By buffering electrical energy through energy storage systems, the quality of electrical energy can be optimized and the stability of new energy microgrids can be improved. So, what role does the energy storage system play in microgrids?
Distributed energy, such as solar energy, wind energy, and biomass energy, is generally affected by external factors such as light, temperature, wind, and climate, and the amount of electricity generated is characterized by randomness and instability. In an independent operation where the microgrid is disconnected from the power grid, the output power of distributed energy in the microgrid changes with the environmental factors, making it unable to provide stable output for the load. When applied to microgrids, the energy storage system can smoothly adjust the fluctuation of distributed energy through an energy management system (EMS) that enables distributed energy to be controlled in coordination with the energy storage system and the main power grid, and provides local utilization of distributed energy to avoid transmission pressure and power loss caused by long-distance transmission to the main power grid. In addition, the energy storage system can also provide a portion of the power supply for the main load during the night or maintenance period of distributed energy, reducing the blackout time.
When microgrids are connected to the main power grid and operate in parallel with it, the electrical energy quality must meet national standards, including power factor, voltage asymmetry, current harmonics distortion rate, and voltage dip. As stated in the first point above, the electrical quality of power in the microgrid cannot be guaranteed without an energy storage system, especially the voltage stability. The application of an energy storage system can play an important role in improving the electrical energy quality of the microgrid. The system can stabilize electrical energy output while adjusting the active and reactive power output of the energy storage system to the microgrid through PCS control, solving problems of voltage dips/drops.
When facing voltage surges or dips in the main power grid, the energy storage system can provide rapid power buffering and quickly absorb/supplement electrical energy to provide active and reactive power support and stabilize voltage fluctuations. The energy storage system can also provide some harmonic control functions for the microgrid.
In the microgrid, the energy storage system can store excess electrical energy generated by distributed energy during low load periods and release it during high load electricity consumption, regulating the load demand. As an essential energy buffering link in the microgrid system, the energy storage system can satisfy peak load electricity consumption while reducing the required capacity of the generator set or transformer.