Claims:CLAIMS
We claim:

1. A control system (10) for controlling a hybrid power plant (1; 1’) comprising at least two of a wind power plant (11), a solar power plant (12) and a power storage plant (13), characterized in that the control system (10), which is adapted to determine an active power output (P(t)) to be delivered from the hybrid power plant (1; 1’) to a grid (2) on the basis of a predefined power profile (PProfile(t)).

2. The control system (10) according claim 1, wherein the control system (10) is further adapted to monitor and / or control one or more of the power production (Pwind) of the wind power plant (11), of the power production (Psolar) of the solar power plant (12) and the state of charge (SOC) of the power storage plant (13).

3. The control system (10) according to claim 1 or 2, wherein the predefined power output (PProfile(t)) is a functional relationship defined through a functional expression, a curve, data points and / or a lookup-table.

4. The control system (10) according to at least one of the preceding claims, wherein a difference between the active power output (P(t)) and the predefined power output (PProfile(t)) is monitored and the difference is used in the control of the active power output (P(t)), in particular an optimal control of the active power output (P(t)).

5. The control system (10) according to claim 5, wherein difference between the active power output (P(t)) and the predefined power output (PProfile(t)) is measured as an integral measure, in particular an integral squared error or an integral time weighted absolute error.

6. The control system (10) according to at least one of the preceding claims, wherein the monitoring of one or more of the power production (?Pwind) of the wind power plant (11), of the power production (?Psolar) of the solar power plant (12) and the state of charge (SOC) of the power storage plant (13) is performed at a Medium Voltage (MV) level.

7. The control system (10) according to any of the preceding claims, wherein the control system (10) is adapted to determine the active power output (P(t)) of at least one of the wind power plant (11), the solar power plant (12) and / or the power storage plant (13) to perform a power forecast (?Pforecast) and to use that in controlling the active power output (P) to the grid (2).

8. The control system (10) according to any of the preceding claims, wherein the control system (10) is further adapted to perform a smoothing of the active power output (P(t)) of at least one of the wind power plant (11), the solar power plant (12) and the power storage plant (13).

9. The control system (10) according to claim 8, wherein the smoothing of the active power (P(t)) of at least one of the wind power plant (11), the solar power plant (12) and the power storage plant (13)is performed on the basis of a short term forecast.

10. The control system (10) according to claim 9, wherein the control system (10) is adapted to control the active power (?PVL, add) of the power storage plant (13) in order to improve the short term forecast (?Pforecast, short_term).

11. A hybrid power plant (1; 1’) with a control system (10) according to at least one of the claims 1 to 10.

12. A method for controlling a hybrid power plant (1; 1’) comprising at least two of a wind power plant (11), a solar power plant (12) and a power storage plant (13), the method comprising the following steps:

a) storing a predefined power profile (PProfile(t)),

b) determining an active power output (P(t)) to be delivered from the hybrid power plant (1; 1’) to a grid (2) on the basis of the predefined power profile (PProfile(t)).

13. A computer program product (102) comprising instructions which, when executed by one or more computers, cause the one or more computers to carry out the steps of the method of claim12.

Dated this 25th day of February, 2019

For Suzlon Energy Limited

To Nandan Pendsey
The Controller of Patents, (IN/PA/726)
The Patent Office, Mumbai AZB & Partners
, Description:3. PREAMBLE TO THE DESCRIPTION

The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION

The invention relates to a control system for controlling a hybrid power plant according to claim 1, to a hybrid power plant according to claim 11, a method for controlling a hybrid power plant according to claim 12 and to a computer program product according to claim 13.

BACKGROUND

A mix of power generation between solar and wind power plants becomes more and more present in the modern power systems. Each year Transmission System Operators (TSOs) observe increased amounts of renewable energy produced by wind turbines and photovoltaic systems to be connected to their grid. Consequently, the stability of the grid is being challenged and for this purpose grid codes (GCs) are constantly adapting to more stringent requirements.

The nature of wind power and solar power has an intermittent character. The variability of the active power production from both wind and solar is a result of the changing nature mainly of wind speed, wind direction and solar irradiation.

The present invention discloses a control system of a hybrid power plant, a method for controlling a hybrid power plant and a computer program product to achieve the same.

OBJECT OF THE INVENTION

It is an object to provide a solution for further improving the quality of the power output of a hybrid power plant.

SUMMARY OF THE INVENTION

The hybrid power plant comprises at least two of a wind power plant, a solar power plant and a power storage plant, i.e. all plants can generate active power, the power storage plant can also store electrical energy e.g. in batteries. The actual power output is one controlled variable. The control system is adapted to determine the active power output P(t) to be delivered from the hybrid power plant to a grid on the basis of a predefined power profile PProfile (t). This means that the time-dependent active power output depends e.g. on an also time-dependent, predetermined power profile required e.g. by a TSO.

In one embodiment, the control system is adapted for monitoring and / or controlling the hybrid power plant by individually controlling the wind power plant, the solar power plant and / or the power storage plant. All of the plants within the hybrid power plant contribute to the total power output. The control system can adjust the mix of the power output and in the case of the power storage plant also the intake of power to achieve the control objective. Therefore, the monitoring and / or control of one or more of the power production of the wind power plant, of the power production of the solar power plant and the state of charge (SOC) of the power storage plant takes place.

In another embodiment, the control system uses a predefined power output PProfile(t) in the form of a functional relationship defined through a functional expression, a curve, data points and / or a lookup-table. With this representation, a control error can be determined which is then used in the generation of the control signals.

The control error in one embodiment is based on a difference between the active power output P(t) and the predefined power output PProfile(t) which is monitored and the difference is used in the control of the active power output P(t), in particular an optimal control of the active power output P(t).In an optimal control context, the actual power output P(t) is controlled to follow the predefined profile PProfile(t), i.e. a time dependent path, as close as possible. The difference between the active power output P(t) and the predefined power output PProfile(t) can e.g. be measured as an integral measure, in particular an integral squared error or an integral time weighted absolute error.
In one embodiment, the monitoring of one or more of the power production (?Pwind) of the wind power plant, of the power production (?Psolar) of the solar power plant and the state of charge of the power storage plant is performed at a Medium Voltage (MV) level.

It is also possible, to improve the control result if the control system is adapted to determine the active power output P(t) of at least one of the wind power plant, the solar power plant and / or the power storage plant by performing a power forecast (?Pforecast) and to use that in controlling the active power output P(t) to the grid.

It is also possible, that the control system is further adapted to perform a smoothing of the active power output P(t) of at least one of the wind power plant, the solar power plant and the power storage plant. In particular, the smoothing of the active power P(t)of at least one of the wind power plant, the solar power plant and the power storage plant is performed on the basis of a short term forecast (e.g. covering wind gusts for wind power plants, cloud cover for solar power plants). And it is also possible that the control system is adapted to control the active power (?PVL, add) of the power storage plant (13) in order to improve the short term forecast (?Pforecast, short_term).

The issue is also addressed by a hybrid power plant with a control system according to at least one of the claims 1 to 11 and by a method for controlling a hybrid power plant comprising at least two of a wind power plant, a solar power plant and a power storage plant, the method comprising the following steps:

a) storing a predefined power profile PProfile(t),

b) determining an active power output P(t) to be delivered from the hybrid power plant (1; 1’) to a grid (2) on the basis of the predefined power profile PProfile(t).

According to an aspect, a computer program product is provided. The computer program product comprises instructions which, when executed by one or more computers, cause the one or more computers to carry out the steps of the aforementioned method.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are shown in the figures, where

Fig. 1 shows a schematic diagram of power production profiles of wind and solar systems;

Fig. 2 shows a profile of an actual power output of an embodiment of a hybrid power plant compared to a ramp-rate power requirement;

Fig. 3 shows a further profile of an actual power output of an embodiment of a hybrid power plant compared to a different ramp-rate power requirement and deployments of power reserves;

Fig. 4 shows an example of a pre-defined power profile over 24h;

Fig. 5 shows a hybrid power plant having an embodiment of hybrid plant control system, a wind power plant, a solar power plant, and a power storage plant;

Fig. 6 shows an embodiment of a control system used in connection with a hybrid power plant;

Fig. 7 shows a different embodiment of hybrid power plant with a plant control system, wind power plants, solar power plants, and power storage plants.

The foregoing and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing figures.

DETAILED DESCRIPTION OF THE INVENTION

In the following, embodiments for control systems 10 for hybrid power plants 1, 1’ are described in the context of the dynamic behavior under dynamic set-point changes and set-point paths for the power output.

Fig. 1 shows exemplary power production profiles of wind and solar power systems. The horizontal axis shows the time over an exemplary duration of three days. The vertical axis shows the active power in an arbitrary scale. Therein, the solid line indicates the active power provided by an exemplary wind power plant comprising one or more wind turbines. As the wind changes, there can be seen strong variations in the produced power. The dashed line, on the other hand, indicates the active power of an exemplary solar, e.g. photovoltaic, power plant. During the night, no power is produced and during daytime, power is produced depending on the position of the sun relative to the solar power plant and on the presence of clouds and the like (note the kink in the curve at the time around 38:00). The dotted line shows the sum of active power produced by the wind power plant and by the solar power plant. As can be seen in Fig. 1, the sum of wind and solar power may balance fluctuations in both of the individual sources in certain circumstances. However, there are situations in which there is no or only little sunlight, and no or only little wind.

It is a very well-known response from TSOs to start involving renewable energy into their security schemes and to force large plants to adopt some smoothing characteristics. Once these smoothing characteristics are imposed, this means that plant owners have to comply immediately with the requirements and present solution with smoothing effect.

In the mix of renewable energy coming especially from wind and solar, battery-based storage solutions provide a technically viable solution to the fulfillment of such stringent requirements. Based on the sizing of the entire battery plant and consequently on the costs directly related to the size, plant owners have the possibility to choose how they can manage the output power of their renewable plants.

An even greater challenge of smoothing out power fluctuations from already installed wind and solar plants is to have hybrid generation with smoothing characteristics. This means that a hybrid power plant having MW range installed capacity of wind, solar and storage has to perform smoothing control algorithms in order to integrate the power from two sources with the sinking/sourcing characteristics of storage.

Another aspect of proving smooth power output is that recently system operators start to demand a certain time-dependent power output. In case this is not met the plant producer suffers from high penalties and in the lowering the profit or even running on a loss.

In Fig. 2 a time-dependent predefined power production profile P¬Profile(t) is shown in form of a ramp.

The required power output is shown as PProfile (t), i.e. the power output is a function of time, not just one fixed value. This means that the path of the change is a requirement by Transmission System Operator.

In the example shown, the power level is held constant at P1until t1. Subsequently, the required power output is ramped up at a constant rate to the power level P2. The power level is required to be reached in the time period t2 – t1. The slope a of the ramp is given by

After t2 the predefined power output P2 remains constant at this level.
Therefore, a hybrid power plant 1, 1’ (see below in the context of Fig. 5, 6, 7) is expected to follow this predefined time-dependent profile PProfile(t).

Due to various reasons, some of them mentioned above, the actual power output P(t) deviates under dynamic operating conditions and fluctuations from the predefined power output PProfile(t) as shown by the dashed line in Fig. 2.

The actual power output P(t) starts to increase after t1 and is kept with an increasing slope higher than the predefined slope a of the predefined power output PProfile(t). It overshoots the ramp of the predefined power profile PProfile(t).The increasing rate slows subsequently, only to increase again around t2. Due to fluctuations at t > t2, the actual power output P(t)does not follow the new constant set power output P2 all the time. To address this issue a control system 10 (see e.g. Fig. 6) is used.

In a further example shown in Fig. 3, the predefined power output PProfile(t)(i.e. a predefined power profile) comprises two ramps, one up-ramp with a positive slope between t1 and t2, one with down-ramp a negative slope between t3 and t4.

In the up-ramp part the actual power output P(t) exceeds the predefined power output PProfile(t)as indicated by the shaded area. The excess power can be stored in a power storage system 13 (see Fig. 5, 7) as indicated by the lower coordinate system in Fig. 3.

In the down-ramp part the actual power output P(t) is less than the predefined power output PProfile(t) as indicated by the shaded area. The deficient power is deployed from a power storage system 13 and / or wind and solar power systems 11, 12 (see Fig. 5, 7).

In the following, it will be shown how a predefined power output PProfile(t)is used by an embodiment of a control system 10 for the hybrid power plant 1.

It should be noted that the predefined power outputs PProfile(t) described in the context of Fig. 2 and 3 are just examples to demonstrate the concept. Other, more complex predefined power outputs PProfile(t) are possible.

One example is given in Fig. 4. Here, the predefined power output PProfile(t) is a time-dependent function for a typical power demand in a grid system over 24 hours. Typically, this function is repeated every 24 hours, as the two peaks around 7 am and 6 pm (the maximum peak) are characteristic for the power requirements in a city. This predefined power output PProfile(t)is a more complex example than the ramps in Fig. 2 and 3.

The time dependency could also take into account seasonal effects. Even if the bimodal structure of the demand in Fig. 4 will be repeatedly present throughout the year, there will be seasonal effects. The concept or a time-dependent predefined power output PProfile(t) extends to all kinds of power use patterns (i.e. the power requirements) which are supposed to be matched by the power output of the hybrid power plant 1.

The predefined power output PProfile(t) can be defined as a curve, a histogram, a look-up table or other means for describing a continuous or discrete functional relationship.

Before going into the details of the control system 10, a hybrid power system 1 is described in the context of Fig. 5.

Fig. 5 shows a hybrid power plant 1 implementing active power reserves and reactive power reserves. The hybrid power plant 1 comprises a control system 10 (with a computer storage 101 and a computer program product 102), a wind power plant 11, a solar power plant 12 and a power storage plant 13.

The wind power plant 11 generally comprises at least one wind turbine generator system, in the following referred to as WTG system 111 and in the example according to Fig. 5 the wind power plant 11 comprises exactly one WTG system 111. The WTG system 111 may be a horizontal-axis wind turbine comprising a nacelle rotatably mounted on a tower. The WTG system 111 comprises a turbine 112 (rotatably mounted on the nacelle) and a generator 113 driven by the turbine 112. The turbine 112 is rotated by the wind so as to produce electrical power by means of the generator 113. The generator 113 is electrically coupled to an optional transformer 15. Further, the wind power plant 11 comprises a wind power plant controller, in the following referred to as WPP controller 110. The WPP controller 110 is adapted to control the turbine 112 (e.g., a pitch angle of one or more turbine blades) and/or the generator 113 (e.g., a set point, e.g. of a torque). Optionally, the WPP controller 110 is further adapted to control the output power at the terminal of transformer 15.

The solar power plant 12 generally comprises at least one thermal solar or photovoltaic system, the latter in the following referred to as PV system 121. In the example according to Fig. 5 the wind power plant 11 comprises exactly one PV system 121. The PV system 121 comprises a plurality of PV arrays 122. A set of PV arrays 122 are connected to one another in a series and a plurality of such serial PV arrays 122 are connected to one another in parallel. The plurality of PV arrays 122 is connected to a converter 14, in the example according to Fig. 5, a DC-to-AC converter. The converter 14 is electrically coupled to an optional transformer 15. Further, the solar power plant 12 comprises a photovoltaic-power-plant controller, in the following referred to as PVPP controller 120. The PVPP controller 120 is adapted to control the converter 14 and/or optional switches for coupling or decoupling at least one PV array 122.Optionally, the PVPP controller 120 is further adapted to control the output power at the terminal of transformer 15.

The power storage plant 13 generally comprises at least one power-storage system 131A. In the example according to Fig. 5, the power storage plant 13 comprises exactly one power-storage system 131A. The power-storage system 131 is neither a WTG system nor a solar power system such as a PV system. According to Fig. 5, the power-storage system 131A comprises an electrochemical power storage device, more precisely, a rechargeable battery 132, e.g. a lithium-ion battery. The battery 132 is connected to a converter 14, in the example according to Fig. 5 a DC-to-AC converter. The converter 14 is electrically coupled to an optional transformer 15. Further, the power storage plant 13 comprises a storage-power-plant controller, in the following referred to as SPP controller 130. The SPP controller 130 is adapted to control the converter 14 and/or optional charging and recharging electronics. Optionally, the SPP controller 120 is further adapted to control the output power at the terminal of transformer 15.

Each of the wind power plant 11, solar power plant 12 and power storage plant 13 are electrically coupled to a junction 17 such as to supply their produced power to the junction 17. The junction 17 is adapted to receive the produced power from each of the wind power plant 11, solar power plant 12 and power storage plant 13, and to output a total produced power. For example, the junction 17 is a 33 kV junction box. The junction 17 is connected to an electrical grid 2 by means of a substation 19. The substation 19 in the present example is a MV substation and comprises a transformer 191 to transform the current supplied by the junction 17 to HV, e.g., 220 kV or 380 kV. The substation 19 further comprises a collector 190 which connects the junction 17 to the transformer 190. The substation 19 is electrically coupled to the electrical grid 2. According to an alternative, the junction 17 and the substation 19 may be designed as one device.

As already mentioned, the hybrid power plant 1 comprises a control system 10. The control system 10 may in one embodiment be coupled with the substation 19.

The control system 10 is communicatively coupled to the WPP controller 110, the PVPP controller 120 and the SPP controller 130. The control system 10 is adapted to control each of the WPP controller 110, the PVPP controller 120 and the SPP controller 130. The control system 10 may also be referred to as hybrid plant controller or HyPC. The control system 10 may be implemented in or as a programmable logic controller, PLC.

The control system 10 – among other tasks described below –determines the active power output P(t) to be delivered from the hybrid power plant 1 to the grid 2 on the basis of the predefined power profile PProfile(t). This is shown schematically in Fig. 6.

The active power output P(t) – i.e. the controlled variable in the feedback loop – is the time-dependent power output which should be provided to the grid 2 by the hybrid power plant 1, 1’.

The set point in this case is not a single value. It is a time-dependent function, the predefined power output PProfile(t).

The objective function of the control system 10, e.g. in the sense of an optimal control task, can be the minimization of the absolute difference between l PProfile(t) – P(t) l.
This difference is also time-dependent. The minimization can use the integral of the squared error (ISE) or the time weighted absolute error (ITAE) as criterion.

The control system 10 uses the determined error, i.e. the determined difference, to generate control signals to the controllers 110, 120, 130 of the wind power plant 11, the solar power plant 12 and / or the power storage plant 13. Therefore, the control signals are fed back to the hybrid power plant 1, 1’. The predefined power output PProfile(t) can be considered as a negative virtual load profile.

The control system 10 can adjust the relative loads taken from the wind power plant 11, the solar power plant 12 and/ or the power storage plant 13 to (e.g. optimally) match the predefined power output P¬Profile(t). This might also include the case discussed in connection with Fig. 3, i.e. the intermediate storing of power in the power storage plant 13 in case the other plants 11, 12 generate more power than prescribed by the predefined power output PProfile(t).

The control system 10 is further communicatively coupled to the substation 19 and/or (in the present example to both) an anemometer 100 (or any other environmental variable detector). Thereby, the control system 10 receives at least one grid variable from the substation 19. For example, the at least one grid variable comprises a grid frequency and/or a grid voltage. Alternatively, the control system 10 comprises a measurement device coupled to the electrical grid 2 and adapted for measuring the at least one grid variable. As a further alternative, the control system 10 may receive at least one grid variable value from a TSO, e.g. by means of a corresponding SCADA interface (indicated with the open dashed line in Fig. 3). The anemometer 100 provides measured values of the wind speed to the control system 10. The anemometer 100 may be arranged on or near the WTG system 111, e.g. on the nacelle of the WTG system 111.

A measurement of the environmental variable, in this example the wind speed, may be indicative for the status at the time of the measurement. Alternatively or in addition, the control system 10 may determine an environmental variable by forecasting a value of the environmental variable. For example, a current value of the environmental variable may be forecasted using past measurements. Alternatively, a future value of the environmental variable may be forecasted using past and/or current measurements. For example, the forecast may be based on measurements taken one day ago or one year ago (in particular at the same time of day). Optionally, these measurements are corrected, e.g. for different temperatures. Further optionally, the forecast may include a weather forecast. The forecast may be a short-term forecast for a value of the environmental variable, e.g.15 to 30 minutes after the forecast. Alternatively, the forecast may be a medium-term forecast for a value of the environmental variable, e.g. 2 to 4 hours after the forecast.

Further, the control system 10 is adapted to receive and/or determine at least one operation status of the wind power plant 11, the solar power plant 12and/or the power storage plant 13. The at least one operation status may comprise one or more of a current active power production (of the wind power plant 11, the solar power plant 12and/or the power storage plant 13), an active power production profile (of the wind power plant 11, the solar power plant 12and/or the power storage plant 13), a state of charge (of the power storage plant 13), a state of health (of the power storage plant 13) and a life-cycle cost of energy. The current active power production (profile) may be determined at MV level.

The control system 10 is thus adapted to receive and/or determine, in particular measure, at least one operation status, at least one grid variable of the electrical grid 2 and at least one environmental variable.

The control system 10 may also be adapted to forecast at least one grid variable, and/or at least one operation status, the latter for example based on a forecast of the environmental value.

For responding to possible deviations from the set profile, the hybrid power plant 1 maintains a hybrid power plant active power reserve ?PHP and a hybrid power plant reactive power reserve ?QHP. These are the power reserves that the hybrid power plant 1 is capable to provide at its point of coupling to the electrical grid 2.

As a base value, the hybrid power plant active power reserve ?PHP and the hybrid power plant reactive power reserve ?QHP are each set by the control system 10 to 1% or to at least 1%. As an example, the control system 10 may set the hybrid power plant active power reserve ?PHP to be in the range of 1% to 20%. Alternatively or in addition, the control system 10 may set the hybrid power plant reactive power reserve ?QHP to be in the range of 1% to 50%. These ranges provide good response capabilities while reducing the annual power yield only a little.

Optionally, the control system 10 may be designed such that the provision of power reserves can be switched on (curtailment mode) or off (maximum-power mode). The control system 10 may be adapted to receive a command for selecting the mode.

Optionally, the control system 10 may be adapted to receive from a TSO and/or an external grid control a set point for the hybrid power plant active power reserve ?PHP and/or for the hybrid power plant reactive power reserve ?QHP.

The control system 10 is further adapted to determine an individual active power reserve?Pwind, ?Psolar, ?Padd and an individual reactive power reserve ?Qwind, ?Qsolar, ?Qstofor each of the wind power plant 11, the solar power plant 12 and the power storage plant 13. It will be appreciated that two or more, or even all of the values for the individual active power reserves ?Pwind, ?Psolar, ?Padd and individual reactive power reserves ?Qwind, ?Qsolar, ?Qsto may be different to one another.

Given the hybrid power plant active power reserve ?PHP and/or the hybrid power plant reactive power reserve ?QHP, the individual power reserves may be calculated by the control system 10 as follows (for active and reactive power):

?PHP = ?Pwind + ?Psolar + ?Padd + ?Pcorr_loss + ?Pcorr_forecast,
?QHP = ?Qwind + ?Qsolar + ?Qsto + ?Qcorr_loss + ?Qcorr_forecast.

Therein, ?Pcorr_loss and ?Qcorr_loss are active and reactive power loss correction factors accounting for losses of power in electrical infrastructure, in particular between the wind power plant 11, the solar power plant 12and/or the power storage plant 13, and the electrical grid 2, e.g. at a hybrid park feeder 18 between junction 17 and substation 19. The losses may depend of the mode of operation of the control system 10. Further, ?Pcorr_forecast and ?Qcorr_forecast are active and reactive power forecast correction factors accounting for a forecasted maximum possible power production of the wind power plant 11 and/or the solar power plant 12. The forecast may be short-term and/or mid-term. The forecast may comprise a weather forecast, a wind-speed forecast and/or a solar-irradiation forecast.

The control system 10 may also determine total active and/or reactive power reserves, ?Ptot and ?Qtot, as a sum of the power reserves of the individual power plants:

?Ptot = ?Pwind + ?Psolar + ?Padd,
?Qtot = ?Qwind + ?Qsolar + ?Qsto.

It directly follows that:

?Ptot = ?PHP - ?Pcorr_loss - ?Pcorr_forecast,
?Qtot = ?QHP - ?Qcorr_loss - ?Qcorr_forecast.

Optionally, the control system 10 may be adapted to receive from a TSO and/or an external grid control a set point for the total active and/or reactive power reserves ?Ptot, ?Qtot.

For a simplified control scheme, the control system 10 may determine the share of the individual power plants by multiplying the total active and/or reactive power reserves ?Ptot, ?Qtot with corresponding coefficients Kwind, Ksolar, Kadd, wherein 0 = Kwind, Ksolar, Kadd= 1:

?Pwind = Kwind?Ptot,
?Psolar = Ksolar?Ptot,
?Padd = Kadd?Ptot,
?Qwind = Kwind?Qtot,
?Qsolar = Ksolar?Qtot,
?Qsto = Kadd?Qtot.

Therein, Kwind + Ksolar + Kadd = 1.

For determining the coefficients Kwind, Ksolar, Kadd and/or the individual active and reactive power reserves?Pwind, ?Psolar, ?Padd, ?Qwind, ?Qsolar, ?Qsto, the control system 10 may monitor the current power production (in particular operation points) of the wind power plant 11 and the solar power plant 12 and, optionally, a status, e.g. the SOC or an optional mix of power-storage systems of the power storage plant 13. Corresponding measurements of the current power production (by the control system 10 or an operatively connected device) may be performed at MV level.

The control system 10 is further adapted to communicate values indicative for the individual active power reserves?Pwind, ?Psolar, ?Padd and for the individual reactive power reserves ?Qwind, ?Qsolar, ?Qstoto the wind power plant 11, the solar power plant 12 and/or the power storage plant 13, in particular to the respective WPP controller 110, PVPP controller 120 and/or SPP controller 130. The control system 10 is communicatively coupled to the wind power plant 11, the solar power plant 12 and/or the power storage plant 13, in particular to the respective WPP controller 110, PVPP controller 120 and/or SPP controller 130, e.g. by means of ethernet and/or one or more optic fibers.

For example, the control system 10 communicates the percentage values for ?Pwind, ?Psolar, ?Padd, ?Qwind, ?Qsolar, ?Qsto to the respective power plants. It will be appreciated that alternatively or in addition, the control system 10 may e.g. communicate the coefficients Kwind, Ksolar, Kadd and the total active and/or reactive power reserves ?Ptot, ?Qtot as values indicative for the individual active power reserves?Pwind, ?Psolar, ?Padd and for the individual reactive power reserves ?Qwind, ?Qsolar, ?Qstoto the wind power plant 11, the solar power plant 12 and/or the power storage plant 13.

The WPP controller 110, the PVPP controller 120 and the SPP controller 130 are adapted to control the WTG system 111, the PV system 121 and the power-storage system 131A, respectively, based on the corresponding values indicative for the active power reserves?Pwind, ?Psolar, ?Padd and reactive power reserves ?Qwind, ?Qsolar, ?Qsto.

List of Reference Numbers

1, 1’ hybrid power plant
10 control system
100 anemometer
101 storage
102 computer program product
11 wind power plant
110 WPP controller
111 WTG system
112 turbine
113 generator
12 solar power plant
120 PVPP controller
121 PV system
122 PV array
13 power storage plant
130 SPP controller
131A-131C power-storage system
132 battery
133 engine-generator
134 supercapacitor
135 curtailment algorithm
14 converter
15 transformer
16 plant transformer
17 junction
18 hybrid park feeder
19 substation
190 collector
191 transformer
2 electrical grid

a slope of a power output
P(t) active power output
PProfile (t) predefined power profile

P1 first power level
P2 second power level

Kwind, Ksolar, Kadd coefficient
?Pcorr_forecast active power forecast correction factor
?Pcorr_loss active power loss correction factor
?PHP hybrid power plant active power reserve
?Ptot total active power reserve
?Pwind, ?Psolar, ?Padd active power reserve
Q reactive power
?Qcorr_forecast reactive power forecast correction factor
?Qcorr_loss reactive power loss correction factor
?QHP hybrid power plant reactive power reserve
?Qtot total reactive power reserve
?Qwind, ?Qsolar, ?Qsto reactive power reserve

t1 first instance
t2 second instance

The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles described herein can be applied to other embodiments without departing from the spirit or scope of the invention. Thus, it is to be understood that the description and drawings presented herein represent a presently preferred embodiment of the invention and are therefore representative of the subject matter which is broadly contemplated by the present invention. It is further understood that the scope of the present invention fully encompasses other embodiments that may become obvious to those skilled in the art and that the scope of the present invention is accordingly not limited.