Ⅰ. Battery energy storage system
Battery energy storage system (BESS) is an emerging FACTS device. It has the ability to control the active power flow, and can adjust the active power and reactive power of the access point at the same time, providing fast response capacity for the high-voltage transmission system, and effectively improving the stability, reliability and power quality of the power system.
So far, due to the lack of effective means of storing electric energy in large quantities in the power system, power generation, transmission, distribution and power consumption must be completed at the same time, which requires the system to be in a dynamic equilibrium state all the time, and instantaneous imbalance may lead to safety and stability problems.
The advent of high-power inverters provides an ideal interface between energy storage systems and various renewable energy solutions and the AC grid.
From a long-term perspective, the energy storage system composed of various types of power sources and inverters can be directly connected to the user load in the distribution network to form a distributed power system. change, and fundamentally solve the control problem of the power system.
There are many types of energy storage power sources that can be used in power systems. The more common ones are superconducting energy storage (SMES), battery energy storage (BESS), flywheel energy storage, supercapacitor energy storage, pumped water energy storage, compressed air energy storage, etc.
Among various types of energy storage power sources, battery energy storage system is an energy storage power source that is more suitable for power systems. It has relatively mature technology, large capacity, safety and reliability, no pollution, low noise, strong environmental adaptability, convenient installation, etc.
Ⅱ. The basic principle of battery energy storage system
The hybrid battery storage system is mainly composed of a battery pack and a converter, and the converter is mainly based on a voltage source converter.
The battery pack generally adopts sodium-sulfur batteries or lead-acid batteries with relatively mature technology. Among them, sodium-sulfur batteries have obvious advantages in energy density, service life, and operating efficiency, so sodium-sulfur batteries are more widely used in energy storage. (Change to the content of lithium battery)
The essence of the converter is a large-capacity voltage inverter, which is an interface circuit between the energy storage battery and the power grid, and realizes the bidirectional energy transfer between the DC energy of the battery and the AC power grid.
Ⅲ. The purpose of battery energy storage system application in power system
The battery energy storage system has a very wide range of applications in the power system. Because it can quickly adjust the active power and reactive power of the access point, it can be used to improve the operating stability of the system and improve the quality of power supply. When its capacity is large enough, it can even play the role of power peaking.
At this stage, there are two main types of applications for battery energy storage systems, depending on where they are connected to the power system:
1. Connect the battery energy storage system to the power generation side
We generally connect the battery energy storage system to the generator end and the exit of the booster substation. When the battery energy storage system is connected to this position, it is mainly used to improve the stable operation ability of the generator.
When the generator is disturbed, the battery energy storage can quickly absorb the unbalanced power flow, alleviate the oscillation of the rotor, and make the output state quantity of the generator more stable when subjected to various disturbances.
2. Connect the battery energy storage system to the load side
When the user side has higher requirements on power quality and voltage waveform, such as electronic chip manufacturing, the battery energy storage system needs to be connected to the load side.
When the battery energy storage system is connected to this position, because it can quickly adjust the active power and reactive power of the access point, when the system is disturbed, it can quickly stabilize the power and the bus voltage of the load, and it can be very good. The stable system voltage ensures the smoothness of the user’s voltage waveform, thereby effectively improving the power quality of the energy storage system.