Distributed power source integration management device and power system

Abstract

A distributed power source integration management device (101) manages the running state of a power system to which a plurality of distributed power sources (102) are connected, the output voltages of the distributed power sources (102) being controlled by a virtual synchronous generator control function that simulates implementation of the operating characteristics of a synchronous generator in a static power source. A receiving unit (301) receives information (311) relating to the running states of the distributed power sources (102). An operation determination unit (303) determines an operation pattern for the plurality of distributed power sources (102) on the basis of the information (311) acquired by the receiving unit (301). A control parameter determination unit (304) determines control parameter values for virtual synchronous generator control that will allow the power system to operate stably in the determined operation pattern by avoiding mutual interference of the virtual synchronous generator control among the plurality of distributed power sources (102).

Description

Distributed power integrated management device and power system

[0001] The present disclosure relates to a distributed power supply integrated management device and a power system.

[0002] Due to the demand for decarbonization, the introduction of distributed power sources using renewable energy into power systems is accelerating. These distributed power sources are connected to the power system using static power conversion devices that do not involve rotational motion. Therefore, compared to rotating machine power sources such as synchronous generators that have traditionally served as the main power sources of power systems, they are characterized by not having the system voltage maintenance effect (so-called inertial force) that is derived from the inertia of rotational motion. Therefore, as the proportion of power sources using static power conversion devices (hereinafter also referred to as "static power sources") increases, there are concerns about a decline in the stability of the power system.

[0003] As a countermeasure to this, a virtual synchronous generator control technology has been proposed, which applies inertial force to a static power supply by implementing control that simulates dynamic characteristics equivalent to those of a rotating machine power supply in the static power supply. For example, Japanese Patent Publication No. 6084863 (Patent Document 1) describes a specific control method for virtual synchronous generator control. In particular, Patent Document 1 describes a power conversion device that can continue operation despite fluctuations in system voltage or system frequency without using a PLL (Phase Locked Loop) circuit for detecting the system frequency.

[0004] Patent No. 6084863

[0005] By introducing virtual synchronous generator control technology such as that described in Patent Document 1, it becomes possible for static power sources to contribute to the stability of the power grid. As a result, it is expected that concerns about stability can be eliminated and the introduction rate of static power sources can be increased, thereby contributing to decarbonization.

[0006] However, when multiple static generators with virtual synchronous generator control are connected and operating simultaneously in a power system or an autonomous microgrid, depending on the control parameter values, the control systems of the different distributed generators may interfere with each other, resulting in divergent operation. As a result, there is a concern that instability may occur in the power system or microgrid.

[0007] Therefore, in a system where multiple distributed power sources coexist, if each individual distributed power source determines or changes its control parameters for its own convenience, there is a concern that the system as a whole will not be able to be consistent, resulting in the instability phenomenon described above and making it impossible to provide a stable power supply.

[0008] The present disclosure has been made to solve such problems, and an object of the present disclosure is to provide a distributed power source integrated management device for implementing a stable power supply while avoiding the occurrence of unstable phenomena due to mutual interference in control between multiple distributed power sources connected to a power grid.

[0009] According to one aspect of the present disclosure, there is provided a distributed power supply integrated management device. The distributed power supply integrated management device manages the operational state of a power system to which a plurality of distributed power supplies are connected, the output voltage of which is controlled by virtual synchronous generator control, in which the operating characteristics of a synchronous generator are simulated and implemented in a static power supply. The distributed power supply integrated management device includes a receiving unit, an operation determination unit, a control parameter determination unit, and a transmitting unit. The receiving unit receives information regarding the operating states of the plurality of distributed power supplies. The operation determination unit determines an operation pattern for the plurality of distributed power supplies based on the information acquired by the receiving unit. The control parameter determination unit determines control parameter values ​​for virtual synchronous generator control for each of the plurality of distributed power supplies in the operation pattern determined by the operation determination unit, such that mutual interference between the virtual synchronous generator controls of the plurality of distributed power supplies can be avoided and the power system can operate stably. The transmitting unit transmits, to each of the plurality of distributed power supplies, an operation command in accordance with the operation pattern determined by the operation determination unit and the control parameter values ​​determined by the control parameter value determination unit.

[0010] In another aspect of the present disclosure, a power system is disclosed. The power system includes a power grid, the distributed power supply integrated management device described above, and a communication path formed between the distributed power supply integrated management device and a plurality of distributed power sources. The power grid is connected to a plurality of distributed power sources, the output voltage of which is controlled by virtual synchronous generator control that simulates the operating characteristics of a synchronous generator on a static power source.

[0011] According to the present disclosure, it is possible to avoid the occurrence of unstable phenomena due to mutual interference in control between multiple distributed power sources connected to a power grid, thereby achieving a stable power supply to the power grid.

[0012] 5 is a block diagram illustrating a schematic configuration of a power system managed by a distributed power system integration management apparatus according to a first embodiment. FIG. 6 is a block diagram illustrating an example configuration of a distributed power source. FIG. 7 is a block diagram illustrating an example control configuration of virtual synchronous generator control applied to each distributed power source. FIG. 8 is a block diagram illustrating the internal configuration of a distributed power system integration management apparatus according to a first embodiment. FIG. 9 is a block diagram illustrating an example of a power system in which a plurality of distributed power sources according to a comparative example equipped with virtual synchronous generator control are connected to a power system. FIG. 10 is a first simulation waveform diagram of the output of each distributed power source in the power system shown in FIG. 5. FIG. 11 is a second simulation waveform diagram of the output of each distributed power source in the power system shown in FIG. 10. FIG. 11 is a conceptual diagram illustrating linear approximation of the output power characteristics of the distributed power sources for introducing a state equation. FIG. 12 is a conceptual diagram illustrating the size of the coefficient matrix A of the state equation. FIG. 13 is a flowchart illustrating an example of a process procedure for determining control parameter values ​​by a distributed power system integration management apparatus according to a first embodiment. FIG. 14 is an example of a block diagram illustrating the control transfer characteristics of a power system including a transfer function used in a distributed power system integration management apparatus according to a second embodiment. FIG. 15 is a conceptual diagram illustrating the gain margin and phase margin of a open-loop transfer function. FIG. 16 is a block diagram illustrating the internal configuration of a distributed power system integration management apparatus according to a third embodiment. FIG. 17 is a block diagram illustrating the internal configuration of a distributed power system integration management apparatus according to a fourth embodiment.

[0013] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the following, the same or corresponding parts in the drawings will be denoted by the same reference numerals, and their description will not be repeated in principle.

[0014] First Embodiment Fig. 1 is a block diagram illustrating a schematic configuration of a power system 10 including a plurality of distributed power sources, which is managed by a distributed power source integrated management device 101 according to a first embodiment.

[0015] As shown in FIG. 1, the power system 10 includes a distributed power supply integrated management device 101, multiple distributed power sources 102a to 102f, a communication path 109 formed between the distributed power supply integrated management device 101 and each of the distributed power sources 102a to 102f, and a power grid 104 to which the multiple distributed power sources 102a to 102f are connected.

[0016] The power system 104 is a network including power sources and consumers (not shown), as well as wiring (not shown) that electrically connects the power sources and consumers. The scale of the network may be the entire jurisdiction area managed by a general electricity transmission and distribution utility, an autonomous microgrid operated independently on a specific municipal scale, or a distribution network within a specific building. The power system 104 may be a system that uses either three-phase AC or single-phase AC.

[0017] The distributed power sources 102a to 102f are among the distributed power sources connected to the power grid 104, and are controlled in output voltage by virtual synchronous generator control, which will be described later, and are managed by the distributed power source integrated management device 101. Hereinafter, the distributed power sources 102a to 102f will be collectively referred to simply as the distributed power sources 102. The distributed power sources 102 can be configured by a solar power generation system, a wind power generation system, a storage battery system, or the like.

[0018] 2 is a block diagram illustrating an example of the configuration of the distributed power source 102. Referring to FIG. 2, the distributed power source 102 includes a control device 103, a power source 105, and a power conversion device 106.

[0019] The power supply 105 can be configured by a power generating element such as a solar cell or a wind power generator, or by a power storage element such as a battery or a capacitor. The power conversion device 106 is a "static power supply" that converts the power from the power supply 105 into AC power for connection to the power grid 104. That is, the power conversion device 106 has a main circuit 107 that performs power conversion by controlling the on / off of a semiconductor switching element (not shown), and a switching control circuit 108 that generates an on / off control signal for the semiconductor switching element in the main circuit 107.

[0020] The control device 103 generates an operation command for the power conversion device 106 in accordance with information from the distributed power supply integration management device 101 shown in Fig. 1. As will be described later, in this embodiment, the control device 103 controls the output voltage of the distributed power sources 102 by virtual synchronous generator control using control parameter values ​​from the distributed power supply integration management device 101. That is, in the control device 103, an operation command for controlling power conversion in the main circuit 107 is generated in accordance with the virtual synchronous generator control. The control device 103 can be configured, for example, by a microcomputer including a processor such as a CPU (Central Processing Unit), a memory, and the like (not shown).

[0021] The switching control circuit 108 controls the on / off of semiconductor switching elements in the main circuit 107 so that power conversion is performed in the main circuit 107 in accordance with an operation command from the control device 103 .

[0022] The distributed power source 102 is not limited to a configuration incorporating a power generation device or a power storage device, but may be configured to convert power from a power source such as another DC system into AC power, as illustrated by the dotted line in Figure 2.

[0023] 1 , in the power system 10, the number N of distributed power sources 102 (N: natural number) is any number equal to or greater than 2. While an example of N=6 is shown in FIG. 1 , it goes without saying that N>6 or 2≦N<6 may also be possible.

[0024] A communication path 109 is formed between the distributed power source integrated management device 101 and each of the distributed power sources 102. The communication path 109 can be formed by either a wired connection or a wireless connection. The distributed power source integrated management device 101 sends and receives information to and from each of the distributed power sources 102a to 102f via the communication path 109, and manages the operating status of each of the distributed power sources 102a to 102f.

[0025] Next, virtual synchronous generator control applied to the distributed power sources will be described. Fig. 3 is a block diagram illustrating an example of the control configuration of virtual synchronous generator control applied to each distributed power source 102. As described above, virtual synchronous generator control is a control for simulating the static power source (main circuit 107) to have operating characteristics equivalent to those of a rotating machine power source.

[0026] For example, the functions of the distributed power supply control unit 200 shown in Fig. 3 can be realized by software processing in which a microcomputer constituting the control device 103 executes a pre-stored program. Alternatively, at least some of the functions of each block in Fig. 3 can also be realized by hardware circuits.

[0027] 3, the distributed power supply control unit 200 includes a virtual synchronous generator control unit 201 and an operation command value generation unit 202. For example, the operation command value generation unit 202 calculates the frequency f and phase θ of the AC voltage output from the distributed power supply 102 in accordance with the calculation result of the virtual synchronous generator control unit 201. Then, the switching control circuit 108 shown in FIG. 2 controls the on / off of the semiconductor switching elements constituting the main circuit 107 so that the main circuit 107 outputs an AC voltage according to the calculated frequency f and phase θ.

[0028] First, we will explain the operating characteristics of a normal rotating machine power supply that are simulated by virtual synchronous generator control. Generally, a rotating machine power supply has a characteristic in which the rotational speed of the rotor fluctuates based on the oscillation equation shown in Equation (1) in response to mechanical input energy Pm input to the rotor from outside and electrical output energy Pe output to the grid.

[0029]

[0030] In equation (1), ω is the rotor rotation speed, ω0 is the rotor's rated rotation speed, M is the rotor's inertia constant, and D is the rotor's damping coefficient. From equation (1), it can be seen that when the mechanical input energy Pm and the electrical output energy Pe are equal (Pm = Pe), the rotor rotation speed ω is maintained constant. On the other hand, when Pm > Pe, the rotor accelerates, and when Pe > Pm, the rotor decelerates. The rotor rotation speed ω is related to the frequency f of the AC voltage output by the rotating machine power supply by a constant multiple (for example, ω = 2π f).

[0031] Next, we will explain the advantages of rotating machine power supplies that stem from this characteristic. Not limited to rotating machine power supplies, if the phase difference δ between the phase of the output voltage of a power supply connected to a power grid and the voltage phase on the power grid side is used, the electrical output energy Pe can be expressed by equation (2).

[0032]

[0033] In equation (2), P is a positive constant determined depending on the internal impedance and voltage amplitude of the generator. Generally, the phase difference δ is used in the range of 0<δ<90 degrees, and within this range, there is a positive correlation between Pe and the phase difference δ.

[0034] Possessing the characteristics of both equations (1) and (2) provides the following advantages. For example, if the phase difference δ suddenly increases due to an external disturbance or the like from a state in which the rotating machine power supply is operating steadily at a constant rotational speed ω with Pm = Pe, Pe increases according to equation (2). As a result, Pm < Pe, and the rotor decelerates according to equation (1). As a result, the phase difference δ gradually decreases, allowing the rotating machine power supply to return to its original steady operating state. Conversely, if the phase difference δ suddenly decreases from the above steady operating state, Pe decreases according to equation (2), and Pm > Pe, allowing the rotor to accelerate according to equation (1). As a result, the phase difference δ increases and decreases, allowing the rotating machine power supply to return to its original steady operating state.

[0035] In this way, the rotating machine power supply has the advantage of being able to self-return to a stable operating state due to the characteristic shown in formula (1).Furthermore, by using the same principle, when multiple different rotating machine power supplies are operated in parallel, there is also the advantage that cross currents occurring between the rotating machine power supplies can be eliminated and the rotation speed and voltage phase can be synchronized.

[0036] In contrast, static power supplies do not have the characteristics shown in the above equation (1), and therefore cannot obtain the above-mentioned advantage of compensating for fluctuations in phase difference δ and automatically returning to a steady operating state. For this reason, virtual synchronous generator control is introduced to simulate the compensation characteristics equivalent to equation (1).

[0037] As shown in FIG. 3, the virtual synchronous generator control unit 201 includes subtractors 211 to 213, an integrator 203, a feedback path 204, and a governor control unit 205.

[0038] The subtractor 211 calculates the command value of the active power output from the distributed power source 102 (power conversion device 106) (hereinafter referred to as the output active power command value P ｒｅｆ ) to the output active power measurement value P ｏｕｔ Subtracting this, the active power deviation ΔP ｏｕｔ Calculate the active power deviation ΔP ｏｕｔ is passed through an integrator 203, which uses the reciprocal (1 / M) of the inertia constant M in equation (1) as an integration constant, and also passes through a feedback path 204, which multiplies the output value of the integrator 203 by the damping coefficient D in equation (1), and is negatively fed back to a subtractor 213.

[0039] Furthermore, the output value of the integrator 203b is negatively fed back to the subtractor 212 by a governor control unit 205 having a first-order lag element (K / (1+T·s)) with a gain K and a time constant T.

[0040] The calculation process by the integrator 203 and the feedback path 204 corresponds to the calculation of the vibration equation of the rotating machine shown in Equation (1). Furthermore, the governor control section 205 is a feedback path for adding a characteristic equivalent to a speed governor provided in the rotating machine power supply. The virtual synchronous generator control section 201 calculates the active power deviation ΔP ｏｕｔBy executing these control calculations on the frequency of the output voltage from the dispersed power source 102 (power conversion device 106), the amount of change in frequency Δf is calculated.

[0041] The operation command value generating unit 202 has an adder 214, a multiplier 206, and an integrator 208. The adder 214 adds the reference frequency fn of the output voltage and the frequency change amount Δf calculated by the virtual synchronous generator control unit 201 to calculate a frequency command value f of the output voltage. The multiplier 206 multiplies the frequency command value f output from the adder 214 by 2π to calculate an angular frequency ω corresponding to the rotation speed. The integrator 208 integrates the angular frequency ω output from the multiplier 206 to calculate a phase command value θ of the output voltage.

[0042] 2, the distributed power source 102 is controlled so that the frequency and phase of the output voltage (AC voltage) of the power conversion device 106 become equal to the frequency command value f and phase command value θ described above. As a result, the distributed power source 102 to which virtual synchronous generator control is applied can obtain operating characteristics equivalent to those of a rotating machine power source, the ability to self-return to a stable operating state, and the ability to eliminate cross currents between different power sources and achieve frequency and phase synchronization.

[0043] 3, the inertia constant M included in the integrator 203, the damping coefficient D included in the feedback path 204, and the gain K and time constant T included in the first-order lag element of the governor control unit 205 are control parameters that can be changed by a designer or administrator. By changing the values ​​of these control parameters, the operating characteristics of the virtual synchronous generator control can be changed.

[0044] Fig. 4 is a block diagram illustrating an example of the internal configuration of the distributed power supply integrated management apparatus 101. Referring to Fig. 4, the distributed power supply integrated management apparatus 101 includes a receiving unit 301, a calculation unit 302, a storage unit 305, and a transmission unit 306. Using the receiving unit 301 and the transmission unit 306, the distributed power supply integrated management apparatus 101 forms a communication path 109 (Fig. 1) between the distributed power supplies 102 connected to the power grid 104.

[0045] The receiving unit 301 receives distributed power source information 311 transmitted from each distributed power source 102. For example, the distributed power source information 311 includes information on the past and present operating states of the distributed power source 102, and information on the control configuration or control-related constants of the distributed power source 102.

[0046] The receiving unit 301 passes the received distributed power source information to the calculation unit 302 as distributed power source information 312. The receiving unit 301 can generate the distributed power source information 312 by performing preprocessing on the received distributed power source information 311 to convert it into a form that can be used for calculations in the calculation unit 302.

[0047] For example, the preprocessing by the receiver 301 may include a process of converting a signal transmitted in accordance with a communication protocol into a signal form that can be processed by the calculator 302, a filtering process of removing or extracting a specific frequency band from the received time-series signal, and a process of calculating active power based on information about the output voltage and output current of the distributed power sources. Note that in the first embodiment, the distributed power source information 311 received by the receiver 301 includes at least the amplitude and phase of the current output voltage of each distributed power source 102 and information about the output active power.

[0048] The storage unit 305 stores in advance information about the configuration and connection state of the distributed power sources 102 and power grids 104 that are managed by the distributed power source integrated management device 101. Furthermore, the storage unit 305 appropriately transfers information 319 that is required for processing in the calculation unit 302 to the calculation unit 302. Furthermore, the storage unit 305 may update, add, or delete stored information based on information 318 from the calculation unit 302.

[0049] In the first embodiment, the information stored in the storage unit 305 includes at least the connection position of each distributed power source 102 and information related to the impedance of the electrical path connecting the distributed power sources 102. For example, the information related to the impedance includes the reluctance of the path. Note that the storage unit 305 is not limited to being a component of the distributed power source integrated management device 101, and may be configured to be connected to the distributed power source integrated management device 101 via wireless or wired communication. For example, the storage unit 305 may be configured using a cloud on the Internet.

[0050] The calculation unit 302 can be configured, for example, by a microcomputer including a CPU and memory (not shown), similar to the control device 103 in Fig. 2. The calculation unit 302 can realize various functions described below for managing each dispersed power source 102 by, for example, executing a pre-stored program based on dispersed power source information 311 from the receiving unit 301 and information 319 received from the storage unit 305.

[0051] In particular, in this embodiment, the calculation unit 302 determines the control details, such as the control system configuration and control parameter values, for each of the multiple distributed power sources 102 in virtual synchronous generator control so as to ensure the operational stability of the power system 104, while taking into consideration mutual interference via the power grid 104. However, for the sake of simplicity, the following description will be given assuming that the control system configuration is fixed to the example shown in Fig. 3. That is, the calculation unit 302 appropriately sets the values ​​of the control parameters (such as the damping coefficient D, the inertia constant M, the time constant T and gain K of the first-order lag system) used in the virtual synchronous generator control shown in Fig. 3 in order to ensure the operational stability of the system (power grid 104) to which the multiple distributed power sources 102 are connected.

[0052] A management technique for ensuring the operational stability of the system will be described in detail below. First, issues that arise when a plurality of distributed power sources equipped with virtual synchronous generator control coexist in a power system 104 will be described using Figures 5 to 7. Figure 5 is a block diagram illustrating an example configuration of a power system in which three comparative example distributed power sources 102(1) to 102(3) equipped with virtual synchronous generator control coexist in a managed power system.

[0053] Three distributed power sources 102(1) to 102(3) according to the comparative example are connected to each other via a common bus 407. Each of the distributed power sources 102(1) to 102(3) is assumed to have the virtual synchronous generator control shown in FIG. 2. Reactances 404 to 406 corresponding to the wiring distance exist between the distributed power sources 102(1) to 102(3) and the common bus 407. In the following, the reactance values ​​of the reactances 404 to 406 are respectively represented by X １ ~X ３ In addition, power sources and consumers 408 other than those to be managed are also connected to the common bus 407.

[0054] Fig. 6 is a first simulation waveform diagram of the output of each of the distributed power sources 102(1) to 102(3) in the power system shown in Fig. 5. Fig. 6 shows the simulation waveform when the output of each distributed power source converges stably.

[0055] In the simulation of Fig. 6, the parameters of the virtual synchronous generator control for each of the dispersed power sources 102(1) to 102(3) were M = 8, D = 100, K = 20, and T = 0.1. １ ~X ３ is the % impedance based on the rating of the distributed power supply, and X １ = 10 (%), X ２ = 20 (%), X ３ = 40(%).

[0056] FIG. 6 shows the output effective power P ｏｕｔ１ ~P ｏｕｔ３ , and the simulation results for frequencies f1 to f3 of the output voltage are shown.

[0057] As shown in FIG. 6, even if the output active powers Pout1 to Pout3 and the frequencies f1 to f3 fluctuate due to disturbances, they subsequently converge to a constant value due to the self-recovery effect of virtual synchronous generator control, and it can be seen that the distributed power sources 102(1) to 102(3) are operating stably.

[0058] In contrast to this, FIG. 7 shows simulation waveforms in the case of divergent operation in which the output of each distributed power source becomes unstable due to inappropriate control parameter values.

[0059] In the simulation of Fig. 7, the parameters of the virtual synchronous generator control for each of the dispersed power sources 102(1) to 102(3) were M = 8, D = 20, K = 20, and T = 0.1. １ ~X ３ is X １ = 10 (%), X ２ = 20 (%), X ３ = 40(%). That is, compared to the simulation in Fig. 6, the value of the damping coefficient D in the virtual synchronous generator control for each of the dispersed power sources 102(1) to 102(3) is set to a smaller value in the simulation in Fig. 7. The other simulation conditions are the same in Figs. 6 and 7.

[0060] As shown in FIG. ｏｕｔ１ +P ｏｕｔ2 +P ｏｕｔ３ When and are constant, a cross current occurs back and forth between the distributed power sources 102(1) to 102(3) due to the influence of disturbances, and the output effective power P ｏｕｔ１ ~P ｏｕｔ３ The frequencies f1 to f3 change so that the oscillations expand divergently. In such a situation, each of the distributed power sources 102(1) to 102(3) typically exceeds its output limit and automatically shuts down.

[0061] 6 and 7, it can be seen that the stability of the operation of the entire power system varies depending on the settings of the control parameters for multiple distributed power sources. In other words, unless the control parameter values ​​for virtual synchronous generator control in each distributed power source are set appropriately, there is a risk that the power system cannot be maintained in a stable state.

[0062] 7 occurs due to mutual interference between multiple distributed power sources, the control parameter values ​​must be set taking into account mutual interference, rather than simply implementing a complete design for each individual distributed power source. Furthermore, the setting range of the control parameters required to stabilize operation may vary depending on the state of the distributed power source and other power sources and consumers 408 connected to the power grid.

[0063] In order to address the issues that arise when multiple distributed power sources equipped with such virtual synchronous generator control coexist in the power system 104, the processing contents of the calculation unit 302 of the distributed power source integrated management device 101 according to embodiment 1 will be described in detail.

[0064] 4 again, the calculation unit 302 includes an operation determination unit 303 for each dispersed power source 102 and a control parameter determination unit 304. The operation determination unit 303 determines the current output effective power (P in FIG. 3 ) of each dispersed power source 102. ｏｕｔ ) and other information, the operation determination unit 303 determines the number of operating dispersed power sources that is necessary and sufficient to supply power to consumers. Furthermore, based on the determination, the operation determination unit 303 generates an operation / stop command for each dispersed power source 102 and issues a command value for output active power (P in FIG. 3 ) to the dispersed power source 102 for which an operation command is generated. ｒｅｆ ) is determined. In addition, in the distributed power source 102 that is charged from the power grid 104, the output active power command value P ｒｅｆ is a negative value (P ｒｅｆ <0). In addition, in the distributed power source 102 for which the operation command is generated, the output active power command value P ｒｅｆ There are also cases where it is set to 0.

[0065] Hereinafter, each combination (operation pattern) of the operating / stopped states of the multiple dispersed power sources 102 connected to the power grid 104 will be referred to as the output active power command value P ｒｅｆ Each pattern subdivided by a combination of these is also referred to as an operation pattern. That is, when the operation decision unit 303 changes the operation pattern (operation / stop state) of the multiple dispersed power sources, or when the operation pattern is the same but the output active power command value P ｒｅｆWhen this is changed, the operation pattern will be changed.

[0066] When determining the number of operating dispersed power sources 102, the current output effective power (P ｏｕｔ The current demand can be roughly determined from the total value of the distributed power sources 102. Then, to ensure that the determined demand can be fully supplied, the number of operating distributed power sources 102 can be determined so that at least the total rated capacity of the operating distributed power sources 102 exceeds the demand.

[0067] At this time, the operation determination unit 303 may determine which distributed power sources 102 to operate, taking into consideration the economic and environmental costs of operating each distributed power source 102, as well as the operation efficiency, and the operation priority among the distributed power sources 102. Furthermore, if the distributed power source 102 for which an operation command is generated includes a storage battery, the operation determination unit 303 may determine the output active power command value (P ｒｅｆ ) may be determined.

[0068] In this way, the operation determination unit 303 issues an operation / stop command for each dispersed power source 102 and an output active power command value P ｒｅｆ The operation determination unit 303 generates the latest operation command information 313, which includes the above information. The operation determination unit 303 generates the latest operation command information 313 when a certain period of time has elapsed or when a predetermined trigger condition in the distributed power source information 312 is met. This allows the operation command information 313 to be successively updated based on the latest distributed power source information 312. For example, the trigger condition is met when any one of the multiple items constituting the distributed power source information 312 has changed.

[0069] In the first embodiment, the control configuration for virtual synchronous generator control in each distributed power source 102 is determined as shown in FIG. 3, and then the control parameter determination unit 304 determines the control parameter values ​​in the control system of FIG. 3. In the first embodiment, the control parameter determination unit 304 determines the control parameter values ​​based on the operation pattern determined by the operation determination unit 303, and on the distributed power source information 312 received from the receiving unit and the information 319 received from the memory unit, while also evaluating the stability of the entire power system.

[0070] A specific example of a method for evaluating stability will be described below. In the first embodiment, the operating characteristics of a power system to be managed are expressed by a state equation, and stability is evaluated from the eigenvalues ​​of the coefficient matrix of the state equation. Here, a specific stability evaluation method will be described for a power system including three distributed power sources equipped with virtual synchronous generator control, as shown in FIG. 5 as an example.

[0071] First, the output effective power P of the first dispersed power source 102(1) ｏｕｔ１ and reactance value X １ and the voltages across them satisfy the relationship shown in the following equation (3). Ｌ and θ Ｌ are the amplitude and phase of the voltage of the common bus 407 at the connection point of the distributed power source 102(1), and V １ and θ １ are the amplitude and phase of the output voltage of the distributed power source 102(1). Also, Δ indicates the amount of minute fluctuation of each variable from the standard value when the power system is operating steadily and stably.

[0072]

[0073] Since the relationship in equation (3) includes nonlinear characteristics, in order to introduce a state equation, a linear approximation as shown in FIG. 8 is performed on the output power characteristics of the distributed power source.

[0074] Referring to FIG. 8, the phase difference (Δθ １ -Δθ Ｌ ) = δ １ When expressed as above, the output effective power P of the dispersed power source 102(1) is ｏｕｔ１ is |V in equation (3). １ ||V Ｌ | / X １ is the maximum value Pmax (amplitude) １ is shown as a sine function (characteristic line 111).

[0075] The phase difference at the operating point 112 on the characteristic line 111 in the stable operation state of the power system is δ １0 Then, the slope of the tangent to the characteristic line 110 at the operating point 112 is cos δ １0This allows obtaining a characteristic line 111 (linear function) relating to the amount of fluctuation Δ from the operating point 112, which is linearly approximated near the operating point 112. The characteristic line 111 is expressed by the following equation (4). In addition, the output effective power P ｏｕｔ２ and P ｏｕｔ３ For the above, equations (5) and (6) can be obtained by performing a similar linear approximation on the amount of fluctuation from the operating point in a stable operating state.

[0076]

[0077] In addition, the phase difference δ in the formula (5) 20 represents the phase difference between the voltage of the common bus 407 at the connection point of the dispersed power source 102(2) and the common bus 407 in a stable operating state and the output voltage of the dispersed power source 102(2). Similarly, the phase difference δ in equation (6) 30 indicates the phase difference between the voltage of the common bus 407 at the connection point of the dispersed power source 102(3) and the common bus 407 and the output voltage of the dispersed power source 102(3) in a stable operating state.

[0078] In formulas (4) to (6), P １ｍ = (| V １ ||V Ｌ | / X １ ) cosδ １０ and P 2ｍ = (| V ２ ||V Ｌ | / X ２ ) cosδ ２０ and P ３ｍ = (| V ３ ||V Ｌ | / X3)・cosδ 30 So, P １ｍ ~P ３ｍ is the reactance value X １ ~X ３ are coefficients that are inversely proportional to

[0079] Furthermore, the output effective power P of the distributed power sources 102(1) to 102(3) ｏｕｔ１ ~P ｏｕｔ３Since the sum of these is equal to the power PL flowing into the power sources other than the managed power sources and the consumer 408, the following equation (7) holds for the amount of fluctuation Δ from the stable operation state.

[0080]

[0081] From equations (4) to (7), Δθ Ｌ By eliminating and rearranging in matrix form, we can obtain equation (8).

[0082]

[0083] On the other hand, the characteristics of the virtual synchronous generator control provided in each of the dispersed power sources 102(1) to 102(3) are expressed as a state equation. When each of the dispersed power sources 102(1) to 102(3) is provided with the virtual synchronous generator control having the configuration shown in FIG. 3, the transfer function is shown in equation (9). When the transfer function of equation (9) is re-expressed as a state equation, the internal state variable x １ ~x ３ By setting the internal state variable x ２ is the internal state variable x １ is the derivative of the internal state variable x ３ is the internal state variable x ２ The equations (10) and (11) correspond to the state equation representation of the virtual synchronous generator control for one distributed power source 102.

[0084]

[0085] When the state equations for the virtual synchronous generator control of the three dispersed power sources 102(1) to 102(3) in FIG. 5, which are represented by equations (10) and (11) and which are established for each of the three dispersed power sources, are integrated into one state equation, equations (12) and (13) are obtained. In equations (12) and (13), the state variable x ｉｊ indicates the j-th state variable of the i-th distributed power source.

[0086]

[0087] Finally, equations (12) and (13) are combined to obtain ΔP ｏｕｔ１ ~ΔP ｏｕｔ３ and Δθ １~Δθ ３ By eliminating, we can obtain equation (14).

[0088]

[0089] Here, for the three dispersed power sources 102(1) to 102(3), the coefficient matrix A (9 rows x 9 columns) in equation (14) is expressed by the following equation (15).

[0090]

[0091] Similarly, the matrix B (9 rows×4 columns) in equation (14) is expressed by the following equation (16).

[0092]

[0093] Equation (14) is a state equation expression that includes all the operating characteristics of the power system to be managed. Then, by calculating the eigenvalues ​​of the coefficient matrix A (Equation (15)) of Equation (14), the oscillation mode of the system can be grasped.

[0094] Generally, the real part of the eigenvalue of the coefficient matrix A indicates the damping rate of the vibration of the system when it is negative, and indicates the divergence rate of the vibration when it is positive. Also, the imaginary part of the eigenvalue indicates the frequency of the vibration.

[0095] Therefore, when the eigenvalues ​​of the coefficient matrix A in equation (14) are calculated, if the real parts of all the calculated eigenvalues ​​are negative, it can be confirmed that the oscillations occurring in this system will be attenuated and stable. In other words, the absolute value of the real parts of the eigenvalues, which are negative values, can be used as a stability index for evaluating the stability of the power system.

[0096] As described above, in this embodiment, in practice, linear approximation is used in the derivation process, and therefore errors occur between the characteristics obtained from the above state equations and the operating characteristics of the actual power system. Therefore, in order to stabilize the operation of the power system, it is desirable that the real parts of all eigenvalues ​​of the coefficient matrix A are negative and that the absolute values ​​of the real parts are equal to or greater than a certain threshold.

[0097] As an example, when the main eigenvalues ​​of the coefficient matrix A described above are derived for a system including three distributed power sources 102(1) to 102(3) as illustrated in FIG. 5 under the setting conditions of the simulation results (stable operation) in FIG. 6, the values ​​are "-11.21523±4.86337i," "-11.221523±4.8632377i," "-11.237589±4.8508335i," and "-11.25±4.8412292i."

[0098] Furthermore, in the case of the setting conditions in the simulation results (unstable operation) of FIG. 7, the main eigenvalues ​​are "-6.1625308±3.2739828i", "-6.2123889±3.2929444i", and "-6.25±3.3071891i".

[0099] Comparing these, it can be seen that although the real parts of the main eigenvalues ​​are all negative in both the cases of Figures 6 and 7, the absolute values ​​of the real parts (negative values) are larger in the case of Figure 6. For example, in order to distinguish between the stable operation of Figure 6 and the unstable operation of Figure 7, it is possible to ensure stable operation of the power system by setting the control parameter values ​​so that the absolute values ​​of the real parts (negative values) of the eigenvalues ​​are 11 or more. Note that the appropriate value of the threshold value may vary depending on the system configuration, so it is desirable to define it in advance based on instantaneous value simulations, etc.

[0100] In this way, by calculating the eigenvalues ​​of the coefficient matrix A of the state equation, it is possible to evaluate the stability of the power system. Here, the coefficient matrix A shown in equation (15) is an example when three distributed power sources 102(1) to 102(3) operate according to virtual synchronous generator control, and has a size of (3 x 3) rows and (3 x 3) columns. However, the size of the coefficient matrix A varies depending on the number of distributed power sources (N: a natural number) that are connected to and operating in the power system. Specifically, when N is the number of distributed power sources for which operation commands have been generated, the size of the coefficient matrix A is (N x 3) rows and (N x 3) columns.

[0101] 9, when N = 2, the coefficient matrix A(2) has a size of 6 rows and 6 columns, since 3 × 2 = 6. When N = 3, the coefficient matrix A(3) has a size of 9 rows and 9 columns, as shown in equation (15), and when N = 4, the coefficient matrix A(4) has a size of 12 rows and 12 columns, since 4 × 3 = 12.

[0102] Furthermore, even if the number (N) of operating distributed power sources operating under virtual synchronous generator control is the same, the reactance value X １ ~X ３ When the combination of operating dispersed power sources changes due to differences in the coefficient matrix A, the coefficient matrix A also changes. Furthermore, when the output active power command value of the operating dispersed power source changes, the operating point 112 (stable operating state) in Fig. 8 changes, which may cause the coefficient matrix A to change.

[0103] Therefore, the coefficient matrix A used for stability evaluation is determined by the operation determination unit 303 in FIG. 3 when the operation / stop command for each dispersed power source 102 and the output active power command value P ｒｅｆ , that is, it may change every time a change occurs in the operation pattern. It is preferable to re-perform the stability evaluation accordingly.

[0104] Fig. 10 shows a flowchart illustrating an example of a process procedure for determining control parameter values ​​by the distributed power source integrated management apparatus according to embodiment 1. The process shown in Fig. 10 is executed, for example, by the microcomputer constituting the calculation unit 302 executing a pre-stored program when the operation pattern (combination of on / off) of at least a plurality of distributed power sources is changed by the operation determination unit 303. This realizes the function of the control parameter determination unit 304 in Fig. 4.

[0105] Alternatively, the process shown in FIG. 10 may be performed by changing the output active power command value P ｒｅｆ 10 may be executed when the operation pattern of the plurality of dispersed power sources 102 is changed by the operation determining unit 303.

[0106] The calculation unit 302 (control parameter determination unit 304) provisionally determines control parameter values ​​for each dispersed power source in step (hereinafter simply referred to as "S") 110. For example, for each dispersed power source to be operated, the values ​​of the inertia constant M, the damping coefficient D, and the gain K and time constant T of the first-order lag element constituting the governor control unit 205 in the virtual synchronous generator control unit 201 illustrated in FIG. 3 are provisionally determined. Note that the initial values ​​of the provisionally determined control parameter values ​​may be predetermined standard values ​​or may be randomly set values. Furthermore, in S110, the coefficient matrix of equation (15) is also provisionally determined using the provisionally determined control parameter values.

[0107] In S120, the calculation unit 302 calculates a stability index of the system using the coefficient matrix A tentatively determined in S110. For example, as described above, the eigenvalues ​​of the coefficient matrix A are calculated. Then, in S130, it is determined whether the stability index calculated in S120 (the eigenvalues ​​of the coefficient matrix A) is within a predetermined stability range. For example, as described above, if the real parts of all the eigenvalues ​​are negative and the absolute values ​​of the real parts are greater than a predetermined threshold, a YES determination is made in S130. On the other hand, if this is not the case, a NO determination is made in S130.

[0108] On the other hand, when the determination in S130 is NO, the calculation unit 302 changes at least some of the control parameter values ​​in S140. In S140, in order to improve the stability of the system, for example, the damping coefficient D and / or the inertia constant M are increased in constant increments (a fixed amount or a fixed ratio) for at least some of the dispersed power sources. Furthermore, if the stability index does not improve sufficiently even after increasing the damping coefficient D and the inertia constant M, the gain K can be further increased.

[0109] Furthermore, the calculation unit 302 returns the process to S110 and provisionally determines a modified coefficient matrix A using the control parameter values ​​changed in S140. Then, in S120, a stability index of the system is calculated using the modified coefficient matrix A, and in S130, it is determined whether the stability index calculated in S120 (eigenvalue of the modified coefficient matrix A) is within a range that ensures stability.

[0110] While the determination in S130 is NO, the processes of S140, S110, S120, and S130 are repeatedly executed. That is, the control parameter value is gradually changed in S140 until the control parameter value that results in a YES determination in S130 is set.

[0111] When the judgment in S130 is YES, the calculation unit 302 uses the values ​​provisionally determined in S110 to finally determine the control parameter values ​​of the virtual synchronous generator control unit 201 of the distributed power source for which the operation command was generated in S150.

[0112] As a result, the operation command information 313 by the operation decision unit 303, specifically, the operation / stop command and the output active power command value P ｒｅｆ Therefore, it is possible to determine the control parameter values ​​that allow the system to operate stably by corresponding to the above.

[0113] Referring again to FIG. 4 , the calculation unit 302 calculates the operation command information 313 (the operation / stop command for each dispersed power source 102 and the output active power command value P ｒｅｆ ) and information 314 (control parameter values ​​for stably operating the system) determined by the control parameter determination unit 304 in response to the operation command information 313 are output to the transmission unit 306 as setting information 315. At this time, information 318 may be transferred to the storage unit 305 for storage. This information 317 may include at least a part of the information output to the transmission unit 306.

[0114] Upon receiving the setting information 315 from the calculation unit 302, the transmission unit 306 transmits to each dispersed power source 102 an operation command value and a control parameter value for that dispersed power source 102. As described above, in the first embodiment, the setting information 315 includes at least the operation / stop command and the output active power command value (operation command information 313) for the dispersed power source 102, and the control parameter values ​​for virtual synchronous generator control provided in each dispersed power source 102 for which an operation command has been generated.

[0115] As described above, according to the distributed power source integrated management device of the first embodiment, even in a power system to which a plurality of distributed power sources are connected, each of which has an output voltage controlled by virtual synchronous generator control, the control parameter values ​​for the virtual synchronous generator control in each distributed power source are appropriately set so that instability due to mutual interference between the distributed power sources does not occur when the operating pattern of the distributed power sources changes. This allows for operation that ensures stability, and a stable power supply that avoids instability due to mutual interference between the controls of the plurality of distributed power sources.

[0116] Embodiment 2. In the first embodiment, the stability index was calculated by finding the eigenvalues ​​of the coefficient matrix A of the state equation, but in the second embodiment, a different method of calculating the stability index will be described. That is, the distributed power supply integration management device according to the second embodiment differs from the distributed power supply integration management device 101 according to the first embodiment only in the function of the control parameter determination unit 304. The configuration and operation of the other parts of the distributed power supply integration management device according to the second embodiment are the same as those of the distributed power supply integration management device 101 according to the first embodiment, and therefore detailed description will not be repeated.

[0117] In the second embodiment, when evaluating the stability of a power system, the control parameter determiner 304 derives a loop transfer function that represents the frequency response of the system. Then, the phase margin and gain margin of the loop transfer function are used as stability indices (S120 in FIG. 9 ) to evaluate the stability of the system in S130 ( FIG. 9 ).

[0118] In the second embodiment, a method of evaluating stability using a loop transfer function will be described for a power system connected to three distributed power sources whose output voltages are controlled by virtual synchronous generator control, as illustrated in FIG. 5 .

[0119] Fig. 11 is an example of a block diagram showing the control transfer characteristics of a power system including a transfer function used in a distributed power source integrated management device according to embodiment 2. Fig. 11 shows a control transfer block diagram that takes into account interference of virtual synchronous generator control provided for three distributed power sources 102(1) to 102(3) in the power system illustrated in Fig. 5.

[0120] In FIG. 11, the active power P on the common bus 407Ｌ , and the output power command value P of the dispersed power sources 102(1) to 102(3). ｒｅｆ１ ~P ｒｅｆ３ , output active power (measured value) P ｏｕｔ１ ~P ｏｕｔ３ , and the phase θ of the output voltage １ ~θ ３ The above-mentioned minute fluctuation amount Δ is introduced for each of the above.

[0121] Here, for the power system illustrated in FIG. 5, equation (8) is established by the linear approximation described in the first embodiment. Furthermore, the output voltages of the distributed power sources 102(1) to 102(3) are controlled by the virtual synchronous generator control of the configuration shown in FIG. 3. Therefore, the transfer function G of the virtual synchronous generator control of each of the distributed power sources 102(1) to 102(3) is ＶＳＧ１ (s) ~ G ＶＳＧ3 Using (s), the transfer characteristics of the power system to which the dispersed power sources 102(1) to 102(3) are connected, reflecting the cross currents (mutual interference) that occur between the dispersed power sources 102(1) to 102(3), are shown in the block diagram of FIG. 11. The transfer function G ＶＳＧ１ (s) ~ G ＶＳＧ3 (s) can be obtained by substituting the control parameter values ​​D, M, T, and K into equation (9).

[0122] In FIG. 11, a cross current ΔP from the dispersed power source 102(1) to the dispersed power source 102(2) ｃｒｓ１２ , the cross current ΔP from the dispersed power source 102(2) to the dispersed power source 102(3) ｃｒｓ２３ , and the cross current ΔP from the dispersed power source 102(1) to the dispersed power source 102(3) ｃｒｓ１３ The total value ΔP of the cross current in each of the dispersed power sources 102(1) to 102(3) is input to the calculators 841 to 843 for addition and subtraction. ｃｒｓ1 ~ΔP ｃｒｓ３ can be obtained.

[0123] Also, the active power fluctuation amount ΔP on the common bus 407 Ｌ is the constant P in equations (4) to (6). １ｍ ΔP is calculated between the dispersed power sources 102(1) to 102(3) by the multipliers 811 to 813 based on ΔP Ｌ１ ~ΔPＬ３ (ΔP Ｌ１ +ΔP Ｌ２ +ΔP Ｌ３ = ΔP Ｌ Adders 834 to 836 receive the ΔP from the multipliers 811 to 813. Ｌ１ ~ΔP Ｌ３ and ΔP from the calculators 841 to 843 ｃｒｓ1 ~ΔP ｃｒｓ３ and are added together to obtain the output active power fluctuation amount ΔP ｏｕｔ１ ~ΔP ｏｕｔ３ are calculated respectively.

[0124] The subtractors 831 to 833 subtract the fluctuation amount ΔP of the output active power command value. ｒｅｆ１ ~ΔP ｒｅｆ３ ΔP from adders 834 to 836 ｏｕｔ１ ~ΔP ｏｕｔ３ By subtracting the above, the fluctuation amount ΔdP of the power deviation ΔPout (FIG. 3) in each of the dispersed power sources 102(1) to 102(3) is １ ~dP ３ Calculate.

[0125] By determining the open-loop transfer function G(1) starting from ΔdP1 in accordance with the control transfer characteristics shown in FIG. 11 , it is possible to grasp the frequency response characteristics of the virtual synchronous generator control by the distributed power source 102(1) taking into account interference with the virtual synchronous generator control by the other distributed power sources 102(2) and 102(3).

[0126] Similarly, by calculating the open-loop transfer function G(2) starting from ΔdP2 and the open-loop transfer function G(3) starting from ΔdP3, it is possible to grasp the frequency response characteristics of the virtual synchronous generator control of the distributed power sources 102(2) and 102(3) taking into account interference with the virtual synchronous generator control of the other distributed power sources.

[0127] Deriving such a loop transfer function is a common technique, and these loop transfer functions can be obtained by applying a known method. It is preferable to derive the form of these loop transfer functions in advance based on the number of operating dispersed power sources and the configuration information of the virtual synchronous generator control unit.

[0128] Furthermore, according to a known technique, the gain margin GM and the phase margin PM shown in FIG. 12 can be further obtained from the Bode plot of the obtained open-loop transfer function.

[0129] 12, a Bode diagram showing the frequency characteristics of the open-loop transfer function is obtained for the gain [dB] and the phase [deg]. The gain margin GM is calculated as follows: ｃ The phase margin PM is defined as the frequency ω at which the phase is −180°. ｐ It is defined as (-1) times the gain at . It is common to use the gain margin GM and phase margin PM as stability indicators when designing a control system, and it is known that the larger the gain margin GM and phase margin PM, the more stable the system.

[0130] Therefore, in the distributed power source integrated management apparatus according to the second embodiment, when the operation patterns of the multiple distributed power sources 102 are changed and the calculation unit 302 (control parameter determination unit 304) executes the process of FIG. 9 , in S110, the transfer function G ＶＳＧ１ (s) ~ G ＶＳＧ3 Using (s), the above-mentioned open-loop transfer functions G(1) to G(3) are obtained.

[0131] 10, the gain margin GM and the phase margin PM of the open-loop transfer functions G(1) to G(3) determined in S110 are calculated as stability indicators. Furthermore, in S130, the gain margin GM and the phase margin PM calculated in S120 are compared with a predetermined determination threshold TH ＧＭ and T.H. ＰＭ When the stability index is greater than the stability index, it can be determined that the stability index is within the stable range (YES determination).

[0132] If the determination in S130 is NO, the control parameter values ​​of the virtual synchronous generator control are changed in S140 to change the transfer function G ＶＳＧ１ (s) ~ G ＶＳＧ3(s) and the open-loop transfer functions G(1) to G(3), and then S120 and S130 are executed. By repeating S140 and S110 to S130 until S130 returns a YES determination, it is possible to determine control parameter values ​​that enable stable system operation in accordance with the operation pattern of the multiple dispersed power sources 102 determined by the operation determination unit 303, as in the first embodiment.

[0133] The above-mentioned gain margin GM and phase margin PM determination threshold value TH ＧＭ and T.H. ＰＭ It is also possible to set the above in advance by comparing the results of the circuit simulation with the stability determination results based on the Bode diagram.

[0134] As described above, the distributed power source integrated management device according to the second embodiment can achieve the same effects as those of the first embodiment by using the frequency response characteristics of the transfer function calculated from the control parameter values ​​(virtual synchronous generator control) as a stability index. That is, even in a power system connected to a plurality of distributed power sources whose output voltages are controlled by virtual synchronous generator control, the control parameter values ​​for the virtual synchronous generator control can be appropriately set so that instability due to mutual interference between the distributed power sources does not occur when the operation patterns of the distributed power sources change. This makes it possible to achieve a stable power supply that avoids instability due to mutual interference in the control of a plurality of distributed power sources.

[0135] Third Embodiment In the third and fourth embodiments, further modifications of the distributed power supply integration management apparatus will be described.

[0136] FIG. 13 is a block diagram illustrating the internal configuration of a distributed power supply integration management apparatus according to the third embodiment.

[0137] 13 , a distributed power supply integration management apparatus 101X according to the third embodiment differs from the distributed power supply integration management apparatus 101 shown in FIG. 4 in that it includes a calculation unit 302X instead of the calculation unit 302. The other configuration of the distributed power supply integration management apparatus 101X is similar to that of the distributed power supply integration management apparatus 101, and therefore detailed description thereof will not be repeated.

[0138] The calculation unit 302X further includes an operation determination unit 303, a control parameter determination unit 304X, and a lookup table 307. As described in FIG. 4, the operation determination unit 303 determines the current output active power (P in FIG. 3) of each dispersed power source 102. ｏｕｔ As described above, the operation command information 313 includes an operation / stop command for each dispersed power source 102 and an output active power command value P ｒｅｆ Includes:

[0139] Unlike the first and second embodiments in which a stability index calculated using provisionally determined control parameter values ​​is evaluated, the control parameter determination unit 304X determines control parameter values ​​(such as damping coefficient D, inertia constant M, time constant T and gain K of the first-order lag system) to be used for virtual synchronous generator control of the distributed power source 102 for which an operation command has been generated by referring to a lookup table 307 that has been created in advance.

[0140] The lookup table 307 is configured to store in advance control parameter values ​​(combinations of the above-mentioned values ​​of D, M, T, and K) that enable stable operation of the system, which are determined in advance from simulation results or the like, for each operation pattern of the multiple dispersed power sources 102 connected to the power grid 104. For example, the lookup table 307 stores control parameter values ​​that have been analyzed in advance according to the first or second embodiment to ensure that the stability index falls within a stable range for each operation pattern of the multiple dispersed power sources 102.

[0141] The control parameter determination unit 304X selects one of a plurality of predefined operation patterns based on the operation command information 313 from the operation determination unit 303, and refers to the lookup table 307. This makes it possible to read, from the lookup table 307, a control parameter value that is stored in advance and that ensures stable operation of the system, corresponding to the operation pattern determined by the operation command information 313. The control parameter value is added to the transmission unit 306 together with the operation command information 313 as part of information 314 from the control parameter determination unit 304X, output, and transmitted to each dispersed power source 102.

[0142] In this way, the distributed power source integrated management device according to the third embodiment can also appropriately set the control parameter values ​​for virtual synchronous generator control so as to prevent instability caused by mutual interference between the distributed power sources when the operation patterns of the distributed power sources change, thereby achieving a stable power supply that avoids instability caused by mutual interference between the controls of multiple distributed power sources.

[0143] In the first and second embodiments, the stability index is calculated and evaluated online using provisionally determined control parameter values, which results in a relatively high computational load, whereas in the third embodiment, such an increase in the online computational load can be avoided. On the other hand, in the third embodiment, appropriate control parameter values ​​must be determined in advance for each operation pattern of the multiple dispersed power sources 102, which raises concerns about an increase in the storage capacity of the lookup table 307 and the workload required for preparation.

[0144] Fourth Embodiment Fig. 14 is a block diagram illustrating the internal configuration of a distributed power supply integration management apparatus according to a fourth embodiment.

[0145] 14, a distributed power supply integrated management apparatus 101Y according to the fourth embodiment differs from the distributed power supply integrated management apparatus 101 shown in Fig. 4 in that it includes a calculation unit 302Y instead of the calculation unit 302. The other configuration of the distributed power supply integrated management apparatus 101Y is similar to that of the distributed power supply integrated management apparatus 101, and therefore detailed description thereof will not be repeated.

[0146] The calculation unit 302Y differs in that it includes an operation determination unit 303, a control parameter determination unit 304Y, and a learning unit 308. As explained in FIG. 4, the operation determination unit 303 determines the current output effective power (P in FIG. 3) of each dispersed power source 102. ｏｕｔ As described above, the operation command information 313 includes an operation / stop command for each dispersed power source 102 and an output active power command value P ｒｅｆ Includes:

[0147] Unlike embodiments 1 and 2 in which a stability index is evaluated using provisionally determined control parameter values, the control parameter determination unit 304Y reflects the learning results of the learning unit 308 and determines control parameter values ​​(such as the damping coefficient D, inertia constant M, time constant T and gain K of the first-order lag system) to be used for virtual synchronous generator control of the distributed power source 102 for which an operation command has been generated.

[0148] The learning unit 308 includes a learning model that receives, for each operation pattern, a combination of control parameter values ​​as input and outputs a stability evaluation (information on whether the control parameter values ​​are stable or unstable, or the stability index in the first and second embodiments) under the combination of control parameter values. For example, the learning model can be configured by an AI (artificial intelligence) learning model.

[0149] As an example, the learning model can be created by machine learning, in which a correspondence between a combination of control parameter values ​​and a stability evaluation result when the combination of control parameter values ​​is used is input as learning data for each operation pattern. When creating the learning model (learning phase), the stability evaluation result can include both the result of actually operating the power system and the simulation result.

[0150] In the inference phase, the learning model is configured to take a movement pattern as input and output an appropriate combination of control parameter values ​​(D, M, T, K). The appropriate combination of control parameter values ​​can be one that, for the movement pattern, results in a positive stability evaluation or a stability index greater than a predetermined threshold.

[0151] The control parameter determination unit 304Y inputs the movement pattern indicated by the movement command information 313 from the movement determination unit 303 into a learning model constituting the learning unit 308. As a result, an appropriate combination of control parameter values ​​for the movement determination pattern is acquired as an output of the learning model.

[0152] The control parameter value is added to the transmitting unit 306 as part of the information 314 from the control parameter determining unit 304Y together with the operation command information 313, and is then transmitted to each dispersed power source 102.

[0153] Furthermore, the control parameter determination unit 304Y can also sequentially update the learning model in the learning unit 308 by additionally inputting new results obtained when the power system is actually operated to the learning unit 308 as learning data.

[0154] In this way, the distributed power source integrated management device according to the fourth embodiment can also appropriately set the control parameter values ​​for virtual synchronous generator control so as to prevent instability due to mutual interference between the distributed power sources when the operation patterns of the distributed power sources change. This makes it possible to achieve a stable power supply that avoids instability due to mutual interference between the controls of multiple distributed power sources. In the fourth embodiment, there is no need to prepare and store the lookup table 307 described in the third embodiment, which is expected to reduce the workload and storage capacity.

[0155] As described above, in the first to fourth embodiments, the configuration of the control system for virtual synchronous generator control in each distributed power source 102 is fixed to the content of FIG. 3 , and the control parameter determiner 304 (304X, 304Y) determines the control parameter values ​​in FIG. 3 . However, the configuration of the control system for virtual synchronous generator control may be switched depending on the operation setting pattern. For example, in FIG. 3 , a configuration (variant) in which the feedback loop of the governor control unit 205 (first-order lag system) is omitted may be applied to some operation patterns. For example, the above configuration (variant) is realized by setting the gain K of the first-order lag system to 0. In other words, the function of the control parameter determiner 304 (304X, 304Y) essentially includes determining the configuration of the control system for virtual synchronous generator control.

[0156] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0157] 10 Power system, 101, 101X, 101Y Distributed power integrated management device, 102, 102a to 102f Distributed power source, 103 Control device, 104 Power system, 105 Power source, 106 Power conversion device, 107 Main circuit, 108 Switching control circuit, 109 Communication path, 110, 111 Characteristic line, 112 Operating point, 200 Distributed power source control unit, 201 Virtual synchronous generator control unit, 202 Operation command value generation unit, 203, 203b, 208 Integrator, 204 Feedback path, 205 Governor control unit, 206, 811, 813 Multiplier, 211 to 213, 831, 833 Subtractor, 214, 834, 836 Adder, 301 Receiving unit, 302, 302X, 302Y Calculation unit, 303 Operation determination unit, 304, 304X, 304Y Control parameter determination unit, 305 Storage unit, 306 Transmission unit, 307 Look-up table, 308 Learning unit, 311, 312 Distributed power source information, 313 Operation command information, 314, 317, 318, 319 Information, 315 Setting information, 404, 406, X1 Reactance, 407 Common bus, 841, 843 Calculator, D, K, M, T Control parameter value, GM Gain margin, G ＶＳＧ１ ~G ＶＳＧ１ Transfer function, PM Phase margin, P ｏｕｔ , P ｏｕｔ１ ~P ｏｕｔ３ Output active power (measured value), P ｒｅｆ , P ｒｅｆ１ ~P ｒｅｆ３ Output active power command value, X １ ~X ３ Reactance value, Δf frequency change amount, f frequency command value, fn reference frequency, θ voltage phase.

Claims

1. A distributed power supply integrated management device that manages the operation state of a power system to which a plurality of distributed power supplies are connected, the output voltage of which is controlled by virtual synchronous generator control in which the operating characteristics of a synchronous generator are simulated and implemented in a static power supply, a receiving unit that receives information regarding the operating states of the plurality of distributed power sources; an operation determination unit that determines an operation pattern of the plurality of distributed power sources based on the information acquired by the receiving unit; a control parameter determination unit that determines control parameter values ​​of the virtual synchronous generator control for each of the plurality of distributed power sources so that mutual interference between the virtual synchronous generator controls of the plurality of distributed power sources can be avoided and the power system can be stably operated in the operation pattern determined by the operation determination unit; and a transmission unit that transmits, to each of the plurality of distributed power sources, an operation command in accordance with the operation pattern determined by the operation determination unit, and the control parameter value determined by the control parameter determination unit.

2. The control parameter determination unit 2. The distributed power source integrated management device according to claim 1, further comprising: a stability index value that quantitatively indicates the operational stability of the power system when the virtual synchronous generator control is executed using the provisionally determined control parameter value; a determination is made as to whether the calculated stability index value is within a predetermined stability range; and if the calculated stability index value is within the stability range, the control parameter value to be transmitted to the plurality of distributed power sources is determined using the provisionally determined control parameter value.

3. The control parameter determination unit 3. The distributed power source integrated management device of claim 2, further comprising: if the stability index value calculated using the provisionally determined control parameter value is not within the stability range, the control parameter value is changed and the process of calculating the stability index is repeated until the calculated stability index value is within the stability range.

4. 3. The distributed power source integrated management device according to claim 2, wherein the stability index is a value of a real part of an eigenvalue of a coefficient matrix of a state equation that expresses operating characteristics of the power system to which the virtual synchronous generator control by the multiple distributed power sources is applied.

5. the stability index is at least one of a phase margin and a gain margin of a loop transfer function derived using a transfer function that represents an operation characteristic of the power system and an operation characteristic of the virtual synchronous generator control of each of the plurality of distributed power sources, in the power system; 3. The distributed power source integrated management device according to claim 2, wherein the open loop transfer function is derived by treating the virtual synchronous generator control provided in any one of the plurality of distributed power sources as a controller, and regarding elements in the power system other than the distributed power source as objects to be controlled.

6. The control parameter determination unit determining the control parameter values ​​for each of the plurality of distributed power sources by referring to a lookup table that is created in advance using the operation pattern determined by the operation determination unit; 2. The distributed power source integrated management device according to claim 1, wherein the lookup table prestores, for each of a plurality of predetermined operation patterns, the control parameter values ​​for each of the plurality of distributed power sources that ensure stable operation of the power system.

7. a learning unit that learns a relationship between the control parameter values ​​of the plurality of distributed power sources and information related to operational stability of the power grid, 2. The distributed power source integrated management device of claim 1, wherein the control parameter determination unit determines the control parameter values ​​for each of the plurality of distributed power sources using an output from the learning unit when the operation pattern determined by the operation determination unit is input to the learning unit.

8. The distributed power source integrated management apparatus according to claim 1 , wherein the operation patterns include a combination of operation commands or stop commands for each of the plurality of distributed power sources.

9. 2 . The distributed power source integrated management apparatus according to claim 1 , wherein the operation patterns include a combination of command values ​​for output active power of each of the plurality of distributed power sources.

10. Further comprising a storage unit that stores information regarding a facility configuration of the power system, 2 . The distributed power source integrated management device according to claim 1 , wherein the control parameter determination unit determines the control parameter values ​​for each of the plurality of distributed power sources based on the information obtained from the receiving unit and the information stored in the storage unit.

11. the plurality of distributed power sources are electrically connected to a common bus of the power system; 11. The distributed power source integrated management apparatus according to claim 10, wherein the information stored in the memory unit includes information related to impedance between each of the plurality of distributed power sources and the common bus.

12. 2 . The distributed power source integrated management apparatus according to claim 1 , wherein the information received by the receiving unit includes a measured value of an output active power of each of the plurality of distributed power sources.

13. 2 . The distributed power source integrated management apparatus according to claim 1 , wherein the information received by the receiving unit includes information on the amplitude and phase of the output voltage of each of the plurality of distributed power sources.

14. the information received by the receiving unit includes measured values ​​of output voltage and output current of each of the plurality of distributed power sources; The distributed power source integrated management device according to claim 13 , wherein the receiving unit calculates an output effective power of each of the plurality of distributed power sources based on the measured value.

15. The distributed power source integrated management apparatus according to claim 1 , wherein the operation command transmitted by the transmission unit includes an operation command or a stop command for each of the plurality of distributed power sources.

16. The distributed power source integrated management apparatus according to claim 1 , wherein the operation command transmitted by the transmission unit includes a command value for an output effective power of each of the plurality of distributed power sources.

17. The distributed power source integrated management device of claim 1, wherein the operation determination unit generates a new operation pattern based on the information at a given point in time in response to the passage of a predetermined period of time or changes in multiple items constituting the information received by the receiving unit.

18. a power system connected to a plurality of distributed power sources, the output voltage of which is controlled by a virtual synchronous generator control in which the operating characteristics of a synchronous generator are simulated and implemented in a static power source; A distributed power supply integration management device according to any one of claims 1 to 17, A power system comprising: a communication path formed between the distributed power supply integrated management device and the plurality of distributed power supplies.

19. Each of the plurality of distributed power sources comprises: a power conversion device that operates as the static power supply so as to convert power from a power supply into AC power that is output to the power grid; The power system according to claim 18 , further comprising: a control device that controls the power conversion device so as to output an AC voltage according to the virtual synchronous generator control.

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