Instruction generating device and instruction generating method in a plurality of power generation systems

Abstract

A processing section of an instruction generating device provided separately from a general inverter performs the following processing. A rotation calculating section calculates a value related to rotation of a rotor of a virtual generator when the virtual generator is driven in accordance with a rotor model that calculates a value related to rotation of the rotor of the virtual generator based on simulation of driving the virtual generator and an effective power command. A target determining section determines a target value of a voltage frequency and a target value of an effective power based on the calculated value related to rotation. An instruction generating section generates a control command for the inverter based on the determined target value of the voltage frequency and the target value of the effective power. A time constant related to a synchronous force of the rotor model and a time constant related to a synchronous force of the alternator are identical.

Description

Technical Field

[0001] This invention relates to an instruction generation apparatus and method for generating control commands for an inverter of a DC power supply device that generates multiple independently operating power generation systems.

[0002] This application claims priority to Japanese Patent Application No. 2019-017468, filed on February 1, 2019, the contents of which are incorporated herein by reference. Background Technology

[0003] Patent Document 1 discloses a distributed power supply system comprising multiple generators that are interconnected with the power grid or operate independently. According to Patent Document 1, when the distributed power supply system operates independently, one generator is controlled by speed using isochronous characteristics, while the remaining generators are controlled by speed using droop characteristics.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2009-081942 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, it is known that a combination of DC power supply devices such as energy storage devices or renewable energy generation devices and an inverter (power regulator) is connected to a busbar equipped with an independently operating AC generator. The AC generator uses a drooping characteristic for speed control. However, when the power supply system with the AC generator is operated independently, the frequency of the bus voltage is prone to fluctuate with load changes. Therefore, when fluctuations occur in the AC generator's voltage frequency, the inverter is prone to disengaging from cooperative operation.

[0009] The purpose of this invention is to provide an inverter, an inverter control device, an inverter control method, and a program for suppressing the disconnection of the DC power supply device caused by load fluctuations in a power supply system having an AC generator and a DC power supply device.

[0010] Solution for solving the problem

[0011] According to a first aspect of the present invention, there is an instruction generation apparatus that generates control instructions for an inverter of a DC power supply device connected to the same bus as an AC generator that supplies power through independent operation. The instruction generation apparatus includes: a rotation calculation unit that calculates values ​​related to the rotation of the rotor of the virtual generator when the virtual generator is driven according to the effective power instruction, based on a rotor model and an effective power instruction that simulates the driving of the virtual generator; a target determination unit that determines a target value for voltage frequency and a target value for effective power based on the calculated rotation-related values; and an instruction generation unit that generates control instructions for the inverter based on the determined target value for voltage frequency and the target value for effective power, wherein the time constant related to the synchronization force of the rotor model is consistent with the time constant related to the synchronization force of the AC generator.

[0012] According to a second aspect of the present invention, the instruction generation device of the first aspect may include a drive torque calculation unit. This drive torque calculation unit calculates a value related to the drive torque of the virtual generator by inputting the voltage frequency of the bus, the frequency command for the inverter, and the effective power command into a speed governor model. The speed governor model determines the value related to the drive torque of the virtual generator based on the effective voltage of the bus, the frequency command, and the effective power command. The rotation calculation unit calculates a value related to the rotation of the virtual generator based on the calculated value related to the drive torque and the rotor model.

[0013] According to the third aspect of the present invention, the time constant related to the droop filter of the speed governor model in the instruction generation device of the first aspect may be consistent with the time constant related to the droop filter of the speed governor of the alternator.

[0014] According to a fourth aspect of the present invention, the instruction generation apparatus of the first to third aspects may include an excitation voltage calculation unit. This excitation voltage calculation unit calculates a value related to the excitation voltage of the virtual generator by inputting the bus voltage and the invalid power instruction for the inverter into an automatic voltage regulator model. The automatic voltage regulator model determines the value related to the excitation voltage of the virtual generator based on the bus voltage and the invalid power instruction. The target determination unit determines the target values ​​of effective power and invalid power based on the calculated values ​​related to rotation and the values ​​related to the excitation voltage.

[0015] According to a fifth aspect of the present invention, the instruction generation apparatus is an apparatus for generating power instructions for controlling an inverter of a DC power supply device connected to the same bus as an AC generator that supplies power through independent operation. The instruction generation apparatus includes: a target determination unit that determines, based on the voltage value of the bus, a target value of a voltage frequency that monotonically increases relative to the voltage value and a target value of an effective power that monotonically decreases relative to the voltage value; and an instruction generation unit that generates control instructions for the inverter based on the determined target value of the voltage frequency and the target value of the effective power.

[0016] According to a sixth aspect of the present invention, in the control device of the inverter of the fifth aspect, the target determination unit determines the target value of the effective power based on the effective power droop function representing the monotonically decreasing relationship between the effective power and the voltage frequency, and the determined target value of the voltage frequency.

[0017] According to the seventh aspect of the present invention, in the control device of the inverter of the sixth aspect, the change in effective power relative to voltage frequency of the effective power droop function is consistent with the effective power droop characteristic of the AC generator.

[0018] According to the eighth aspect of the present invention, in the control device of an inverter in any of the aspects from the fifth to the seventh aspect, the target determination unit determines a target value of ineffective power that decreases monotonically relative to the voltage value of the bus, and the instruction generation unit generates control instructions for the inverter based on the determined target value of the voltage frequency, the target value of the effective power, and the target value of the ineffective power.

[0019] According to the ninth aspect of the present invention, in the control device of the inverter of the eighth aspect, the target determination unit determines the target value of the invalid power based on the invalid power droop function, which represents the monotonically decreasing relationship between invalid power and voltage value, and the determined voltage value of the bus.

[0020] According to the tenth aspect of the present invention, in the control device of the inverter of the ninth aspect, the intercept of the voltage value of the ineffective power droop function and the intercept of the ineffective power are below the intercept of the voltage value of the ineffective power droop characteristic of the alternator and the intercept of the ineffective power.

[0021] According to the eleventh aspect of the present invention, the instruction generation method is a method for generating control instructions for an inverter of a DC power supply device connected to the same bus as an AC generator that supplies power through independent operation. The instruction generation method includes: calculating, based on the driving of a simulated virtual generator and calculating values ​​related to the rotation of the rotor of the virtual generator and an effective power instruction, values ​​related to the rotation of the rotor of the virtual generator when the virtual generator is driven according to the effective power instruction; determining, based on the calculated values ​​related to the rotation, a target value for the voltage frequency and a target value for the effective power; and generating control instructions for the inverter based on the determined target value for the voltage frequency and the target value for the effective power, wherein the time constant related to the synchronization force of the rotor model is consistent with the time constant related to the synchronization force of the AC generator.

[0022] According to a 12th aspect of the invention, the instruction generation method is a method for generating power instructions for controlling an inverter of a DC power supply device connected to the same bus as an AC generator that supplies power through independent operation. The instruction generation method includes: determining, based on the voltage value of the bus, a target value of a voltage frequency that monotonically increases relative to the voltage value and a target value of an effective power that monotonically decreases relative to the voltage value; and generating control instructions for the inverter based on the determined target value of the voltage frequency and the target value of the effective power.

[0023] The effects of the invention

[0024] The instruction generation device of at least one of the above methods can control the inverter in a power supply system having an AC generator and a DC power supply device, so that the AC generator and the DC power supply device respectively bear the load variation. Attached Figure Description

[0025] Figure 1 This is a schematic block diagram showing the structure of the power supply system according to the first embodiment.

[0026] Figure 2 This is a schematic block diagram showing the structure of the instruction generation apparatus according to the first embodiment.

[0027] Figure 3 This is a block diagram illustrating an example of an AVR model according to the first embodiment.

[0028] Figure 4 This is a line drawing illustrating an example of a governor model according to the first embodiment.

[0029] Figure 5This is a block diagram illustrating an example of a rotor model according to the first embodiment.

[0030] Figure 6 This is a schematic block diagram showing the structure of the instruction generation apparatus according to the second embodiment.

[0031] Figure 7 This is a flowchart illustrating the operation of the inverter in the energy storage device of the second embodiment.

[0032] Figure 8 It is a schematic block diagram showing the structure of a computer according to at least one embodiment. Detailed Implementation

[0033] <First Embodiment>

[0034] Figure 1 This is a schematic block diagram showing the structure of the power supply system according to the first embodiment.

[0035] Structure of Power Supply Systems

[0036] The power supply system 1 of the first embodiment includes a generator 10, a solar generator 20, an energy storage device 30, a command generation device 33, and a power control device 40. The power supply system 1 supplies power to the load L through independent operation. That is, the power supply system 1 is a so-called microgrid system or off-grid system. The generator 10, the solar generator 20, and the energy storage device 30 are connected to a busbar, through which power is supplied to the load L.

[0037] The engine generator 10 includes an engine 11, a generator 12, a speed governor 13, and an AVR 14 (Automatic Voltage Regulator). The engine generator 10 is an AC generator that generates alternating current by driving the generator 12 through the rotation of the engine 11.

[0038] The speed governor 13 controls the engine speed 11 via the Hz-kW droop characteristic. The speed governor characteristic of the engine generator 10 is represented, for example, by the slope of a linear function that connects a curve related to the rated output and rated frequency with a curve related to the stable frequency under no-load conditions when the load is disconnected from the rated output. That is, the Hz-kW droop characteristic is that the output decreases as the frequency increases. Alternatively, in other embodiments, the speed governor characteristic can also be implemented using PID (Proportional Integral Differential) control. The AVR 14 controls the current supplied to the excitation coil of the generator 12 via the V-kbar droop characteristic, adjusting the terminal voltage of the generator 12. The V-kbar droop characteristic is that the ineffective power decreases as the voltage increases. Alternatively, in other embodiments, other alternators can be used instead of the engine generator 10.

[0039] The solar generator 20 includes solar cells 21 and an inverter 22. Solar cells 21 are DC power supply devices that convert sunlight into direct current (DC) electricity. The inverter 22 converts the DC electricity generated by the solar cells 21 into alternating current (AC) electricity. Alternatively, the inverter 22 and solar cells 21 do not necessarily need to be configured in a one-to-one pair. For example, multiple solar cells 21 can be connected to a single inverter 22. Furthermore, in other embodiments, solar cells 21 can be replaced by other renewable energy generators, such as wind turbines.

[0040] The energy storage device 30 includes a secondary battery 31 and an inverter 32. The inverter 32, according to instructions from the instruction generation device 33, converts the DC power output from the secondary battery 31 into AC power and supplies it to the bus. Furthermore, according to instructions from the power control device 40, the inverter 32 converts a portion of the AC power flowing in the bus into DC power to charge the secondary battery 31. For example, a lithium-ion secondary battery can be used as the secondary battery 31. The inverter 32 is a general-purpose inverter that operates according to control instructions related to P-Q control. Alternatively, in other embodiments, the inverter 32 may also be an inverter that operates according to control instructions related to target values ​​for apparent power, power factor angle, and voltage frequency.

[0041] Furthermore, the inverter 32 and the secondary battery 31 do not necessarily need to be configured in a one-to-one manner. For example, multiple secondary batteries 31 can be connected to one inverter 32.

[0042] The instruction generation device 33 generates control instructions for controlling the inverter 32 based on instructions from the power control device 40, and outputs these instructions to the inverter 32. The control instructions for the inverter 32 include target values ​​for effective power, ineffective power, and voltage frequency. The instruction generation device 33 is located separately from the inverter 32.

[0043] The power control device 40 monitors the power level of the bus and outputs power generation commands to the engine generator 10 and charge / discharge commands to the energy storage device 30. For example, when the power generation of the solar generator 20 is above a predetermined threshold, such as during the day, the power control device 40 outputs a power generation command to the engine generator 10 to reduce or stop the power generation. Furthermore, when the power generation of the solar generator 20 is below the predetermined threshold, such as at night or during inclement weather, the power control device 40 outputs a power generation command to the engine generator 10 to increase the power generation.

[0044] Furthermore, for example, the power control device 40, based on the fluctuations in the generated power of the solar generator 20, outputs charging and discharging commands to the inverter 32 through processing performed in the command generation device 33 to smooth out these fluctuations. Additionally, the power control device 40 compares the sum of the power supplied to the bus with the power demand of the load L, and based on the power difference, outputs charging and discharging commands to the inverter 32 through processing performed in the command generation device 33.

[0045] Structure of the Instruction Generation Device

[0046] Figure 2 This is a schematic block diagram showing the structure of the instruction generation apparatus according to the first embodiment.

[0047] The instruction generation apparatus 33 of the first embodiment includes an ammeter 322, a voltmeter 323, and a computer 324. The ammeter 322 measures the current at the output terminal of the inverter 32. The voltmeter 323 measures the voltage at the output terminal of the inverter 32. The computer 324 generates control instructions based on the measurements from the ammeter 322 and the voltmeter 323.

[0048] The computer 324 has a model storage unit 3241, an instruction receiving unit 3242, a measurement value acquisition unit 3243, an excitation voltage calculation unit 3244, a drive torque calculation unit 3245, a rotation calculation unit 3246, a target determination unit 3247, and an instruction generation unit 3248.

[0049] The model storage unit 3241 stores mathematical models simulating the behavior of a virtual generator. Specifically, the model storage unit 3241 stores an AVR model M1 simulating the behavior of the AVR of the virtual generator, a governor model M2 simulating the behavior of the governor of the virtual generator, and a rotor model M3 simulating the behavior of the rotor of the virtual generator. The AVR model M1, by inputting the measured value of invalid power, the invalid power command value, the effective voltage value, and the voltage command value, outputs the excitation voltage and electrical torque of the virtual generator. The governor model M2, by inputting the measured value of effective power, the effective power command value, the angular velocity of the virtual generator rotor, and the angular velocity command value, outputs the drive torque value of the virtual generator. The rotor model M3, by inputting the electrical torque value and the drive torque value of the virtual generator, outputs the angular velocity and phase angle of the virtual generator rotor. Details of each mathematical model will be described later.

[0050] The command receiving unit 3242 receives charging and discharging commands from the power control device 40. The discharging command includes a command value for effective power, a command value for ineffective power, a voltage command value, and an angular velocity command value.

[0051] The measurement value acquisition unit 3243 acquires the measurement values ​​of the ammeter 322 and the voltmeter 323. In addition, the measurement value acquisition unit 3243 calculates the voltage and current values ​​that contribute to the effective power, the voltage and current values ​​that contribute to the ineffective power, the effective voltage value, the effective power value, and the ineffective power value based on the measurement values ​​of the ammeter 322 and the voltmeter 323 and the phase angle of the rotor of the virtual generator.

[0052] The excitation voltage calculation unit 3244 calculates the excitation voltage and electrical torque of the virtual generator by inputting the invalid power command value and voltage command value received by the command receiving unit 3242, and the invalid power value and effective voltage value obtained by the measurement value acquisition unit 3243 into the AVR model M1. The excitation voltage and electrical torque values ​​of the virtual generator are examples of values ​​related to the excitation voltage of the virtual generator.

[0053] The drive torque calculation unit 3245 calculates the drive torque value of the virtual generator by inputting the effective power command value and angular velocity command value received by the command receiving unit 3242, the effective power measurement value obtained by the measurement value acquisition unit 3243, and the angular velocity of the virtual generator rotor calculated by the rotation calculation unit 3246 in the previous control into the speed governor model M2. The drive torque value is an example of a value related to the drive torque of the virtual generator.

[0054] The rotation calculation unit 3246 inputs the electrical torque value calculated by the excitation voltage calculation unit 3244 and the drive torque value calculated by the drive torque calculation unit 3245 into the rotor model M3 to calculate the angular velocity and phase angle of the virtual generator's rotor. The angular velocity and phase angle of the virtual generator's rotor are examples of values ​​related to the rotation of the virtual generator's rotor.

[0055] The target determination unit 3247 determines the target values ​​for effective power and ineffective power based on the excitation voltage value calculated by the excitation voltage calculation unit 3244, the voltage and current values ​​contributing to effective power and contributing to ineffective power obtained by the measurement value acquisition unit 3243, and the rotor phase angle calculated by the rotation calculation unit 3246. Furthermore, the target determination unit 3247 determines the target value for voltage frequency based on the angular velocity of the virtual generator's rotor.

[0056] The instruction generation unit 3248 generates control commands for the inverter 32 based on the target values ​​for effective power, ineffective power, and voltage frequency determined by the target determination unit 3247. The instruction generation unit 3248 then outputs the generated control commands to the inverter 32.

[0057] The Structure of Mathematical Models

[0058] Figure 3 This is a block diagram illustrating an example of an AVR model according to the first embodiment.

[0059] The AVR model M1 inputs the measured value Q of invalid power and the invalid power command value Q. ＊ Effective voltage value V g and voltage command value V ＊ The output virtual generator's excitation voltage E and electrical torque T e Specifically, AVR model M1 has summing points M11, M12, M13, P-block M14, I-block M15, and P-block M16. Summing point M11 obtains the measured value Q of the invalid power and the invalid power command value Q. ＊ The difference. P block M14 performs a proportional gain K-based adjustment on the output of the summing point M11. A1 P control. Proportional gain K A1 This is equivalent to the V-kbar droop gain of a virtual generator. The summing point M12 yields the effective voltage value V. g With voltage command value V ＊ The difference. Addition point M13 obtains the difference between the output of addition point M12 and the output of P block M14. I block M15 performs an integral gain K-based adjustment on the output of addition point M13. A2 The integral control yields the excitation voltage value E. Block M16 multiplies the excitation voltage value E by the ineffective current value I.q And divide by the rotor's angular velocity ω R The electric torque Te of the virtual generator is obtained.

[0060] Figure 4 This is a block diagram illustrating an example of a governor model according to the first embodiment.

[0061] The speed controller model M2 is input by the measured effective power value P and the effective power command value P. ＊ The angular velocity ω of the virtual generator's rotor R and the angular velocity command value ω ＊ The output virtual generator's drive torque value Td is then calculated. Specifically, the governor model M2 has summing points M21, M22, M23, P block M24, PI block M25, and a primary delay block M26. Summing point M21 obtains the measured effective power value P and the effective power command value P. ＊ The difference. P block M24 performs a proportional gain K-based adjustment on the output of summing point M21. B1 P control. Proportional gain K B1 This is equivalent to the Hz-kW droop gain of a virtual generator. Additionally, the proportional gain K... B1 From relative to the effective voltage value V g The voltage function is monotonically decreasing. Therefore, P-block M24 is determined based on the effective voltage value V. g The proportional gain K is determined according to the V-kW droop characteristic. B1 Calculations are performed on block M24 (P). The angular velocity ω of the virtual generator's rotor is obtained by summing the values ​​at point M22. R With angular velocity command value ω ＊ The difference. Addition point M23 obtains the sum of the output of addition point M22 and the output of P block M24. PI block M25 performs a proportional gain K-based adjustment on the output of addition point M23. B2 and integral gain K B3 PI control. The delay block M26 modulates the output of the PI block M25 with the time constant K. B4 The relevant delay control yields the drive torque value T. d Furthermore, the time constant KB4 is equal to the time constant of the speed controller 13. Also, in this specification, "equal time constants" or "consistent time constants" do not necessarily mean completely identical; they include a substantially consistent range (e.g., ±3dB).

[0062] Figure 5 This is a block diagram showing an example of a rotor model according to the first embodiment.

[0063] Rotor model M3 is input with the electrical torque value T of the virtual generator. e and driving torque value T dOutput the angular velocity ω of the virtual generator's rotor. R and phase angle θ R Specifically, the rotor model M3 has an addition point M31, a primary delay block M32, and an I-block M33. The addition point M31 yields the electrical torque T of the virtual generator. e and driving torque T d The difference. The first delay block M32 performs a first delay control on the output of the summing point M31, related to the integral gain M and the time constant D, to obtain the rotor's angular velocity ω. R Additionally, the time constant D is a braking coefficient related to the braking force of the braking winding, and is equal to the braking coefficient of generator 12. Furthermore, the integral gain M is the gain equivalent to the inertial torque of the rotor of the virtual generator, and is equal to the inertial torque of the rotor of engine 11. Block M33 controls the angular velocity ω of the rotor... R Integrate and multiply by the proportional gain ω BASE The phase θ of the rotor of the virtual generator is obtained. R Proportional gain ω BASE It is the reference frequency of the bus.

[0064] "action"

[0065] Based on the above structure, computer 324, using AVR model M1, speed controller model M2, and rotor model M3, calculates the rotation angle, angular velocity, and excitation voltage of the virtual generator according to the effective power command value, ineffective power command value, voltage command value, angular velocity command value, and the measurements from ammeter 322 and voltmeter 323. Based on the rotation angle, angular velocity, and excitation voltage of the virtual generator, computer 324 determines the target values ​​for effective power, ineffective power, and voltage frequency, and generates control commands for inverter 32 accordingly. Inverter 32 operates according to the control commands generated by command generation device 33, achieving characteristics equivalent to a virtual generator.

[0066] Here, the time constant of the virtual generator in this embodiment is the same as that of the engine generator 10. However, the V-kbar droop gain, Hz-kW droop gain, impedance, etc., do not necessarily need to be the same as those of the engine generator 10. For example, by setting the Hz-kW droop gain of the virtual generator to be more gradual than that of the engine generator 10, the effective power load of the inverter 32 during load L fluctuations can be greater than that of the engine generator 10. Furthermore, for example, by making the V-kbar droop gain of the virtual generator steeper than that of the engine generator 10, the ineffective power load of the inverter 32 during load L fluctuations can be less than that of the engine generator 10.

[0067] Functions and Effects

[0068] The instruction generation device 33 of the first embodiment uses a rotor model M3 with a time constant related to the synchronization force equal to that of the engine generator 10 to calculate the angular velocity of the virtual generator's rotor, determines the target value of the output voltage based on this angular velocity, and generates control commands for the inverter 32. In this way, by aligning the time constant related to the synchronization force of the virtual generator with that of the engine generator 10, when a change in load L occurs, the instruction generation device 33 can change the voltage frequency of the inverter 32 in a manner that matches the change in the voltage frequency of the engine generator 10. That is, in the power supply system 1, the instruction generation device 33 of the first embodiment can prevent the energy storage device 30 from disconnecting even if the voltage frequency of the engine generator 10 changes due to a change in load L.

[0069] Furthermore, in the first embodiment, the instruction generation device 33 is provided separately from the inverter 32. Therefore, by providing the instruction generation device 33 within the already installed energy storage device 30, it is possible to prevent the disconnection of the energy storage device 30 without modifying the inverter 32.

[0070] Furthermore, the command generation device 33 of the first embodiment uses a rotor model M3 with a time constant related to the synchronization force equal to that of the engine generator 10 to calculate the angular velocity of the virtual generator's rotor, determines the target value of the output voltage based on this angular velocity, and generates control commands for the inverter 32. In this way, by aligning the time constant related to the synchronization force of the virtual generator with that of the engine generator 10, when a change in load L occurs, the command generation device 33 can adjust the output of the inverter 32 to match the change in output of the engine generator 10. That is, in the power supply system 1, the command generation device 33 of the first embodiment allows the engine generator 10 and the energy storage device 30 to respectively handle changes in load L.

[0071] Furthermore, the instruction generation device 33 of the first embodiment uses the speed governor model M2 to calculate the drive torque value of the virtual generator. Therefore, the instruction generation device 33 can control the effective power of the inverter 32 through the Hz-kW droop characteristics. Alternatively, the instruction generation device 33 of other embodiments can also determine the drive torque value independently of the speed governor model M2. Additionally, the time constant related to the droop filter of the speed governor model of the first embodiment is consistent with the time constant related to the droop filter of the speed governor 13 of the engine generator 10. Therefore, when a change in load L occurs, the computer 324 can change the output frequency of the inverter 32 in a way that matches the change in the output frequency of the engine generator 10.

[0072] Furthermore, in the first embodiment, the computer 324 of the inverter 32 uses the AVR model M1 to calculate the excitation voltage value of the virtual generator. Therefore, the computer 324 can control the inefficient power of the inverter 32 through droop characteristics. Alternatively, in other embodiments, the computer 324 can also control inefficient power without relying on the AVR model M1.

[0073] Variations

[0074] In the first embodiment, the instruction generation device 33 generates control instructions for the inverter 32 of the energy storage device 30, but this is not the case in other embodiments. For example, in other embodiments, the instruction generation device 33 may also generate control instructions for the inverter 22 of the solar generator 20. In this case, the solar generator 20 needs to have an energy storage device capable of absorbing the deviation between the generated power of the solar cells 21 and the output power of the inverter 22 caused by the inertia of the virtual generator. Furthermore, in other embodiments, the above-described control may be performed on a portion of the multiple inverters 32, while normal control may be performed on the other inverters 32.

[0075] In the first embodiment, the rotation calculation unit 3246 calculates the rotor's phase and angular velocity as values ​​related to the rotor's rotation, but is not limited to these. For example, in other embodiments, the rotation calculation unit 3246 may also calculate other values ​​such as the rotor's rotational frequency and rotational speed. Furthermore, in the first embodiment, the drive torque calculation unit 3245 calculates the drive torque value as a value related to the virtual generator's drive torque, but is not limited to this. For example, in other embodiments, the drive torque calculation unit 3245 may also calculate other values ​​such as the rotor's rotational force. Furthermore, in the first embodiment, the excitation voltage calculation unit 3244 calculates the excitation voltage value as a value related to the virtual generator's excitation voltage, but is not limited to this. For example, in other embodiments, the excitation voltage calculation unit 3244 may also calculate other values ​​related to the virtual generator's excitation current.

[0076] In addition, in the first embodiment, using Figure 3 The calculations are performed using the mathematical model shown in Figure 5, but are not limited to this. For example, in other embodiments, calculations can also be performed based on the results of representing the engine generator 10 using the PARK model.

[0077] <Second Embodiment>

[0078] In the first embodiment, the instruction generation device 33 generates control instructions for the inverter 32 by simulating the behavior of a virtual generator. In contrast, the second embodiment does not simulate the behavior of a virtual generator to generate control instructions for the inverter 32.

[0079] Structure of the Instruction Generation Device

[0080] Figure 6 This is a schematic block diagram showing the structure of the instruction generation apparatus according to the second embodiment.

[0081] The inverter 32 of the second embodiment includes a current meter 322, a voltmeter 323, and a computer 324. The current meter 322 measures the current at the output terminal of the inverter 32. The voltmeter 323 measures the bus voltage. The computer 324 generates control commands for the inverter 32 based on the measurement value of the voltmeter 323 and outputs the control commands to the inverter 32.

[0082] The computer 324 of the second embodiment includes a control function storage unit 3251, a measurement value acquisition unit 3252, a target frequency determination unit 3253, a target effective power determination unit 3254, a target invalid power determination unit 3255, an instruction generation unit 3256, and an instruction receiving unit 3257.

[0083] The control function storage unit 3251 stores a target frequency function F1 representing the relationship between bus voltage and bus voltage frequency, an effective power droop function F2 representing the relationship between bus voltage frequency and effective power, and an ineffective power droop function F3 representing the relationship between bus voltage and ineffective power. The target frequency function F1 is a function in which the bus voltage frequency monotonically increases relative to the bus voltage. Furthermore, in this embodiment, "monotonically increasing" means that when the value of one increases, the value of the other always increases or remains unchanged (monotonically non-decreasing). Similarly, "monotonically decreasing" means that when the value of one increases, the value of the other always decreases or remains unchanged (monotonically non-increasing). The target frequency function F1 is a function representing the change in the bus voltage frequency output by the engine generator 10 relative to the change in bus voltage. The effective power droop function F2 is a function in which the effective power monotonically decreases relative to the bus voltage frequency. The slope of the effective power droop function F2 (the amount of change in effective power relative to the bus voltage frequency) is equal to the slope related to the Hz-kW droop characteristic of the governor 13 of the engine generator 10. The ineffective power droop function F3 is a function of ineffective power decreasing monotonically with respect to the bus voltage. The slope of the ineffective power droop function F3 (the change in ineffective power with respect to the bus voltage) is equal to the slope related to the V-kbar droop characteristic of the AVR14 of the engine generator 10. On the other hand, the intercepts of the bus voltage and the ineffective power of the ineffective power droop function F3 are less than or equal to the intercepts of the bus voltage and the ineffective power related to the V-kbar droop characteristic of the AVR14 of the engine generator 10. That is, the ineffective power calculated by the ineffective power droop function F3 is always less than or equal to the ineffective power output by the engine generator 10 according to the V-kbar droop characteristic of the AVR14. In addition, in this specification, "equal" and "consistent" do not necessarily mean completely consistent, but include a range of substantially consistent.

[0084] The measurement acquisition unit 3252 acquires measurement values ​​from the ammeter 322 and the voltmeter 323.

[0085] The target frequency determination unit 3253 determines the target value of the voltage frequency by substituting the measured value of the bus voltage into the target frequency function F1 stored in the control function storage unit 3251.

[0086] The target effective power determination unit 3254 determines the target value of the effective power by substituting the target value of the voltage frequency determined by the target frequency determination unit 3253 into the effective power droop function F2 stored in the control function storage unit 3251.

[0087] The target ineffective power determination unit 3255 determines the target value of ineffective power by substituting the measured value of the bus voltage into the ineffective power droop function F3 stored in the control function storage unit 3251.

[0088] The target frequency determination unit 3253, the target effective power determination unit 3254, and the target ineffective power determination unit 3255 are examples of target determination units.

[0089] The instruction generation unit 3256 generates control instructions for the inverter 32 based on the target value of the voltage frequency determined by the target frequency determination unit 3253, the target value of the effective power determined by the target effective power determination unit 3254, and the target value of the ineffective power determined by the target ineffective power determination unit 3255.

[0090] The command receiving unit 3257 receives a power command from the power control device 40 and updates the effective power droop function F2 and the ineffective power droop function F3 stored in the control function storage unit 3251 according to the power command. Specifically, the command receiving unit 3257 receives a power command representing the maximum value of the effective power and the maximum value of the ineffective power output to the energy storage device 30. This power command is generated based on the power generation capacity of the engine generator 10 and the solar generator 20. The command receiving unit 3257 updates the effective power droop function F2 without changing its slope, so that the intercept value of the effective power axis becomes the maximum value of the effective power represented by the power command. In addition, the command receiving unit 3257 updates the ineffective power droop function F3 without changing its slope, so that the intercept value of the ineffective power axis becomes the maximum value of the ineffective power represented by the power command.

[0091] The Operation of an Inverter

[0092] Figure 7 This is a flowchart illustrating the operation of the inverter in the energy storage device of the second embodiment.

[0093] The measurement acquisition unit 3252 of the computer 324 acquires the measured value of the bus voltage from the voltmeter 323 (step S1). The target frequency determination unit 3253 determines the target value of the voltage frequency by substituting the measured value of the bus voltage acquired in step S1 into the target frequency function F1 stored in the control function storage unit 3251 (step S2). That is, when the bus voltage decreases due to the increase of the load L, the target frequency determination unit 3253 lowers the target frequency. On the other hand, when the bus voltage increases due to the decrease of the load L, the target frequency determination unit 3253 increases the target frequency. As a result, the voltage frequency output by the inverter 32 changes in the same way as the voltage frequency output by the engine generator 10. That is, as the load L increases, the generated power of the engine generator 10 increases and the voltage frequency decreases, but the target frequency determination unit 3253 can achieve the same voltage frequency change as the engine generator 10 by lowering the target frequency when the bus voltage decreases.

[0094] Next, the target effective power determination unit 3254 determines the target value of the effective power by substituting the target value of the voltage frequency determined in step S2 into the effective power droop function F2 stored in the control function storage unit 3251 (step S3). The effective power droop function F2 has the same slope as the droop characteristic of the engine generator 10. Therefore, by determining the target value of the effective power based on the target value of the voltage frequency using the effective power droop function F2 in step S3, the inverter 32 can output effective power in a way that matches the droop characteristic of the engine generator 10. As a result, the effective power can be shared between the engine generator 10 and the energy storage device 30.

[0095] Furthermore, the target ineffective power determination unit 3255 determines the target value of ineffective power by substituting the measured value of the bus voltage obtained in step S1 into the ineffective power droop function F3 stored in the control function storage unit 3251 (step S4). The intercepts of the bus voltage and the ineffective power of the ineffective power droop function F3 are below the intercepts of the bus voltage and the ineffective power related to the V-kbar droop characteristics of the AVR14 of the engine generator 10. That is, the ineffective power calculated by the ineffective power droop function F3 is always below the ineffective power output by the engine generator 10 according to the V-kbar droop characteristics of the AVR14. As a result, ineffective power can be shared between the engine generator 10 and the energy storage device 30, and the engine generator 10, which has a lower power factor than the inverter 32, can share a relatively larger amount of ineffective power.

[0096] The instruction generation unit 3256 generates control instructions for the inverter 32 based on the target value of the effective power determined in step S3 and the target value of the ineffective power determined in step S4 (step S5). The instruction generation unit 3256 outputs the generated control instructions to the inverter 32 (step S6). Thus, the inverter 32 can output power with the target value of the effective power determined in step S3 and the target value of the ineffective power determined in step S4.

[0097] Functions and Effects

[0098] Thus, the instruction generation device 33 of the second embodiment determines the target value of the voltage frequency and the target value of the effective power based on the bus voltage value. At this time, the higher the bus voltage, the higher the target value of the voltage frequency, and the lower the target value of the effective power. Therefore, the voltage frequency and effective power of the energy storage device 30 can be changed without lag relative to the fluctuations in the engine generator 10, which operates according to the droop characteristics. Therefore, according to the instruction generation device 33, in the power supply system 1 having an engine generator 10 as an AC generator and an energy storage device 30 as a DC power supply device, the engine generator 10 and the energy storage device 30 can each bear the fluctuations in the load L.

[0099] Furthermore, in the second embodiment, the instruction generation device 33 is installed separately from the inverter 32. Therefore, by installing the instruction generation device 33 within the already installed energy storage device 30, the disconnection of the energy storage device 30 can be prevented without modifying the inverter 32.

[0100] Furthermore, in the second embodiment, the command generation device 33 determines the target value of the effective power based on the effective power droop function F2, which represents the monotonically decreasing relationship between the effective power and the voltage frequency. The change in effective power relative to the voltage frequency in the effective power droop function F2 is consistent with the effective power droop characteristic of the engine generator 10. Therefore, the command generation device 33 can change the effective power output of the inverter 32 in a way that matches the droop characteristic of the engine generator 10.

[0101] Furthermore, in other embodiments, this is not the only limitation. For example, in other embodiments, the change in effective power relative to voltage frequency in the effective power droop function F2 of the command generation device 33 may not be consistent with the effective power droop characteristic of the engine generator 10. Additionally, in other embodiments, the command generation device 33 may replace the effective power droop function F2 with a function representing a monotonically decreasing relationship between effective power and bus voltage, determining the effective power based on the measured value of the bus voltage.

[0102] Furthermore, the instruction generation device 33 of the second embodiment determines the target value of the ineffective power based on the bus voltage. Therefore, the inverter 32 can allow the engine generator 10 and the energy storage device 30 to respectively bear the ineffective power generated by the fluctuation of the load L. Additionally, the instruction generation device 33 of the second embodiment determines the target value of the ineffective power based on the ineffective power droop function F3, which represents the monotonically decreasing relationship between the ineffective power and the voltage value. The voltage intercept and the ineffective power intercept of the ineffective power droop function F3 are below the voltage intercept and the ineffective power intercept of the ineffective power droop characteristic of the engine generator 10. Therefore, the instruction generation device 33 can share the ineffective power with the engine generator 10 and the energy storage device 30, and allow the engine generator 10, which has a lower power factor than the inverter 32, to bear a relatively larger share of the ineffective power. However, other embodiments are not limited to this. For example, the instruction generation device 33 in other embodiments can also be controlled to prevent the inverter 32 from bearing ineffective power and only bear effective power.

[0103] In the second embodiment, the inverter 32 of the energy storage device 30 is controlled as described above, but other embodiments are not limited to this. For example, in other embodiments, the inverter 22 of the solar generator 20 may also be controlled in the same way. In addition, in other embodiments, the above-described control may be performed on a portion of the multiple inverters 32, while the other inverters 32 may be controlled normally.

[0104] <Computer Architecture>

[0105] Figure 8 It is a schematic block diagram showing the structure of a computer according to at least one embodiment.

[0106] The computer 324 of at least one embodiment described above includes a processor 91, a main memory 92, a storage unit 93, and an interface 94. The operations of each of the aforementioned processing units are then stored in the storage unit 93 as a program. The processor 91 reads the program from the storage unit 93, expands it in the main memory 92, and executes the aforementioned processing according to the program. Furthermore, the processor 91, according to the program, secures a storage area in the main memory 92 corresponding to the aforementioned control function storage unit 3251.

[0107] The program can also be used to implement a portion of the functions that enable the computer 324 to perform. For example, the program can also function by combining with other programs already stored in memory 93, or with other programs installed in other devices. Additionally, in other embodiments, the computer 324 may have a custom LSI (Large Scale Integrated Circuit) such as a PLD (Programmable Logic Device), in addition to or replacing the above-described structure. Examples of PLDs include PAL (Programmable Array Logic), GAL (Generic Array Logic), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Array). In this case, some or all of the functions implemented by the processor 91 can be implemented through this integrated circuit.

[0108] Examples of storage devices 93 include HDDs (Hard Disk Drives), SSDs (Solid State Drives), magnetic disks, optical disks, CD-ROMs (Compact Disc Read Only Memory), DVD-ROMs (Digital Versatile Disc Read Only Memory), and semiconductor memory. Storage device 93 can be an internal medium directly connected to the bus of computer 324, or an external medium connected to computer 324 via interface 94 or a communication line. Furthermore, when the program is distributed to computer 324 via a communication line, computer 324 receiving the distribution can also expand the program on main memory 92 and execute the aforementioned processing. In at least one embodiment, storage device 93 is a non-transitory tangible storage medium.

[0109] In addition, this program can also be used to implement some of the functions described above. Furthermore, this program can also achieve the above functions by combining with other programs already stored in storage 93, i.e., a so-called differential file (differential program).

[0110] The above description of one embodiment is based on the accompanying drawings. However, the specific structure is not limited to the structure described above, and various design changes can be made.

[0111] Industrial availability

[0112] In a power supply system having an AC generator and a DC power supply device, the instruction generation device of at least one of the above methods can control the inverter so that the AC generator and the DC power supply device respectively bear the load variation.

[0113] Label Explanation

[0114] 1. Power supply system

[0115] 10-engine generator

[0116] 11 engines

[0117] 12 generators

[0118] 13 Speed ​​Controller

[0119] 14 AVR

[0120] 20 Solar generators

[0121] 21 Solar cells

[0122] 22 Inverters

[0123] 30. Energy storage device

[0124] 31 Secondary batteries

[0125] 32 Inverters

[0126] 33 Instruction generation device

[0127] 322 Ammeter

[0128] 323 Voltmeter

[0129] 324 Computer

[0130] 3241 Model Storage Unit

[0131] 3242 Command Receiving Unit

[0132] 3243 Measurement Acquisition Section

[0133] 3244 Excitation Voltage Calculation Unit

[0134] 3245 Drive Torque Calculation Unit

[0135] 3246 Rotational Calculation Unit

[0136] 3247 Target Decision Department

[0137] 3248 Instruction Generation Unit

[0138] 3251 Control Function Storage Section

[0139] 3252 Measurement Acquisition Section

[0140] 3253 Target Frequency Determination Unit

[0141] 3254 Target Effective Power Determination Unit

[0142] 3255 Target Ineffective Power Determination Unit

[0143] 3256 Instruction Generation Unit

[0144] 3257 Command Receiving Unit

[0145] 40 Power control device

Claims

1. An instruction generation apparatus for generating control instructions for an inverter of a DC power supply device, the inverter operating based on the control instructions including target values ​​for effective power, ineffective power, and voltage frequency, and converting DC power into AC power, the DC power supply device being connected to the same bus as an AC generator that supplies power through independent operation. The instruction generation device includes: The rotation calculation unit calculates values ​​related to the rotation of the rotor of the virtual generator when the virtual generator is driven according to the effective power command, based on the rotor model that simulates the driving of the virtual generator and calculates values ​​related to the rotation of the rotor of the virtual generator, and the effective power command. The target determination unit determines the target value of the voltage frequency and the target value of the effective power based on the calculated values ​​related to the rotation. as well as The instruction generation unit generates a control instruction that includes the determined target value of the voltage frequency and the target value of the effective power, and outputs the control instruction to the inverter. The instruction generation device is located separately from the device including the inverter connected to the DC power supply device. The time constant related to the synchronizing force of the rotor model is consistent with the time constant related to the synchronizing force of the alternator. The instruction generation device includes a drive torque calculation unit. This drive torque calculation unit calculates values ​​related to the drive torque of the virtual generator by inputting the bus voltage frequency, the inverter frequency command, and the effective power command into the speed governor model. The speed governor model determines the values ​​related to the drive torque of the virtual generator based on the bus effective voltage, frequency command, and effective power command. The rotation calculation unit calculates values ​​related to the rotation of the virtual generator based on the calculated values ​​related to the driving torque and the rotor model.

2. The instruction generation apparatus as described in claim 1, wherein, The time constant related to the droop filter of the speed governor model is the same as the time constant related to the droop filter of the speed governor of the alternator.

3. The instruction generation apparatus as described in claim 1 or 2, wherein, The instruction generation device includes an excitation voltage calculation unit. This unit calculates values ​​related to the excitation voltage of the virtual generator by inputting the bus voltage and the invalid power command for the inverter into the automatic voltage regulator model. The automatic voltage regulator model determines the values ​​related to the excitation voltage of the virtual generator based on the bus voltage and the invalid power command. The target determination unit determines the target values ​​for effective power and ineffective power based on the calculated values ​​related to the rotation and the excitation voltage.

4. An instruction generation apparatus for generating control instructions for an inverter of a DC power supply device, the inverter operating based on the control instructions including target values ​​for effective power, ineffective power, and voltage frequency, and converting DC power into AC power, the DC power supply device being connected to the same bus as an AC generator that supplies power through independent operation. The instruction generation device includes: The target determination unit determines the target value of the effective power that decreases monotonically relative to the voltage value of the bus. as well as The instruction generation unit generates a control instruction containing the determined target value of the effective power, and outputs the control instruction to the inverter. The instruction generation device is located separately from the device including the inverter connected to the DC power supply device. The target determination unit determines a target value for the voltage frequency that increases monotonically relative to the voltage value, and determines the target value for the effective power based on the effective power droop function that represents the relationship between effective power and voltage frequency that decreases monotonically and the determined target value for the voltage frequency.

5. The instruction generation apparatus as described in claim 4, wherein, The change in effective power relative to voltage frequency in the effective power droop function is consistent with the effective power droop characteristic of the AC generator.

6. The instruction generation apparatus as described in claim 4 or 5, wherein, The target determination unit determines a target value for ineffective power that decreases monotonically relative to the voltage value of the bus. The instruction generation unit generates control instructions for the inverter based on the determined target values ​​for effective power and ineffective power.

7. The instruction generation apparatus as described in claim 6, wherein, The target determination unit determines the target value of the invalid power based on the invalid power droop function, which represents the monotonically decreasing relationship between invalid power and voltage value, and the determined voltage value of the bus.

8. The instruction generation apparatus as described in claim 7, wherein, The voltage intercept of the ineffective power droop function and the ineffective power intercept are below the voltage intercept of the ineffective power droop characteristic of the AC generator and the ineffective power intercept.

9. A method for generating instructions, wherein an instruction generating device generates control instructions for an inverter of a DC power supply device, the inverter operating based on the control instructions including target values ​​for effective power, ineffective power, and voltage frequency, and converting DC power into AC power, the DC power supply device being connected to the same bus as an AC generator that supplies power through independent operation. The instruction generation method includes: The steps involve calculating the values ​​related to the rotation of the rotor of the virtual generator when the virtual generator is driven according to the effective power command, based on the rotor model that simulates the driving of the virtual generator and calculates the values ​​related to the rotation of the rotor of the virtual generator, and the effective power command. The step of determining the target value of the voltage frequency and the target value of the effective power based on the calculated values ​​related to the rotation; as well as The steps include generating control commands that contain the determined target values ​​for the voltage frequency and the effective power, and outputting the control commands to the inverter. The instruction generation device is located separately from the device including the inverter connected to the DC power supply device. The time constant related to the synchronizing force of the rotor model is consistent with the time constant related to the synchronizing force of the alternator. By inputting the bus voltage frequency, the inverter frequency command, and the effective power command into the speed controller model, values ​​related to the drive torque of the virtual generator are calculated. The speed controller model determines these values ​​based on the bus effective voltage, frequency command, and effective power command. Based on the calculated value related to the driving torque and the rotor model, the value related to the rotation of the virtual generator is calculated.

10. A method for generating instructions, wherein an instruction generating device generates control instructions for an inverter of a DC power supply device, the inverter operating based on the control instructions including target values ​​for effective power, ineffective power, and voltage frequency, and converting DC power into AC power, the DC power supply device being connected to the same bus as an AC generator that supplies power through independent operation. The instruction generation method includes: The step of determining the target value of the effective power that decreases monotonically relative to the voltage value of the bus; as well as The steps of generating the control command containing the determined target value of the effective power and outputting the control command to the inverter. The instruction generation device is located separately from the device including the inverter connected to the DC power supply device. A target value for the voltage frequency that monotonically increases relative to the voltage value is determined, and the target value for the effective power is determined based on the effective power droop function that represents the relationship between effective power and voltage frequency that monotonically decreases, and the determined target value for the voltage frequency.

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