Frequency Modulation Control Strategy Of Microgrid With Distributed Generation And Hybrid Energy Storage System

Because distributed generation is affected by natural environment,climate,geographical environment and other factors,its output is characterized by intermittent periodicity and variability.The direct grid connection of distributed generation has created great challenges to the stability and safety of power system,the frequency of high-voltage transmission grid and power quality,which not only increases the operating cost,but also seriously reduces the regulation frequency level of power system along with the grid connection of regional distributed generation.Therefore,how to efficiently stabilize the fluctuation of automatic output rated power of distributed generation,flexibly control the active power output,and make it have stable frequency modulation capability has become a hot research topic at present.Firstly,the microgrid system structure with distributed generation and hybrid energy storage is established,and then the core parts of the structure are elaborated in detail.Then,the key contents of microgrid system with distributed generation are analyzed,and the improvement of microgrid frequency after introducing wavelet packet decomposition is described in detail,which provides the basis and ideas for the design of the subsequent hybrid energy storage system.Secondly,based on the economy of grid-connected operation of distributed generation,the operation control strategy of frequency regulation in microgrid with distributed generation and hybrid energy storage system is pointed out.Aiming at the contradiction of frequency fluctuation in microgrid with distributed generation,the hybrid energy storage system composed of chemical storage battery and super working capacitor is used to coordinate management,so as to maintain the frequency stability of microgrid and provide the possibility for microgrid to further absorb clean energy such as wind power.Finally,the output characteristics of distributed generation are analyzed,and the system power deviation signal is decomposed into low frequency and high frequency parts by wavelet packet,which can maximize the output power of distributed generation on the premise of meeting the stability of the system Then,the high frequency part of the power shortage is further divided,and the preliminary allocation scheme of frequency modulation power of the energy storage system is determined.The energy storage output is corrected twice by Logistic regression function,and then the energy storage self-adaptive adjustment frequency and the energy storage charge distribution state are considered simultaneously.The simulation results show that the optimal decomposition level obtained by wavelet packet decomposition has good adaptability for stabilizing the output power fluctuation of distributed generation,and the effect of grid connection of distributed generation power is better.By controlling the primary power distribution of energy storage and comparing the energy storage performance,the power distribution between the two energy storage modes is realized,and the influence of the output power of distributed generation on the power grid is better stabilized.Logistic regression function is adopted,which not only limits the maximum output of energy storage system,but also improves the regulation characteristics and application economy of hybrid energy storage system.This strategy can realize the optimal distribution of distributed generation power,make the hybrid energy storage work in a suitable range,effectively prolong the life of energy storage system,ensure that the distributed wind power output of the system is fully utilized,improve the wind power grid-connected ability and increase the efficiency and economy.