Distributed power integrated 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

[Technical Field]

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

[0002] Due to the demand for decarbonization, the introduction of distributed power sources using renewable energy into power grids is accelerating. These distributed power sources are connected to the grid 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 for power grids, they are characterized by not having the system voltage maintenance effect (so-called inertial force) that results from the inertia of rotational motion. Therefore, as the proportion of power sources that use 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 grid.

[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 the same dynamic characteristics as a rotating machine power supply in the static power supply. For example, Japanese Patent 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. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6084863 Summary of the Invention [Problem to be solved by the invention]

[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 autonomously operating microgrid, the control Opa Depending on the parameter values, the control systems of different distributed power sources may interfere with each other, causing divergent behavior, which may result in instability 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. [Means for solving the problem]

[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. [Effects of the Invention]

[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. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a block diagram illustrating a schematic configuration of a power system managed by a distributed power integration management apparatus according to a first embodiment. [Figure 2] FIG. 1 is a block diagram illustrating an example of the configuration of a distributed power source. [Figure 3] FIG. 2 is a block diagram illustrating an example of a control configuration for virtual synchronous generator control applied to each distributed power source. [Figure 4] 1 is a block diagram illustrating an internal configuration of a distributed power supply integration management device according to a first embodiment. [Figure 5] FIG. 1 is a block diagram showing an example of a power system in which a plurality of distributed power sources are connected to a power grid according to a comparative example equipped with virtual synchronous generator control. [Figure 6] 6 is a first simulation waveform diagram of the output of each distributed power source in the power system shown in FIG. 5. FIG. [Figure 7] 6 is a second simulation waveform diagram of the output of each distributed power source in the power system shown in FIG. 5. FIG. [Figure 8] FIG. 1 is a conceptual diagram illustrating linear approximation of the output power characteristics of a distributed power source for introducing a state equation. [Figure 9] FIG. 2 is a conceptual diagram illustrating the size of a coefficient matrix A of a state equation. [Figure 10] 10 is a flowchart illustrating an example of a procedure for determining a control parameter value by the distributed power integration management apparatus according to the first embodiment. [Figure 11] 10 is an example of a block diagram showing a control transfer characteristic of a power system including a transfer function used in a distributed power integration management apparatus according to a second embodiment. [Figure 12] FIG. 1 is a conceptual diagram illustrating a gain margin and a phase margin of a loop transfer function. [Figure 13] FIG. 11 is a block diagram illustrating the internal configuration of a distributed power supply integration management device according to a third embodiment. [Figure 14] FIG. 10 is a block diagram illustrating the internal configuration of a distributed power supply integration management device according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[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] Embodiment 1 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 apparatus 101 according to the first embodiment.

[0015] As shown in FIG. 1, the power system 10 includes a distributed power supply integrated management device 101, a plurality of 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 plurality of 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 company, 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 indicate distributed power sources whose output voltages are controlled by virtual synchronous generator control, which will be described later, and which are managed by the distributed power source integrated management device 101. Hereinafter, when the distributed power sources 102a to 102f are collectively referred to, they will also be simply referred to 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] FIG. 2 shows a block diagram illustrating an example of the configuration of the distributed power source 102. Referring to FIG. 2, the distributed power supply 102 includes a control device 103, a power supply 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 supply 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 again, 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 distributed power sources will be described. 3 is a block diagram illustrating an example of the control configuration of virtual synchronous generator control applied to each dispersed 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, which is 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), depending on the mechanical input energy Pm input to the rotor from outside and the electrical output energy Pe output to the grid.

[0029]

number

[0030] In equation (1), ω is the rotor rotational speed, ω0 is the rotor's rated rotational 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 rotational speed ω is maintained constant. Conversely, when Pm > Pe, the rotor accelerates, and when Pe > Pm, the rotor decelerates. The rotor rotational speed ω is related by a constant multiple of the frequency f of the AC voltage output by the rotating machine power supply (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]

number

[0033] In equation (2), P0 is a positive constant determined depending on the internal impedance and voltage amplitude of the generator. Generally, the phase difference δ is operated in the range of 0 < δ < 90 [deg], and within this range, there is a positive correlation between Pe and the phase difference δ.

[0034] Possessing both the properties of formulas (1) and (2) provides the following advantages. For example, when the rotational electrical power source is operating in a steady state with Pm = Pe and a constant rotational speed ω, and the phase difference δ suddenly increases due to the influence of a disturbance or the like, Pe increases according to Equation (2). As a result, since Pm < Pe, the rotor decelerates according to Equation (1). Consequently, the phase difference δ gradually decreases, so the rotational electrical power source can return to the original steady state of operation. Conversely, when the phase difference δ suddenly decreases from the above steady state of operation, Pe decreases according to Equation (2), so since Pm > Pe, the rotor accelerates according to Equation (1). As a result, the phase difference δ increases Add and the rotational electrical power source can return to the original steady state of operation.

[0035] In this way, the rotational electrical power source has the advantage of being able to self-return to a stable operating state due to having the characteristics shown in Equation (1). Also, based on the same principle, when a plurality of different rotational electrical power sources are operating in parallel, there is an advantage in that the cross current generated between the rotational electrical power sources can be eliminated and the rotational speed and voltage phase can be synchronized.

[0036] On the other hand, since the static power source does not have the characteristics shown in Equation (1) above, it cannot obtain the advantage of compensating for fluctuations in the phase difference δ and self-returning to the steady state of operation as described above. For this reason, in order to simulate having a compensation characteristic corresponding to Equation (1), a virtual synchronous generator control is introduced.

[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 subtracts the measured value of the active power output P ref from the command value of the active power output from the distributed power source 102 (power conversion device 106) (hereinafter, the output active power command value P out ) to calculate the active power deviation ΔP out . The active power deviation ΔP outis 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 integrator 20 of 3 The output value 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 out By executing these control calculations on the frequency, the amount of change Δf in the frequency of the output voltage from the dispersed power source 102 (power conversion device 106) is calculated.

[0041] The operation command value generation 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, and can acquire the ability to automatically 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. As shown in 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 format 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 apparatus 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 dispersed power source 102 and information related to the impedance of the electrical path connecting the dispersed power sources 102. For example, the information related to the impedance includes the link of the path. a Incidentally, the storage unit 305 is not limited to being a constituent element of the distributed power supply integrated management apparatus 101, and may be configured to be connected to the distributed power supply integrated management apparatus 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 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 distributed power source 102 in virtual synchronous generator control provided for each of the multiple distributed power sources 102, so as to ensure the operational stability of the power system 104 that it manages, 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 illustrated 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] The management method for ensuring the operational stability of the system will be described in detail below. First, using Figures 5 to 7, we will explain the issues that arise when a plurality of distributed power sources equipped with virtual synchronous generator control coexist in a power system 104. Figure 5 is a block diagram illustrating an example of the configuration of a power system in which three distributed power sources 102(1) to 102(3) according to a comparative example, equipped with virtual synchronous generator control, coexist in a power system to be managed.

[0053] Three distributed power sources 102(1) to 102(3) according to the comparative example are connected to one another via a common bus 407. Each of the distributed power sources 102(1) to 102(3) is equipped with the virtual synchronous generator control shown in FIG. 2. Reactances 404 to 406 corresponding to the wiring distances exist between the distributed power sources 102(1) to 102(3) and the common bus 407, respectively. Below, the reactance values ​​of the reactances 404 to 406 are denoted as X1 to X3, respectively. 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] 6, the virtual synchronous generator control parameters for each of the dispersed power sources 102(1) to 102(3) were M=8, D=100, K=20, and T=0.1. Furthermore, the reactance values ​​X1 to X3 were set as % impedances based on the rated values ​​of the dispersed power sources, with X1=10(%), X2=20(%), and X3=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 constant values ​​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, FIG. 7 shows simulation waveforms for a 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 virtual synchronous generator control parameters for each of the dispersed power sources 102(1) to 102(3) were set to M = 8, D = 20, K = 20, and T = 0.1. The reactance values ​​X1 to X3 were set to X1 = 10(%), X2 = 20(%), and X3 = 40(%). That is, compared to the simulation of Fig. 6, the damping coefficient D in the virtual synchronous generator control for each of the dispersed power sources 102(1) to 102(3) was set to a smaller value in the simulation of Fig. 7. The other simulation conditions were the same between Figs. 6 and 7.

[0060] As shown in Figure 7, P out1 +P out2 +P out3 butUnder the condition that the power supply voltage is constant, a cross current occurs between the dispersed power sources 102(1) to 102(3) due to the influence of external 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 dispersed 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 depends on the settings of the control parameters for multiple distributed power sources. In other words, if the control parameter values ​​for virtual synchronous generator control in each distributed power source are not 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 dispersed power sources, the control parameter values ​​must be set taking into account mutual interference rather than simply implementing a complete design for each dispersed power source. Furthermore, the setting range of the control parameters required to stabilize operation may vary depending on the state of the dispersed 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 the first embodiment 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 also issues a command value for output active power (P 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 negative (P ref <0). In addition, in the distributed power source 102 where the operation command is generated, the output active power command value P ref There are also cases where it is set to 0.

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

[0066] When determining the number of operating distributed power sources 102, the current output effective power (P out ) is used to obtain an outline of the current demand. Then, to ensure that the determined demand can be fully supplied, the number of operating dispersed power sources 102 can be determined so that at least the total rated capacity of the operating dispersed power sources 102 exceeds the demand.

[0067] At this time, the operation determination unit 303 may determine the 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 refThe 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, based on the distributed power source information 312 received from the receiving unit and the information 319 received from the memory unit, while 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 operational characteristics of the 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 active power P of the first dispersed power source 102(1) out1 The relationship shown in the following equation (3) holds regarding the reactance value X1 and the voltage across it. In equation (3), V L and θ L are the amplitude and phase of the voltage of the common bus 407 at the connection point of the dispersed power source 102(1), and V1 and θ1 are the amplitude and phase of the output voltage of the dispersed 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]

number

[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 (Δθ1-Δθ L ) = δ1, the output effective power P out1 is |V1||V in equation (3). L | / X1 is a sine function of the phase difference δ1 with the maximum value Pmax (amplitude) 110 ) is shown.

[0075] Characteristic Line 110 The phase difference at the operating point 112 in the stable operation state of the power system above is δ 10 Then, the slope of the tangent to the characteristic line 110 at the operating point 112 is cosδ 10 This makes it possible to obtain 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]

number

[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 30indicates 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 equations (4) to (6), P 1m =(|V1||V L | / X1)·cosδ 10 and P 2m =(|V2||V L | / X2)·cosδ 20 and P 3m =(|V3||V L | / X3)·cosδ 30 It is. P 1m ~P 3m are coefficients that are inversely proportional to the reactance values ​​X1 to X3, respectively.

[0079] Furthermore, the output effective power P of the dispersed power sources 102(1) to 102(3) out1 ~P out3 The sum of these is equal to the power PL flowing into the power sources other than the managed ones and the consumers 408, so the following equation (7) holds for the amount of fluctuation Δ from the stable operation state.

[0080]

number

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

[0082]

number

[0083] On the other hand, the characteristics of the virtual synchronous generator control provided to each of the distributed power sources 102(1) to 102(3) are expressed as a state equation. When each of the distributed 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). Furthermore, when the transfer function of equation (9) is re-expressed as a state equation, equations (10) and (11) can be obtained by setting internal state variables x1 to x3. Note that the internal state variable x2 is obtained by differentiating the internal state variable x1, and the internal state variable x3 is obtained by differentiating the internal state variable x2. Equations (10) and (11) correspond to the state equation expressions of the virtual synchronous generator control for one distributed power source 102.

[0084]

number

[0085] When the state equations of the virtual synchronous generator control of the three dispersed power sources 102(1) to 102(3) in Fig. 5, which are expressed as 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]

number

[0087] Finally, by integrating equations (12) and (13), ΔP out1 ~ΔP out3 and Δθ1 to Δθ3 are eliminated, the formula (14) can be obtained.

[0088]

number

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

[0090]

number

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

[0092]

number

[0093] Equation (14) is a state equation expression that includes all the operating characteristics of the power system to be managed. Then, by finding 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, if the eigenvalues ​​of the coefficient matrix A in equation (14) are found and the real parts of all the found eigenvalues ​​are negative, it can be confirmed that the oscillations occurring in this system will be damped 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 to evaluate 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 dispersed 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 value of the real parts (negative values) is 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 this threshold may change depending on the system configuration, so it is desirable to define it in advance based on instantaneous value simulations, etc.

[0100] In this way, the stability of the power system can be evaluated by calculating the eigenvalues ​​of the coefficient matrix A of the state equation. 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 (3×3) rows and (3×3) 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 are generated, the size of the coefficient matrix A is (N×3) rows and (N×3) columns.

[0101] As shown in Figure 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 dispersed power sources operating under virtual synchronous generator control is the same, if the combination of operating dispersed power sources is different, mainly due to differences in reactance values ​​X1 to X3, the coefficient matrix A will also change. Furthermore, if the output active power command value of the operating dispersed power source changes, the operating point 112 (stable operating state) in Figure 8 will change, which may also change the coefficient matrix A.

[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 performed, for example, by the microcomputer constituting the calculation unit 302 executing a pre-stored program when the operation pattern (combination of operation / stop) 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 setting the output active power command value P ref 10 may also be executed when the operation pattern of the plurality of dispersed power sources 102 is changed. That is, the process shown in FIG. 10 can be executed when the operation determining unit 303 changes the operation pattern of the plurality of dispersed power sources 102.

[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, damping coefficient D, and 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 stable 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 fixed increments (a fixed amount or a fixed ratio) in 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 included in 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 by S140 until the control parameter value that results in a YES determination in S130 is set.

[0111] When the determination in S130 is YES, in S150 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.

[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. 318 may include at least a portion of the information output to the transmitter 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 value 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, whose output voltages are controlled by virtual synchronous generator control, the control parameter values ​​of 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 makes it possible to achieve 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 is calculated by finding the eigenvalues ​​of the coefficient matrix A of the state equation, but in the second embodiment, a different calculation method for 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 configurations and operations 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 determination unit 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 407 L , 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 minute fluctuation amount Δ is introduced into each of the phases θ1 to θ3 of the output voltage.

[0121] Here, for the power system illustrated in FIG. 5, equation (8) is established by the linear approximation described in the first embodiment. In addition, the output voltages of the distributed power sources 102(1) to 102(3) are controlled by the virtual synchronous generator control having the configuration shown in FIG. 3. Therefore, the output voltages of the distributed power sources 102(1) to 102(3) are controlled by the virtual synchronous generator control having the configuration shown in FIG. 102(3) The transfer function G of each virtual synchronous generator control VSG1 (s)~G VSG3 Using the transfer function G(s), the transfer characteristics of the power system to which the dispersed power sources 102(1) to 102(3) are connected are shown in the block diagram of FIG. 11, reflecting the cross currents (mutual interference) that occur between the dispersed power sources 102(1) to 102(3). 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, a 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 between the distributed power sources 102(1) to 102(3) by calculations in the multipliers 811 to 813 based on ΔP L1 ~ΔP L3 (ΔP L1 +ΔP L2 +ΔP L3 =ΔP L The 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 amounts ΔdP1 to dP3 of the power deviation ΔPout (FIG. 3) for each of the dispersed power sources 102(1) to 102(3) are calculated.

[0125] By calculating 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 dispersed power source 102(1) taking into account interference with the virtual synchronous generator control by the other dispersed 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 dispersed power sources 102(2) and 102(3) taking into account interference with the virtual synchronous generator control of the other dispersed 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] As shown in FIG. 12, a Bode diagram showing the frequency characteristics of the open-loop transfer function is obtained for the gain [dB] and the phase [deg]. Phase margin PM is defined as the phase [deg] at the frequency ωc where the gain is 0 [dB], Gain margin GM is defined as (-1) times the gain at the frequency ωp where the phase is -180[deg]. 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 supply integrated management apparatus according to the second embodiment, the operation patterns of the multiple distributed power supplies 102 are changed, and the calculation unit 302 (control parameter determination unit 304) 10 When the process of (1) is performed, 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 found.

[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 of FIG. 10, the gain margin GM and the phase margin PM calculated in S120 are compared with a predetermined determination threshold TH GM and TH 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 result of 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 the determination in S130 is YES, it is possible to determine control parameter values ​​that enable stable operation of the system 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 TH GM and TH 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] Embodiment 3 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 integrated management apparatus 101X according to the third embodiment differs from the distributed power supply integrated management apparatus 101 shown in FIG. 4 in that it includes a calculation unit 302X instead of the calculation unit 302. Other configurations of the distributed power supply integrated management apparatus 101X are similar to those of the distributed power supply integrated 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 explained in FIG. 4, the operation determination unit 303 determines the current output active power (P in FIG. 3) of each dispersed generation 102. out ) and other distributed power source information 312. As described above, the operation command information 313 includes an operation / stop command for each distributed 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 a damping coefficient D, an inertia constant M, a time constant T and a gain K of a 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 D, M, T, and K values) that enable stable system operation, 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 out, 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, and is then output 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 dispersed power sources when the operation patterns of the dispersed power sources change. This makes it possible to achieve a stable power supply that avoids instability caused by mutual interference between the controls of multiple dispersed 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] Embodiment 4 FIG. 14 is a block diagram illustrating the internal configuration of a distributed power supply integration management apparatus according to the 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. Other configurations of the distributed power supply integrated management apparatus 101Y are similar to those 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 generation 102. out ) and other distributed power source information 312. As described above, the operation command information 313 includes an operation / stop command for each distributed power source 102 and an output active power command value P ref Includes:

[0147] Unlike the first and second embodiments in which the stability index is evaluated using provisionally determined control parameter values, the control parameter determination unit 304Y determines the control parameter values ​​(such as the damping coefficient D, the inertia constant M, the 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 the operation command has been generated, reflecting the learning results of the learning unit 308.

[0148] The learning unit 308 includes a learning model that receives a combination of control parameter values ​​for each operation pattern 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 the learning model constituting the learning unit 308. As a result, the movement pattern is output as the learning model. Sakupa A suitable combination of control parameter values ​​for the turn is obtained.

[0152] The control parameter value is sent to the transmitter 306 together with the operation command information 313 as part of the information 314 from the control parameter determination unit 304Y. In contrast The output is transmitted to each distributed power source 102 .

[0153] In addition, 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 that instability due to mutual interference between the dispersed power sources does not occur when the operation patterns of the dispersed 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 dispersed 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 dispersed power source 102 is fixed to the content of FIG. 3, and the control parameter determination unit 304 (304X, 304Y) determines the control parameter values ​​in FIG. 3. Sakupa The configuration of the control system for virtual synchronous generator control may be switched depending on the turn. For example, in FIG. 3, a configuration (modification) 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 (modification) is realized by setting the gain K of the first-order lag system to 0. In other words, the function of the control parameter determination unit 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. [Explanation of symbols]

[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 Receiver, 302, 302X, 302Y Calculation unit, 303 Operation determination unit, 304, 304X, 304Y, control parameter determination unit, 305, storage unit, 306, transmission unit, 307, lookup table, 308, learning unit, 311, 312, distributed power source information, 313, operation command information, 314 ,3 18,319 information, 315 configuration information, 404,40 6 Reactance, 407 Common bus, 841,843 Operator, D,K,M,T Control parameter value, GM Gain margin, G VSG1 ~G VSG3 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, X1 to X3 reactance values, 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 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, a receiving unit that receives information about the operating states of the plurality of dispersed 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 ​​for the virtual synchronous generator control for each of the plurality of distributed power sources 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 sources can be avoided and the power grid can operate stably; a transmitting unit that transmits, to each of the plurality of distributed power sources, an operation command according to 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 operational stability of the power system when the virtual synchronous generator control is executed using the provisionally determined control parameter values; 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 values ​​to be transmitted to the plurality of distributed power sources are determined using the provisionally determined control parameter values.

3. The control parameter determination unit 3. The distributed power source integrated management device of claim 2, wherein, if the value of the stability index 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 value of the stability index 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 plurality of 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 controlled objects.

6. The control parameter determination unit determining the control parameter values ​​for each of the plurality of distributed power sources by referencing a lookup table 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 stores in advance the control parameter values ​​for each of the plurality of distributed power sources that allow the power system to operate stably, for each of a plurality of predetermined operation patterns.

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 device 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 system according to claim 1, wherein the operation patterns include combinations of command values ​​for output active power of each of the plurality of distributed power sources.

10. Further, a storage unit that stores information about an equipment 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; The distributed power source integrated management device according to claim 10 , wherein the information stored in the storage unit includes information relating to impedance between each of the plurality of distributed power sources and the common bus.

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

13. 2. The distributed power source integrated management device 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 the output effective power of each of the plurality of distributed power sources based on the measured value.

15. The distributed power source integrated management device 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 output active power of each of the plurality of distributed power sources.

17. 2. The distributed power supply integrated management device of claim 1, wherein the operation determination unit generates a new operation pattern based on the information at that time, either after a predetermined period of time has elapsed or in response to changes in multiple items that make up 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 virtual synchronous generator control, which simulates the operating characteristics of a synchronous generator implemented in a static power source; A distributed power supply integration management device according to any one of claims 1 to 17; 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 a power conversion device that operates as the static power supply 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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