Review On Coordinated Control Strategy Of Multi-source Complementary Micro Grid Based On Hybrid Energy Storage

This paper is supported by the key technological research project in Inner Mongolia Autonomous Region grant 2019GG319,research on optimization of microgrid's composite energy storage system,DC voltage stability suppression and multi-source coordinated control method.The main work and innovation are as follows:First of all,based on the analysis of the overall system structure and control method of multi-source complementary micro grid based on composite energy storage,the mathematical model of composite energy storage,photovoltaic power generation and microturbine power generation system units in the micro grid is established,which lays the foundation for the research of multi-source complementary coordinated control strategy.Secondly,as the basic unit for stabilizing the fluctuation of photovoltaic output power,the optimal allocation of hybrid energy storage power instructions is the key to achieving coordinated control of multi-source complementary microgrids.Introduce the basic principle of ensemble empirical mode decomposition(EEMD),use EEMD to decompose the unbalanced power generated in the system,and analyze the intrinsic mode functions(IMF)after decomposition.After the obtained IMF component is subjected to Hilbert transform,it is divided into high-frequency and low-frequency fluctuation components according to the crossover frequency.On the basis that all energy storage equipment meets the operating conditions,the sum of high-frequency and low-frequency fluctuation components is taken as the initial power command of the power type and energy type energy storage system respectively.Aiming at the problem that the large power density of the power storage system can easily cause the state of charge(SOC)to cross the line,a fuzzy controller was designed to optimize the initial power command of the hybrid energy storage.When the state of charge of the power storage system is approaching the limit,the power command of the hybrid energy storage system is renewed with the change of the adjustment coefficient Ksc,to alleviate the trend of SOC of power-type energy storage over-the-line,to achieve the secondary optimal allocation of power for the hybrid energy storage.Finally,based on the analysis of composite energy storage characteristics and optimal distribution,a multi-source complementary coordinated control strategy is proposed.According to the amplitude of voltage fluctuation,combined with the operation characteristics of super capacitor and battery,the photovoltaic power generation system and microturbine power generation system are included in the control range,and the multi-mode coordinated control operation model of the system is established.By adjusting the working state of photovoltaic,hybrid energy storage and microturbine power generation system,the purpose of stabilizing DC bus voltage is achieved.In order to verify the effectiveness and rationality of the multi-source complementary coordinated control strategy,a complete system simulation model is built.The simulation results show that the control strategy can effectively maintain the system bus voltage fluctuation in a reasonable range,optimize the charging and discharging process of hybrid energy storage,and extend its service life.