The present invention relates to an electrical grid control device and a power generation system.
In order to maintain stability of an electrical grid, electrical grid monitoring devices decide a control method of a circuit breaker and a thermal power generator while monitoring a voltage and a frequency in the electrical grid. One of the electrical grid monitoring devices is known as a remedial action scheme (RAS) (NERC; “Remedial Action Scheme” Definition Development, June 2014, [Searched on Apr. 24, 2020], Internet <https://www.nerc.com/pa/Stand/Prjct201005_2SpclPrtctnSstmPhs2/FAQ_RAS_Definition_0604 final.pdf>). The RAS is a method for calculating analysis of a plurality of assumed system accidents every predetermined time and deciding a control method of a synchronous generator or a circuit breaker of a load immediately after accident occurrence. In Spain, the electrical grid monitoring device called a “central power supply command station for renewable energy” is established, and there is a movement to control renewable energy power generation as well in addition to the circuit breaker and the thermal power generator. On the other hand, since an output of the renewable energy power generation fluctuates depending on the weather, the influence on a stable operation of the electrical grid is large.
Under such circumstances, in recent years, there has been a demand for contribution to a system stable operation of the renewable energy power generation. For example, paragraph 0019 of JP 2013-48504 A describes that “
However, when an accident occurs in the electrical grid, the voltage and the frequency of the electrical grid fluctuate in a complicated manner. According to the technique described in JP 2013-48504 A, the frequency vibration can be suppressed, but the electrical grid may not be appropriately stabilized only by this technique.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electrical grid control device and a power generation system capable of appropriately stabilizing an electrical grid.
In order to solve the above problems, there is provided an electrical grid control device of the present invention includes a data acquisition unit that acquires measurement data including a voltage value and a current value of each unit in an electrical grid to which a power conversion device is connected, and a control method selection unit that selects a control method when active power and reactive power output to the electrical grid by the power conversion device are controlled based on the acquired measurement data.
According to the present invention, the electrical grid can be appropriately stabilized.
Hereinafter, first, the stability of an electrical grid when there is an accident in the electrical grid will be described, and the influence of the accident on the stability when renewable energy power generation is interconnected to the system will be described. Thereafter, a control method of the renewable energy power generation contributing to the electrical grid will be described.
A state in which the electrical grid is stable refers to a state in which a voltage and a frequency of the system are maintained within thresholds in both normal and accident conditions.
When the accident occurs in the electrical grid, the voltage and the frequency greatly fluctuate. Thereafter, the fluctuations in the voltage and frequency may be diverged to units of the electrical grid depending on a timing of accident removal by a protective relay system or the like.
The fluctuations in the voltage and frequency after the accident removal change depending on an output state of the renewable energy power generation. For example, Japan Science and Technology Agency, Analysis on Transient Stabilities in Decarbonizing Power Systems with Large-scale Integration of Renewable Power Sources, March 2017, [Searched on Apr. 24, 2020], Internet <https://www.jst.go.jp/lcs/pdf/fy2016-pp-16.pdf> indicates that the output state of the renewable energy power generation influences the frequency of the electrical grid. In other words, it is possible to contribute to a stable operation of the electrical grid by appropriately controlling the output state of the renewable energy power generation. A method for contributing to the stable operation of the system after the accident removal by the renewable energy power generation is classified according to four control methods C1 to C4 according to the voltage and frequency in the accident condition.
Control Method C1 (First Control Method): When System Voltage Drops and Frequency Increases
In this case, there is a possibility that a step-out phenomenon occurs in a synchronous generator in the electrical grid. Thus, it is preferable that an output of the synchronous generator is increased by suppressing active power of the renewable energy power generation and outputting capacitive reactive power (lead reactive power), step-out is suppressed, and the system voltage is simultaneously maintained. More specifically, the renewable energy power generation may output the capacitive reactive power, and a power factor may be less than a predetermined value thpf1 (not shown).
Control Method C2 (Second Control Method): When the System Voltage Decreases and the Frequency Decreases
In this case, there is a possibility that the generator in the electrical grid falls off. Therefore, it is preferable that the system voltage is maintained while maintaining the supply and demand balance in the electrical grid by increasing the active power of the renewable energy power generation and outputting the capacitive reactive power. More specifically, the renewable energy power generation may output the capacitive reactive power, and the power factor may be set to be equal to or greater than the predetermined value thpf1.
Control Method C3 (Third Control Method): When the System Voltage Increases and the Frequency Increases
In this case, there is a possibility that a load in the electrical grid falls off. Therefore, it is preferable that an apparent load look large by suppressing the active power of the renewable energy power generation and outputting an inductive reactive power (delay reactive power), and thus, the supply and demand balance is maintained. More specifically, the renewable energy power generation may output the inductive reactive power, and thus, the power factor may be set to be less than a predetermined value thpf2 (not shown).
Control Method C4 (Fourth Control Method): When the System Voltage Increases and the Frequency Decreases
In this case, there is a possibility that the generator in the electrical grid falls off. Therefore, it is preferable that an insufficient active power is increased by accelerating output recovery of the renewable energy power generation, a voltage of the electrical grid is lowered by outputting the inductive reactive power, and the supply and demand balance is maintained by making the apparent load look small. More specifically, the renewable energy power generation may output the inductive reactive power, and the power factor may be set to be equal to or greater than the predetermined value thpf2.
In an actual electrical grid, a control method contributing to the system stabilization changes depending on a synchronous generator, a renewable energy power generation power source, a position of an accident point, the magnitude of demand, and the like. Therefore, the above-described RAS or the like that monitors the electrical grid may calculate a voltage threshold and a frequency threshold serving as triggers for switching between the control methods by calculation in advance and may distribute the calculated values to each renewable energy power generation. Each renewable energy power generation power source can suppress the fluctuation in the voltage and the frequency in the accident condition of the electrical grid by changing the control methods C1 to C4 in the accident condition based on the distributed voltage threshold and frequency threshold.
In
The power generation power sources 30A and 30B are, for example, renewable energy power generation power sources such as wind power generation. The PCSs 20A and 20B convert A frequency of AN AC power output from the power generation power sources 30A and 30B into a system frequency of the electrical grid 40, and output the system frequency to the electrical grid 40. Thus, the PCSs 20A and 20B include AC/DC converters 22A and 22B, storage batteries 23A and 23B, DC/AC converters 24A and 24B, and control devices 25A and 25B, respectively. In the illustrated example, two PCSs 20A and 20B and two power generation power sources 30A and 30B are provided, but three or more PCSs and power generation power sources may be provided, or one each may be provided.
The measurement units 50 and 60 output, as measurement data, instantaneous values of a voltage and a current of the electrical grid 40 at measurement points 58 and 68, respectively, at predetermined sampling cycles. The calculation server 10 calculates a voltage threshold and a frequency threshold with which the above-described control methods C1 to C4 are switched based on the measurement data supplied from the measurement units 50 and 60 and the like. The control devices 25A and 25B decide the control methods C1 to C4 based on the voltage threshold and the frequency threshold received from the calculation server 10, and generate an active power command value and a reactive power command value based on the decided control method. The DC/AC converters 24A and 24B output active power and reactive power corresponding to these command values to the electrical grid 40.
The calculation server 10 and the control devices 25A and 25B include hardware as a general computer, such as a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), and a solid state drive (SSD), and the SSD stores an operating system (OS), a control program, various kinds of data, and the like. The OS and the control program are developed in the RAM and is executed by the CPU.
In this figure, the insides of the calculation server 10 and the control device 25A illustrate functions realized by these control program and the like. Although the inside of the control device 25B is not illustrated, the control device 25B also has functions similar to those of the control device 25A.
The measurement unit 50 includes a sensor 52 and a measurement transmission unit 54. The sensor 52 measures instantaneous values of the voltage, the current, and the like of the electrical grid 40. The measurement transmission unit 54 transmits, as measurement data, the measurement result of the sensor 52 to the calculation server 10 for each predetermined sampling period.
The measurement unit 60 also includes a sensor 62 and a measurement transmission unit 64 which have similar functions. Here, since instantaneous values of the voltage, the current, and the like output from the measurement unit 60 are values at the measurement point 68 (interconnection point) at which the PCSs 20A and 20B (see
The calculation server 10 includes a data acquisition unit 220, an initial section calculation unit 230, a threshold candidate selection unit 266 (candidate selection unit), a transient calculation unit 250, and a threshold transmission unit 268 (control method selection unit or threshold generation unit). The control device 25A includes a threshold reception unit 270, a switch operation decision unit 272, and a PCS control unit 280.
The data acquisition unit 220 acquires measurement data such as instantaneous voltage values and instantaneous current values at the corresponding measurement points 58 and 68, and 88 from the measurement units 50, 60, and 80. The initial section calculation unit 230 calculates a voltage and a current in each unit in the electrical grid 40 at the time of calculation. The calculation method in the initial section calculation unit 230 is, for example, effective value tidal flow calculation.
The threshold candidate selection unit 266 stores a plurality of combinations of candidates for the voltage threshold and the frequency threshold to be transmitted to the PCSs 20A and 20B. One combination is selected from among the plurality of combinations. The transient calculation unit 250 calculates changes in the voltage and the frequency of the electrical grid 40 before the system accident removal by using the combination of the threshold candidates selected by the threshold candidate selection unit 266 and the calculated values of the voltage and the current calculated by the initial section calculation unit 230.
The threshold candidate selection unit 266 sequentially selects the combinations of the threshold candidates that can be applied after the system accident removal. Accordingly, whenever the combination of the threshold candidates is selected, the transient calculation unit 250 simulates (calculates) the changes in the voltage and the frequency of the electrical grid 40 after the system accident removal when the threshold candidates are adopted as the voltage threshold and the frequency threshold.
Among the plurality of threshold candidates, the threshold candidates with which it is determined that the fluctuation of the voltage and the frequency of the electrical grid 40 becomes sufficiently small are adopted as the voltage threshold and the frequency threshold to be set to the PCSs 20A and 20B. The adopted voltage threshold and frequency threshold are transmitted from the threshold transmission unit 268 to the threshold reception unit 270 of each of the PCSs 20A and 20B. The voltage threshold and the frequency threshold received by the threshold reception unit 270 in each PCS are supplied to each PCS control unit 280.
The PCS control unit 280 decides a control method to be adopted among the above-described control methods C1 to C4 based on the voltage threshold, the frequency threshold, the interconnection point voltage Vpcs, and the interconnection point current Ipcs. The PCS control unit 280 decides the active power command value and the reactive power command value of the PCSs 20A and 20B based on the decided control method, and further generates the voltage command value based on these power command values. The switch operation decision unit 272 decides switching methods of the corresponding DC/AC converters 24A and 24B (see
In
The α-β conversion unit 232 converts the measurement values of the three-phase voltage and current into information on a two-phase fixed coordinate system of a α phase and a β phase based on the DFT result. The d-q conversion unit 234 converts the information on the two-phase fixed coordinate system into information on a rotating coordinate system with a predetermined reference voltage as a reference, and acquires information on effective values. The reference voltage may be decided in advance by an operator of the present system. When the measurement values of all the voltages and currents at the measurement points 58, 68, and 88 are converted into the effective values, the PQ calculation unit 236 calculates tidal flow amounts of the active power and the reactive power at each measurement point. The effective value tidal flow calculation unit 238 calculates a flow of the power of the entire system based on the active power and the reactive power at each measurement point.
In
The transient calculation unit 250 calculate behaviors of the synchronous generator 70, the electrical grid 40, and the PCSs 20A and 20B when the accident occurs in the electrical grid 40 by using the time-discrete calculation algorithm 257, the synchronous generator behavior calculation model 251, the electrical grid model 252, and the PCS behavior calculation model 300. The synchronous generator behavior calculation model 251 is a model used in the time-discrete calculation algorithm 257, and for example, a Park model can be adopted. The electrical grid model 252 is an effective value calculation model used in the time-discrete calculation algorithm 257, and is, for example, an impedance map of a target system. The PCS behavior calculation model 300 is an effective value calculation model used in the time-discrete calculation algorithm 257, and is, for example, a model of only a current control portion of the PCS. The calculation model change unit 256 changes the PCS behavior calculation model 300 in response to a command from the threshold candidate selection unit 266.
This model reproduces and simulates a part of the control blocks of the PCS control unit 280 of the PCSs 20A and 20B, and is an ideal current source model assuming that a current output command value of the PCS is output to the electrical grid 40 with no change. A comparator 302 outputs “1” when the interconnection point voltage Vpcs (see
An in-normal P command creation unit 312 outputs an active power command value of the PCS in the normal condition. An in-accident P command creation unit 314 outputs an active power command value of the PCS in the accident condition. A switch 316 selects the former when the logic signal LG is “1”, selects the latter when the logic signal LG is “0”, and outputs the selection result as an active power command value Pref. An in-normal Q command creation unit 352 outputs a reactive power command value of the PCS in the normal condition, and an in-accident Q command creation unit 354 outputs a reactive power command value of the PCS in the accident condition. A switch 356 selects the former when the logic signal LG is “1”, selects the latter when the logic signal LG is “0”, and outputs the selection result as a reactive power command value Qref0.
The logical configurations of the in-normal P command creation unit 312, the in-accident P command creation unit 314, the in-normal Q command creation unit 352, and the in-accident Q command creation unit 354 differ depending on the configuration of the PCS, but the configurations described in WECC; WECC Type 3 Wind Turbine Generator Model-Phase II: Jan. 23, 2014 can be applied, for example. A subtractor 318 outputs a difference value between the active power command value Pref and an actual active power output value Pfb (active power) in order to perform feedback control. A gain and ramp rate control unit 350 applies a gain to the difference value (Pref−Pfb) limits the ramp plate, and outputs the result as a d-axis current command value Idref. Accordingly, the active power output value Pfb is feedback-controlled such that the difference value (Pref−Pfb) approaches zero.
A control logic change unit 320 (control method selection unit or control method change unit) decides a flag FG based on the interconnection point voltage Vpcs, an interconnection point frequency Fpcs, a voltage threshold Vth, and a frequency threshold Fth. A value of the flag FG is any integer from “0” to “4”. The voltage threshold Vth and the frequency threshold Fth are threshold candidates belonging to the combination selected by the threshold candidate selection unit 266 (see
A gain and ramp rate control unit 350 includes a switch unit 336, five gain application units 330 to 334, and five ramp limiters 340 to 344. The gain application units 330 to 334 correspond to the values “0” to “4” of the flag FG, and apply gains APR0 to APR4 to the difference values when the difference value (Pref−Pfb) are input.
The ramp limiters 340 to 344 also correspond to the values “0” to “4” of the flag FG, are connected in series to the corresponding gain application units 330 to 334, and limit ramp rates of the input signal to limit values P_Ramp0 to P_Ramp4 (ramp limit values) or less. The switch unit 336 selects a corresponding circuit of these five series circuits based on the values “0” to “4” of the flag FG output from the control logic change unit 320.
A switch unit 358 selects any one of reactive power command values Qref0 to Qref4 (parameters) based on the values “0” to “4” of the flag FG, and outputs the selected command value as the reactive power command value Qref. A subtractor 362 outputs a difference value between the reactive power command value Qref and an actual reactive power output value Qfb (reactive power) in order to perform feedback control. A gain application unit 364 applies a gain AQR to the difference value when the difference value (Qref−Qfb) is input so as to correspond to the values “0” to “4” of the flag FG. The ramp rate limiter 366 is connected in series to the gain application unit 364, limits the ramp rate of the input signal to a limit value Q_Ramp or less, and outputs the result as a q-axis current command value Iqref.
In
When the determination result is “No” in step S10, the processing proceeds to step S26. Here, the control logic change unit 320 sets the flag FG to “0”. Accordingly, in the normal condition (when the logic signal LG is “1”), the output signals of the in-normal P command creation unit 312 and the in-normal Q command creation unit 352 (see
On the other hand, when the determination result is “Yes” in step S10, the processing proceeds to step S12. Here, it is determined whether or not there is a timing at which the interconnection point voltage Vpcs is less than the voltage threshold Vth during the accident (in a period in which the logic signal LG is “0”). When the determination result is “Yes” in step S12, the processing proceeds to step S14, and it is determined whether or not there is a timing at which the interconnection point frequency Fpcs is the frequency threshold Fth during the accident.
When the determination result is “Yes” in step S14, the processing proceeds to step S18, and the control logic change unit 320 sets the flag FG to “1”. On the other hand, when the determination result is “No” in step S14, the processing proceeds to step S20, and the control logic change unit 320 sets the flag FG to “2”.
When the determination result is “No” in step S12 (Vpcs Vth is constantly satisfied in the accident condition), the processing proceeds to step S16, and it is determined whether or not there is a timing at which the interconnection point frequency Fpcs is the frequency threshold Fth during the accident.
When the determination result is “Yes” in step S16, the processing proceeds to step S22, and the control logic change unit 320 sets the flag FG to “3”. On the other hand, when the determination result is “No” in step S16, the processing proceeds to step S24, and the control logic change unit 320 sets the flag FG to “4”. When any of steps S18 to S26 is executed, this routine ends.
The values “1” to “4” of the flag FG correspond to the above-described control methods C1 to C4, respectively. Accordingly, for example, when the flag FG is “1”, the PCS behavior calculation model 300 (see
A table TBL1 represented in this figure is a table that stores various combinations as the threshold candidates for the voltage threshold Vth and the frequency threshold Fth for the PCS 20A (see
These combination candidates may be, for example, input by a manual operation of a user, or may be randomly decided by a computer by narrowing a range of each threshold. In
When the processing proceeds to step S30 in
Subsequently, when the processing proceeds to step S34, the transient calculation unit 250 executes transient calculation. That is, the voltages, the frequencies, and the like of the electrical grid 40 in the system accident condition and after the accident removal are calculated. Subsequently, when the processing proceeds to step S36, the threshold candidate selection unit 266 acquires a voltage fluctuation amount and a frequency fluctuation amount at the cooperation point 78 (see
The threshold candidate selection unit 266 stores the calculation result in step S36, that is, the voltage fluctuation amount and the frequency fluctuation amount together with the combination No. in a database DB1. Subsequently, when the processing proceeds to step S40, the threshold candidate selection unit 266 determines whether or not the search is ended for all the combinations stored in the table TBL1, that is, whether or not the voltage fluctuation amount and the frequency fluctuation amount are calculated. Here, when the determination result is “No”, the processing returns to step S30. That is, any combination that is not selected yet is selected, and the tasks of processing of steps S32 to S36 described above are executed.
When the determination result is “Yes” in step S40, the processing proceeds to step S42. Here, the threshold candidate selection unit 266 selects one combination No. based on the voltage fluctuation amount and the frequency fluctuation amount of each combination No. For example, a combination No. having a minimum voltage fluctuation amount may be selected, or a combination No. having a minimum frequency fluctuation amount may be selected. Thus, the tasks of processing of this routine are ended.
After the tasks of processing of this routine are ended, the threshold candidate selection unit 266 (see
As illustrated in
The AVR 284 outputs a voltage command value Vref based on the d-axis current command value Idref and the q-axis current command value Iqref. The voltage command value Vref is supplied to the switch operation decision unit 272 (see
Next, a renewable energy power generation system according to a preferred second embodiment will be described. In the following description, units corresponding to the units of the above-described first embodiment are denoted by the same reference numerals, and the description thereof may be omitted. First, the entire configuration of the present embodiment is similar to that of the first embodiment (
In
In the above-described first embodiment, the calculation server 10 transmits the voltage threshold Vth and the voltage threshold Vth to the control devices 25A and 25B. Instead, the present embodiment is different in that the calculation server 10 transmits various parameters to the control devices 25A and 25B. The parameters transmitted from the calculation server 10 to the control devices 25A and 25B are, for example, the gains APR0 to APR4, the limit values P_Ramp0 to P_Ramp4, the reactive power command values Qref1 to Qref4, the gain AQR, the limit value Q_Ramp, and the like illustrated in
Hereinafter, a method of deciding the reactive power command values Qref1 to Qref4 in the calculation server 10 will be described as an example.
A table TBL2 represented in
When the processing proceeds to step S50 in
Subsequently, when the processing proceeds to step S54, the transient calculation unit 250 executes transient calculation. That is, the voltages, the frequencies, and the like of the electrical grid 40 in the system accident condition and after the accident removal are calculated. Subsequently, when the processing proceeds to step S56, the parameter candidate selection unit 466 acquires the voltage fluctuation amount and the frequency fluctuation amount at the cooperation point 78 (see
The parameter candidate selection unit 466 stores the calculation result in step S56, that is, the voltage fluctuation amount and the frequency fluctuation amount together with the combination No. in a database DB2. Subsequently, when the processing proceeds to step S60, the parameter candidate selection unit 466 determines whether or not the search is ended for all the combinations stored in the table TBL2, that is, whether or not the voltage fluctuation amount and the frequency fluctuation amount are calculated. Here, when the determination result is “No”, the processing returns to step S50. That is, any combination that is not selected yet is selected, and the tasks of processing of steps S52 to S56 described above are executed.
When the determination result is “Yes” in step S60, the processing proceeds to step S62. Here, the parameter candidate selection unit 466 selects one combination No. based on the voltage fluctuation amount and the frequency fluctuation amount of each combination No. For example, a combination No. having a minimum voltage fluctuation amount may be selected, or a combination No. having a minimum frequency fluctuation amount may be selected. Thus, the tasks of processing of this routine are ended.
After the tasks of processing of this routine are ended, the parameter candidate selection unit 466 (see
Next, a renewable energy power generation system according to a preferred third embodiment will be described. In the following description, units corresponding to the units of the above-described first embodiment are denoted by the same reference numerals, and the description thereof may be omitted. First, the entire configuration of the present embodiment is similar to those of the first and second embodiments (
The accumulation control unit 482 accumulates, as teaching data, the measurement data acquired from the measurement units 50, 60, 80, and the like and the data acquired from the PCSs 20A and 20B in the teaching data storage device 480. The learning model generation unit 484 generates a learning model LM having the measurement data acquired by the data acquisition unit 220 as input data, and the various parameters in the PCS behavior calculation model 300 (see
That is, the above-described “various parameters” are the voltage threshold Vth, the frequency threshold Fth, the gains APR0 to APR4, the limit values P_Ramp0 to P_Ramp4, the reactive power command values Qref1 to Qref4, the gain AQR, the limit value Q_Ramp, or the like. The parameter decision unit 486 generates the above-described various parameters based on the measurement data acquired by the data acquisition unit 220 and the learning model LM.
In the above-described first and second embodiments, the values of the parameters to be set in the control devices 25A and 25B are decided in a round-robin manner. However, when the calculation result by the transient calculation unit 250 is accumulated, the above-described various parameters can be decided based on a demand distribution in the electrical grid 40, power generation outputs of the PCSs 20A and 20B, an output of the synchronous generator 70, and the like by performing pattern recognition by machine learning or the like without performing round-robin calculation.
In
Here, the data group T101 indicates active power consumptions and power factors at the demand points 91 and 92 and the like (see
The data group T102 includes active powers and reactive powers output from the synchronous generators 70 and 71 and the like to the electrical grid 40 in the normal condition.
The data group T103 includes the active and reactive powers, the gains APR0 to APR4, the limit values P_Ramp0 to P_Ramp4, the reactive power command values Qref0 to Qref4, and the like supplied from the PCSs 20A and 20B to the electrical grid 40 in the normal condition.
The data group T104 includes the voltage fluctuation amount and the frequency fluctuation amount at the measurement point 68 after the accident removal.
The data groups T101, T102, and T103 represent states of the electrical grid 40 before the occurrence of the accident. Since these data groups influence the voltage fluctuation and the frequency fluctuation of the electrical grid 40 in the accident condition and after the accident removal, these data groups are included in the teaching data T10. The teaching data T10 can be accumulated by combining the calculation results of the transient calculation unit 250 and calculation conditions.
According to the preferred embodiment as described above, the electrical grid control device (10, 25A, 25B) includes the data acquisition unit (220) that acquires the measurement data including the voltage value and the current value of each unit in the electrical grid (40) to which the power conversion device (20A, 20B) is connected, and the control method selection unit (268, 320) that selects the control methods (C1 to C4) when the active power (Pfb) and the reactive power (Qfb) output to the electrical grid (40) by the power conversion device (20A, 20B) are controlled based on the acquired measurement data. Accordingly, the electrical grid (40) can be appropriately stabilized by selecting an appropriate control method (C1 to C4).
It is more preferable that the control method selection unit (268, 320) includes the threshold generation unit (268) that outputs the voltage threshold (Vth) and the frequency threshold (Fth), and the control method change unit (320) that selects the control method (C1 to C4) based on a comparison result between the interconnection point voltage (Vpcs) and the interconnection point frequency (Fpcs) at the predetermined interconnection point (68) of the electrical grid (40) with the voltage threshold (Vth) and the frequency threshold (Fth). Accordingly, the appropriate control methods (C1 to C4) can be selected based on the state of the interconnection point (68).
It is more preferable that the control method selection unit (268,320) has a function of switching between the gains (APR1 to APR4) related to the active power (Pfb) based on the selected control methods (C1 to C4). Accordingly, the appropriate gains (APR1 to APR4) related to the active power (Pfb) can be selected according to the control methods (C1 to C4).
It is more preferable that the control method selection unit (268,320) has a function of switching between the ramp rate limit values (P_Ramp0 to P_Ramp4) related to the active power (Pfb) based on the selected control methods (C1 to C4). Accordingly, the appropriate ramp limit value (P_Ramp0 to P_Ramp4) related to the active power (Pfb) can be selected according to the control methods (C1 to C4).
It is more preferable that the control method selection unit (268, 320) has a function of switching between the reactive power command values (Qref1 to Qref4) for commanding the reactive power (Qfb) based on the selected control methods (C1 to C4). Accordingly, the appropriate reactive power command values (Qref1 to Qref4) cab be selected according to the control methods (C1 to C4).
It is more preferable that the electrical grid control device (10, 25A, 25B) further includes the transient calculation unit (250) that calculates the fluctuations in the voltage and frequency in the electrical grid (40) when the accident occurs in the electrical grid (40) and the candidate selection unit (266, 466) that acquires the calculation result in the transient calculation unit (250) while changing the candidates for the parameters (Vth, Fth, Qref0 to Qref4, and the like) given to the transient calculation unit (250) and selects any candidate as the parameter (Vth, Fth, Qref0 to Qref4, and the like) based on the acquired calculation result. Accordingly, the preferable candidate can be selected as the parameter (Vth, Fth, Qref0 to Qref4, and the like) from among the plurality of candidates based on the calculation result in the transient calculation unit (250).
It is more preferable that after the transient calculation unit (250) outputs the calculation result, the electrical grid control device (10, 25A, 25B) further includes the accumulation control unit (482) that accumulates the active power consumptions and the power factors at the demand point (91, 92) to which the load is connected in the electrical grid (40), the active power (Pfb) and the reactive power (Qfb) output from the power conversion device (20A, 20B), the gains (APR1 to APR4) and the ramp rate limit values (P_Ramp0 to P_Ramp4) related to the active power (Pfb), the reactive power command values (Qref1 to Qref4) for commanding the reactive power (Qfb), the voltage fluctuation amount of the interconnection point voltage (Vpcs) and the frequency fluctuation amount of the interconnection point frequency (Fpcs) at the predetermined interconnection point (68) of the electrical grid (40) after the accident removal in the storage device (480), the learning model generation unit (484) that generates the learning model (LM) having the data accumulated in the storage device (480) as the teaching data, the measurement data as the input data, and the parameter (Vth, Fth, Qref0 to Qref4, and the like) as the output, and the parameter decision unit (486) that outputs the parameters (Vth, Fth, Qref0 to Qref4, and the like) based on the learning model (LM) and the measurement data. Accordingly, the parameters (Vth, Fth, Qref0 to Qref4, and the like) can be output based on the learning model (LM).
It is more preferable that the control method selection unit (268, 320) has a function of selecting the control method (C1 to C4) to be applied from among the first control method (C1) for outputting the capacitive reactive power to the electrical grid (40) by means of the power conversion device (20A, and 20B) and setting the power factor of the power conversion device (20A, 20B) to be less than the predetermined first power factor (thpf1), the second control method (C2) for outputting the capacitive reactive power to the electrical grid (40) and setting the power factor of the power conversion device (20A, 20B) to be equal to or greater than the first power factor (thpf1) by means of the power conversion device (20A, 20B), the third control method (C3) for outputting the inductive reactive power to the electrical grid (40) and setting the power factor of the power conversion device (20A, 20B) to be less than the predetermined second power factor (thpf2) by means of the power conversion device (20A, 20B), and the fourth control method (C4) for outputting the inductive reactive power to the electrical grid (40) and setting the power factor of the power conversion device (20A, 20B) to be equal to or greater than the second power factor (thpf2) by means of the power conversion device (20A, 20B). Accordingly, it is possible to appropriately decide which of the capacitive reactive power and the inductive reactive power is to be generated and what range the power factor is to be set according to the control methods (C1 to C4).
The present invention is not limited to the above-described embodiments, and various modifications are possible. The aforementioned embodiments are described in detail in order to facilitate easy understanding of the present invention, and are not limited to necessarily include all the described components. Some of the components of a certain embodiment can be substituted into the components of other embodiments, and the components of other embodiments can be added to the component of a certain embodiment. Other components can be removed, added, and substituted from, to, and into some of the components of each of the aforementioned embodiments. Control lines and information lines represented in the drawings illustrate lines which are considered to be necessary for the description, and not all the control lines and information lines in a product are necessarily illustrated. Almost all the configurations may be considered to be actually connected to each other. Modifications possible for the above-described embodiments are, for example, as follows.
(1) In steps S40 and S42 (see
(2) In each of the above-described embodiments, the power generation power sources 30A and 30B are not necessarily required to be the renewable energy power generation power sources. That is, as long as the power sources can control the active powers and the reactive powers supplied to the electrical grid 40 through the PCSs 20A and 20B, various power sources can be applied as the power generation power sources 30A and 30B.
(3) Since the hardware of the calculation server 10 and the control devices 25A and 25B in the above-described embodiment can be realized by the general computer, the flowcharts illustrated in
(4) The tasks of processing illustrated in
Number | Date | Country | Kind |
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2020-087222 | May 2020 | JP | national |