Energy storage system with anti-backflow function and anti-backflow method thereof

Abstract

The invention discloses an energy storage system with an anti-countercurrent function and an anti-countercurrent method thereof, an infrared technology is used for monitoring a high-voltage meter and detecting the direction and the size of current in real time, and a specific algorithm and an ems strategy are combined to take anti-countercurrent measures in advance so as to restrain the descending trend of the current, so that the anti-countercurrent function is realized. By monitoring and controlling the charging and discharging process of the energy storage system in real time, the current countercurrent phenomenon is prevented, impact and fluctuation on a power grid are avoided, stable operation of the power grid is guaranteed, and the stability of the power grid is maintained; by cutting off countercurrent in time, user equipment is protected from being damaged, loss of users is reduced, maintenance cost and failure rate of a power grid are reduced, and economic benefits and social benefits of the power grid are improved. By monitoring and controlling the charging and discharging process of the energy storage device in real time, the current countercurrent phenomenon is prevented, the energy storage device is protected against damage, and the service life of the energy storage device is prolonged.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage, and in particular relates to an energy storage system with an anti-backflow function and an anti-backflow method thereof. Background Art

[0002] In the existing energy storage monitoring system, real-time monitoring and reverse flow control of current are the key to ensure the stable operation of energy storage. Traditional energy storage monitoring methods often have problems such as low accuracy and slow response, and cannot effectively deal with the current reverse flow phenomenon in a timely manner. Therefore, it is of great practical significance to develop a high-precision, fast-response current real-time monitoring and reverse flow prevention system.

[0003] When the energy storage system or photovoltaic power is greater than the power of the local load, the unabsorbed electricity must be sent to the grid. Since the flow direction of this energy is energy storage, photovoltaic components-inverter-load-grid, it is different from the current direction of the grid system, which is called "reverse flow".

[0004] The anti-backflow protection device is a power protection technology, which is mainly used to prevent the occurrence of backflow in the power system to protect the safety of equipment and systems. Usually, an anti-backflow device is installed on the AC side to monitor the current flow direction to control the power generation at the DC end of the energy storage.

[0005] Energy storage backflow prevention is an important measure to ensure the safe and stable operation of the energy storage system. Its principle is mainly to monitor and control the flow of current through a series of hardware devices and control strategies to prevent the energy storage power from exceeding the current effective load.

[0006] Disadvantages of existing technology:

[0007] 1. Unable to effectively determine the time point of backflow: Delays in data processing and analysis may make it impossible to immediately determine the time point of backflow; current technology may not be able to monitor the occurrence of backflow in real time or accurately.

[0008] 2. Response platform control of EMS: The granularity of the connection between the response platform and EMS is not fine enough, and unexpected situations often occur in the effects of control and entity operation.

[0009] Data collection timeliness: As the real-time nature of data collection increases, the complexity and cost of implementation will also increase significantly; due to the high-frequency real-time requirements of data collection, the quality and integrity of some data may be sacrificed; real-time data collection will generate a large amount of data flow, which places higher requirements on the storage and transmission systems. Summary of the invention

[0010] The purpose of the present invention is to overcome the shortcomings of the prior art, and proposes a method of using infrared technology to monitor the high-voltage meter, detecting the direction and size of the current in real time, and combining a specific algorithm and EMS strategy to take anti-backflow measures in advance to curb the downward trend of the current, and prevent the occurrence of current reverse flow by real-time monitoring and controlling the charging and discharging process of the energy storage system, avoiding shocks and fluctuations on the power grid, thereby ensuring the stable operation of the power grid and maintaining the stability of the power grid; by timely cutting off the reverse current, protecting user equipment from damage, reducing user losses, reducing the maintenance cost and failure rate of the power grid, and improving the economic and social benefits of the power grid; by real-time monitoring and controlling the charging and discharging process of the energy storage device, preventing the occurrence of current reverse flow, protecting the energy storage device from damage, and extending its service life, an energy storage system with anti-backflow function and an anti-backflow method thereof.

[0011] The technical solution of the present invention to solve the above technical problems is as follows:

[0012] An energy storage system with anti-backflow function includes a battery management system BMS, an energy management system EMS, an energy storage converter PCS and a control architecture:

[0013] The battery management system BMS is responsible for monitoring, evaluating, protecting and balancing the battery. The BMS and the battery cells together constitute the battery system;

[0014] The energy management system EMS is responsible for data collection, network monitoring and energy scheduling;

[0015] The energy storage converter PCS controls the charging and discharging process of the energy storage battery pack and performs AC to DC conversion;

[0016] The control architecture is physically divided into four layers: physical layer, data link layer, network layer and application layer; the anti-backflow strategy control logic of the energy storage system is as follows:

[0017] High-voltage side backflow prevention: Use infrared to monitor the high-voltage meter, monitor the direction and size of the current in real time, and ensure the normal flow of current; the algorithm is that the high-voltage active power is too low, when the active power <= the rate error power (the company's high-voltage rate a* scale 0.01*4 hours, use hours as the unit to make a backflow prevention strategy in advance to curb the downward trend), and the EMS strategy is on, set to discharge state, and backflow prevention is on;

[0018] Low-voltage side backflow prevention: monitor the low-voltage meter. Several conditions need to be considered for low voltage. Is the power on the high-voltage side too low? The algorithm is the same as above. Is the energy storage running? The added active power of all PCSs is greater than 0. Turn on the backflow prevention.

[0019] When backflow occurs, determine whether the company allows backflow: If not allowed, install anti-backflow monitoring equipment and adjust the anti-backflow strategy according to the company's current operating status.

[0020] Preferably, the anti-backflow strategy can be adjusted according to the current operating status of the enterprise in two situations:

[0021] 1. Enterprises allow energy storage to be transmitted across transformers. In this case, high-voltage incoming lines need to be monitored:

[0022] When the following four conditions are met at the same time, reverse flow discharge is started: 1. The reverse power of the incoming line is greater than 0 or the forward power is less than the rate error; 2. The EMS operation mode is strategy or the EMS operation mode is direct control, the active power setting is greater than 0, and the power to be adjusted is less than the current set power; 3. The PCS is actually discharging; 4. There is no pause sign, the operation mode is switched to the direct control mode, and reverse flow prevention is started. The power is reduced according to the current high-voltage power setting of the enterprise. When the enterprise's electricity consumption recovers, the following six conditions must be met to gradually increase the energy storage power: 1. The EMS operation mode is direct control mode; 2. The current forward power is greater than the rate error; 3. The current EMS set power is less than 100KW; 4. The PCS power is greater than or equal to 0; 5. The rising power to be adjusted is greater than the current set power; 6. There is no pause mark. The operation mode is switched back to the strategy mode. At the same time, it is forced to switch to the strategy mode for charging before each charging period in the morning and afternoon. According to the above steps, the cloud platform makes a judgment and sends the strategy to the energy storage EMS. The EMS acts according to the strategy and sends a command to the BMS. The BMS makes actions such as reducing power or increasing power, and the monitoring device sends back the action information to the cloud platform;

[0023] 2. Standard energy storage anti-backflow process,

[0024] In this case, the incoming line to which the energy storage belongs needs to be monitored. This situation controls the corresponding energy storage module and does not affect the operation of other modules. When four conditions are met at the same time, reverse flow discharge is started: 1. The reverse power of the incoming line is greater than 0 or the forward power is less than the rate error. 2. The EMS operation mode of the energy storage module is strategy or the EMS operation mode is direct control, the active power setting is greater than 0, and the power to be adjusted is less than the current set power. 3. The PCS is actually discharging. 4. There is no pause sign, the operation mode is switched to direct control mode, and anti-backflow is started. The power reduction is set according to the current high-voltage power of the enterprise. When the company's electricity consumption recovers, six conditions must be met to gradually increase the energy storage power: 1. The EMS operation mode of the energy storage module is direct control mode, 2. The current forward power is greater than the rate error, 3. The current set power of EMS is less than 100KW, 4. The PCS power is greater than or equal to 0, 5. The rising power to be adjusted is greater than the current set power, 6. There is no pause sign, and the operation mode is switched back to the strategy mode. At the same time, it is forced to switch to the strategy mode for charging before each charging period in the morning and afternoon. According to the above steps, the cloud platform makes a judgment and the strategy is sent to the energy storage module EMS. EMS sends a command to the BMS according to the strategy action. The BMS takes actions such as reducing power or increasing power. At the same time, the monitoring device sends back the action information to the cloud platform.

[0025] Preferably, the battery management system BMS measures basic parameters of the battery, including voltage, current, and temperature, to prevent overcharging and overdischarging of the battery and extend the service life of the battery.

[0026] Preferably, the energy management system BMS calculates and analyzes the remaining battery capacity SOC and the battery health state SOH of the battery, and reports abnormal information in a timely manner; the energy management system BMS is divided into a device layer, a communication layer and an application layer.

[0027] Preferably, the device layer: needs to be supported by energy collection and transformation; the communication layer: mainly includes links, protocols, and transmission; the information layer: mainly includes cache middleware, databases, and servers, among which the database system is responsible for data processing and data storage, recording real-time data and important historical data, and providing historical information query; the application layer: the expression form includes APP and Web, providing managers with a visual monitoring and operation interface, and the specific functions cover energy conversion decision-making, energy data transmission and collection, real-time monitoring and control, operation and maintenance management analysis, electric energy / power visual analysis, and remote real-time control.

[0028] Preferably, the energy storage converter PCS includes a DC / AC bidirectional converter and a control unit, which controls the converter to charge or discharge the battery according to the sign and size of the power instruction, thereby adjusting the active power and reactive power of the power grid, and can directly supply power to the AC load in the absence of a power grid.

[0029] Preferably, the energy storage converter PCS is the interface between the battery and the power grid or AC load, and can communicate with the BMS through the CAN interface to obtain battery status information, which determines the power quality and dynamic characteristics of the energy storage system output and also greatly affects the battery life.

[0030] Preferably, the physical layer: mainly connects to various sensors in the network for measurement, protection, control, and governance;

[0031] Data link layer: includes on-site intelligent gateways and network switches;

[0032] Network layer: The communication network adopts standard Ethernet and TCP / IP communication protocols, and the physical media can be optical fiber, network cable, or shielded twisted pair cable;

[0033] Application layer: The platform provides two access methods: WEB and APP. Its functions include energy consumption analysis, equipment management, operation and maintenance management, and user reports. It mainly realizes remote centralized monitoring and control, energy efficiency analysis, energy consumption and revenue, etc., to assist users in participating in demand response and electricity market transactions.

[0034] Preferably, the energy storage system supports Modbus RTU, Modbus TCP, and DL / T645-2007 communication protocols; it can formulate and automatically execute control strategies such as planning curves, peak shaving and valley filling, demand control, dynamic capacity expansion, and backup power supply, and realize integrated intelligent collaboration of source, network, load, and storage internally.

[0035] A backflow prevention method for an energy storage system with a backflow prevention function, S1. Real-time monitoring and data acquisition: using a high-precision infrared sensor to monitor the current direction and magnitude of a high-voltage meter in real time, and transmitting the collected data to a data processing unit for analysis and processing;

[0036] S2. High-voltage active power judgment: The data processing unit calculates the high-voltage active power based on the collected current data and compares it with the preset rate error power (the company's high-voltage rate a* scale 0.01*4 hours). If the high-voltage active power is less than or equal to the rate error power, it is determined that the high-voltage active power is too low;

[0037] S3. EMS strategy status detection: At the same time, the data processing unit also needs to detect the status of the EMS strategy. When the EMS strategy is in the on state (set to the discharge state), the system will execute the anti-backflow strategy;

[0038] S4. Execution of anti-backflow strategy: When the high-voltage active power is too low and the EMS strategy is turned on, the system will start the anti-backflow strategy, which may include but is not limited to: adjusting the grid structure, changing the load distribution, starting the backup power supply, etc., to curb the downward trend of the current and ensure the stable operation of the power system;

[0039] S5. Early warning mechanism: In order to prevent the occurrence of current reverse flow, the system should set up an early warning mechanism. When the high-voltage active power is close to the multiplier error power, the system should issue a warning signal to remind the operator to pay attention and take corresponding measures;

[0040] S6. Automated control: In order to quickly respond and effectively curb the downward trend of current, the execution of the anti-backflow strategy should be automated as much as possible. Through preset rules and algorithms, the system can automatically determine whether the anti-backflow strategy needs to be executed and automatically perform the corresponding operations;

[0041] S7. Multi-strategy combination: The anti-backflow strategy can be flexibly combined and adjusted according to the actual situation. When the grid structure is complex or the load changes greatly, a combination of multiple strategies can be used to improve the anti-backflow effect;

[0042] S8. Real-time monitoring and feedback: During the implementation of the anti-backflow strategy, the system should monitor the grid status and current changes in real time, and adjust and optimize the strategy based on the feedback results.

[0043] Beneficial effects of the present invention:

[0044] 1. Stable system operation: The energy storage system's anti-backflow technology can ensure that when the power system is connected to the grid, it prevents the reverse flow of electricity from the energy storage system into the grid, thereby maintaining the stable operation of the system. By precisely controlling the charging and discharging process of the energy storage system, the anti-backflow technology can balance the supply and demand of the grid, reduce the fluctuation and imbalance of the grid, and improve the stability of the power system.

[0045] 2. Energy utilization optimization: Energy storage system anti-backflow technology can optimize energy utilization and improve energy utilization efficiency. In the power system, the intermittent and volatile nature of renewable energy leads to unstable power supply. Energy storage systems can smooth out the fluctuations of renewable energy by storing and releasing electrical energy, thus achieving a stable and reliable power supply. At the same time, anti-backflow technology can avoid the loss of electrical energy during transmission and further improve energy utilization efficiency.

[0046] 3. Improve safety: The energy storage system's anti-backflow technology can significantly improve the safety of the power system. In the power system, various reasons may cause problems such as abnormal grid voltage and frequency fluctuations, causing damage to power equipment and power-consuming equipment. The energy storage system uses anti-backflow technology to quickly cut off the connection with the grid when the grid voltage is abnormal, preventing electric energy from flowing back into the grid, thereby protecting the safety of power equipment and power-consuming equipment. In addition, the energy storage system can also provide emergency power supply in the event of a grid failure to ensure the normal operation of important loads.

[0047] 4. Intelligent control: The application of anti-backflow technology has promoted the development of intelligent control of energy storage systems. Modern energy storage systems use advanced control algorithms and communication technologies to achieve real-time monitoring, prediction and control of energy storage systems. Through intelligent control, energy storage systems can automatically adjust charging and discharging strategies according to the real-time needs of the power grid and the power generation of renewable energy to achieve optimal scheduling and distribution of electric energy. This intelligent control method can improve the response speed and adaptability of the power system and meet the ever-changing power demand.

[0048] 5. Extend equipment life: The energy storage system's anti-backflow technology helps extend the life of the equipment. In the power system, the reverse flow of electric energy may cause damage and aging of power equipment. Anti-backflow technology can avoid the reverse flow of electric energy during transmission, reducing the degree of damage and aging of power equipment. At the same time, the energy storage system can reduce the operating load and temperature of power equipment by precisely controlling the charging and discharging process, further extending the service life of the equipment.

[0049] 6. Power system reliability: Energy storage system backflow prevention technology is of great significance to improving the reliability of power systems. In power systems, power supply interruptions or fluctuations may occur due to various reasons, affecting users' power demand and the normal operation of power equipment. Energy storage systems can provide stable power support when power supply is interrupted or fluctuates through backflow prevention technology, ensuring users' power demand and the normal operation of power equipment. In addition, energy storage systems can also provide emergency power supply in the event of power grid failure, improving the reliability and resilience of power systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a schematic diagram of the process of allowing the enterprise to transfer energy storage across transformers in the present invention;

[0051] Figure 2 It is a schematic diagram of the process flow of the standard energy storage anti-backflow process in the present invention. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical effect and technical solution of the embodiment of the present invention clearer, the technical solution in the embodiment of the present invention is clearly and completely described below in conjunction with the drawings in the embodiment of the present invention; it is obvious that the described embodiment is a part of the embodiment of the present invention. Based on the embodiment disclosed in the present invention, other embodiments obtained by ordinary technicians in this field without making creative work should all fall within the scope of protection of the present invention.

[0053] Example 1

[0054] An energy storage system with anti-backflow function, comprising:

[0055] 1) Battery Management System BMS:

[0056] It plays a sensing role and is mainly responsible for battery monitoring, evaluation, protection and balancing; BMS and battery cells together form the battery system

[0057] BMS measures the basic parameters of the battery, including voltage, current, temperature, etc., to prevent the battery from overcharging and over-discharging and extend the battery life.

[0058] BMS needs to calculate and analyze the battery's SOC (remaining battery capacity) and SOH (battery state of health) and report abnormal information in a timely manner.

[0059] 2) Energy Management System EMS:

[0060] Assume a decision-making role, mainly responsible for data collection, network monitoring and energy scheduling;

[0061] constitute

[0062] Energy management systems are generally divided into device layer, communication layer and application layer.

[0063] Equipment layer: requires energy collection and conversion (PCS, BMS) support;

[0064] Communication layer: mainly includes links, protocols, transmission, etc.

[0065] Information layer: mainly includes cache middleware, database, and server. The database system is responsible for data processing and data storage, recording real-time data and important historical data, and providing historical information query;

[0066] Application layer: The application layer includes APP and Web, which provide managers with a visual monitoring and operation interface. The specific functions include energy conversion decision-making, energy data transmission and collection, real-time monitoring and control, operation and maintenance management analysis, electric energy / power visual analysis, remote real-time control, etc.

[0067] 3) Energy storage converter PCS:

[0068] It plays an executive role, and its main function is to control the charging and discharging process of the energy storage battery pack and perform AC to DC conversion.

[0069] It consists of a DC / AC bidirectional converter, a control unit, etc. It controls the converter to charge or discharge the battery according to the sign and size of the power command, thereby adjusting the active power and reactive power of the power grid. It can directly supply power to the AC load when there is no power grid.

[0070] PCS is the interface between the battery and the grid or AC load. It can communicate with BMS through the CAN interface to obtain battery status information. It not only determines the power quality and dynamic characteristics of the energy storage system output, but also greatly affects the battery life.

[0071] 2. Control Architecture

[0072] Physically, it is divided into four layers: physical layer, data link layer, network layer and application layer.

[0073] Physical layer: mainly connected to various sensors in the network for measurement, protection, control and management. Data link layer: includes field intelligent gateways, network switches and other equipment.

[0074] Network layer: The communication network adopts standard Ethernet and TCP / IP communication protocols, and the physical media can be optical fiber, network cable, shielded twisted pair, etc. The system supports Modbus RTU, Modbus TCP, DL / T645-2007 and other communication protocols. The system can formulate and automatically execute control strategies such as planning curves, peak shaving and valley filling, demand control, dynamic expansion, backup power supply, etc., and realize the integrated intelligent coordination of source, network, load and storage.

[0075] Application layer: The platform provides two access methods: WEB and APP. Its functions include energy consumption analysis, equipment management, operation and maintenance management, user reports, etc. It mainly realizes remote centralized monitoring and control, energy efficiency analysis, energy consumption and revenue, etc., to assist users in participating in demand response and electricity market transactions.

[0076] 3. Anti-backflow strategy control logic

[0077] High pressure side anti-backflow

[0078] Use infrared to monitor the high-voltage meter, monitor the direction and size of the current in real time, and ensure the normal flow of current. The algorithm is that the high-voltage active power is too low (when the active power <= the error power (the high-voltage power of the enterprise a* scale 0.01*4 (hours), the anti-backflow strategy is made in advance in hours to curb the downward trend.)) and the EMS strategy is on (set to discharge state), the anti-backflow is on;

[0079] Low pressure side anti-backflow

[0080] Use Hynd meter or Chint Kunlun meter to monitor the low pressure meter. Several conditions need to be considered for low pressure, including whether the power on the high pressure side is too low (same algorithm), whether the energy storage is running (the total active power of all PCS is greater than 0), and whether the backflow prevention is turned on;

[0081] When reverse flow occurs, determine whether the enterprise allows reverse flow:

[0082] If not allowed;

[0083] Install anti-backflow monitoring equipment;

[0084] Adjust the anti-backflow strategy according to the current operating status of the enterprise;

[0085] There are two situations:

[0086] 1. Enterprises allow energy storage to be transmitted across transformers (e.g. Figure 1 In this case, the high voltage incoming line needs to be monitored.

[0087] When 4 conditions are met at the same time, reverse flow discharge is started: 1. The reverse power of the incoming line is greater than 0 or the forward power is less than the rate error. 2. The EMS operation mode is strategy or the EMS operation mode is direct control, the active power setting is greater than 0, and the power to be adjusted is less than the current set power. 3. The PCS is actually discharging 4. There is no pause sign. The operation mode is switched to direct control mode, and the anti-reverse flow is started. The power reduction is set according to the current high-voltage power of the enterprise. When the enterprise's electricity consumption recovers, 6 conditions must be met to gradually increase the energy storage power. 1. The EMS operation mode is direct control mode 2. The current forward power is greater than the rate error 3. The current set power of EMS is less than 100KW 4. The PCS power is greater than or equal to 0.5. The rising power to be adjusted is greater than the current set power 6. There is no pause sign. The operation mode is switched back to strategy mode. At the same time, before each charging period in the morning and afternoon, it is forced to switch to strategy mode for charging. According to the above steps, the cloud platform makes a judgment and sends the strategy to the energy storage EMS. The EMS acts according to the strategy and sends a command to the BMS. The BMS takes actions such as reducing or increasing power, and the monitoring equipment sends the action information back to the cloud platform.

[0088] 2. Standard energy storage anti-backflow process (such as Figure 2 shown),

[0089] In this case, it is necessary to monitor the incoming line to which the energy storage belongs. This situation controls the corresponding energy storage module and does not affect the operation of other modules. When the four conditions are met at the same time, the reverse flow is started: 1. The reverse power of the incoming line is greater than 0 or the forward power is less than the rate error. 2. The EMS operation mode of the energy storage module is strategy or the EMS operation mode is direct control, the active power setting is greater than 0, and the power to be adjusted is less than the current set power. 3. The PCS is actually discharging 4. There is no pause mark. The operation mode is switched to direct control mode, the anti-backflow is started, and the power reduction is set according to the current high-voltage power of the enterprise. When the enterprise's electricity consumption recovers, 6 conditions must be met to increase the energy storage power slowly. 1. The EMS operation mode of the energy storage module is direct control mode 2. The current forward power is greater than the rate error 3. The current set power of EMS is less than 100KW 4. The PCS power is greater than or equal to 0 5. The rising power to be adjusted is greater than the current set power 6. There is no pause mark The operation mode is switched back to the strategy mode. At the same time, it is forced to switch to the strategy mode for charging before each charging period in the morning and afternoon. According to the above steps, the cloud platform makes a judgment and sends the strategy to the energy storage module EMS. The EMS acts according to the strategy and sends a command to the BMS. The BMS takes actions such as reducing or increasing power, and the monitoring device sends the action information back to the cloud platform.

[0090] The main innovative points of the present invention are:

[0091] 1. Maintaining grid stability

[0092] One of the main purposes of energy storage system anti-reverse flow technology is to maintain the stability of the power grid. By real-time monitoring and controlling the charging and discharging process of the energy storage system, the occurrence of current reverse flow can be prevented, and the impact and fluctuation on the power grid can be avoided, thereby ensuring the stable operation of the power grid. This is of great significance for maintaining the safety and reliability of the power system.

[0093] 2. Reduce user losses

[0094] Current reverse flow may cause damage to user equipment or data loss, resulting in economic losses and inconvenience to users. Energy storage system reverse flow prevention technology can protect user equipment from damage and reduce user losses by timely cutting off reverse current. At the same time, this technology can also reduce the maintenance cost and failure rate of the power grid, and improve the economic and social benefits of the power grid.

[0095] 3. Protecting Energy Storage Devices

[0096] Energy storage devices are the core components of energy storage systems. Their performance and life directly affect the overall performance and service life of energy storage systems. Current reverse flow may damage energy storage devices and shorten their service life. Energy storage system anti-reverse flow technology prevents the occurrence of current reverse flow by real-time monitoring and controlling the charging and discharging process of energy storage devices, protects energy storage devices from damage, and extends their service life.

Claims

1. An energy storage system with anti-backflow function, including a battery management system BMS, an energy management system EMS, an energy storage converter PCS and a control architecture: characterized in that: The energy storage system is equipped with anti-backflow monitoring equipment. The battery management system BMS is responsible for monitoring, evaluating, protecting and balancing the battery. The BMS and the battery cells together constitute the battery system; The energy management system EMS is responsible for data collection, network monitoring and energy scheduling; The energy storage converter PCS controls the charging and discharging process of the energy storage battery pack and performs AC to DC conversion; The control architecture is physically divided into four layers: physical layer, data link layer, network layer and application layer. The control logic of the energy storage system's anti-backflow strategy is as follows: High-voltage side backflow prevention: Use infrared to monitor the high-voltage meter, monitor the direction and size of the current in real time, and ensure the normal flow of current; the algorithm is that the high-voltage active power is too low, when the active power <= the rate error power (the company's high-voltage rate a* scale 0.01*4 hours, use hours as the unit to make a backflow prevention strategy in advance to curb the downward trend), and the EMS strategy is on, set to discharge state, and backflow prevention is on; Low-voltage side backflow prevention: monitor the low-voltage meter. Several conditions need to be considered for low voltage. Is the power on the high-voltage side too low? The algorithm is the same as above. Is the energy storage running? The added active power of all PCSs is greater than 0. Turn on the backflow prevention. When backflow occurs, determine whether the company allows backflow: If not allowed, install anti-backflow monitoring equipment and adjust the anti-backflow strategy according to the company's current operating status.

2. The energy storage system with anti-backflow function according to claim 1, characterized in that: Adjusting the anti-backflow strategy according to the current operating status of the enterprise can be divided into two situations:

1. Enterprises allow energy storage to be transmitted across transformers. In this case, high-voltage incoming lines need to be monitored: When the following four conditions are met at the same time, reverse flow discharge is started:

1. The reverse power of the incoming line is greater than 0 or the forward power is less than the rate error; 2. The EMS operation mode is strategy or the EMS operation mode is direct control, the active power setting is greater than 0, and the power to be adjusted is less than the current set power; 3. The PCS is actually discharging; 4. There is no pause sign, the operation mode is switched to the direct control mode, and reverse flow prevention is started. The power is reduced according to the current high-voltage power setting of the enterprise. When the enterprise's electricity consumption recovers, the following six conditions must be met to gradually increase the energy storage power:

1. The EMS operation mode is direct control mode; 2. The current forward power is greater than the rate error; 3. The current EMS set power is less than 100KW; 4. The PCS power is greater than or equal to 0; 5. The rising power to be adjusted is greater than the current set power; 6. There is no pause mark. The operation mode is switched back to the strategy mode. At the same time, it is forced to switch to the strategy mode for charging before each charging period in the morning and afternoon. According to the above steps, the cloud platform makes a judgment and sends the strategy to the energy storage EMS. The EMS acts according to the strategy and sends a command to the BMS. The BMS makes actions such as reducing power or increasing power, and the monitoring device sends back the action information to the cloud platform; 2. Standard energy storage anti-backflow process, In this case, the incoming line to which the energy storage belongs needs to be monitored. This situation controls the corresponding energy storage module and does not affect the operation of other modules. When four conditions are met at the same time, reverse flow discharge is started:

1. The reverse power of the incoming line is greater than 0 or the forward power is less than the rate error.

2. The EMS operation mode of the energy storage module is strategy or the EMS operation mode is direct control, the active power setting is greater than 0, and the power to be adjusted is less than the current set power.

3. The PCS is actually discharging.

4. There is no pause sign, the operation mode is switched to direct control mode, and anti-backflow is started. The power reduction is set according to the current high-voltage power of the enterprise. When the company's electricity consumption recovers, six conditions must be met to gradually increase the energy storage power:

1. The EMS operation mode of the energy storage module is direct control mode, 2. The current forward power is greater than the rate error, 3. The current set power of EMS is less than 100KW, 4. The PCS power is greater than or equal to 0, 5. The rising power to be adjusted is greater than the current set power, 6. There is no pause sign, and the operation mode is switched back to the strategy mode. At the same time, it is forced to switch to the strategy mode for charging before each charging period in the morning and afternoon. According to the above steps, the cloud platform makes a judgment and the strategy is sent to the energy storage module EMS. EMS sends a command to the BMS according to the strategy action. The BMS takes actions such as reducing power or increasing power. At the same time, the monitoring device sends back the action information to the cloud platform.

3. The energy storage system with anti-backflow function according to claim 1, characterized in that: The battery management system BMS measures basic parameters of the battery, including voltage, current, and temperature, to prevent overcharging and overdischarging of the battery and extend the service life of the battery.

4. The energy storage system with anti-backflow function according to claim 3, characterized in that: The energy management system BMS calculates and analyzes the remaining battery capacity SOC and the battery health state SOH of the battery, and reports abnormal information in a timely manner; the energy management system BMS is divided into a device layer, a communication layer and an application layer.

5. The energy storage system with anti-backflow function according to claim 4, characterized in that: Equipment layer: requires energy collection and transformation as support; Communication layer: mainly includes links, protocols, and transmission; Information layer: mainly includes cache middleware, database, and server, among which the database system is responsible for data processing and data storage, recording real-time data and important historical data, and providing historical information query; Application layer: The forms of expression include APP and Web, which provide managers with a visual monitoring and operation interface. The specific functions include energy conversion decision-making, energy data transmission and collection, real-time monitoring and control, operation and maintenance management analysis, electric energy / power visual analysis, and remote real-time control.

6. The energy storage system with anti-backflow function according to claim 1, characterized in that: The energy storage converter PCS includes a DC / AC bidirectional converter and a control unit, which controls the converter to charge or discharge the battery according to the sign and size of the power instruction, thereby adjusting the active power and reactive power of the power grid, and can directly supply power to the AC load when there is no power grid.

7. The energy storage system with anti-backflow function according to claim 6, characterized in that: The energy storage converter PCS is the interface between the battery and the power grid or AC load. It can communicate with the BMS through the CAN interface to obtain battery status information, which determines the power quality and dynamic characteristics of the energy storage system output and also greatly affects the battery life.

8. The energy storage system with anti-backflow function as claimed in claim 1, characterized in that: the physical layer: Mainly, it is connected to various sensors in the network for measurement, protection, control and governance; Data link layer: includes on-site intelligent gateways and network switches; Network layer: The communication network adopts standard Ethernet and TCP / IP communication protocols, and the physical media can be optical fiber, network cable, or shielded twisted pair cable; Application layer: The platform provides two access methods: WEB and APP. Functions include energy consumption analysis, equipment management, operation and maintenance management, and user reports. It mainly realizes remote centralized monitoring and control, energy efficiency analysis, energy consumption and revenue, etc., to assist users in participating in demand response and electricity market transactions.

9. The energy storage system with anti-backflow function according to claim 8, characterized in that: The energy storage system supports Modbus RTU, Modbus TCP, and DL / T645-2007 communication protocols; it can formulate and automatically execute control strategies such as planning curves, peak shaving and valley filling, demand control, dynamic capacity expansion, and backup power supply, and realize integrated intelligent collaboration of sources, networks, loads, and storage.

10. A backflow prevention method for an energy storage system with backflow prevention function as claimed in claim 1, characterized in that: S1. Real-time monitoring and data collection: Use high-precision infrared sensors to monitor the current direction and size of the high-voltage meter in real time, and transmit the collected data to the data processing unit for analysis and processing; S2. High-voltage active power judgment: The data processing unit calculates the high-voltage active power based on the collected current data and compares it with the preset rate error power (the enterprise's high-voltage rate a* scale 0.01*4 hours). If the high-voltage active power is less than or equal to the rate error power, it is determined that the high-voltage active power is too low; S3. EMS strategy status detection: At the same time, the data processing unit also needs to detect the status of the EMS strategy. When the EMS strategy is in the on state (set to the discharge state), the system will execute the anti-backflow strategy; S4. Execution of anti-backflow strategy: When the high-voltage active power is too low and the EMS strategy is turned on, the system will start the anti-backflow strategy, which may include but is not limited to: adjusting the grid structure, changing the load distribution, starting the backup power supply, etc., to curb the downward trend of the current and ensure the stable operation of the power system; S5. Early warning mechanism: In order to prevent the occurrence of current reverse flow, the system should set up an early warning mechanism. When the high-voltage active power is close to the multiplier error power, the system should issue a warning signal to remind the operator to pay attention and take corresponding measures; S6. Automated control: In order to quickly respond and effectively curb the downward trend of current, the execution of the anti-backflow strategy should be automated as much as possible. Through preset rules and algorithms, the system can automatically determine whether the anti-backflow strategy needs to be executed and automatically perform the corresponding operations; S7. Multi-strategy combination: The anti-backflow strategy can be flexibly combined and adjusted according to the actual situation. When the grid structure is complex or the load changes greatly, a combination of multiple strategies can be used to improve the anti-backflow effect; S8. Real-time monitoring and feedback: During the implementation of the anti-backflow strategy, the system should monitor the grid status and current changes in real time, and adjust and optimize the strategy based on the feedback results.

Images