What is energy storage? It is an important part of the six major links in the power production process of "collection-generating-transmission-distribution-use-storage". The energy storage system can realize energy transfer and promote the application of new energy;
Microgrids can be established to provide electricity for areas without electricity; peak and frequency regulation can be used to improve the stability of power system operation. Energy storage systems are of great strategic significance to the construction of smart grids.
Energy storage methods include: battery energy storage, inductor-type energy storage, capacitor-type energy storage and other types of energy storage.
The battery energy storage system is a system that uses lithium batteries as energy storage carriers to store and supply electric energy within a certain period of time, and the electric energy provided has functions such as smooth transition, peak shaving and valley filling, frequency regulation and voltage regulation.
Inductor-type energy storage: The use itself is an energy storage element, and the stored energy is proportional to its own inductance and the square of the current flowing through it: E = L*I*I/2.
Since inductors have resistance at room temperature, and the resistance consumes energy, many battery energy storage technologies use superconductors. Inductive energy storage is not yet mature, and its application is relatively small;
Capacitor-type energy storage: It is also an energy storage element, and the stored electric energy is proportional to its own capacitance and the square of the terminal voltage : E = C*U*U/2.
Capacitive energy storage is easy to maintain and does not require superconductors. Supercapacitors are produced by utilizing the characteristics of capacitor-type energy storage to provide instantaneous high power, and are suitable for applications such as lasers and flash lamps. In addition, there are other battery energy storage methods: such as mechanical energy storage.
Including energy storage, photovoltaics, hydropower, etc., the energy storage system is the core component of the microgrid, and is often used in conjunction with photovoltaics and wind power.
Because battery energy storage has the advantages of relatively mature technology, large capacity, safety and reliability, low noise, strong environmental adaptability, and easy installation, energy storage systems often use batteries to store electrical energy.
At present, the energy storage system is mainly composed of energy storage units and monitoring and dispatching management units: energy storage units include battery energy storage groups, battery management systems, energy storage converters, etc.; monitoring and dispatching management units include central control systems, energy management systems Wait.
At present, the more commonly used application modes are: energy-based energy storage systems, power-based energy storage systems, grid-level energy storage systems, commercial energy storage systems, and household energy storage systems.
The technology of the energy storage system mainly includes the management of the energy storage bidirectional inverter, the energy storage battery, and the reasonable scheduling of the system energy by the monitoring and dispatching management unit.
1. Battery management system
The battery management system ( BMS) is installed in the energy storage battery pack, and is responsible for the collection of voltage, temperature, current, capacity and other information, real-time status monitoring and fault analysis for the battery energy storage pack.
At the same time, it communicates with PCS, monitoring and dispatching system on-line through CAN bus to realize the optimal charge and discharge management control of the battery.
Each cluster of battery packs in the system is equipped with a battery management system, which can achieve the purpose of effectively and efficiently using each cluster of energy storage batteries and the overall rational allocation.
2. Monitoring and scheduling management system
The monitoring and dispatching management system is the energy dispatching and management center of the battery energy storage unit, including the central control system ( MGCC) and the energy management system (EMS).
Responsible for collecting all battery management system data, energy storage converter data and power distribution cabinet data, issuing control commands to each part, controlling the operation of the entire energy storage system, and rationally arranging the work of energy storage converters;
The system can either run automatically according to the preset charging and discharging time, power and operating mode, or it can run under the immediate command of the operator.
Among them, the energy management system is the neural control system of the battery energy storage system. In order to realize the reasonable dispatch of energy, according to the peak-to-valley characteristics of the power grid, the economic operation of the micro-grid can be realized. It has operation optimization, load forecasting, power generation forecasting, resource scheduling, power flow control and other functions.