A high-voltage chain energy storage control system and a control method thereof

Abstract

The application relates to a high-voltage chain energy storage control system and a control method thereof, which comprises a single-phase or multi-phase control loop and a central controller connected with the single-phase or multi-phase control loop, wherein each phase of the control loop comprises a plurality of battery power sub-modules connected in sequence, and the plurality of battery power sub-modules are in communication connection with the central controller. The application combines low-voltage battery modules with modular multi-level converters, establishes a high-voltage chain energy storage control system based on battery power sub-modules, realizes synchronous and real-time control of the energy storage system, shortens the control cycle, improves the stability of the power grid frequency and power, and increases the reliability of the power grid. The battery power sub-modules in the control loop are sequentially connected through optical fibers, so that the influence of the potential difference between different modules on the communication link caused by discharge is avoided; the control loops are connected with optical cables to form a ring-shaped communication redundancy, so that the single optical cable failure does not cause all communication interruptions.

Description

Technical Field

[0001] This invention relates to the field of new energy storage control technology, and in particular to a high-voltage chain energy storage control system and its control method. Background Technology

[0002] Energy storage technology based on chemical batteries has advantages such as fast response and short construction period. Currently, most lithium battery energy storage systems are designed as 400V / 630KVA standard containers and then coupled to the high-voltage power grid stage by stage through transformers. As the capacity increases, the number of transformer coupling stages increases, the number of standard containers installed is huge, and the power conversion efficiency is greatly reduced. Summary of the Invention

[0003] Based on the above-mentioned situation of the prior art, the purpose of this invention is to provide a high-voltage chain energy storage control system and its control method, which combines a low-voltage battery module with a modular multilevel converter and establishes a high-voltage chain energy storage control system based on the battery power sub-module, so as to realize synchronous and real-time control of the energy storage system, shorten the control cycle, improve the grid frequency stability and power stability, and increase the reliability of the grid.

[0004] To achieve the above objectives, according to one aspect of the present invention, a high-voltage chain-type energy storage control system is provided, comprising a single-phase or multi-phase control loop and a central controller connected to the single-phase or multi-phase control loop; wherein,

[0005] Each phase of the control loop includes N battery power sub-modules connected end to end, where N is a positive integer greater than 2;

[0006] Each of the battery power submodules includes a first communication port and a second communication port; the first communication port includes a first transmitting port and a first receiving port; the second communication port includes a second transmitting port and a second receiving port;

[0007] The second transmitting port of the i-th battery power submodule is communicatively connected to the first receiving port of the (i+1)-th battery power submodule, and the second receiving port of the i-th battery power submodule is communicatively connected to the first transmitting port of the (i+1)-th battery submodule, where 1≤i≤N-1;

[0008] The first communication port of the first battery power submodule and the second communication port of the Nth battery power submodule are connected to the central controller.

[0009] Furthermore, the central controller includes a communication module and a protection control module;

[0010] The communication module includes multiple sets of communication ports, each set of communication ports including a first transmitting port and a first receiving port, as well as a second transmitting port and a second receiving port;

[0011] Each phase's control loop is connected to a set of communication ports in the communication module; wherein, the first transmitting port of the first battery power submodule in the phase control loop is connected to the first receiving port of the set of communication ports, and the first receiving port is connected to the first transmitting port of the set of communication ports; the second transmitting port of the Nth battery power submodule is connected to the second receiving port of the set of communication ports, and the second receiving port is connected to the second transmitting port of the set of communication ports.

[0012] Furthermore, the battery power submodule includes a battery unit, a filter unit, a power submodule unit, a communication unit, and a control unit;

[0013] The battery unit, filter unit, and power submodule unit are connected in sequence, and all of them, along with the communication unit, are connected to the control unit.

[0014] Furthermore, the protection control module receives the power parameters of each battery power submodule through the communication module, and calculates the power setting value of each battery power submodule in combination with the preset power command value.

[0015] According to a second aspect of the present invention, a control method for a high-voltage chain energy storage control system as described in the first aspect of the present invention is provided, comprising the steps of:

[0016] The central controller receives the power parameters of each battery power submodule and calculates the power setting value of each battery power submodule by combining them with the preset power command value.

[0017] The central controller obtains the PWM drive pulses for each battery power sub-module based on the power setting value, and transmits the PWM drive pulses to each battery power sub-module through the communication module.

[0018] The central controller sends cyclic synchronization data frames to each battery power submodule, and each battery power submodule achieves synchronous output according to the cyclic synchronization data frames.

[0019] Furthermore, the central controller receives the power parameters of each battery power submodule and, in conjunction with preset power command values, calculates the power setting value for each battery power submodule, including:

[0020] The central controller receives real-time power setpoints and calculates the power setpoints for each battery power submodule based on the status feedback of the battery power submodules; and performs closed-loop adjustment of the output of the energy storage control system based on the power measurement feedback value of the actual output of the grid-connected energy storage.

[0021] Furthermore, the cyclic synchronization data frame acquires the actual values ​​of the internal clock and reference clock of each battery power submodule;

[0022] Before the next cyclic synchronization data frame is sent, the central controller calculates the clock adjustment value of each battery power submodule based on the data obtained from the cyclic synchronization data frame, and sends it to each battery power submodule in the next cyclic synchronization data frame.

[0023] Furthermore, the central controller transmits the PWM drive pulses to each battery power submodule via the communication module, including:

[0024] The drive pulse of each battery power submodule is stored in the transmission buffer and copied to the transmission process before the cyclic synchronization data frame is sent.

[0025] When a cyclic synchronization data frame arrives at a communication unit of a battery power submodule, the communication unit decodes the cyclic synchronization data frame. If the cyclic synchronization data frame corresponds to the address of the battery power submodule, the corresponding data content is copied to the communication unit of the battery power submodule.

[0026] When the cyclic synchronization data frame leaves, the communication unit sends an interrupt request to the control unit and transmits the data to the control unit.

[0027] Furthermore, it also includes:

[0028] The central controller achieves balanced compensation control under three-phase unbalanced load based on the measured real-time current and voltage values ​​of the three-phase power grid. It performs vector transformation on the measured real-time current and voltage values ​​of the three-phase power grid to obtain the three-phase compensation current, calculates the instantaneous reactive power using the instantaneous reactive power method, and realizes closed-loop control based on the reactive power as the feedback quantity of the compensation current of each phase.

[0029] Furthermore, it also includes:

[0030] The central controller performs voltage equalization adjustment for each battery power submodule based on the capacitor voltage of the battery power submodule: the capacitor voltage U of all battery power submodules is collected in each control cycle. c According to the capacitor voltage U c Sort by size;

[0031] During capacitor discharge, the capacitor voltage U c The higher the battery power submodule, the larger the duty cycle of its PWM drive pulse; capacitor voltage U c The lower the battery power of the submodule, the smaller the duty cycle of its PWM drive pulse.

[0032] During capacitor charging, the capacitor voltage U c The higher the battery power submodule, the smaller the duty cycle of its PWM drive pulse; capacitor voltage U c The lower the battery power submodule, the larger the duty cycle of its PWM drive pulse.

[0033] In summary, this invention provides a high-voltage chain-type energy storage control system and its control method. The system includes a single-phase or multi-phase control loop and a central controller connected to the single-phase or multi-phase control loop. Each phase of the control loop includes multiple battery power sub-modules connected end-to-end. These multiple battery power sub-modules are communicatively connected to the central controller. The central controller receives the power parameters of each battery power sub-module and, in conjunction with a preset power command value, calculates the power setpoint value of each battery power sub-module to control each battery power sub-module.

[0034] The present invention has the following beneficial technical effects:

[0035] (1) This invention combines a low-voltage battery module with a modular multilevel converter and establishes a high-voltage chain energy storage control system based on the battery power sub-module, thereby realizing synchronous and real-time control of the energy storage system, shortening the control cycle, improving the frequency stability and power stability of the power grid, and increasing the reliability of the power grid.

[0036] (2) By connecting the battery power sub-modules in the control loop one after the other through optical fiber, the impact of discharge caused by the potential difference between different modules on the communication link is avoided; the optical cables connecting each control loop form a ring communication redundancy, which avoids the interruption of all communications due to a single optical cable failure, and enables the communication link of each phase control loop to be independent, which can reduce the number of communication nodes on the link and reduce transmission delay.

[0037] (3) The control method of the present invention introduces the carrier phase-shift pulse width modulation technology used in the mature chain static var compensator (STATCOM) into the control strategy of the chain battery power sub-module. It can be flexibly adjusted in real time according to the number of sub-modules and the working status of the battery pack, which facilitates the dynamic adjustment of the life of the entire battery pack. Attached Figure Description

[0038] Figure 1 This is an overall block diagram of the high-voltage chain energy storage control system according to an embodiment of the present invention;

[0039] Figure 2 This is a schematic diagram of the circuit structure of the battery power submodule;

[0040] Figure 3 This is a flowchart of the control method of the high-voltage chain energy storage control system according to an embodiment of the present invention;

[0041] Figure 4 This is a power control block diagram of the central controller. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0043] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings. According to a first embodiment of the present invention, a high-voltage chain-type energy storage control system is provided, the overall block diagram of which is shown below. Figure 1 As shown, it includes a single-phase or multi-phase control loop and a central controller connected to the single-phase or multi-phase control loop. Figure 1 Taking a three-phase control circuit as an example, it includes a phase A control circuit, a phase B control circuit, and a phase C control circuit. Each phase control circuit includes N battery power sub-modules connected sequentially, where N is a positive integer greater than 2, and is related to the voltage of the battery power sub-modules and the voltage level of the connected high-voltage system. When this high-voltage chain energy storage control system is connected to a 10kV system, there can be 10 cascaded battery power sub-modules per phase; when this high-voltage chain energy storage control system is connected to a 35kV system, there can be 40 cascaded battery power sub-modules per phase.

[0044] Each battery power submodule includes a first communication port and a second communication port; the first communication port includes a first transmitting port and a first receiving port; the second communication port includes a second transmitting port and a second receiving port; the second transmitting port of the i-th battery power submodule is communicatively connected to the first receiving port of the (i+1)-th battery power submodule, and the second receiving port of the i-th battery power submodule is communicatively connected to the first transmitting port of the (i+1)-th battery submodule, where 1≤i≤N-1; the first communication port of the 1st battery power submodule and the second communication port of the Nth battery power submodule are communicatively connected to the central controller. The battery power submodules in each control loop are connected sequentially end-to-end via optical fiber, which avoids the impact of discharge caused by potential differences between different modules on the communication link. Simultaneously, each phase control loop is connected by optical cables to form a ring communication redundancy, thereby preventing a single optical cable failure from causing communication interruption across all modules. The control loops of each phase arm are independent of each other, which reduces the number of communication nodes on the link and reduces transmission delay. For example, when each phase includes 40 battery power submodules, the communication delay per phase in a 100M communication rate link is less than 50µs.

[0045] The central controller includes a communication module and a protection control module. The communication module includes multiple sets of communication ports, each set including a first transmitting port, a first receiving port, a second transmitting port, and a second receiving port. Each phase's control loop is communicatively connected to one set of communication ports in the communication module. Specifically, the first transmitting port of the first battery power submodule in the phase's control loop is communicatively connected to the first receiving port of the communication port set, and the first receiving port is communicatively connected to the first transmitting port of the communication port set. The second transmitting port of the Nth battery power submodule is communicatively connected to the second receiving port of the communication port set, and the second receiving port is communicatively connected to the second transmitting port of the communication port set. The protection control module receives the power parameters of each battery power submodule through the communication module and, in conjunction with preset power command values, calculates the power setpoint for each battery power submodule.

[0046] In this embodiment of the invention, the central controller can implement communication management functions for the three-phase control loop, including real-time data communication and synchronization signal management; it can also implement balancing compensation under three-phase unbalanced loads, voltage balancing of each battery power sub-module, and phase-shifted PWM pulse management for all battery power sub-modules; it can implement protection functions for the entire system, including overvoltage protection, overcurrent protection, and transient protection; and it can implement open-loop control and non-real-time communication functions for the system, including communication with the upper-level scheduling system, SCADA system, and HMI system. This central controller can, for example, be implemented by a multi-core, multi-tasking computer system using a real-time operating system, with a minimum execution cycle of 50µs, and has Ethernet communication modules, CAN communication modules, PCIe communication modules, and data logging communication modules.

[0047] For balance compensation control under three-phase unbalanced load, the following method can be adopted: Based on the measured real-time current and voltage values ​​of the three-phase power grid, perform vector transformation on the real-time current and voltage values ​​of the three-phase power grid to obtain the three-phase compensation current, then use the instantaneous reactive power method to calculate the instantaneous reactive power, and use the reactive power as the feedback quantity based on the compensation current of each phase to realize closed-loop control.

[0048] For voltage equalization adjustment of each battery power submodule, the following method can be adopted: Collect the capacitor voltage U of all battery power submodules in each control cycle. c According to the capacitor voltage U c Sort by size. During capacitor discharge, the capacitor voltage U c The higher the battery power submodule, the larger its PWM duty cycle; capacitor voltage U c The lower the battery power submodule, the smaller the duty cycle of its PWM drive pulse during discharge. During capacitor charging, the capacitor voltage U... cThe higher the battery power submodule, the smaller the duty cycle of its PWM drive pulse; capacitor voltage U c The lower the battery power submodule, the larger the duty cycle of its PWM drive pulse.

[0049] The battery power submodule includes a battery unit, a filter unit, a power submodule unit, a communication unit, and a control unit. Figure 2 The circuit structure diagram of the battery power submodule is shown below, such as... Figure 2 As shown, the battery unit, filter unit, and power submodule unit are connected sequentially, and all are connected to the control unit along with the communication unit. This control unit can be implemented, for example, using an FPGA, and can exchange data through the submodule control interface. The control unit includes an ADC sampling circuit for acquiring the battery voltage U of the battery power submodule. bat It can be used for battery SOC calculation, etc., and the filter circuit current i L It can be used for battery charging and discharging power calculations, etc.; capacitor voltage U C It can be used for submodule voltage balancing control; submodule current i SM This can be used for submodule power calculations, as well as for parameters such as IGBT temperature. It is obtained through the submodule current i... SM The monitoring and control unit can realize IGBT overcurrent protection, IGBT overtemperature protection, IGBT short circuit protection, and monitor capacitor voltage U. C The monitoring enables protection functions such as capacitor overvoltage protection. The power submodule unit includes an energy storage capacitor and an H-bridge switching circuit. The structure of this power submodule unit can refer to existing power submodule structures and will not be described further here. In this embodiment of the invention, a low-voltage battery module is combined with a modular multilevel converter to form the battery power submodule, and multiple battery power submodules are connected in a chain structure.

[0050] The high-voltage chain-type energy storage control system of this invention also includes a chain-type energy storage grid connection point measurement module based on a high-speed digital signal processor (DSP). This measurement module is used for power and frequency calculations at the 35kV / 10kV grid connection point of the chain-type energy storage system. The frequency calculation is implemented by a DSP0211 module connected to the central controller via a PCIe bus. This module integrates a high-speed signal processor and a current and voltage acquisition module. High-speed calculations required for power control, such as the Fast Fourier Transform algorithm and the Phase-Locked Loop algorithm, are performed here. Simultaneously, the position feedback and opening / closing control of the circuit breaker connected to the grid connection point are also implemented in this module. The communication cycle between this module and the controller is 50µs.

[0051] According to a second embodiment of the present invention, a control method for a high-voltage chain energy storage control system is provided. This high-voltage chain energy storage control system is, for example, the system provided in the first embodiment of the present invention. The flowchart of the method is as follows: Figure 3 As shown, it includes the following steps:

[0052] The central controller receives power parameters from each battery power submodule and, in conjunction with preset power command values, calculates the power setpoint for each battery power submodule. The power control block diagram of the central controller for this step is shown below. Figure 4 As shown, the protection and control module of the central controller includes a power command receiving unit and a power calculation unit. The power command receiving unit is connected to the energy management system (EMS) communication interface module and the monitoring system (SCADA) control communication interface module, respectively, and receives power adjustment commands from the EMS and SCADA communication interface modules. The energy management system communicates with the central control system via protocols such as IEC60870-5-104, generally transmitting real-time active power commands from the superior power dispatching system to the central controller. The central controller adjusts the power output of the entire chain energy storage system in real time according to the set value. Specifically, the energy management system (EMS) interface module writes the real-time power set value into the power calculation unit. The power calculation unit calculates the power output of each battery power submodule based on the status feedback of the battery power submodules and sends it to the corresponding battery power submodule communication unit through periodic control data frames using PWM pulse duty cycle parameters. At the same time, the power measurement feedback based on the actual output of the energy storage at the grid connection point is fed back to the central controller power calculation unit, and the output of the energy storage system is adjusted in a closed loop according to the feedback value. The Supervisory Control and Data Acquisition (SCADA) system communicates with the central controller via protocols such as IEC 61850 to acquire information, status, and various parameters of the chain energy storage system for data display, archiving, and event logging. Simultaneously, operators can manually control the chain energy storage system's activation, deactivation, and power output through the SCADA system.

[0053] The central controller obtains the PWM drive pulse width of each battery power submodule based on the power setting value and transmits the PWM drive pulse width to each battery power submodule through the communication module. The central controller receives the voltage measurement value, current measurement value, and battery voltage measurement value of each battery power submodule and, in conjunction with a preset power command value, calculates the PWM control pulse duty cycle of each battery power IGBT module using carrier phase-shift pulse width modulation (CPS-PWM) technology. This duty cycle is then sent to the control unit of each battery power submodule in the form of PWM control pulse width parameters via a periodic data frame from the central controller. The transmission process can be implemented through the following steps: the central controller stores the calculated PWM drive pulse of each battery power submodule in a transmission buffer and copies it to the transmission process before sending a cyclic synchronization data frame; when a cyclic synchronization data frame arrives at a communication unit of a battery power submodule, the communication unit decodes the cyclic synchronization data frame. If the cyclic synchronization data frame corresponds to the address of that battery power submodule, the corresponding data content is copied to the communication unit of that battery power submodule; when the cyclic synchronization data frame leaves, the communication unit sends an interrupt request to the control unit and transmits the data to the control unit. The control unit calculates the on / off time in the next modulation cycle based on the duty cycle of the PWM drive pulse, and controls the IGBT power transistor to turn on and off according to the on / off time when the next modulation cycle arrives.

[0054] The central controller sends synchronization control data frames to each battery power submodule to synchronize the PWM drive pulse outputs of each submodule. Initially, the central controller, acting as the master node, sends synchronization data frames to each battery power submodule to synchronize all devices in the network. The jitter is approximately 100ns (nanoseconds), enabling synchronized output from the battery power submodule communication ports and ensuring consistent output actions. The power regulation pulse of each phase control loop is controlled by a synchronization clock, with output pulse consistency within 30-100ns. The pulse output control deviation between the three-phase control loops is less than 50us, meeting the requirements for three-phase power balance. The central controller sends cyclic synchronization data frames to each battery power submodule. Each synchronization data frame message records the actual values ​​of the internal clock and reference clock of each battery power submodule, such as those obtained from its control unit. Before sending the next synchronization data frame, the clock adjustment value for each battery power submodule is calculated based on the data obtained from the previous synchronization data frame and sent back to each battery power submodule to synchronize their clocks. After a repetitive process of approximately 2 seconds, the synchronization accuracy can reach 100ns. Meanwhile, the synchronization signal output frequency of the control unit can be set to the carrier frequency of the PWM pulse controlled by the IGBT of the battery power submodule. Therefore, the PWM drive pulses of all battery power submodules can be synchronously output according to the synchronization pulse output frequency.

[0055] The central controller periodically outputs control parameters and exchanges synchronous data with each battery power submodule. The central controller periodically outputs parameters such as the PWM control pulse width from each battery power submodule, and each submodule periodically exchanges battery voltage / SOC and voltage and current data at measurement points on the submodule with the central controller. During the cyclic phase, the periodic synchronous data exchange and the central controller's periodic output of control parameters enable real-time control as fast as 50µs, allowing the battery power submodules to achieve rapid frequency and power control. The central controller acquires the status information of the battery power submodules through periodic data exchange, including maximum power, real-time power, and battery SOC information. This data is used by the central controller to calculate and allocate the output of each battery power submodule.

[0056] The central controller also performs balance compensation control under three-phase unbalanced loads based on the measured real-time current and voltage values ​​of the three-phase power grid; and performs voltage equalization adjustment for each battery power submodule based on the capacitor voltage of the battery power submodule. For balance compensation control under three-phase unbalanced loads, the following method can be adopted: Based on the measured real-time current and voltage values ​​of the three-phase power grid, perform vector transformation on the real-time current and voltage values ​​to obtain the three-phase compensation current; then calculate the instantaneous reactive power using the instantaneous reactive power method; and implement closed-loop control based on the reactive power as feedback quantity according to the compensation current of each phase. For voltage equalization adjustment of each battery power submodule, the following method can be adopted: Collect the capacitor voltage U of all battery power submodules in each control cycle. c According to the capacitor voltage U c Sort by size. During capacitor discharge, the capacitor voltage U c The higher the battery power submodule, the larger the duty cycle of its PWM drive pulse; capacitor voltage U c The lower the battery power submodule, the smaller the duty cycle of its PWM drive pulse. During capacitor charging, the capacitor voltage U... c The higher the battery power submodule, the smaller the duty cycle of its PWM drive pulse; capacitor voltage U c The lower the battery power submodule, the larger the duty cycle of its PWM drive pulse.

[0057] In summary, this invention relates to a high-voltage chain-type energy storage control system and its control method. The system includes a single-phase or multi-phase control loop and a central controller connected to the single-phase or multi-phase control loop. Each phase of the control loop includes multiple battery power sub-modules connected end-to-end. These multiple battery power sub-modules are communicatively connected to the central controller. The central controller receives power parameters from each battery power sub-module and, in conjunction with preset power command values, calculates the power setpoint for each battery power sub-module to control it. This invention combines low-voltage battery modules with modular multilevel converters and establishes a high-voltage chain-type energy storage control system based on battery power sub-modules. This achieves synchronous and real-time control of the energy storage system, shortens the control cycle, improves grid frequency and power stability, and increases grid reliability. By connecting each battery power submodule in the control loop end to end with optical fiber, the impact of discharge caused by the potential difference between different modules on the communication link is avoided; the optical cables connecting each control loop form a ring communication redundancy, which avoids the failure of a single optical cable causing communication interruption in all areas, and enables the communication link of each phase control loop to be independent, which can reduce the number of communication nodes on the link and reduce transmission delay.

[0058] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A high-voltage chain-type energy storage control system, characterized in that, It includes a single-phase or multi-phase control loop and a central controller connected to the single-phase or multi-phase control loop; wherein, Each phase of the control loop includes N battery power sub-modules connected end to end, where N is a positive integer greater than 2; Each of the battery power submodules includes a first communication port and a second communication port; the first communication port includes a first transmitting port and a first receiving port; the second communication port includes a second transmitting port and a second receiving port; The second transmitting port of the i-th battery power submodule is communicatively connected to the first receiving port of the (i+1)-th battery power submodule, and the second receiving port of the i-th battery power submodule is communicatively connected to the first transmitting port of the (i+1)-th battery submodule, where 1≤i≤N-1; The first communication port of the first battery power submodule and the second communication port of the Nth battery power submodule are communicatively connected to the central controller; The central controller includes a communication module and a protection control module; The communication module includes multiple sets of communication ports, each set of communication ports including a first transmitting port and a first receiving port, as well as a second transmitting port and a second receiving port; Each phase's control loop is connected to a set of communication ports in the communication module; wherein, the first transmitting port of the first battery power submodule in the phase control loop is connected to the first receiving port of the set of communication ports, and the first receiving port is connected to the first transmitting port of the set of communication ports; the second transmitting port of the Nth battery power submodule is connected to the second receiving port of the set of communication ports, and the second receiving port is connected to the second transmitting port of the set of communication ports.

2. The system according to claim 1, characterized in that, The battery power submodule includes a battery unit, a filter unit, a power submodule unit, a communication unit, and a control unit; The battery unit, filter unit, and power submodule unit are connected in sequence, and all of them, along with the communication unit, are connected to the control unit.

3. The system according to claim 2, characterized in that, The protection and control module receives the power parameters of each battery power submodule through the communication module, and calculates the power setting value of each battery power submodule in combination with the preset power command value.

4. A control method for a high-voltage chain-type energy storage control system as described in any one of claims 1-3, characterized in that, Including the following steps: The central controller receives the power parameters of each battery power submodule and calculates the power setting value of each battery power submodule by combining them with the preset power command value. The central controller obtains the PWM drive pulses for each battery power sub-module based on the power setting value, and transmits the PWM drive pulses to each battery power sub-module through the communication module. The central controller sends cyclic synchronization data frames to each battery power submodule, and each battery power submodule achieves synchronous output according to the cyclic synchronization data frames.

5. The method according to claim 4, characterized in that, The central controller receives the power parameters of each battery power submodule and, in conjunction with preset power command values, calculates the power setting value for each battery power submodule, including: The central controller receives real-time power setpoints and calculates the power setpoints for each battery power submodule based on the status feedback of the battery power submodules; and performs closed-loop adjustment of the output of the energy storage control system based on the power measurement feedback of the actual output of the grid-connected energy storage.

6. The method according to claim 5, characterized in that, The cyclic synchronization data frame acquires the actual values ​​of the internal clock and reference clock of each battery power submodule; Before the next cyclic synchronization data frame is sent, the central controller calculates the clock adjustment value of each battery power submodule based on the data obtained from the cyclic synchronization data frame, and sends it to each battery power submodule in the next cyclic synchronization data frame.

7. The method according to claim 6, characterized in that, The central controller transmits PWM drive pulses to each battery power sub-module via a communication module, including: The drive pulse of each battery power submodule is stored in the transmission buffer and copied to the transmission process before the cyclic synchronization data frame is sent. When a cyclic synchronization data frame arrives at a communication unit of a battery power submodule, the communication unit decodes the cyclic synchronization data frame. If the cyclic synchronization data frame corresponds to the address of the battery power submodule, the corresponding data content is copied to the communication unit of the battery power submodule. When the cyclic synchronization data frame leaves, the communication unit sends an interrupt request to the control unit and transmits the data to the control unit.

8. The method according to claim 7, characterized in that, Also includes: The central controller achieves balanced compensation control under three-phase unbalanced load based on the measured real-time current and voltage values ​​of the three-phase power grid. It performs vector transformation on the measured real-time current and voltage values ​​of the three-phase power grid to obtain the three-phase compensation current, calculates the instantaneous reactive power using the instantaneous reactive power method, and realizes closed-loop control based on the reactive power as the feedback quantity of the compensation current of each phase.

9. The method according to claim 8, characterized in that, Also includes: The central controller performs voltage equalization adjustment for each battery power submodule based on the capacitor voltage of the submodule: the capacitor voltage U of all battery power submodules is collected in each control cycle. c According to the capacitor voltage U c Sort by size; During capacitor discharge, the capacitor voltage U c The higher the battery power submodule, the larger the duty cycle of its PWM drive pulse; capacitor voltage U c The lower the battery power of the submodule, the smaller the duty cycle of its PWM drive pulse. During capacitor charging, the capacitor voltage U c The higher the battery power submodule, the smaller the duty cycle of its PWM drive pulse; capacitor voltage U c The lower the battery power submodule, the larger the duty cycle of its PWM drive pulse.

Images