Multi-feeder shared energy storage type power flow controller and control method thereof

Abstract

The invention belongs to the field of power distribution network energy storage power flow optimization, and provides a multi-feeder shared energy storage type power flow controller and a control method thereof.The multi-feeder shared energy storage type power flow controller comprises a power flow adjusting module which is composed of a plurality of power flow adjusting half-bridge modules sharing a direct current bus, and each power flow adjusting half-bridge module is connected with one feeder; the power flow regulation half-bridge module is connected in series among the plurality of feeder lines; the shared energy storage module is connected with a plurality of feeder lines through a power balance half-bridge module, so that energy interaction between the shared energy storage module and the plurality of feeder lines is realized; according to the multi-feeder shared energy storage type power flow controller provided by the invention, through a designed control method, power flow control and shared energy storage of connected multi-end feeders can be realized on the premise of stable operation, and flexible, networked and shared transformation of a power distribution system is assisted; and the resource utilization rate, regulation and control flexibility and power supply reliability of the power distribution network are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of distribution network energy storage flow optimization, and in particular relates to a multi-feeder shared energy storage type flow controller and a control method thereof. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] The widespread access of new sources and loads such as distributed wind and solar power generation and electric vehicle charging stations to the distribution network has seriously affected the operation level and power supply quality of traditional distribution networks, including a series of problems such as excessive system power fluctuations, node voltage exceeding the limit, feeder congestion, and reduced power supply reliability.

[0004] In response to the above problems, many scholars at home and abroad have proposed many solutions. Among them, the solutions of constructing a flexible interconnection device (FID) with reactive power compensation or flow regulation capabilities or configuring an energy storage system (ESS) for the system are relatively mature, and there are projects that have achieved demonstration applications. However, both solutions have certain disadvantages, which limit their large-scale development. ESS can smooth the fluctuation of wind and solar power, reduce peaks and fill valleys, provide inertia and damping support for the power grid, improve the regulation capability of the power grid, improve the quality of power, and provide an effective solution for the consumption of high-proportion wind and solar power. However, the configuration of ESS alone occupies a large area and is expensive, so it is difficult to achieve large-scale application in the existing distribution network; FID uses power electronic switches to provide interconnection ports for different distribution feeders, which can realize the normalization of the distribution network "soft connection", and can also significantly enhance the flexible regulation capability of the distribution network, but it does not have the time transfer capability of ESS for loads, and when expanding the port, it is necessary to expand the full power structure, which also faces the problems of high cost and large volume, and it is difficult to achieve large-scale application. Therefore, it is urgent to propose improvement methods for the existing solutions to further optimize the modern distribution network with high penetration rate of distributed energy access. Summary of the invention

[0005] In order to solve the above problems, the present invention proposes a multi-feeder shared energy storage type flow controller and its control method. The present invention is based on the existing FID and ESS solutions for improvement, integrating the advantages of the two solutions, and proposes a new device that can simultaneously have the flow regulation and energy storage functions between multiple interconnected feeders, that is, it has the ability to transfer energy flow at the "spatial level" while also having the ability to transfer energy flow at the "temporal level". The device has multi-port expansion capabilities, and there is no need to increase the full-power topology when increasing the number of feeders. It has the characteristics of modularization and easy expansion, so the cost and volume are greatly reduced, which can effectively solve the key problems that restrict the large-scale development of FID and ESS.

[0006] According to some embodiments, a first solution of the present invention provides a multi-feeder shared energy storage type power flow controller, which adopts the following technical solution: A multi-feeder shared energy storage type power flow controller, comprising: A power flow regulation module, which is composed of a plurality of power flow regulation half-bridge modules sharing a DC bus, each of which is connected to a feeder line, and the power flow regulation half-bridge modules are connected in series between the plurality of feeders; The shared energy storage module is used to release energy to the feeder when the power system is insufficient and to store energy when the power system has surplus energy. The shared energy storage module is connected to multiple feeders through a power balancing half-bridge module to achieve energy interaction between the shared energy storage module and the multiple feeders.

[0007] Furthermore, the power flow regulation module adopts series voltage-type power flow regulation, that is, the power flow control of the feeder is achieved by controlling the output voltage of the power flow regulation half-bridge module.

[0008] Furthermore, the shared energy storage module, as the parallel part of the power flow controller, adopts a cascaded H-bridge structure.

[0009] According to some embodiments, a second solution of the present invention provides a control method for a multi-feeder shared energy storage type power flow controller, which adopts the following technical solution: A control method for a multi-feeder shared energy storage type power flow controller according to the first solution includes: The power flow control of the feeder is achieved by adjusting the output voltage amplitude and phase of the power flow regulating half-bridge module connected in series on the feeder; By controlling the AC side voltage of the shared energy storage module, the command value tracking of the active and reactive components of the energy storage current components is achieved, thereby adjusting the active and reactive power of the balanced feeder; By balancing the feeder power flow, the charging and discharging power of the shared energy storage module can be controlled.

[0010] Furthermore, the power flow control of the feeder is realized by adjusting the output voltage amplitude and phase of the power flow regulating half-bridge module connected in series on the feeder, specifically: Based on the topological structure of the multi-feeder shared energy storage power flow controller, the unified overall system equation consisting of the multi-feeder shared energy storage power flow controller and the power system describing the power flow of a certain feeder and the output voltage of the half-bridge module is determined; The unified overall system equation of the multi-feeder shared energy storage power flow controller and the power system based on the power flow of a certain feeder and the output voltage of the half-bridge module is obtained, and the unified overall system dynamic voltage equation of the multi-feeder shared energy storage power flow controller and the power system is obtained, and the PACK transformation is performed on it to obtain the dynamic equation in the dq coordinate system; The dynamic equation in the dq coordinate system is used to adjust the output voltage amplitude and phase of the power flow regulation half-bridge module to achieve power flow control of the feeder.

[0011] Furthermore, the active power command value of the balancing feeder is determined by the target charging and discharging active power value of the shared energy storage module.

[0012] Furthermore, when the q-axis component of the remaining feeder current of the balanced feeder is removed to achieve zero-static error following of the system instructions, the q-axis component of the balanced feeder is determined by the q-axis component of the shared energy storage module current. By controlling the q-axis component of the shared energy storage module current, the reactive power of the balanced feeder is controlled.

[0013] Furthermore, the shared energy storage module can provide reactive power compensation for the power system so that the reactive components of all feeders reach the command value.

[0014] Furthermore, the capacitor voltage of the power balancing half-bridge module is equal to the DC bus voltage, and the DC bus voltage is stabilized by controlling the energy flowing into the power balancing half-bridge module to be zero.

[0015] Furthermore, by controlling the shared energy storage module and the power flow regulation module, the active power and reactive power of the remaining feeders except the balanced feeder, the charging and discharging power of the shared energy storage module, and the reactive power of the balanced feeder can all be decoupled and actively controlled.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention first proposes a topological structure of a multi-feeder shared energy storage flow controller that has the advantages of both FID and ESS; secondly, the device operation principle, power control principle and energy balance mechanism are analyzed; finally, based on the principle analysis, a device operation control method based on PI control is proposed to realize multi-terminal flow control and energy balance of the device, and simulation verification is carried out to ensure the safe and stable operation of the device; the interconnection of multiple AC feeders with the same energy storage system is realized, and there is a complex energy interaction between multiple ports. The DC bus of the device acts as an energy buffer, providing a flow path for active power. Maintaining the constant voltage of the DC bus is a prerequisite for ensuring the stable operation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0018] Figure 1 This is a connection diagram of a multi-feeder shared energy storage type power flow controller system in an embodiment of the present invention; Figure 2 This is a topological structure diagram of a multi-feeder shared energy storage type power flow controller in an embodiment of the present invention; Figure 3 is a typical topology diagram based on the series voltage regulation method in an embodiment of the present invention; Figure 4 is an equivalent circuit diagram of a distribution network based on a series voltage regulation method in an embodiment of the present invention; Figure 5 is a relationship diagram between the control variable and the controlled quantity of the feeder power flow in an embodiment of the present invention; Figure 6 Schematic diagram of a feeder power flow decoupling control method according to an embodiment of the present invention; Figure 7 Schematic diagram of a method for controlling charging and discharging power of a shared energy storage module in an embodiment of the present invention; Figure 8 is a schematic diagram of a system energy balance control method in an embodiment of the present invention; Fig. 9 It is a simulation waveform diagram of active power of feeder and energy storage in an embodiment of the present invention; Fig.10 It is a feeder reactive power simulation waveform diagram in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0020] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0021] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0022] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0023] Terminology explanation: CHB-ESS - cascaded H-bridge energy storage system (CHB-ESS) based on cascaded H-bridge power conversion; HBSM - Half Bridge Substructure; FBSM - Full Bridge Substructure; PFCM-Power Flow Control Module; Battery-Battery.

[0024] Embodiment 1 like Figure 1 As shown, this embodiment provides a multi-feeder shared energy storage type power flow controller, including: A power flow regulation module, which is composed of a plurality of power flow regulation half-bridge modules sharing a DC bus, each of which is connected to a feeder line, and the power flow regulation half-bridge modules are connected in series between the plurality of feeders; The shared energy storage module is used to release energy to the feeder when the power system is insufficient and to store energy when the power system has surplus energy. The shared energy storage module is connected to multiple feeders through a power balancing half-bridge module to achieve energy interaction between the shared energy storage module and the multiple feeders.

[0025] The power flow regulation module adopts series voltage type power flow regulation, that is, the power flow control of the feeder is realized by controlling the output voltage of the power flow regulation half-bridge module.

[0026] The shared energy storage module serves as the parallel part of the power flow controller and adopts a cascaded H-bridge structure.

[0027] Multi-feeder shared energy storage power flow controller is applied to 10kV distribution network. The system connection diagram is as follows: Figure 1 As shown, the device is divided into two major modules: a flow regulation module and a shared energy storage module.

[0028] The power flow regulation module is connected to multiple feeders. By adjusting the output voltage of the port power electronic device, the power flow regulation between multiple feeders can be realized, that is, the "spatial level" transfer of energy flow can be realized, and the remaining capacity of the feeder can be fully utilized to optimize the system power flow distribution. The shared energy storage module is a large-capacity ESS that can interact with multiple feeders. When distributed energy is in surplus, energy can be stored. When system power is insufficient, the energy storage module releases energy, thereby achieving peak shaving and valley filling, that is, realizing the transfer of energy flow at the "time level".

[0029] Specifically, this embodiment takes a structure as an example for analysis, including but not limited to the structure, in which the flow regulation module is composed of a flow regulation half-bridge module with a common DC bus, each feeder is connected to a flow regulation half-bridge module, and there is also a power balancing half-bridge module connected to the shared energy storage module; the shared energy storage module is a cascaded H-bridge structure, which can realize a large-capacity energy storage function, such as Figure 2 shown.

[0030] Embodiment 2 This embodiment provides a control method for a multi-feeder shared energy storage type power flow controller, based on a multi-feeder shared energy storage type power flow controller as described in Embodiment 1, including: The power flow control of the feeder is achieved by adjusting the output voltage amplitude and phase of the power flow regulating half-bridge module connected in series on the feeder; By controlling the AC side voltage of the shared energy storage module, the command value tracking of the active and reactive components of the energy storage current components is achieved, thereby adjusting the active and reactive power of the balanced feeder; By balancing the feeder power flow, the charging and discharging power of the shared energy storage module can be controlled.

[0031] The shared energy storage module can provide reactive power compensation for the power system so that the reactive components of all feeders reach the command value.

[0032] According to the proposed device topology, the power flow regulation half-bridge of the power flow regulation module is connected in series between the feeders, so the system power flow regulation method adopts series voltage type power flow regulation. The series voltage type power flow regulation method uses a controllable voltage source instead of impedance, and changes the power flow distribution of the power system by adjusting the amplitude and phase of the controllable voltage source connected in series with the feeder. This type of device usually has no energy storage element inside and can be equivalent to a reactive voltage source. Its working principle is as follows Figure 3 as well as Figure 4 shown.

[0033] The typical series voltage type power flow regulation method is the static synchronous series compensator (SSSC). This type of device can only output reactive voltage, with limited control freedom, and cannot achieve decoupling control of active power and reactive power of the feeder. However, in the structure proposed in this article, the shared energy storage module, as a parallel part, can achieve power interaction with the feeder and can provide active and reactive power. Therefore, the proposed device can achieve decoupling control of active power and reactive power of the connected feeder, which can be achieved by PI control.

[0034] The power flow control of the feeder is achieved by adjusting the output voltage amplitude and phase of the power flow regulating half-bridge module connected in series on the feeder, specifically: Based on the topological structure of the multi-feeder shared energy storage power flow controller, the unified overall system equation consisting of the multi-feeder shared energy storage power flow controller and the power system describing the power flow of a certain feeder and the output voltage of the half-bridge module is determined; Based on the system equation of a certain feeder power flow and the output voltage of the half-bridge module, the system dynamic voltage equation of the multi-feeder shared energy storage power flow controller and the power system is obtained, and the PACK transformation is performed on it to obtain the dynamic equation in the dq coordinate system; The dynamic equation in the dq coordinate system is used to adjust the output voltage amplitude and phase of the power flow regulation half-bridge module to achieve power flow control of the feeder.

[0035] Based on the device topology, the system equation describing the jth feeder power flow and the output voltage of the half-bridge module can be obtained as shown in equation (1), which shows that the feeder power flow connected to the device is controlled by the power flow regulating half-bridge output voltage. P , Q , V , I , X Represents the active power, reactive power, voltage, current, and reactance of each feeder, respectively. Subscript 1~ j Then it corresponds to 1~ j Feeders, among which feeder 1 is used as a balancing feeder for balancing the energy of the entire multi-feeder shared energy storage type power flow controller and the power system as a whole.

[0036] in, P , Q , V , I , X Respectively represent the active power, reactive power, voltage, current, and reactance of each feeder connected to each port of the device, with subscripts 1~ j Then it corresponds to 1~ jFeeders, among which feeder 1 is used as a balancing feeder for balancing the energy of the entire multi-feeder shared energy storage type power flow controller and the power system as a whole. Feeder 1~ n The voltage drop across the impedance, They are feeder 1~ n The fundamental component of the output voltage of the connected power flow regulation half-bridge and balance regulation half-bridge modules, , are the fundamental components of the voltage and current of the CHB-ESS bridge arm, respectively. The superscript → means vector, and the superscript * means conjugate. To balance the half bridge and the j The voltage difference of the power flow regulating half bridge connected to the feeder. Figure 2 As shown, Represents the device connected to 1~ n The node voltage of the feeder, Representative 1~ n The current of the feeder, Representative 1~ n The equivalent inductance of the feed line, Representative 1~ n The output voltage of the power flow regulating half bridge connected to the feeder, Represents balanced regulation of half-bridge output voltage, represents the PFCM DC bus voltage, Represents the output voltage of the parallel CHB-ESS part, all variables are subscripted a , b , c Represents the abc values ​​of the variables.

[0037] (1); Further, the system dynamic voltage equation of the multi-feeder shared energy storage power flow controller and the power system as a whole can be obtained as shown in equation (2). After performing PARK transformation, we can obtain d - q The dynamic equation in the coordinate system is shown in formula (3): (2); (3); By Laplace transforming equation (3), we can obtain the series equivalent regulation voltage, feeder node voltage and feeder current. dq The frequency domain form of the fundamental frequency dynamic equation in the coordinate system is: (4); From formula (1), it can be seen that the feeder of the device jThe current depends on the node voltage of the feeder and the equivalent output voltage of the power flow regulating half bridge. According to formula (4), the transfer function relationship between the series equivalent output voltage of the power flow regulating half bridge, the feeder node voltage and the feeder current can be obtained, as follows: Figure 5 As shown in the figure, the relationship between the control variable and the controlled quantity of the feeder power flow is shown. It can be seen that the feeder current is in the process of regulation. d Axis and q There is coupling between the axis components and they will be affected by the voltage disturbance of the feeder node. Figure 5 Based on the mathematical model, the feeder power flow control strategy can be designed.

[0038] exist dq In the coordinate system, the feeder power flow regulation control strategy of the device can be decomposed into the outer loop reference current calculation link and the inner loop current controller. Among them, the outer loop part controls and calculates the output current of the inner loop current controller according to the command value. d- q Axis reference value and , and the inner loop current controller adjusts the equivalent output voltage of the series half-bridge Make dq The shaft current quickly tracks its reference value and According to the relationship between feeder power and feeder voltage and current described in equation (1), the feeder j The reference values ​​of active power and reactive power are and , then the feeder j The current reference value can be calculated as: (5); For the inner loop current controller, from (3), we can see that the controller output variable is j Feeder current d Axis and q Axis Component and , is the control variable feeder 1 and feeder j Equivalent series voltage d Axis and q Axis Component and , , , and is the disturbance variable, and the feeder d Axis and q There is coupling between the shaft currents. Using the PI controller, the feeder j (=2, 3, …, n) to perform closed-loop control on the current, taking into account dq The influence of the current coupling term between axes and the voltage disturbance term at the feeder node. The coupling compensation term of the current is introduced , , and To achieve current decoupling control and add voltage feedforward compensation , , and To offset the influence of feeder node voltage disturbance, we can get dq Series equivalent voltage in coordinate system and Therefore, the series equivalent voltage reference value in power flow regulation control can be expressed as: (6); From formula (6), we can get dq Series equivalent voltage reference value under the axis and After that, the Park inverse transformation can be used to convert it to the voltage reference value in the abc coordinate system. , and Therefore, the feeder power flow control method can be designed as follows: Figure 6 shown.

[0039] For the shared energy storage module charging and discharging power control, the system dynamic equation can be similarly obtained as shown in equation (7). After PARK transformation, we can get dq The dynamic equation in the coordinate system is shown in formula (8): (7); (8); By controlling the AC side voltage of the shared energy storage module, the command value tracking of the active component and reactive component of the energy storage current component is realized, and the active power and reactive power of the balanced feeder-feeder 1 can be adjusted. In fact, feeder 1 can be set as a balanced feeder, so its given active power command value can be determined by the target charging and discharging active power command value of the shared energy storage module, that is: (9); For the reactive component, according to Kirchhoff's law, the current in feeder 1 is q Quantity satisfies: (10); in, is the current of the shared energy storage module q Axis component. From formula (10), we can know that after removing the balanced feeder, the remaining feeder - feeder 2~n Current q When the axis component realizes the control system instruction of the multi-feeder shared energy storage type power flow controller without static error, the current of the balanced feeder-feeder 1 q The q-axis component is determined by the q-axis component of the shared energy storage module current. q The axis component can effectively control the reactive power of the balanced feeder - feeder 1, that is, while controlling the charging and discharging power of the shared energy storage module, it can also provide reactive power compensation for the connected power system, so that the reactive components of all feeders reach the command value. Based on the above analysis, the shared energy storage module charging and discharging power control method can be obtained as follows: Figure 8 shown.

[0040] In summary, in order to realize the remaining feeder line without the balanced feeder - feeder 2~ n Based on the decoupling and independent control of active power and reactive power, the power of the energy storage branch is closely related to the balanced feeder flow. Since the active power of the balanced feeder can be self-balanced according to the power conservation relationship, the charging and discharging power of the shared energy storage module can be controlled by the balanced feeder flow. The shared energy storage module can also provide reactive power compensation function for the power system at the same time. Therefore, feeder 2~ n The active power and reactive power of the energy storage system, the charging and discharging power of the shared energy storage module, and the reactive power of the balanced feeder can all be decoupled and actively controlled.

[0041] The multi-feeder shared energy storage type power flow controller realizes the interconnection of multiple AC feeders with the same energy storage system. There are complex energy interactions between multiple ports. The DC bus is used as an energy buffer to provide a flow path for active power. Maintaining the constant voltage of the DC bus is a prerequisite for ensuring the stable operation of the multi-feeder shared energy storage type power flow controller system. Analysis shows that the capacitor voltage of the power balance adjustment half-bridge connected to the shared energy storage module is equivalent to the DC bus voltage. Therefore, the DC bus voltage can be stabilized by controlling the energy flowing into the capacitor to 0. The power expression flowing into the capacitor is shown in formula (11). In order to make the energy flowing into the capacitor 0, its DC component should be 0. The expression of the output voltage of the balanced adjustment half-bridge can be obtained as shown in formula (12). (11); (12); Based on the above principle, the control method can be further designed as follows Figure 7 As shown in the figure, this control method also uses PI control. The upper control layer controls the DC amount flowing into the capacitor to 0, thereby ensuring the stability of the capacitor voltage. The lower control layer injects zero-sequence voltage to ensure three-phase balance. The principle is further explained below: Assume that the three-phase current of the CHB-ESS port is: (13); Assume that the zero-sequence voltage injected into the balanced half-bridge voltage is as follows: (14); Among them, Δ u a and Δ u b All are the output signals of the P controller, specifically: (15); In the above formula, is the proportional factor of P control in MIM phase-to-phase balancing control. From equations (14) and (15), the interaction between the injected zero-sequence voltage and the power generated by CHB-ESS can be obtained as follows: (16); It can be seen from the above formula (16) that the injected zero-sequence voltage can realize the power interaction between the three phases of PFCM, but it will not generate additional power to affect the upper control. Therefore, this zero-sequence voltage injection method can achieve the balance of the three-phase DC bus voltage of PFCM. In order to further eliminate the steady-state error of voltage control, a PI controller can also be used. In summary, the two-layer voltage control strategy of PFCM DC bus can be obtained as shown. Among them, due to the current flowing into the PFCM DC bus by CHB-ESS and i p The reference direction is opposite. and The phase is the same, so the PI controller output is multiplied by ,Right now In Oriented Rotation Coordinate System d The sign of the axis component is reversed to obtain a balanced regulated half-bridge output voltage d Axis component command value, and give balanced adjustment half-bridge output voltage q If the axis component command value is 0, then after the inverse Park transformation The phase is the same. Finally, the PFCM DC bus voltage control strategy can be designed as follows Figure 7 shown.

[0042] Based on the above analysis, the multi-feeder shared energy storage power flow controller proposed in this paper can realize the power flow control and shared energy storage of the connected multi-terminal feeders under the premise of stable operation through the designed control method, which helps the flexible, networked and shared transformation of the distribution system, and is conducive to improving the resource utilization, regulation flexibility and power supply reliability of the distribution network.

[0043] Simulation Verification In order to verify the feasibility and effectiveness of the multi-feeder shared energy storage power flow controller and its control method, this paper carried out simulation verification in the 10kV distribution network application scenario based on the Matlab / Simulink simulation platform, and made it work under three conditions: charging, discharging and providing reactive power compensation of the energy storage sharing module. The control system power flow command values ​​of the multi-feeder shared energy storage power flow controller under specific simulation conditions are shown in Table 1: Table 1 Simulation conditions

[0044] The simulation results of system power flow and energy storage charging and discharging power control under three working conditions are as follows: Figure 8 and Fig. 9 As shown, the results show that the multi-feeder shared energy storage type flow controller and its control method proposed in the present invention can realize flow optimization and energy sharing among multiple feeders, and can greatly improve the utilization rate, flexibility and reliability of modern distribution networks with high penetration of new energy. The control system of the multi-feeder shared energy storage type flow controller can freely give the flow value of each feeder according to demand.

[0045] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A multi-feeder shared energy storage type power flow controller, characterized in that: include: A power flow regulation module, which is composed of a plurality of power flow regulation half-bridge modules sharing a DC bus, each of which is connected to a feeder line, and the power flow regulation half-bridge modules are connected in series between the plurality of feeders; The shared energy storage module is used to release energy to the feeder when the power system is insufficient and to store energy when the power system has surplus energy. The shared energy storage module is connected to multiple feeders through a power balancing half-bridge module to achieve energy interaction between the shared energy storage module and the multiple feeders.

2. A multi-feeder shared energy storage type power flow controller as claimed in claim 1, characterized in that: The power flow regulation module adopts series voltage type power flow regulation, that is, the power flow control of the feeder is realized by controlling the output voltage of the power flow regulation half-bridge module.

3. A multi-feeder shared energy storage type power flow controller as claimed in claim 1, characterized in that: The shared energy storage module serves as the parallel part of the power flow controller and adopts a cascaded H-bridge structure.

4. A control method based on a multi-feeder shared energy storage type power flow controller as claimed in any one of claims 1 to 3, characterized in that: include: The power flow control of the feeder is achieved by adjusting the output voltage amplitude and phase of the power flow regulating half-bridge module connected in series on the feeder; By controlling the AC side voltage of the shared energy storage module, the command value tracking of the active and reactive components of the energy storage current components is achieved, thereby adjusting the active and reactive power of the balanced feeder; By balancing the feeder power flow, the charging and discharging power of the shared energy storage module can be controlled.

5. A control method for a multi-feeder shared energy storage type power flow controller as claimed in claim 4, characterized in that: The power flow control of the feeder is achieved by adjusting the output voltage amplitude and phase of the power flow regulating half-bridge module connected in series on the feeder, specifically: Based on the topological structure of the multi-feeder shared energy storage power flow controller, the unified overall system equation consisting of the multi-feeder shared energy storage power flow controller and the power system describing the power flow of a certain feeder and the output voltage of the half-bridge module is determined; The unified overall system equation of the multi-feeder shared energy storage power flow controller and the power system based on the power flow of a certain feeder and the output voltage of the half-bridge module is obtained, and the unified overall system dynamic voltage equation of the multi-feeder shared energy storage power flow controller and the power system is obtained, and the PACK transformation is performed on it to obtain the dynamic equation in the dq coordinate system; The dynamic equation in the dq coordinate system is used to adjust the output voltage amplitude and phase of the power flow regulation half-bridge module to achieve power flow control of the feeder.

6. A control method for a multi-feeder shared energy storage type power flow controller as claimed in claim 4, characterized in that: The active power command value of the balancing feeder is determined by the target charging and discharging active power value of the shared energy storage module.

7. A control method for a multi-feeder shared energy storage type power flow controller as claimed in claim 4, characterized in that: When the q-axis component of the residual feeder current of the balanced feeder is removed to achieve zero-static error following of the system instruction, the q-axis component of the balanced feeder is determined by the q-axis component of the shared energy storage module current. By controlling the q-axis component of the shared energy storage module current, the reactive power of the balanced feeder is controlled.

8. A control method for a multi-feeder shared energy storage type power flow controller as claimed in claim 7, characterized in that: The shared energy storage module can provide reactive power compensation for the power system so that the reactive components of all feeders reach the command value.

9. A control method for a multi-feeder shared energy storage type power flow controller as claimed in claim 4, characterized in that: The capacitor voltage of the power balancing half-bridge module is equal to the DC bus voltage, and the DC bus voltage is stabilized by controlling the energy flowing into the power balancing half-bridge module to be zero.

10. A control method for a multi-feeder shared energy storage type power flow controller according to claim 1, characterized in that: By controlling the shared energy storage module and the power flow regulation module, the active power and reactive power of the remaining feeders except the balanced feeder, the charging and discharging power of the shared energy storage module and the reactive power of the balanced feeder can all be decoupled and actively controlled.

Images