GB2596503A

GB2596503A - Power generation system and plant control device

Info

Publication number: GB2596503A
Application number: GB2002133.3A
Authority: GB
Inventors: Mitsugi Yasuaki; Takada Mamoru
Original assignee: Toshiba Mitsubishi Electric Industrial Systems Corp
Current assignee: Toshiba Mitsubishi Electric Industrial Systems Corp
Priority date: 2019-08-02
Filing date: 2019-08-02
Publication date: 2022-01-05
Anticipated expiration: 2039-08-02
Also published as: GB202002133D0; JPWO2021024293A1; WO2021024293A1; JP6981528B2; GB2596503B; AU2019316537B2; GB2596503A8; AU2019316537A1

Abstract

This power generation system is provided with: a plurality of power conversion devices for converting DC power from a DC power supply to AC power; and a plant control device for controlling the plurality of power conversion devices. The plant control device includes a virtual synchronous generator model unit for outputting power command values on the basis of the current and voltage values at a system interconnection point on the output side of the plurality of power conversion devices. The plurality of power conversion devices output AC powers according to the power command values. The plurality of power conversion devices may include a first power conversion device and a second power conversion device. The DC power supply to which the first power conversion device is connected may be a renewable energy generation device, and the DC power supply to which the second power conversion device is connected may be a storage battery. The DC power supply to which each of the plurality of power conversion devices is connected may be a DC power supply in which the renewable energy generation device that is a first DC power supply and the storage battery that is a second DC power supply are connected in parallel with each other.

Description

[Title] Power generation system and plant control device

[Technical Field]

[0001] The present application relates to a power generation system and a plant control device.

[Background]

10002] Conventionally, for example, as disclosed in JP-A-2014-168351. a power conversion device configured to operate as a VSG (virtual synchronous generator) is known.

[Citation List] [Patent Literature] [0003] [PTL 1] JP 2014-168351 A

[Summary]

[Technical Problem] [0004] In the above prior art, control for simulating the VSG is implemented in one power conversion device. Actually, there is some limitation in capacity of one power conversion device. Because of this limitation, in the above conventional technology, there is a problem that it is difficult to simulate the VSG having large power generation.

[0005] The present application has been made to solve the problem as described above, and an object thereof is to provide an improved power generation system and a plant control device so as to be able to simulate a VSG with a plurality of power conversion devices [Solution to Problem] [0006] A power generation system according to the present application includes: a plurality of power conversion devices for converting DC power from a DC power source into AC power; and a plant control device for controlling the plurality of power conversion devices, wherein, the plant control device includes a virtual synchronous generator model part for outputting a power command value based on a current value and a voltage value at a grid connection point on an output side of the plurality of power conversion devices, and wherein the plurality of power conversion devices output the AC power according to the power command value.

[0007] A power generation system and a plant control device according to the present application includes: a plant control device for controlling a plurality of power conversion devices for converting DC power from a DC power source into AC power, wherein the plant control device includes a virtual synchronous generator model part for outputting a power command value based on a current value and a voltage value at a grid connection point on an output side of the plurality of power conversion device, and is configured to cause the plurality of power conversion devices to output the AC power in accordance with the power command value. [Advantageous Effects of Invention] [0008] According to the present application, since the plant control device has a virtual synchronous generator model part, each of the plurality of power conversion devices does not have to include a model in the control circuit thereof. Since the plant control device can integrally control the plurality of power conversion devices, the entire system including the plurality of power conversion devices can simulate a VSG (virtual synchronous generator).

[Brief Description of Drawings]

[0009] FIG. 1 is a diagram of a power generation system and a plant control device according to an embodiment.

FIG. 2 is a diagram of a configuration of an inverter control circuit in the power generation system according to the embodiment.

FIG. 3 is a diagram of a configuration of a power generation system and a plant control device according to a modification of the embodiment.

[Description of Embodiments]

[0010] FIG. 1 is a diagram of a configuration of a power generation system 1 and a plant control device 10 according to an embodiment. The power generation system 1 is operated with an electric power grid 100 via a grid connection point S so as to perform gird interconnection operation. As shown in FIG. 1, the power generation system 1 includes a power generation plant 2, an interconnection transformer 3, a potential transformer 5, and a current transformer 4. The power generation plant 2 includes a plurality of power conversion devices 22, a plurality of DC power supplies 23, 24, a plurality of switches 20, and a plant control device 10.

[0011] As shown in FIG. 1, the interconnection transformer 3 is interposed between the power generation plant 2 and the grid connection point. Output signals from the potential transformer 5 and the current transformer 4 are transmitted to the plant control device 10. Thus the plant control device 10 can measure a value of a grid current Is and a value of a grid voltage Vs at the grid connection point. As shown in FIG. 1, series circuits each including a switch 20 and a transformer 21 are interposed between the interconnection transformer 3 and each of the plurality of power conversion devices 22.

[0012] The plurality of power conversion devices 22 convert DC power from the plurality of DC power supplies 23 and 24 into AC power. The power conversion device 22 is specifically a three-phase AC inverter circuit configured by a plurality of semiconductor switching elements.

10013] The plurality of power conversion devices 22 include a first power conversion device 22 and a second power conversion device 22. The DC power source 23 to which the first power conversion device 22 connects is a renewable energy power generation device, such as a photovoltaic power generation module. The DC power source 24 to which the second power conversion device 22 is connected is a storage battery. Such a system is also referred to as an AC-link system. It should be noted that, the second power conversion device 22 and the DC power supply 24 are provided as a power storage system (Energy Storage System: ESS) 25. The power conversion devices are also referred to as power conditioner systems (PCSs).

[0014] The plant control device 10 controls the plurality of power conversion devices 22. The plant control device 10 is also referred to as a Power Plant Controller (PPC). The plant control device 10 includes a virtual synchronous generator model part 10a. The virtual synchronous generator model part 10a outputs power command values P*, Q* based on the grid current value Is and the grid voltage value Vs. The power command values P*, Q* include an active power command value P* and a reactive power command value Q*. The plurality of power conversion devices 22 output the AC power in accordance with the power command values P*, Q*. Thereby, VSG control at a plant level is achieved A virtual synchronous generator is also referred to as a VSG.

[0015] The virtual synchronous generator model part 10a includes a rotor equationof-motion model, a governor model, and an AVR control model. Thus, the plant control device 10 is configured to have a control model which simulates a rotor motion equation of a synchronous generator, a governor, and an AVR. The virtual synchronous generator model part 10a performs control so that a power flow at the grid connection point S corresponds virtually to an output from the synchronous generator.

[0016] A model configuration of a virtual synchronous generator including a rotor motion equation model, a governor model, and an AVR control model is disclosed in, for example. JP-A-2014-168351, and thus the model configuration has already been known and is not a novel matter. Therefore, description of a detailed configuration of the model is omitted.

[0017] Since the plant control device 10 has the virtual synchronous generator model part 10a, each control circuit of the plurality of power conversion devices 22 does not have to include a model. Since the plant control device 10 can integrally control the plurality of power conversion devices 22, the entire system including a plurality of power conversion devices 22 can simulate the VSG (virtual synchronous generator). This results in that system price per unit capacity becomes inexpensive, because benefit from having a larger scale can be obtained. [0018] In the embodiment, the plant control device 10 optimally controls the plurality of power conversion devices 22 in the power generation plant 2 to achieve frequency stabilization and voltage stabilization of the electric power grid 100. A grid frequency and the grid voltage Vs are maintained, and advantageous effect of the grid stabilization is obtained.

[0019] Further, the virtual synchronous generator model part 10a is implemented in the plant control device 10 rather than in each inverter control circuit 22h. Accordingly, there is an advantage that hardware modification and software modification are not necessary in each inverter control circuit 22b in many power conversion devices 22.

[0020] Moreover, according to the embodiment, it is possible to simulate the virtual synchronous generator in the entire system including the plurality of power conversion devices 22 connected in the AC-link manner. Since the AC-link manner can connect storage batteries to the second power conversion device 22 collectively, (here is an advantage that storage batteries does not have to connect to each power conversion device 22 as in a DC-link manner. According to the system configuration of the AC-link system illustrated in FIG. 1, since the storage batteries can be integrated and installed in one place without being dispersed in the power generation plant 2, cost cutting relating to the storage battery configuration is also expected [0021] FIG. 2 is a diagram of a configuration of an inverter control circuit in the power generation system 1 according to an embodiment. Each of the plurality of power conversion devices 22 includes a power conversion circuit 22a and an inverter control circuit 22h. The inverter control circuit 22b is a power conversion control circuit for controlling the power conversion circuit 22a in accordance with the power command values PS, Q*.

[0022] The inverter control circuit 22b preferably includes a PLL circuit 22c. The PLL circuit 22c is a phase locked loop circuit. Since the PLL circuit 22c can implement phase synchronization control, control timings of the plurality of power conversion devices 22 can be aligned. It should be noted that the technique of JP 2014-168351 is intended to achieve control without using a PLL circuit, and this viewpoint is clearly different from the present embodiment which intentionally uses the PLL circuit 22c.

10023] The power command values P*, Q* which the plant control device 10 transmits to the inverter control circuit 22b are preferably analog signals. The analog signal does not have to perform digital arithmetic processing as a digital signal. Transmitting of the power command value P5. Q. by the analogue signal makes it possible to simplify or omit arithmetic processing in the inverter control circuit 22b. This can increase a feedback control speed.

[0024] Further, in the embodiment, the plant control device 10 directly acquires the grid current Is and the grid voltage Vs via the current transformer 4 and the potential transformer 5 without using a measuring instrument called a multimeter. This achieves higher speed in signal transmission compared with using the multimeter, resulting in an advantage to increase control speed.

[0025] The plant control device 10 preferably performs feedback control in control cycle of 10msec or less based on the grid voltage Vs and the grid current Is. If the feedback control cycle is 10msec or less, high-speed feedback control can be implemented, at an adequate response speed in practical use, such that grid voltage fluctuation or grid frequency fluctuation and the like on the power system 100 side is considered in calculation of the power command values P*, (/' in the VSG model 10a.

[0026[ FIG. 3 is a diagram of a configuration of the power generation system 1 and the plant control device 10 according to a modification of the embodiment. As shown in FIG. 3, in the power generation system I. the plurality of DC power supplies 23 and 24 to which the plurality of power conversion devices 22 respectively connect may be configured such that a first DC power source 23 of a renewable energy power generation device and a second DC power source 24 of a storage battery are connected in parallel. The VSG (virtual synchronous generator) can be simulated in the entire system including the plurality of power conversion devices 22 connected in a DC-link manner.

10027] The power generation system 1 and the plant control device 10 according to the embodiment may be provided as a power generation method and a plant control method according to the embodiment. The power generation method and the plant control method according to the embodiment may be implemented by adding the plant control device 10 according to the embodiment in a posteriori to an existing power generation system and an existing plant control device.

[Reference Signs List] [0028] 1 Power generation system 2 Power generation plant 3 Interconnection transformer 4 Current transformer Potential transformer 10 Plant control device 10a Virtual synchronous generator model part (VSG model part) Switch 21 Transformer 22 Power conversion device (PCS) 22a Power conversion circuit 22h Inverter control circuit 22c PLL circuit 23 DC power supply (photovoltaic power generation module) 24 DC power supply (storage battery) Storage system Electric power grid Is Grid current Q' Power command value S Grid connection point Vs Grid voltage

Claims

Claims [Claim 1] A power generation system comprising: a plurality of power conversion devices each converting DC power from a DC power source into AC power; and a plant control device controlling the plurality of power conversion devices, wherein the plant control device includes a virtual synchronous generator model part for outputting a power command value based on a current value and a voltage value at a grid connection point on an output side of the plurality of power conversion devices, and wherein the plurality of power conversion devices output the AC power according to the power command value.[Claim 2] The power generation system according to claim 1, wherein the plurality of power conversion devices include a first power conversion device and a second power conversion device, wherein the DC power source to which the first power conversion device connects is a renewable energy power generation device, and wherein the DC power source to which the second power conversion device connects is a storage battery.[Claim 3] The power generation system according to claim 1, wherein at least one of DC power sources to which the plurality of power conversion devices respectively connect is configured such that a first DC power source of a renewable energy power generation device and a second DC power source of a storage battery are connected in parallel.[Claim 4] The power generation system according to any one of claims 1 to 3, wherein the power command value transmitted from the plant control device to the power conversion device is an analog signal.[Claim 5] The power generation system according to any one of claims 1 to 4, wherein the plant control device performs feedback control in control cycle of 10msec or less based on the current value and the voltage value at the grid connection point.[Claim 6] The power generation system according to any one of claims 1 to 5, wherein each of the plurality of power conversion devices includes a power conversion circuit and a power conversion control circuit controlling the power conversion circuit in accordance with the power command value, and wherein the power conversion control circuit includes a PLL circuit. [Claim 7] A plant control device for controlling a plurality of power conversion devices converting DC power from a DC power source into AC power, comprising: a virtual synchronous generator model part for outputting a power command value based on a current value and a voltage value at a grid connection point on an output side of the plurality of power conversion device, wherein the plant control device is configured to cause the plurality of power conversion devices to output the AC power based on the power command value.