS. 8A, 8B, and FIGS. 9A-9D. FIGS. 9A-9D are explanatoryviews
showing a display example onto the display device 11 of the return pattern calculation
25 result of the power conditioning system. Here, the display onto a display screen is considered.
A frequency deviation in the isolated power system and a time-series waveform of the power
conditioning system output before and after the return pattern calculation of the power
conditioning system are displayed in contrast on the screen. Moreover, a time-series waveform
of the node voltage V is also displayed, and the return operation status of the power conditioning
30 system is displayed together with each time instance. By displaying in this manner, "when has
a failure occurred?" and/or the return pattern calculation result of the power conditioning system
can be clearly transmitted to a user.
Here, an example of outputting to the screen is shown, but the above-described
information may be provided to a user as the data in a format printable onto a document or the
13
^ like. Moreover, FIGS. 7 A, 7B show an example (the frequency deviation and the output of the
power conditioning system) of the display screen of normal return pattern information, while
FIGS. 8A, 8B show an example (the frequency deviation and the output of the power
conditioning system) of the display screen of abnormal return pattern information.
5 [0032]
Next, FIG 10 is a view showing a second embodiment of the present invention.
The second embodiment differs from the first embodiment in that the return pattern command
system and the power conditioning system are separated. That is, in FIG 1, the power
conditioning system output control section 34 and the power conditioning system 50 are included
10 in the return pattern command system 200, while in FIG 10, only the power conditioning system
output control section 34 is included in the return pattern command system 200. This has an
advantage in that if a power conditioning system output command value 350 is transmitted to the
power conditioning system 50 by the communication section 30 of the power conditioning
system output control section 34, then the effect of the present invention can be exhibited and the
15 return pattern command system 200 can be installed at any place.
[0033]
Next, a third embodiment is described. The third embodiment is characterized
in that the calculation of the return pattern. Because other configurations and the steps of
calculation are the same, the description thereof is omitted.
20 [0034]
Because the voltage is oscillating after removing an accident, the following
determination and calculation are performed by using a voltage, which is obtained by removing
the oscillation component through a filter.
[0035]
25 That is, the return pattern is prepared from a variation AV of the voltage V and a
time instance t. FIGS. 11 A, 11B show an example of the display screen of an example of the
calculation (the frequency deviation and the output of the power conditioning system) of the
return pattern of the power conditioning system in the embodiment. As shown in FIGS. 11 A.
11B, in order for the voltage to return, the accident needs to be removed. Then, the return
30 pattern is formed so that the voltage recovers to a threshold value VC (e.g., 70%) after removing
this accident, and after a lapse of tA (e.g., 2.1) seconds, the outputting of the power conditioning
system starts, and then prior to a lapse of ts (e.g., 4.1) seconds the output of the power
conditioning system recovers to 100% (0.1 p.u. in the view).
The above description has been made with regard to the embodiments, but the
^ ^ present invention is not limited thereto, and it is clear to those skilled in the art that various kinds
of changes and modifications can be made within the spirit of the present invention and the
scope of the attached claims.
INDUSTRIAL APPLICABILITY
5 [0036]
The present invention is useful in a power conditioning system coupled to a
photovoltaic generation device, a wind power generation device, or the like, the power
conditioning system being capable of introducing a photovoltaic generation device, a wind
power generation device, or the like so as not to affect a system fluctuation in the frequency or
10 the like in the event of a system failure, and is also useful in a control equipment for the power
conditioning system and a control method for the power conditioning system.

w CLAIMS
[Claim 1]
A power conditioning system that converts a generated power based on renewable
energy and supplies the resulting electric power to an electric power system, the power
conditioning system comprising:
an output suppression control section that reduces an output based on fluctuation
information of the electric power system; and
a return control section that increases the output in a predetermined return pattern
after the output decreases, wherein
the return pattern is formed so as to be variable by external instruction
information.
[Claim 2]
The power conditioning system according to claim 1, further comprising a
receiver that receives the return pattern as the instruction information, and wherein the return
control section increases the output according to the received return pattern.
[Claim 3]
The power conditioning system according to claim 2, wherein the return pattern is
calculated based on an estimation of a frequency time-series waveform made by a frequencyfluctuation
simulation.
[Claim 4]
The power conditioning system according to claim 2, wherein when the
instruction information cannot be obtained, the return control section increases the output in a
predetermined return pattern.
[Claim 5]
The power conditioning system according to claim 3, wherein when the
instruction information cannot be obtained, the return control section increases the output in a
predetermined return pattern.
[Claim 6]
The power conditioning system according to claim 5, further comprising a
database for storing return pattern information, wherein the predetermined return pattern is
formed based on information of the database.
[Claim 7]
A control equipment of a power conditioning system, the control equipment
controlling the power conditioning system that converts a generated power based on renewable
energy and supplies the resulting electric power to an electric power system, the control
equipment comprising:
a return pattern generation section that prepares the return pattern information so
as to increase the output of the power conditioning system in a predetermined return pattern after
a decrease in the output of the power conditioning system associated with the fluctuation
information of the electric power system; and
a transmitter transmitting the return pattern information. I
[Claim 8]
The control equipment of a power conditioning system according to claim 7. the
control equipment: estimating a frequency time-series waveform by a frequency fluctuation
simulation in an isolated power system when the isolated power system is generated due to a
system failure; and transmitting the return pattern information based on the estimation.
[Claim 9]
The control equipment of a power conversion equipment according to claim 8. the
control equipment:
calculating a plurality of inflection points of the frequency time-series waveform
in calculating the return pattern information; and
calculating the first two points among the inflection points; and calculating return
pattern information for causing an output between a time instance of the first inflection point and
a time instance of the second inflection point to monotonically increase so as to set an output
condition of the power conditioning system at the time instance of the first inflection point to
zero and set the output condition of the power conditioning system at the time instance of the
second inflection point to a maximum output.
[Claim 10]
A control method for a power conditioning system, comprising the steps of:
based on fluctuation information of an electric power system, reducing an output
that is obtained by converting a generated power based on renewable energy by a power
conditioning system; and
upon receipt of external instruction information, after the output decreases,
increasing an output of the power conditioning system in a return pattern that is variable based
on the instruction information; and
supplying an electric power converted by the power conditioning system to an
electric power system.
[Claim 11]
J
|
i
^ ^ A control method for a control equipment of a power conditioning system, the
control equipment controlling the power conditioning system that converts a generated power
based on renewable energy and supplies the resulting electric power to an electric power system,
the method comprising the steps of:
after a decrease in an output of the power conditioning system in associated with
fluctuation information of the electric power system, preparing return pattern information so as
to increase the output of the power conditioning system in a predetermined return pattern: and
transmitting the return pattern to the power conditioning system.