WO2024060062A1

WO2024060062A1 - Power equalization method and apparatus for electric power system, and computer device and storage medium

Info

Publication number: WO2024060062A1
Application number: PCT/CN2022/120188
Authority: WO
Inventors: 卢艳华; 余东旭
Original assignee: 宁德时代未来能源(上海)研究院有限公司
Priority date: 2022-09-21
Filing date: 2022-09-21
Publication date: 2024-03-28

Abstract

The present application discloses a power equalization method and apparatus for an electric power system, and a computer device and a storage medium. The electric power system comprises a flexible direct-current power transmission sub-system and an MMC-BESS sub-system. The method comprises: determining a working mode of the electric power system, switching the electric power system to a corresponding working mode, and performing power equalization according to a preset power equalization strategy corresponding to the working mode. The method implements flexible switching of multiple working modes of an electric power system; moreover, power equalization is performed according to preset power equalization strategies corresponding to the working modes, such that power equalization in the multiple working modes is implemented, thereby improving the flexibility of power equalization regulation and control.

Description

Power balancing methods, devices, computer equipment and storage media for power systems

Technical field

The present application relates to the technical field of power system energy storage, and in particular to a power balancing method, device, computer equipment, storage medium and computer program product for a power system.

Background technique

Building a new power system with new energy as the main body is an important support for achieving the goals of carbon peak and carbon neutrality. Therefore, it is increasingly important to ensure the safety, controllability, flexibility and efficiency of the new power system.

At present, due to the inherent strong randomness, volatility and intermittent nature of new energy power generation, after large-scale distributed energy is connected to the power grid, the BMS (Battery Management System) has gradually increased its requirements for battery management control capabilities. All of the above make the operation and control of the distribution network face the coupling influence of multiple uncertain factors. Therefore, it often occurs that the three-phase power of the power system is unbalanced due to poor operation and control of the distribution network, and the power quality and power supply of the power system are affected. Reliability cannot be effectively guaranteed.

Therefore, it is necessary to provide a solution that can solve the power imbalance of the power system and ensure the power quality and power supply reliability of the power system.

Contents of the invention

In view of the above problems, this application provides a power system power balancing method, device, computer equipment, computer-readable storage medium and computer program product, which can realize power balancing of the power system, improve the flexibility of power balancing control, and ensure the power system power quality and power supply reliability.

In a first aspect, the present application provides a power balancing method for an electric power system, wherein the electric power system includes a flexible direct current transmission electronic system and an MMC-BESS (Modular Multilevel Converter based Battery Energy Storage System-MMC-BESS, a battery energy storage system based on modular multilevel converter) subsystem;

Power system power balancing methods include:

Determine the operating mode of the power system;

Switch the power system to the corresponding working mode;

Power balancing is performed according to a preset power balancing strategy corresponding to the working mode.

The technical solution of the embodiment of the present application provides a power balancing solution applied to a power system including a flexible direct transmission electronic system and an MMC-BESS subsystem. Specifically, after determining the working mode of the power system, the power system can be correspondingly Switching to the corresponding working mode realizes the flexible switching of multiple working modes of the power system, and performs power balancing according to the preset power balancing strategy corresponding to each working mode, realizing multiple working modes such as flexible-direct transmission mode or The power balance of the flexible and direct transmission energy storage mode achieves a power system that can meet the power balance in various working scenarios. While realizing the power balance of the power system, it also improves the flexibility of power balance control, thereby improving the power system's ability to absorb and regulate power, and ensuring the power quality and power supply reliability of the power system.

In some embodiments, determining the operating mode of the power system includes:

Obtain fault monitoring data of the flexible direct transmission electronic system and MMC-BESS subsystem;

Determine the working mode of the power system based on fault monitoring data.

In the technical solution of the embodiment of the present application, by acquiring the fault monitoring data of the flexible direct current transmission electronic system and the MMC-BESS subsystem and determining the working mode, abnormal situations can be discovered in time to avoid power support in the event of a fault, which affects the efficiency of power support and ensures the normal operation of the power system.

In some embodiments, the working mode includes a flexible-direct power transmission mode, a flexible-direct power transmission and battery energy storage mode, or a cascaded H-bridge energy storage mode;

Based on fault monitoring data, determining the working mode of the power system includes:

If the flexible direct current electronic system is judged to be faulty according to the fault monitoring data, the working mode is determined to be the cascade H-bridge energy storage mode;

If it is determined that the MMC-BESS subsystem is faulty based on the fault monitoring data, the working mode is determined to be the flexible-direct transmission mode;

If it is determined based on the fault monitoring data that neither the flexible direct transmission electronic system nor the MMC-BESS subsystem has a fault, the working mode is determined to be the flexible direct transmission and battery energy storage power mode.

The technical solution of the embodiment of the present application provides a variety of working modes, and determines whether the flexible direct transmission electronic system and the MMC-BESS subsystem are faulty through fault monitoring data, and then based on the fault conditions of the above two subsystems, targeted Selecting the corresponding working mode can ensure safe and accurate power balancing.

In some embodiments, the operating mode includes a flexible direct current transmission mode, a flexible direct current transmission and battery energy storage mode, or a cascaded H-bridge energy storage mode;

Switching the power system to the corresponding working mode includes:

According to the preset mode switching strategy corresponding to the determined working mode, the battery module and flexible direct transmission electronic system of the MMC-BESS subsystem are switched and controlled to switch the power system to the corresponding working mode.

In the technical solution of the embodiment of the present application, the battery module and flexible direct transmission electronic system of the MMC-BESS subsystem are switched on and off according to the preset mode switching strategy corresponding to the working mode, thereby realizing multiple tasks of the power system simply and efficiently. Mode switching improves the flexibility of mode switching.

In some embodiments, according to the preset mode switching strategy corresponding to the determined working mode, switch control is performed on the battery module of the MMC-BESS subsystem and the flexible direct transmission electronic system to switch the power system to the corresponding The working modes include:

If the working mode is the flexible-direct power transmission mode, turn off the battery module of the MMC-BESS subsystem to switch the power system to the flexible-direct power transmission mode;

Alternatively, if the working mode is the flexible direct current transmission and battery energy storage mode, the battery status of the battery modules of the MMC-BESS subsystem is monitored, abnormal battery modules and normal battery modules are screened out, the abnormal battery modules are shut down, and the normal battery modules are powered on and off to switch the power system to the flexible direct current transmission and battery energy storage mode;

Or, if the working mode is the cascaded H-bridge energy storage mode, disconnect the loop of the flexible direct transmission electronic system to switch the power system to the cascaded H-bridge energy storage mode.

In the technical solution of the embodiment of the present application, by monitoring the status of the battery modules, abnormalities are screened out, and by controlling the battery module switches, the battery modules with problems are closed and screened out, thereby avoiding the adverse impact of abnormal battery modules on the power system. , realizing multi-mode switching of the power system.

In some embodiments, if a battery module of the MMC-BESS subsystem fails, the fault type of the failed battery module is identified;

According to the identified fault type, the corresponding BMS control strategy is called to perform fault analysis and processing.

In the technical solution of the embodiment of the present application, during the switching process of the working mode, the battery module fault is solved by identifying the fault type of the battery module and calling the corresponding BMS control strategy, which can comprehensively and efficiently solve the battery module fault, effectively Avoid safety issues caused by battery module failure.

In some embodiments, powering on and off a normal battery module includes:

Monitor the battery status parameters of normal battery modules;

Sort normal battery modules according to their battery status parameters;

According to the preset control strategy, the sorted normal battery modules are powered on and off in sequence.

In the technical solution of the embodiment of the present application, by monitoring the battery modules and sorting the normal battery modules according to their battery status parameters, the remaining power of each normal battery module can be clearly determined, and the battery modules can be powered on and off according to the remaining power. The power on and off operations of batteries with high remaining power can be completed first, and the battery charging and discharging can be completed first, thereby improving the efficiency of power support subsequently.

In some embodiments, sequentially powering on and off the sorted normal battery modules according to the preset control strategy includes:

The first battery switch and the second battery switch of the sequenced normal battery module are closed in sequence, and then the first battery switch is opened. The first battery switch includes a battery switch with a resistor, and the second switch includes a battery switch.

In the technical solution of the embodiment of the present application, the switch with a resistor has the function of buffering battery charge and discharge. Therefore, performing power on and off operations in the above manner can enable the battery module to perform smooth transitional charge and discharge and protect the battery.

In some embodiments, performing power balancing according to a preset power balancing strategy corresponding to the working mode includes:

If the working mode is flexible-direct transmission mode, obtain the external grid load data of the power system, and perform power balancing based on the external grid load data;

Or, if the working mode is flexible direct transmission and battery energy storage mode, monitor the load data of the external power grid to obtain the load data of the flexible direct transmission electronic system and the AC side power surplus data of the MMC-BESS subsystem. According to the flexible direct transmission electronics The load data of the system and the AC side power surplus data of the MMC-BESS subsystem are used for power balancing;

Or, if the working mode is the cascaded H-bridge energy storage mode, obtain the AC side power surplus data of the MMC-BESS subsystem and the status data of the battery module of the MMC-BESS subsystem. According to the AC side power of the MMC-BESS subsystem Surplus data and battery module status data are used for power support.

In the technical solution of the embodiment of this application, different power balancing strategies are used for power balancing for each working mode, realizing power balancing of the power system in the flexible and direct transmission mode, and the mode of combining battery energy storage and flexible and direct transmission. Power balancing and power balancing in cascaded H-bridge mode achieve a power system that satisfies power balancing in a variety of working scenarios.

In some embodiments, performing power balancing based on the load data of the flexible direct transmission electronic system and the AC side power surplus data of the MMC-BESS subsystem includes:

If, based on the load data of the flexible direct current transmission subsystem and the AC side power surplus data of the MMC-BESS subsystem, it is determined that the flexible direct current transmission subsystem needs power support and the AC side surplus power of the MMC-BESS subsystem meets the support conditions, the AC side surplus power of the MMC-BESS subsystem is transmitted to the flexible direct current transmission subsystem through flexible direct current transmission to perform power balancing;

If based on the load data of the flexible direct transmission electronic system and the AC side power surplus data of the MMC-BESS subsystem, it is determined that the flexible direct transmission electronic system needs power support and the AC side surplus power of the MMC-BESS subsystem does not meet the support conditions, then Transmit the AC side surplus power of the MMC-BESS subsystem to the flexible direct transmission electronic system, and control the battery module of the MMC-BESS subsystem to discharge support to the flexible direct transmission electronic system for power balancing;

If it is determined based on the load data of the flexible direct transmission electronic system and the AC side power surplus data of the MMC-BESS subsystem that the flexible direct transmission electronic system needs power support and there is no power surplus in the MMC-BESS subsystem, the battery module will be controlled to support the flexible direct transmission electronic system. The direct input electronic system and MMC-BESS subsystem provide discharge support for power balancing.

In the technical solution of the embodiment of this application, by comparing the load data of the flexible direct transmission electronic system and the AC side power surplus data of the MMC-BESS subsystem, corresponding measures are taken for power support in a targeted manner, and the power supply under various conditions is achieved. Power equalization.

In some embodiments, power support based on the AC side power surplus data of the MMC-BESS subsystem and the status data of the battery module includes:

If based on the AC side power surplus data of the MMC-BESS subsystem and the status data of the battery module, it is determined that the MMC-BESS subsystem has an AC side power surplus and the battery module is rechargeable, the battery module will be charged and the battery module will be in Hot standby status;

If it is determined that the AC side of the MMC-BESS subsystem needs power support based on the AC side power surplus data of the MMC-BESS subsystem and the status data of the battery module, the battery module is controlled to provide discharge support to the AC side of the MMC-BESS subsystem. , for power balancing.

In the technical solution of the embodiment of the present application, by monitoring the status of the battery module, battery modules with abnormal status or unable to be charged and discharged can be screened out in a timely manner to ensure normal power balancing, and further control the battery module through the AC side power surplus data. Charging and discharging the battery can quickly and reasonably complete power balancing.

In some embodiments, before charging the battery module, the method further includes:

Monitor the battery status parameters of the battery module;

Sort the battery modules according to their battery status parameters;

The first battery switch and the second battery switch of the sequenced battery modules are closed in sequence, and then the first battery switch is opened. The first battery switch includes a battery switch with a resistor, and the second switch includes a battery switch.

In the technical solution of the embodiment of the present application, since the switch with a resistor has the function of buffering battery charge and discharge, before charging the battery module, the battery module is powered on and off in the above manner, so that the battery module can Smooth transition of charge and discharge to protect the battery.

In some embodiments, before controlling the battery module to provide discharge support to the AC side of the MMC-BESS subsystem, the method further includes:

Monitor the battery status parameters of the battery module;

Sort the battery modules according to their battery status parameters;

The first battery switch and the second battery switch of the sequenced battery modules are closed in sequence, and then the first battery switch is opened to provide power support to the AC side of the MMC-BESS subsystem. The first battery switch includes a battery switch with a resistor. The second switch includes a battery throw-in/out switch.

In the technical solution of the embodiment of the present application, since the switch SW2 is a switch with a resistor, it has the function of buffering the charge and discharge of the battery. Therefore, before power support is provided for the AC side power, the battery module is powered on and off in the above manner. It enables the battery module to perform smooth transitional charge and discharge, protects the battery, and ensures the safety of power support.

In the second aspect, this application provides a power balancing device for a power system. The device includes: a controller, and a power system connected to the controller. The power system includes a VSC flexible direct transmission electronic system and an MMC-BESS subsystem;

The controller is used to determine the working mode of the power system, perform switching control on the VSC flexible direct transmission electronic system and MMC-BESS subsystem, switch the power system to the corresponding working mode, and adjust the power according to the preset power balancing strategy corresponding to the working mode. balanced.

The power balancing device of the power system in the embodiment of the present application provides a power balancing solution applied to the power system including the flexible direct transmission electronic system and the MMC-BESS subsystem. Specifically, after the controller determines the working mode of the power system, By controlling the switching of the flexible direct transmission electronic system and the MMC-BESS subsystem, the power system is switched to the corresponding working mode, thereby realizing flexible switching of multiple working modes of the power system, and according to the preset corresponding to each working mode. The designed power balancing strategy is used for power balancing, achieving power balancing in multiple working modes such as flexible-to-direct transmission mode or flexible-to-direct transmission and energy storage mode, achieving a power system that satisfies power balancing in a variety of working scenarios. While realizing the power balance of the power system, it also improves the flexibility of power balance control, thereby improving the power system's ability to absorb and regulate power, and ensuring the power quality and power supply reliability of the power system.

In a third aspect, this application provides a computer device. The computer device includes a memory and a processor. The memory stores a computer program. When the processor executes the computer program, the steps in the power balancing method of the power system are implemented.

In a fourth aspect, this application also provides a computer-readable storage medium. A computer-readable storage medium has a computer program stored thereon. When the computer program is executed by a processor, the steps in the power balancing method of the power system are implemented.

In a fifth aspect, this application also provides a computer program product. A computer program product includes a computer program that implements the steps in the power balancing method of the power system when executed by a processor.

The above description is only an overview of the technical solutions of the present application. In order to have a clearer understanding of the technical means of the present application, they can be implemented according to the content of the description, and in order to make the above and other purposes, features and advantages of the present application more obvious and understandable. , the specific implementation methods of the present application are specifically listed below.

BRIEF DESCRIPTION OF THE DRAWINGS

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are for the purpose of illustrating preferred embodiments only and are not to be construed as limiting the application. Also, the same parts are represented by the same reference numerals throughout the drawings. In the attached picture:

FIG1 is an application environment diagram of a power balancing method for a power system according to some embodiments of the present application;

Figure 2 is a schematic flowchart of a power balancing method for a power system in some embodiments of the present application;

Figure 3 is a topology diagram of the MMC-BESS subsystem in some embodiments of the present application;

Figure 4 is a schematic structural diagram of the sub-module of the bridge arm in the MMC-BESS subsystem in some embodiments of the present application;

Figure 5 is a detailed flowchart of a power balancing method for a power system in some embodiments of the present application;

Figure 6 is a schematic diagram of power system working mode switching in some embodiments of the present application;

Figure 7 is a detailed flowchart of a power balancing method for a power system in some embodiments of the present application;

Figure 8 is a schematic structural diagram of a power balancing device of a power system in some embodiments of the present application;

Figure 9 is an internal structure diagram of a computer device in one embodiment.

Detailed ways

The embodiments of the technical solution of the present application will be described in detail below with reference to the accompanying drawings. The following examples are only used to illustrate the technical solution of the present application more clearly, and are therefore only used as examples and cannot be used to limit the protection scope of the present application.

Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the technical field belonging to this application; the terms used herein are for the purpose of describing specific embodiments only and are not intended to be used in Limitation of this application; the terms "including" and "having" and any variations thereof in the description and claims of this application and the above description of the drawings are intended to cover non-exclusive inclusion.

In the description of the embodiments of this application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying the relative importance or implicitly indicating the quantity or specificity of the indicated technical features. Sequence or priority relationship. In the description of the embodiments of this application, "plurality" means two or more, unless otherwise explicitly and specifically limited.

Reference herein to "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The appearances of this phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those skilled in the art understand, both explicitly and implicitly, that the embodiments described herein may be combined with other embodiments.

In recent years, in order to improve the power grid's ability to absorb and regulate a high proportion of renewable energy, building a new power system with new energy as the main body has become a hot topic. However, due to the inherent strong randomness, volatility and intermittent nature of new energy power generation, the difficulty of spatio-temporal balance of power in the power system will be significantly increased after large-scale new energy is connected to the power grid. Therefore, some experts believe that the key to ensuring the balance between power supply and demand at different time scales and high-level consumption of new energy is to improve the flexible adjustment capabilities of the new power system.

Due to its advantages in long-distance and large-capacity power transmission, DC transmission technology plays an important role in the process of optimal allocation of energy resources. In traditional technology, common high-voltage direct current transmission architectures include the following: high-voltage direct current transmission (Line Commutated Converter Based High Voltage Direct Current, LCC-HVDC) system based on grid commutation converter, modular multi-level commutation based on Modular Multilevel Converter Based High Voltage Direct Current (MMC-HVDC) system, etc. Early hybrid DC transmission systems, such as LCC-MMC parallel hybrid DC transmission systems, mostly had a single sending end and a single receiving end, and used different types of converters at both ends.

The inventor noticed that in the above-mentioned DC transmission system, only the mode of conventional DC to flexible DC transmission was considered, and the mutual support of two-way transmission and load was not considered, nor was the switching from double-end to single-end was considered. From this point of view, the power system's Regulation is obviously not flexible enough to guarantee the power quality and power supply reliability of the power system. Moreover, there are still the following problems in traditional technology: in the current energy storage system, PCS (Power Conversion System, energy storage converter) and energy storage battery are independent of each other, high investment costs, multiple PCSs connected in parallel are prone to oscillation, two-level/three-level Level PCS power conversion efficiency is low, a large number of batteries are connected in series and parallel, requiring BMS to have strong battery management capabilities, and the three-phase imbalance of the 10kV distribution network and line overload/light load problems are generally serious.

The inventor found that MMC-BESS has two external ports, AC and DC, and has the functions of AC grid connection, DC grid connection and energy storage. When used in the power grid, it can be connected to the AC and DC grids separately or simultaneously. MMC-BESS adopts an integrated modular design, which can realize the flexible regulation of the output power of the energy storage system and optimize the battery pack management capability. At the same time, it eliminates grid-connected harmonics, reduces investment costs, reduces the DC voltage that the battery bears and the requirements of the BMS for the battery management capability. The system network loss is lower, the economic benefits are better, and the operation reliability is higher. Therefore, it is believed that the study of the load support method based on the multi-scenario mode switching of MMC-BESS has important research significance for the new power system with new energy as the main body.

Based on the above considerations, in order to solve the problem that the output power control of the traditional power transmission system is not flexible enough to stably achieve power balance and ensure the power quality and power supply reliability of the power system, a flexible direct transmission electronic system and MMC-BESS are proposed. For the power system of the subsystem, first, determine the working mode of the power system. The working mode includes flexible-direct power transmission mode, flexible-direct power transmission and battery energy storage mode, or cascade H-bridge energy storage mode, and switch the power system to the corresponding working mode. , realizes the flexible switching of multiple working modes, and performs power balancing according to the preset power balancing strategy corresponding to each working mode, realizing the combination of power balancing, energy storage and flexible direct transmission in the flexible and direct transmission mode. The power balance in the mode and the power balance in the cascaded H-bridge mode achieve a power system that meets the power balance in various working scenarios. While realizing the power balance of the power system, it also improves the flexibility of power balance control. performance, thereby improving the power system’s ability to absorb and regulate power, and ensuring the power quality and power supply reliability of the power system.

The power system power balancing method provided by the embodiment of the present application can be applied in the application environment as shown in Figure 1. Among them, the terminal 102 communicates with the control end 104 of the power system through the network. The power system includes an interconnected flexible direct transmission electronic system and an MMC-BESS subsystem. The data storage system may store data that server 104 needs to process. The data storage system can be integrated on the control terminal 104 or placed on the cloud or other network servers. Specifically, the power system personnel may send a control instruction to the control terminal 104 through the terminal 102. The control terminal 104 responds to the control instruction, determines the working mode of the power system, and then switches the power system to the corresponding working mode, and then obtains and works. The preset power balancing strategy corresponding to the mode performs power balancing according to the preset power balancing strategy corresponding to the working mode. The working mode includes a flexible direct power transmission mode, a flexible direct power transmission and battery energy storage mode, or a cascaded H-bridge energy storage mode. model. Among them, the terminal 102 can be, but is not limited to, various personal computers, laptops, smart phones, tablets, Internet of Things devices and portable wearable devices. The Internet of Things devices can be smart speakers, smart TVs, smart air conditioners, smart vehicle-mounted devices, etc. . Portable wearable devices can be smart watches, smart bracelets, head-mounted devices, etc. The control terminal 104 can be implemented as an independent server or a server cluster composed of multiple servers.

In one embodiment, as shown in Figure 2, a power balancing method for a power system is provided. This method is explained by taking the method applied to the control end 104 of the power system in Figure 1 as an example. The power system includes interconnected Flexible direct transmission electronic system and MMC-BESS subsystem, the method includes the following steps:

Step 100: Determine the working mode of the power system, where the working mode includes a flexible direct power transmission mode, a flexible direct power transmission and battery energy storage mode, or a cascaded H-bridge energy storage mode.

In this embodiment, the power system is a hybrid flexible direct current transmission system, the flexible direct current transmission electronic system can be a VSC-based flexible high-voltage direct current transmission electronic system (hereinafter referred to as the VSC side), and the MMC-BESS subsystem can be an integrated modular system. New energy storage system of multi-level converter (Modular Multilevel Converter based Battery Energy Storage System, MMC-BESS), that is, the power system can be VSC+MMC-BESS double-terminal or multi-terminal grid flexible direct transmission with battery energy storage. The system (referred to as VSC+MMC-BESS flexible direct transmission energy storage system) is used for the engineering integration of AC/DC microgrid/distribution network technology and battery energy storage technology. In addition, the power system also includes a BMS system. Generally speaking, the flexible direct transmission mode is the VSC+VSC double-terminal grid flexible direct transmission mode, which can be understood as a mode in which only the flexible direct transmission electronic system participates in power support. The flexible direct transmission and battery energy storage mode is the VSC+MMC-BESS dual The end- or multi-end grid flexible direct transmission mode can be understood as a mode in which both the flexible direct transmission electronic system and the MMC-BESS subsystem participate in power support. The cascaded H-bridge energy storage mode is the MMC-BESS AC end direct energy storage mode, which can be understood It is a mode in which only the AC side of the MMC-BESS subsystem participates in power support.

Among them, the topology of the MMC-BESS subsystem can be shown in Figure 3. The MMC-BESS subsystem consists of three phase clusters. Each phase cluster is divided into upper and lower bridge arms. Each bridge arm contains N sub-modules (Sub-Module, SM). The sub-module consists of a half-bridge circuit, a battery and a filter capacitor, in which the battery is directly connected in parallel to both ends of the filter capacitor. Specifically, the sub-modules in the bridge arm are shown in Figure 4. The sub-modules include half-bridge energy storage sub-modules and full-bridge energy storage sub-modules. Both half-bridge energy storage sub-modules and full-bridge energy storage sub-modules are Including power module and battery module. As shown in Figure 4, the half-bridge circuit in the power module contains 2 IGBTs (Insulated Gate Bipolar Transistor), a capacitor, a resistor and a bypass switch SW1, which is controlled by the IGBT switch. The charging at both ends of the capacitor is controlled, and a DC voltage is formed at both ends of the capacitor; the full-bridge circuit of the power module contains 4 IGBTs, a capacitor, a resistor and a bypass switch SW1. The IGBT switch is used to control charging at both ends of the capacitor. A DC voltage is formed; the battery module has a resistor switch SW2 and a battery switch SW3, and a battery cluster, in which the resistor switch SW2 functions as a battery charge and discharge buffer. There are two fuses between the power module and the battery module for overcurrent protection.

In this embodiment, the working mode can be determined by receiving a control instruction, responding to the control instruction, and determining the working mode of the power system, or by monitoring the operating status of the power system, obtaining fault monitoring data, and determining the working mode based on the fault monitoring data. Specifically, the working mode can be any one of a flexible direct current transmission power mode, a flexible direct current transmission and battery energy storage power mode, or a cascaded H-bridge energy storage power mode.

Step 200, switch the power system to the corresponding working mode.

After obtaining the working mode, the power system can be switched to the corresponding working mode directly according to the obtained working mode. For example, if the working mode is the flexible-direct power transmission mode, the power system is switched to the flexible-direct power transmission mode. If the working mode is the flexible-direct power transmission and battery energy storage mode, the power system is switched to the flexible-direct power transmission and battery energy storage mode. If the working mode is the cascaded H-bridge energy storage mode, the power system is switched to the cascaded H-bridge energy storage mode. That is to say, the power system in this embodiment can be switched to multiple operating modes.

Step 300: Perform power balancing according to a preset power balancing strategy corresponding to the working mode.

Power balancing may also be called load support, power transfer or power support. Power balancing strategy refers to the strategy or rules used to maintain the power balance of the power system. In this embodiment, a corresponding power balancing strategy is set in advance for each working mode. The working mode and the power balancing strategy are in one-to-one correspondence. When the working mode is determined, the power balancing strategy is also determined. The specific , the corresponding power balancing strategy can be obtained according to the working mode. In this embodiment, the power balancing strategy may include a flexible-direct transmission power balancing strategy, a flexible-direct transmission and battery energy storage power balancing strategy, or a cascaded H-bridge energy storage power balancing strategy. When the power system is switched to any working mode among the flexible direct transmission mode, flexible direct transmission and battery energy storage mode, or cascaded H-bridge energy storage mode, the power balancing strategy corresponding to the working mode can be obtained correspondingly, and then according to Power balancing strategy performs power balancing.

In another embodiment, the active power and reactive power can also be controlled through the secondary architecture system by setting the voltage and power of the load. The power system also has the ability to adjust the bus or feeder voltage and balance the bus or feeder load through four-quadrant control. Ability. Specifically, the secondary architecture system includes the field layer, the control layer and the operator control layer. The field layer includes control and protection equipment that communicates with the MMC-BESS subsystem, including AC energy consumption devices, DC circuit breakers, stabilizing devices, valve controls, BMS devices, and battery modules and power modules. The field layer According to the optical fiber connection between the upper and lower levels, data interaction with the control layer, complete the control of AC energy-consuming devices such as the input and withdrawal of preparation signals, complete the control of DC circuit breakers with signals such as opening and closing failure protection tripping, and complete DC emergency power Control of control commands, converter blocking, networked/islanded signal stabilization devices.

The BMS monitors and pre-warns the SOC of the battery module, and transmits the status of the problematic battery module to the valve control system. The valve control system receives the modulation wave sent by the control layer, and suppresses, modulates, voltage equalizes and switches the switching frequency through the bridge arm circulation current. Optimize the power module and battery module switch control, bypass switch (SW1) control, battery resistance switch (SW2) control, battery switch on and off switch (SW3) control, and the system can be controlled into flexible and direct transmission mode, flexible and direct transmission and battery energy storage mode or cascade H-bridge mode. At the same time, according to the input of redundant modules and the withdrawal of faulty modules, the stability of the DC system is ensured. At the same time, the BMS sends the battery status to the remote personnel control layer in real time through IEC61850 MMS for real-time monitoring.

The control layer is the core of the secondary system control and protection. It receives the operation commands from the operator and receives the line connection status, unlocking, island grid connection, voltage and current signals of other circulating stations through the 2M SDH optical fiber network. The converter station control layer coordinates the control and has the voltage takeover function, grid voltage range control, power flow optimization function, and related sequential control interlocking functions, which are sent to the pole control A/B. The pole control A/B receives the NBGS (neutral bus grounding switch) switch status and the opposite end operation status of other converter stations through the 2M optical fiber channel for inter-station communication. The bipolar control receives the commands from the operator control layer, performs sequential control interlocking, bipolar active and reactive power distribution of the entire station, additional control, power surplus control, stability and wide-area coordination interface and control, and sends the control commands to the pole control. The pole control receives the commands sent by the upper layer, performs deviation slope control, tap control, power control, and sequential control interlocking, and combines the commands sent by the operator control layer to select the mode and generate control instructions, and performs constant DC voltage control, constant active power control, constant reactive power control, constant AC voltage control, constant frequency control, and island (VF (voltage frequency) control). The control mode and control instructions are sent to the current inner loop controller through the outer loop controller, and the bridge arm voltage reference value is output to form a modulation wave, which is sent to the valve control.

The remote personnel control layer mainly includes the monitoring background, including the engineering station, Web interface station, time synchronization server, simulation server, protection and fault recording information management station, energy management system, etc., and also receives the management of the remote dispatching layer.

Specifically, the ability to balance the bus or feeder load through four quadrants can be: assuming the AC side terminal voltage of the VSC is Uc, the bus or feeder voltage is Us, and the angle between Uc and Us is θ, then it can be controlled by controlling Uc*sinθ The size and direction of active power can be controlled by controlling Us-Uc*cosθ, thereby achieving four-quadrant control.

Specifically, when operating in the first quadrant, Uc*cosθ>Us and θ>0, the MMC-BESS subsystem can output active power and emit reactive power to realize the functions of power support and voltage support.

When operating in the second quadrant, Uc*cosθ>Us and θ<0, the MMC-BESS subsystem can absorb the power surplus of the power grid system while emitting reactive power to provide voltage support for the system.

When operating in the third quadrant, Uc*cosθ<Us and θ<0, the MMC-BESS subsystem absorbs the power surplus of the grid system and absorbs the excess reactive power of the grid to solve the bus or feeder overvoltage problem.

When operating in the fourth quadrant, Uc*cosθ<Us and θ>0, the MMC-BESS subsystem can absorb excess reactive power from the grid while providing active power to the grid.

The technical solution of the embodiment of this application provides a power balancing solution applied to a power system including a flexible direct transmission electronic system and an MMC-BESS subsystem. The entire solution determines the working mode of the power system and switches the power system to the corresponding The working mode realizes flexible switching of multiple working modes, and performs power balancing according to the preset power balancing strategy corresponding to each working mode, realizing multiple working modes such as flexible direct transmission mode or flexible direct transmission energy storage mode. Under the power balance, a power system can meet the power balance in various scenarios. While realizing the power balance of the power system, it also improves the flexibility of power balance control, thereby improving the power consumption and power consumption of the power system. Control capabilities to ensure the power quality and power supply reliability of the power system.

In some embodiments, as shown in Figure 5, step 100 includes: step 120, obtaining fault monitoring data of the flexible direct transmission electronic system and the MMC-BESS subsystem, and determining the working mode of the power system based on the fault monitoring data.

Fault monitoring data refers to data that can indicate whether a fault occurs in the operation of the monitored power system. That is, the fault monitoring data can be data that represents the normal operation of the power system, or it can be data that represents the failure of the power system. Specifically, it can be to monitor whether the flexible direct transmission electronic system and the MMC-BESS subsystem have short circuits, open circuits, battery overcharges, battery overdischarges, thermal management failures, insulation failures, wiring failures and other abnormal conditions. In this embodiment, the working mode may be determined based on whether the flexible direct transmission electronic system and the MMC-BESS subsystem are faulty. Specifically, it can be to obtain the fault monitoring data of the flexible direct transmission electronic system and the MMC-BESS subsystem, and based on the fault monitoring data, determine whether the flexible direct transmission electronic system and the MMC-BESS subsystem are faulty, and then determine the working mode of the power system. . In other embodiments, the determination of the working mode may also include: receiving a control instruction carrying the working mode, and parsing out the working mode in the control instruction to determine the specific working mode. Specifically, it can be to receive the message data carrying the control instruction sent by the external dispatcher through the preset communication protocol. The control instruction carries the working mode field, and then determine whether the message data is legal. When it is determined that the message data is legal, Finally, the command segment and data segment of the message header in the message data are identified, and the working mode field contained in the data segment is parsed to determine the corresponding working mode.

In the technical solution of the embodiment of the present application, by obtaining the fault monitoring data of the flexible direct transmission electronic system and the MMC-BESS subsystem and determining the working mode, abnormal situations can be discovered in time and power support can be avoided in the event of a fault. Affects the efficiency of power support and ensures the normal operation of the power system.

In some embodiments, step 120 includes:

Step 122: If it is determined that the flexible direct transmission electronic system is faulty based on the fault monitoring data, the working mode is determined to be the cascade H-bridge energy storage mode.

Step 124: If it is determined that the MMC-BESS subsystem is faulty based on the fault monitoring data, the working mode is determined to be the flexible-direct power transmission mode.

Step 126: If it is determined based on the fault monitoring data that neither the flexible direct power transmission electronic system nor the MMC-BESS subsystem has a fault, then the working mode is determined to be the flexible direct power transmission and battery energy storage mode.

Following the above embodiment, determining the working mode based on the fault monitoring data can be: if the fault monitoring data indicates that the flexible direct transmission electronic system is faulty, it means that the flexible direct transmission electronic system cannot participate in power support normally, that is, the working mode is determined to be cascade H. In the bridge energy storage mode, if the fault monitoring data indicates that the MMC-BESS subsystem is faulty, it means that the MMC-BESS subsystem cannot participate in power support normally, that is, the working mode is determined to be the flexible-direct transmission mode. If the fault monitoring data indicates that the MMC-BESS If there is no failure in the subsystem and the flexible direct transmission electronic system, it means that the system is operating normally. At this time, it is determined that the working mode is the flexible direct transmission and battery energy storage mode, that is, it operates in the normal working mode. Fault types include but are not limited to at least one of short circuit, open circuit, battery overcharge, battery over discharge, thermal management failure and insulation failure, wiring failure and other abnormal conditions.

In the technical solution of the embodiment of this application, fault monitoring data is used to determine whether the flexible direct transmission electronic system and the MMC-BESS subsystem are faulty, and then based on the fault conditions of the above two subsystems, the corresponding working mode is selected in a targeted manner, which can Ensure safe and accurate power balancing.

In some embodiments, step 200 includes: performing switch control on the battery module and flexible direct transmission electronic system of the MMC-BESS subsystem according to the preset mode switching strategy corresponding to the determined working mode, and switching the power system to the corresponding Operating mode.

In practical applications, a corresponding mode switching strategy is preset for each working mode. The mode switching strategy can be to use the BMS to monitor and early warn the SOC of the battery modules in the power system, and to update the status of the problematic battery modules. Passed to the valve control system, the valve control system receives the modulated wave sent by the control layer, and controls the power module and battery module of the MMC-BESS subsystem, as well as the flexible direct transmission electronics through bridge arm circulation suppression, modulation, voltage equalization and switching frequency optimization. The system performs switch control, bypass switch (SW1) control, battery resistance switch (SW2) control, and battery on/off switch (SW3) control to realize switching of working modes. At the same time, the stability of the DC system is ensured according to the input of redundant modules and the withdrawal of faulty modules.

As shown in Figure 5, in some embodiments, step 200 includes:

Step 220, if the working mode is the flexible-direct power transmission mode, turn off the battery module of the MMC-BESS subsystem to switch the power system to the flexible-direct power transmission mode.

Step 240, or if the working mode is flexible direct power transmission and battery energy storage mode, monitor the battery status of the battery module of the MMC-BESS subsystem, screen out the abnormal battery modules and normal battery modules, close the abnormal battery module, and check the normal battery The module performs power on and off operations to switch the power system to flexible and direct power transmission and battery energy storage modes.

Step 260, or if the working mode is the cascade H-bridge energy storage mode, disconnect the loop of the flexible direct transmission electronic system to switch the power system to the cascade H-bridge energy storage mode.

In specific implementation, as shown in Figure 6, the switching process of the working mode can be: for the flexible-to-direct power transmission mode (the double-ended power grid VSC+VSC is used as an example in Figure 6), switch SW2 and switch SW3 in Figure 4 are turned on, that is, Turn off all battery modules in the MCC-BESS subsystem and switch the power system to flexible and direct power transmission mode. For flexible and direct power transmission and battery energy storage modes (the double-ended power grid VSC+MCC-BESSC is used as an example in Figure 6), the status of the battery module is first monitored through the BMS system. For example, the battery module is monitored for short circuit, open circuit, overcharge, etc. Abnormal conditions such as over-discharge, over-temperature, and insulation failure are used to screen out abnormal battery modules and normal battery modules. Then, the abnormal battery module is opened, that is, the switch SW2 and the switch SW3 are turned on to close the abnormal battery module, and then the normal battery module is powered on and off to switch the power system to flexible direct power transmission and battery energy storage mode. For the cascaded H-bridge energy storage mode (the double-terminal grid MMC-BESSC (cascaded H-bridge) is used as an example in Figure 6), the power transmission support at both ends or multiple ends of the DC is not considered, and the flexible direct transmission electronic system based on VSC is skipped. (hereinafter referred to as the VSC side) AC circuit breaker, DC circuit breaker and the corresponding knife switch, DC transfer switch and grounding switch are opened to realize the switching of the single-ended MMC-BESS, that is, the cascade H-bridge energy storage mode. It can be understood that if the power system is operating in the flexible-direct power transmission and battery energy storage mode, if the flexible-direct energy storage subsystem or the MCC-BESS subsystem fails, the system will be transferred from the flexible-direct power transmission and battery energy storage subsystem in the above manner. The battery energy storage mode switches to flexible-direct power transmission mode or cascaded H-bridge energy storage mode. The above working modes can be switched according to the actual situation. For example, the switching of the working mode can also be from the flexible direct power transmission and battery energy storage mode to the cascaded H-bridge energy storage mode or the flexible direct power transmission mode, or it can also be switched from the cascaded H-bridge energy storage mode or the flexible direct power transmission mode. to flexible-direct power transmission and battery energy storage modes.

In some embodiments, if a battery module of the MMC-BESS subsystem fails, the fault type of the failed battery module is identified, and the corresponding BMS control strategy is called according to the identified fault type to perform fault analysis and processing.

If a battery module of the MMC-BESS subsystem fails during the actual switching process of the flexible direct current transmission mode, the fault type of the faulty battery module can be identified, and the corresponding BMS control strategy can be called according to the identified fault type to perform fault analysis and processing. Specifically, if a battery module in the MMC-BESSC subsystem cannot be cut off normally, it can be considered to close the bypass switch connected to the battery module and select a normal battery module from the redundant submodule to put it into operation. In the switching process of the flexible direct current transmission and battery energy storage mode, the abnormal battery module is screened out. According to the different types of abnormalities, such as battery overcharge, battery short circuit or thermal management failure, the BMS system can be called to execute existing control strategies such as abnormal handling strategies to solve the abnormalities, and strictly control charging and discharging to avoid abnormal problems such as overcharging, overdischarging and overheating. If a DC circuit breaker has a problem and cannot be closed correctly during the actual switching process of the cascaded H-bridge energy storage mode, a backup protection strategy can be adopted, such as pulling open the backup switch connected to the DC circuit breaker to trip the DC circuit breaker. It is understandable that the above method is only used as an example. During the working mode switching process, if an abnormal situation occurs, the abnormal situation can be solved by combining the main control and the backup control.

In the technical solution of the embodiment of the present application, the status of the battery module is monitored through the BMS, and the abnormalities are screened out. The battery modules with problems are screened out and shut down, thereby avoiding the adverse effects of abnormal battery modules on the power system. The multi-mode switching of the power system is realized by controlling the battery resistance switch (SW2) of the battery module, the battery insertion and withdrawal switch (SW3), and the corresponding knife switches.

In some embodiments, powering on and off the normal battery module includes: monitoring the battery status parameters of the normal battery module, sorting the normal battery modules according to the battery status parameters of the normal battery module, and sorting the sorted battery modules according to the preset control strategy. Normally, the battery module performs power on and off operations in sequence.

Battery status parameters include SOC (State of Charge, state of charge), SOS (State of Safe, safety state), SOH (State of Health, health state) and/or SOF (State of Function, battery safety state) and other battery states parameter. The battery SOC value refers to the state of charge, which is used to reflect the remaining capacity of the battery. Its value is defined as the ratio of the remaining capacity to the battery capacity, commonly expressed as a percentage. Following the above embodiment, in this embodiment, powering on and off the normal battery module can be performed by monitoring the SOC value of the normal battery module through the BMS system, obtaining the SOC value of each normal battery module, and then powering the normal battery module according to the SOC value. Sort in descending order, and then, according to the preset control strategy, start from the normal battery module with the highest SOC value, and sequentially power on and off the sorted normal battery modules. It is understandable that the sorting method can also be sorting in ascending order, depending on the actual situation.

In another embodiment, sorting the normal battery modules according to the battery status parameters of the normal battery modules may also include obtaining the SOS value, SOH value or SOF value of each battery module, and sorting the normal battery modules according to the SOS value, SOH value or SOF value. Modules are sorted. In another embodiment, the battery status parameters including SOC value, SOS value, SOH value and SOF value can also be normalized to obtain the normalized SOX. Based on the size of the SOX value, the battery can be set accordingly. The scores of the modules are sorted according to the high score. In other embodiments, the sorting can also be performed based on a combination of SOC value, SOS value, SOH value and SOF value. There is no limitation here, as long as the battery modules with good performance status can be screened out. In other embodiments, the normal battery modules may also be sorted according to the voltage or power of the battery modules, which is not limited here.

In the technical solution of the embodiment of the present application, the battery modules are monitored through the BMS system, and the normal battery modules are sorted according to the SOC value of the normal battery modules, so that the remaining power of each normal battery module can be clarified. Subsequently, according to the remaining power, Powering on and off the battery module at high and low levels can prioritize the powering on and off of batteries with high remaining power, complete battery charging and discharging first, and subsequently improve the efficiency of power support.

In some embodiments, according to the preset control strategy, sequentially powering on and off the sorted normal battery modules includes: sequentially closing the first battery switch and the second battery switch of the sorted normal battery modules, and then turning off the first battery switch. As for the battery switch, the first battery switch includes a battery switch with a resistor, and the second switch includes a battery throw-in/out switch.

Following the above embodiment, in practice, the applicant found that when charging the battery, the battery throw-in and withdrawal switch connected to the battery module, that is, SW3 in this application, is usually directly closed to charge the battery module. However, as mentioned above, This method is prone to the problem of battery overcharging, which can easily cause battery failure. In order to solve this problem, a resistor switch is introduced. Before closing the battery switch, the resistor switch is first closed to smooth the battery through resistance consumption. The effect of sending electricity. After the specific sorting of the normal battery modules is completed, the switches SW2 and SW3 of the normal battery modules are closed in sequence according to the sorted order, and then the switch SW2 is opened to complete the power on and off operations in sequence.

In the technical solution of the embodiment of the present application, since the switch SW2 is a switch with a resistor, it has the function of buffering the battery charge and discharge. Therefore, performing the power on and off operation in the above manner can enable the battery module to perform smooth transitional charge and discharge, and the battery To protect.

In another embodiment, according to the preset control strategy, sequentially powering on and off the sequenced normal battery modules can also be: replacing the resistive switch in the above embodiment with an inductive switch such as SW4, and then closing the normal battery modules in sequence. The switch SW4 and switch SW3 of the battery module are turned off, and then the switch SW2 is turned off. In this way, the impedance of the inductive switch achieves a smooth charging effect. In another embodiment, a capacitor may be connected in parallel at both ends of the battery module. The capacitor is connected to the switch SW5 and the discharge circuit. The switch SW5 and the switch SW3 are closed at the same time to charge the capacitor and the battery module at the same time, and consume part of the power through the capacitor. To achieve the effect of smooth power delivery, when the SOC of the battery module reaches a preset threshold such as 80%, turn off the switch SW5, then close the automatic discharge circuit with the capacitor, completely discharge the capacitor, and wait for the next power-on and off operation. It can be understood that the capacitor's discharge circuit only needs to be able to completely discharge the capacitor, and the specific circuit structure is not limited here.

In the solution of the embodiment of the present application, capacitors or inductive switches are introduced to buffer the charge and discharge of the battery, avoid overcharging when charging the battery module, and realize the protection of the battery module.

As shown in Figure 5, in some embodiments, step 300 includes:

Step 320: If the working mode is the flexible-direct transmission mode, obtain the external power grid load data of the power system, and perform power balancing based on the external power grid load data.

Step 340, if the working mode is the flexible direct transmission and battery energy storage mode, monitor the load data of the external power grid, obtain the load data of the flexible direct transmission electronic system and the AC side power surplus data of the MMC-BESS subsystem, and obtain the load data of the flexible direct transmission electronic system and the AC side power surplus data of the MMC-BESS subsystem. The load data of the electronic system and the AC side power surplus data of the MMC-BESS subsystem are used for power balancing.

Step 360, if the working mode is the cascaded H-bridge energy storage mode, obtain the AC side power surplus data of the MMC-BESS subsystem and the status data of the battery module of the MMC-BESS subsystem. According to the AC side of the MMC-BESS subsystem Power surplus data and battery module status data are used for power support.

The external power grid load data refers to the load data of the double-terminal power grid or the multi-terminal power grid connected to the power system. During specific implementation, power balancing according to the preset power balancing strategy corresponding to the working mode can be: if the working mode is a flexible direct transmission mode (VSC+VSC double-terminal grid flexible direct transmission mode), then obtain the load data of the outer end grid , based on the load data of the external power grid, determine the target power grid that needs power support, and provide power support to the target power grid through flexible and direct transmission for power balancing. For example, if the load data of VSC-side grid A is 90% and the load data of VSC-side grid B is 30%, then the power of VSC-side grid B will be transmitted to VSC-side grid A through flexible direct transmission, so that VSC The load data of terminal grid A and VSC terminal grid B are 60%.

If the working mode is flexible direct transmission and battery energy storage mode, monitor the load data of the external power grid, obtain the load data of the flexible direct transmission electronic system and the AC side power surplus data of the MMC-BESS subsystem, and then, according to the flexible direct transmission electronic system The load data of the system and the AC side power surplus data of the MMC-BESS subsystem determine the end that needs power support, and the power can be balanced through flexible direct transmission. Specifically, in the flexible-to-direct power transmission and battery energy storage modes, the MMC-BESS subsystem can have 12 power support modes, which can be:

1. In the mode where the battery is neither charging nor discharging, the DC side transmits power to the AC side.

2. In the mode where the battery is neither charging nor discharging, the AC side transmits power to the DC side.

3. In battery charging mode, the AC side and DC side charge the battery at the same time.

4. In battery charging mode, the DC side charges the battery and transmits power to the AC side at the same time.

5. In battery charging mode, the AC side charges the battery and transmits power to the DC side at the same time.

6. In battery charging mode, the DC side operates independently from the battery and the battery is charged.

7. In the battery charging mode, the AC side is charged independently of the battery, and the battery is charged.

8. In battery discharge mode, the battery discharges to both the DC side and the AC side simultaneously.

9. In battery discharge mode, the battery and AC side transmit power to the DC side at the same time.

10. In battery discharge mode, the battery and DC side transmit power to the AC side at the same time.

11. In battery discharge mode, the DC side operates independently from the battery and the battery is discharged.

12. In battery discharge mode, the AC side and the battery operate independently and the battery discharges.

If the working mode is the cascaded H-bridge energy storage mode, obtain the AC side power surplus data of the MMC-BESS subsystem and the status data of the battery module of the MMC-BESS subsystem. According to the AC side power surplus data of the MMC-BESS subsystem and Battery module status data for power support. As mentioned in the above embodiment, since the DC conversion switch and grounding switch at the VSC end have been opened, at this time, there is no need to consider the power support at both ends of the DC or the multi-terminal power grid. Only the energy conversion at the AC port of the MMC-BESS subsystem needs to be considered. Therefore, it can be determined whether the AC side needs to be charged and discharged based on the AC side power surplus data of the MMC-BESS subsystem and the status data of the battery module. In the above content, the load data and work can be obtained by obtaining the power curve of the external power grid, and the load data is obtained based on the power curve. You can also collect the voltage and current of the power grid at each end, obtain the power data based on the voltage and current, and then combine the preset linear relationship between load and power (power is inversely proportional to load) to determine the load data or power surplus data. In another embodiment, the load data can also be obtained by on-site operators scheduling according to actual load conditions.

If it is determined based on the load data of the flexible direct transmission electronic system and the AC side power surplus data of the MMC-BESS subsystem that the flexible direct transmission electronic system needs power support and the AC side surplus power of the MMC-BESS subsystem meets the support conditions, then the The AC side surplus power of the MMC-BESS subsystem is transmitted to the flexible direct transmission electronic system through flexible direct transmission for power balancing.

If based on the load data of the flexible direct transmission electronic system and the AC side power surplus data of the MMC-BESS subsystem, it is determined that the flexible direct transmission electronic system needs power support and the AC side surplus power of the MMC-BESS subsystem does not meet the support conditions, then The AC side surplus power of the MMC-BESS subsystem is transmitted to the flex-direct transmission electronic system, and the battery module of the MMC-BESS subsystem is controlled to discharge support to the flex-direct transmission electronic system for power balancing.

During specific implementation, the power balance in the VSC+MMC-BESS double-terminal or multi-terminal grid flexible direct transmission mode can be: real-time monitoring of the load size at both ends of the line, based on the load data of the flexible direct transmission electronic system and the MMC-BESS subsystem The AC side power surplus data determines the end that needs power support and the side with power surplus. If other terminals (including the flexible direct transmission electronic system (VSC terminal)) require power support, and the AC power of the MMC-BESS subsystem is sufficient to support the power of other terminals, at this time, open all battery units of the MMC-BESS subsystem, that is, disconnect Turn on all switches SW3, and transmit active power and reactive power to the end that needs power support through flexible direct transmission; if the AC power of MMC-BESS is insufficient to support the power support of other ends, at this time, the input can be discharged normally according to the BMS monitoring The battery unit transmits the AC side surplus power of the MMC-BESS subsystem (hereinafter referred to as the MMC-BESS end) to the flexible direct power transmission electronic system in the form of flexible direct power transmission, and controls the battery module of the MMC-BESS subsystem to transmit power to the flexible direct transmission electronic system. Direct input electronic system for discharge support. If the VSC end requires power support, but there is no power surplus at the MMC-BESS end, the battery module at the MMC-BESS end is controlled to perform discharge support, close SW3, and wait for the battery to be discharged, then open the switch SW3 and wait for the charging time. After the charging is completed, Then wait for discharge again. If the VSC end does not need power support and the load is small, there is a power surplus, while the AC side load of the MMC-BESS end is large and power support is needed. At this time, the MMC-BESS end is powered by flexible direct transmission based on the VSC mode. Support, if there is insufficient power support at the VSC end, the BMS monitors the dischargeable battery and the transmission line to work together to provide power support. If there is a surplus load at the MMC-BESS end and the power grid on other sides does not need power support, turn off the power transmission support mode, charge the battery unit directly through the MMC-BESS end AC, and turn off the switch SW3 of the battery unit that has been charged. Put it into hot standby state.

If based on the AC side power surplus data of the MMC-BESS subsystem and the status data of the battery module, it is determined that the MMC-BESS subsystem has an AC side power surplus and the battery module is rechargeable, the battery module will be charged and the battery module will be in Hot standby status.

During the specific implementation, in the cascade H-bridge energy storage mode, only the energy conversion of the MMC-BESS DC port and AC port is considered, and the BMS is used to monitor whether the status of the battery module is normal and whether it can be charged and discharged. If the battery module status is abnormal or cannot be charged, When discharging, turn on the switch SW3 of the battery module to turn off the battery module. If the battery module is in normal condition and can be charged and discharged, corresponding measures will be taken for power balancing based on the AC side power surplus data. Specifically, when there is a surplus of power on the AC side, the battery module is charged and placed in a hot standby state. If the AC side requires power support, the battery module is controlled to discharge support for the AC side of the MMC-BESS subsystem. , for power balancing.

In some embodiments, charging the battery module also includes: monitoring the SOC value of the battery module, sorting the battery modules according to the SOC value of the battery module, and sequentially closing the first battery switch and the third battery switch of the sorted battery module. Second battery switch, and then disconnect the first battery switch. The first battery switch includes a battery switch with a resistor, and the second switch includes a battery switch.

Following the above embodiment, when the battery module is in a normal state and can be charged and discharged, and there is surplus power on the AC side, the SOC value of the battery module can be monitored through the BMS system to obtain the SOC value of each normal battery module, and then, based on the SOC value, The normal battery modules are sorted in descending order, and according to the sorted order, the switches SW2 and SW3 of the normal battery module are closed in sequence, and then the switch SW2 is opened. In another embodiment, as described in the above embodiment, the battery modules can also be sorted according to the SOS value, SOH value or other battery status parameters of each battery module, and the battery modules can also be sorted according to other voltages and powers. The sorting will not be described in detail here, as long as the battery modules with good performance status can be filtered out. In other embodiments, the normal battery modules may also be sorted in ascending order according to the SOC value, which is not limited here.

In the technical solution of the embodiment of the present application, since the switch SW2 is a switch with a resistance, it has the function of buffering the battery charge and discharge. Therefore, before charging the battery module, the battery module is powered on and off in the above manner, so that the battery module can be powered on and off in the above manner. The battery module performs smooth transitional charge and discharge to protect the battery.

In some embodiments, before controlling the battery module to support the AC side of the MMC-BESS subsystem in discharging, it also includes: monitoring the SOC value of the battery module, sorting the battery modules according to the SOC value of the battery module, and closing the sorted ones in turn. The first battery switch and the second battery switch of the battery module are then disconnected to provide power support to the AC side of the MMC-BESS subsystem. The first battery switch includes a battery switch with a resistor, and the second switch includes a battery. Throw in and out switch.

Similarly, if the battery module is in normal condition and can be charged and discharged, and the AC side power needs to be supported, you can also use the SOC of the battery module monitored by the BMS to close SW2 in sequence, then connect to SW3, and then disconnect SW2 to perform the AC side control. Power support.

In the technical solution of the embodiment of the present application, since the switch SW2 is a switch with resistance, it has the function of battery charging and discharging buffering. Therefore, before power support is provided to the AC side power, the battery module is powered on and off in the above-mentioned manner, which can enable the battery module to smoothly transition between charging and discharging, protect the battery, and ensure orderly power support.

In order to explain in detail the technical solution of the power balancing method of the power system of this application, the entire power balancing solution will be described in detail below with reference to Figure 7 and a specific embodiment. In this embodiment, the power balancing method of the power system includes the following steps:

Step 1: Obtain fault monitoring data of the flexible direct current transmission subsystem and the MMC-BESS subsystem.

Step 1-2: If it is determined that the MMC-BESS subsystem is faulty based on the fault monitoring data, it is determined that the working mode is the flexible-direct power transmission mode, and then step 2-2 is entered.

Step 1-4: If it is determined based on the fault monitoring data that neither the flexible direct power transmission electronic system nor the MMC-BESS subsystem has a fault, it is determined that the working mode is the flexible direct power transmission and battery energy storage power mode, and then step 2-4 is entered.

Step 1-6: If it is determined that the flexible direct transmission electronic system is faulty based on the fault monitoring data, it is determined that the working mode is the cascade H-bridge energy storage mode, and then step 2-6 is entered.

Step 2-2, if the working mode is the flexible and direct power transmission mode, turn off the battery module of the MMC-BESS subsystem to switch the power system to the flexible and direct power transmission mode, and enter step 3-2.

Step 2-4, if the working mode is flexible direct power transmission and battery energy storage mode, monitor the battery status of the battery module of the MMC-BESS subsystem, screen out abnormal battery modules and normal battery modules, close the abnormal battery module, and monitor the normal battery SOC value of the module, sort the normal battery modules according to the SOC value of the normal battery module, close the switches SW2 and SW3 of the sorted normal battery modules in turn, and then open the switch SW2 to switch the power system to flexible and direct transmission. In battery storage mode, go to steps 3-4.

Step 2-6, if the working mode is the cascade H-bridge energy storage mode, disconnect the loop of the flexible direct transmission electronic system to switch the power system to the cascade H-bridge energy storage mode, and enter step 3-6.

Step 3-2, if the working mode is the flexible-direct transmission mode, obtain the external grid load data of the power system, and perform power balancing based on the external grid load data.

Step 3-4, if the working mode is flexible direct transmission and battery energy storage mode, monitor the load data of the external power grid to obtain the load data of the flexible direct transmission electronic system and the AC side power surplus data of the MMC-BESS subsystem;

Step 3-4-2, if based on the load data of the flexible direct transmission electronic system and the AC side power surplus data of the MMC-BESS subsystem, it is determined that the flexible direct transmission electronic system requires power support and the AC side surplus power of the MMC-BESS subsystem is When the support conditions are met, the AC side surplus power of the MMC-BESS subsystem will be transmitted to the flexible direct transmission electronic system through flexible direct transmission for power balancing.

In step 3-4-4, if it is determined that the flexible direct current transmission system requires power support and the AC side surplus power of the MMC-BESS subsystem does not meet the support conditions based on the load data of the flexible direct current transmission system and the AC side surplus power data of the MMC-BESS subsystem, the AC side surplus power of the MMC-BESS subsystem is transmitted to the flexible direct current transmission system, and the battery module of the MMC-BESS subsystem is controlled to perform discharge support on the flexible direct current transmission system to achieve power balancing.

In step 3-4-6, if it is determined that the flexible direct current transmission system requires power support and the MMC-BESS subsystem does not have a power surplus based on the load data of the flexible direct current transmission system and the AC side power surplus data of the MMC-BESS subsystem, the battery module is controlled to provide discharge support to the flexible direct current transmission system and the MMC-BESS subsystem to achieve power balancing.

Step 3-6, if the working mode is the cascade H-bridge energy storage mode, obtain the AC side power surplus data of the MMC-BESS subsystem and the status data of the battery module of the MMC-BESS subsystem;

Step 3-6-2, if based on the AC side power surplus data of the MMC-BESS subsystem and the status data of the battery module, it is determined that the MMC-BESS subsystem has an AC side power surplus and the battery module can be charged, then monitor the battery module. SOC value, sort the battery modules according to the SOC value of the battery module, close the switches SW2 and SW3 of the sorted battery modules in sequence, and then open the switch SW to charge the battery module and put the battery module in a hot standby state;

Step 3-6-4, if it is determined that the AC side of the MMC-BESS subsystem requires power support based on the AC side power surplus data of the MMC-BESS subsystem and the status data of the battery module, then the battery will be adjusted based on the SOC value of the battery module. The modules are sequenced, and the switches SW2 and SW3 of the sequenced battery modules are closed in turn, and then the switches SW are opened to control the battery modules to discharge support to the AC side of the MMC-BESS subsystem for power balancing.

It should be understood that although the steps in the flowcharts involved in the above embodiments are shown in sequence as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated in this article, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least some of the steps in the flowcharts involved in the above embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily executed at the same time, but may be executed at different times. The execution order of these steps or stages is not necessarily sequential, but may be performed in turn or alternately with other steps or at least part of the steps or stages in other steps.

Based on the same inventive concept, embodiments of the present application also provide a power system power balancing device for implementing the above-mentioned power system power balancing method. The solution to the problem provided by this device is similar to the solution described in the above method. Therefore, the specific limitations in the embodiments of the power balancing device for one or more power systems provided below can be found in the above description of the power system. The limitations of the power equalization method will not be described again here.

In one embodiment, as shown in Figure 8, a power balancing device for a power system is provided, including: a controller 810, and a power system 820 connected to the controller 810. The power system includes a VSC flexible direct transmission electronic system 822 and MMC-BESS subsystem 824;

The controller is used to determine the working mode of the power system, perform switch control on the VSC flexible direct transmission electronic system 822 and the MMC-BESS subsystem 824, switch the power system 820 to the corresponding working mode, and balance the power according to the preset power corresponding to the working mode. strategy for power balancing.

The power balancing device of the above power system provides a power balancing solution for the power system including the flexible direct transmission electronic system and the MMC-BESS subsystem. In the entire solution, the controller determines the working mode of the power system and switches the power system to The corresponding working mode realizes flexible switching of multiple working modes, and performs power balancing according to the preset power balancing strategy corresponding to each working mode, realizing multiple working modes such as flexible direct transmission mode or flexible direct transmission power storage. Power balance in energy mode achieves a power system that meets power balance in various scenarios. While achieving power balance of the power system, it also improves the flexibility of power balance control, thereby improving the power consumption of the power system. The power supply and control capabilities ensure the power quality and power supply reliability of the power system.

In some embodiments, the controller 810 is also used to obtain fault monitoring data of the VSCVSC flexible direct transmission electronic system 822822 and the MMC-BESS subsystem 824, and determine the working mode of the power system based on the fault monitoring data.

In some embodiments, the controller 810 is also configured to determine that the working mode is the cascade H-bridge energy storage mode if it is determined based on the fault monitoring data that the VSC flexible direct transmission electronic system 822 has a fault. If it is determined based on the fault monitoring data that the MMC-BESS If the subsystem 824 fails, the working mode is determined to be the flexible direct transmission mode. If it is determined based on the fault monitoring data that neither the VSC flexible direct transmission electronic system 822 nor the MMC-BESS subsystem 824 fails, the working mode is determined to be the flexible direct transmission mode. and battery storage power mode.

In some embodiments, the controller 810 is also used to control the switching of the battery module of the MMC-BESS subsystem 824 and the VSC flexible direct transmission electronic system 822 according to the preset mode switching strategy corresponding to the determined working mode, so as to switch the power The system switches to the corresponding working mode.

In some embodiments, the controller 810 is also used to shut down the battery module of the MMC-BESS subsystem 824 to switch the power system to the flexible-to-direct power transmission mode if the working mode is to the flexible-to-direct power transmission mode. In the power transmission and battery storage mode, the battery status of the battery module of the MMC-BESS subsystem 824 is monitored, abnormal battery modules and normal battery modules are screened out, the abnormal battery module is turned off, and the normal battery module is powered on and off to restore the power system. Switch to the flexible direct power transmission and battery energy storage mode. If the working mode is the cascade H-bridge energy storage mode, disconnect the loop of the VSC flexible direct transmission electronic system 822 to switch the power system to the cascade H-bridge energy storage mode.

In some embodiments, the controller 810 is also used to monitor the battery status parameters of normal battery modules, sort the normal battery modules according to the battery status parameters of the normal battery modules, and sequence the sorted normal battery modules according to the preset control strategy. Perform power on and off operations.

In some embodiments, the controller 810 is also used to sequentially close the first battery switch and the second battery switch of the sequenced normal battery module, and then open the first battery switch. The first battery switch includes a battery switch with a resistance, The second switch includes a battery throw-in/out switch.

In some embodiments, the controller 810 is also used to obtain the external power grid load data of the power system if the working mode is the flexible-direct power transmission mode, and perform power balancing according to the external power grid load data; if the working mode is the flexible-direct power transmission and In the battery energy storage mode, the external power grid load data is monitored to obtain the load data of the VSC flexible direct transmission electronic system 822 and the AC side power surplus data of the MMC-BESS subsystem 824. According to the load data of the VSC flexible direct transmission electronic system 822 and The AC side power surplus data of the MMC-BESS subsystem 824 is used for power balancing; if the working mode is the cascade H-bridge energy storage mode, the AC side power surplus data of the MMC-BESS subsystem 824 and the MMC-BESS subsystem 824 are obtained. The status data of the battery module performs power support based on the AC side power surplus data of the MMC-BESS subsystem 824 and the status data of the battery module.

In some embodiments, the controller 810 is also configured to determine that the VSC flexible direct transmission electronic system 822 needs power support based on the load data of the VSC flexible direct transmission electronic system 822 and the AC side power surplus data of the MMC-BESS subsystem 824 and When the AC side surplus power of the MMC-BESS subsystem 824 meets the support conditions, the AC side surplus power of the MMC-BESS subsystem 824 is transmitted to the VSC flexible direct transmission electronic system 822 through flexible direct transmission for power balancing; if according to The load data of the VSC flexible direct transmission electronic system 822 and the AC side power surplus data of the MMC-BESS subsystem 824 determine that the VSC flexible direct transmission electronic system 822 needs power support and the AC side surplus power of the MMC-BESS subsystem 824 does not meet the support requirement. When the conditions are met, the AC side surplus power of the MMC-BESS subsystem 824 is transmitted to the VSC flexible direct transmission electronic system 822, and the battery module of the MMC-BESS subsystem 824 is controlled to discharge support to the VSC flexible direct transmission electronic system 822, so as to Perform power balancing; if based on the load data of the VSC flexible direct transmission electronic system 822 and the AC side power surplus data of the MMC-BESS subsystem 824, it is determined that the VSC flexible direct transmission electronic system 822 requires power support and the MMC-BESS subsystem 824 does not exist When the power is surplus, the battery module is controlled to provide discharge support to the VSC flexible direct transmission electronic system 822 and the MMC-BESS subsystem 824 for power balancing.

In some embodiments, the controller 810 is also configured to determine, based on the AC side power surplus data of the MMC-BESS subsystem 824 and the status data of the battery module, that there is an AC side power surplus in the MMC-BESS subsystem 824 and that the battery module can be charged. When, the battery module is charged and placed in a hot standby state; if based on the AC side power surplus data of the MMC-BESS subsystem 824 and the status data of the battery module, it is determined that the AC side needs of the MMC-BESS subsystem 824 During power support, the battery module is controlled to provide discharge support to the AC side of the MMC-BESS subsystem 824 to perform power balancing.

Each module in the power balancing device of the above-mentioned power system can be implemented in whole or in part by software, hardware, and combinations thereof. Each of the above modules can be embedded in or independent of the processor of the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above modules.

In one embodiment, a computer device is provided. The computer device may be a server, and its internal structure diagram may be as shown in Figure 9. The computer device includes a processor, memory, and network interfaces connected through a system bus. Wherein, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes non-volatile storage media and internal memory. The non-volatile storage medium stores operating systems, computer programs and databases. This internal memory provides an environment for the execution of operating systems and computer programs in non-volatile storage media. The database of the computer equipment is used to store data such as fault monitoring data, load data, and battery status monitoring data of the power system. The network interface of the computer device is used to communicate with external terminals through a network connection. The computer program implements a power balancing method for an electric power system when executed by a processor.

Those skilled in the art can understand that the structure shown in Figure 9 is only a block diagram of a partial structure related to the solution of the present application, and does not constitute a limitation on the computer equipment to which the solution of the present application is applied. Specific computer equipment can May include more or fewer parts than shown, or combine certain parts, or have a different arrangement of parts.

In one embodiment, a computer device is provided, including a memory and a processor. A computer program is stored in the memory. When the processor executes the computer program, it implements the steps in the power balancing method of the power system.

In one embodiment, a computer-readable storage medium is provided, a computer program is stored thereon, and when the computer program is executed by a processor, the steps in the power balancing method of an electric power system are implemented.

In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the power balancing method for an electric power system.

It should be noted that the user information (including but not limited to user equipment information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all It is information and data authorized by the user or fully authorized by all parties.

Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage. In the media, when executed, the computer program may include the processes of the above method embodiments. Any reference to memory, database or other media used in the embodiments provided in this application may include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive memory (ReRAM), magnetic variable memory (Magnetoresistive Random Access Memory (MRAM), ferroelectric memory (Ferroelectric Random Access Memory, FRAM), phase change memory (Phase Change Memory, PCM), graphene memory, etc. Volatile memory may include random access memory (Random Access Memory, RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can be in many forms, such as static random access memory (Static Random Access Memory, SRAM) or dynamic random access memory (Dynamic Random Access Memory, DRAM). The databases involved in the various embodiments provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include blockchain-based distributed databases, etc., but are not limited thereto. The processors involved in the various embodiments provided in this application may be general-purpose processors, central processing units, graphics processors, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to this.

The technical features of the above embodiments can be combined in any way. To simplify the description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, all possible combinations should be used. It is considered to be within the scope of this manual.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features can be equivalently replaced; and these modifications or substitutions do not deviate from the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present application. The scope shall be covered by the claims and description of this application. In particular, as long as there is no structural conflict, the technical features mentioned in the various embodiments can be combined in any way. The application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

A power balancing method for a power system, characterized in that the power system includes a flexible direct transmission electronic system and an MMC-BESS subsystem;

The power balancing method of the power system comprises:

Determine the operating mode of the power system;

Switch the power system to the corresponding working mode;

Power balancing is performed according to a preset power balancing strategy corresponding to the working mode.
The method of claim 1, wherein determining the operating mode of the power system includes:

Obtain fault monitoring data of the flexible direct transmission electronic system and MMC-BESS subsystem;

According to the fault monitoring data, the working mode of the power system is determined.
The method according to claim 2, wherein determining the working mode of the power system according to the fault monitoring data includes:

If it is determined that the flexible direct transmission electronic system is faulty based on the fault monitoring data, it is determined that the working mode is the cascade H-bridge energy storage mode;

Or, if it is determined that the MMC-BESS subsystem is faulty based on the fault monitoring data, it is determined that the working mode is the flexible-direct power transmission mode;

Alternatively, if it is determined according to the fault monitoring data that neither the flexible direct current transmission subsystem nor the MMC-BESS subsystem has any fault, then the operating mode is determined to be the flexible direct current transmission and battery energy storage power mode.
The method of claim 3, wherein switching the power system to a corresponding working mode includes:

According to the preset mode switching strategy corresponding to the determined working mode, the battery module of the MMC-BESS subsystem and the flexible direct transmission electronic system are switched and controlled to switch the power system to the corresponding working mode.
The method according to claim 4, characterized in that the battery module of the MMC-BESS subsystem and the flexible direct transmission electronic system are switched according to a preset mode switching strategy corresponding to the determined working mode. Control, switching the power system to the corresponding working mode includes:

If the working mode is the flexible direct power transmission mode, then turn off the battery module of the MMC-BESS subsystem to switch the power system to the flexible direct power transmission mode;

Or, if the working mode is the flexible power transmission and battery energy storage mode, monitor the battery status of the battery module of the MMC-BESS subsystem, screen out abnormal battery modules and normal battery modules, and close the abnormal battery module, Perform power on and off operations on the normal battery module to switch the power system to the flexible and direct power transmission and battery energy storage modes;

Alternatively, if the working mode is the cascaded H-bridge energy storage mode, disconnect the loop of the flexible direct transmission electronic system to switch the power system to the cascaded H-bridge energy storage mode.
The method of claim 5, further comprising:

If the battery module of the MMC-BESS subsystem fails, identify the fault type of the failed battery module;

According to the identified fault type, the corresponding BMS control strategy is called to perform fault analysis and processing.
The method according to claim 5, characterized in that said powering on and off the normal battery module includes:

Monitoring the battery status parameters of the normal battery modules;

Sort the normal battery modules according to the battery status parameters of the normal battery modules;

According to the preset control strategy, the sorted normal battery modules are powered on and off in sequence.
The method according to claim 7, characterized in that, according to the preset control strategy, sequentially powering on and off the sorted normal battery modules includes:

Sequentially close the first battery switch and the second battery switch of the sequenced normal battery module, and then open the first battery switch. The first battery switch includes a battery switch with a resistor, and the second switch includes a battery switch. Back off switch.
The method according to any one of claims 3 to 7, wherein performing power balancing according to a preset power balancing strategy corresponding to the working mode includes:

If the working mode is the flexible-to-direct power transmission mode, obtain the external power grid load data of the power system, and perform power balancing based on the external power grid load data;

If the working mode is the flexible direct power transmission and battery energy storage mode, monitor the load data of the external power grid to obtain the load data of the flexible direct transmission electronic system and the AC side power surplus data of the MMC-BESS subsystem. , perform power balancing based on the load data of the flexible direct transmission electronic system and the AC side power surplus data of the MMC-BESS subsystem;

If the working mode is the cascaded H-bridge energy storage mode, obtain the AC side power surplus data of the MMC-BESS subsystem and the status data of the battery module of the MMC-BESS subsystem. According to the MMC -The AC side power surplus data of the BESS subsystem and the status data of the battery module are used for power support.
The method of claim 8, wherein performing power balancing based on the load data of the flexible direct transmission electronic system and the AC side power surplus data of the MMC-BESS subsystem includes:

If based on the load data of the flexible direct transmission electronic system and the AC side power surplus data of the MMC-BESS subsystem, it is determined that the flexible direct transmission electronic system requires power support and the AC side surplus of the MMC-BESS subsystem is When the power meets the support conditions, the AC side surplus power of the MMC-BESS subsystem is transmitted to the flexible direct transmission electronic system through flexible direct transmission for power balancing;

If based on the load data of the flexible direct transmission electronic system and the AC side power surplus data of the MMC-BESS subsystem, it is determined that the flexible direct transmission electronic system requires power support and the AC side surplus of the MMC-BESS subsystem is When the power does not meet the support conditions, the AC side surplus power of the MMC-BESS subsystem is transferred to the flexible direct transmission electronic system, and the battery module of the MMC-BESS subsystem is controlled to control the flexible direct transmission electronics. The system performs discharge support for power balancing;

If based on the load data of the flexible direct transmission electronic system and the AC side power surplus data of the MMC-BESS subsystem, it is determined that the flexible direct transmission electronic system requires power support and the MMC-BESS subsystem does not have a power surplus. When, the battery module is controlled to provide discharge support to the flexible direct transmission electronic system and the MMC-BESS subsystem to perform power balancing.
The method of claim 9, wherein performing power support based on the AC side power surplus data of the MMC-BESS subsystem and the status data of the battery module includes:

If it is determined based on the AC side power surplus data of the MMC-BESS subsystem and the status data of the battery module that the MMC-BESS subsystem has an AC side power surplus and the battery module is chargeable, then the charging the battery module and placing the battery module in a hot standby state;

If it is determined that the AC side of the MMC-BESS subsystem needs power support based on the AC side power surplus data of the MMC-BESS subsystem and the status data of the battery module, the battery module is controlled to provide power to the MMC. -The AC side of the BESS subsystem provides discharge support for power balancing.
The method according to claim 11, characterized in that before charging the battery module, it also includes:

Monitor battery status parameters of the battery module;

sorting the battery modules according to the battery status parameters of the battery modules;

Sequentially close the first battery switch and the second battery switch of the sequenced battery modules, and then open the first battery switch. The first battery switch includes a battery switch with a resistor, and the second switch includes a battery switch. switch.
The method according to claim 11, characterized in that before controlling the battery module to provide discharge support to the AC side of the MMC-BESS subsystem, it further includes:

Monitor battery status parameters of the battery module;

Sort the battery modules according to the battery status parameters of the battery modules;

Sequentially close the first battery switch and the second battery switch of the sequenced battery modules, and then open the first battery switch to provide power support to the AC side of the MMC-BESS subsystem. The first battery switch includes A battery switch with a resistor, the second switch includes a battery switch.
A power balancing device for a power system, characterized in that the device includes: a controller, and a power system connected to the controller, where the power system includes a VSC flexible direct transmission electronic system and an MMC-BESS subsystem;

The controller is used to determine the working mode of the power system, perform switch control on the VSC flexible direct transmission electronic system and the MMC-BESS subsystem, and switch the power system to the corresponding working mode. Perform power balancing according to the preset power balancing strategy corresponding to the above working mode.
A computer device includes a memory and a processor, the memory stores a computer program, and is characterized in that when the processor executes the computer program, the steps of the method described in any one of claims 1 to 13 are implemented.
A computer-readable storage medium having a computer program stored thereon, characterized in that, when the computer program is executed by a processor, the steps of the method described in any one of claims 1 to 13 are implemented.
A computer program product, comprising a computer program, characterized in that, when executed by a processor, the computer program implements the steps of the method according to any one of claims 1 to 13.