Research On The Energy Model And Capacity Configuration Of Hybrid Energy Storage System In Micro Grid

It’s an important way of distributed generation to solve our energy shortage and environmental pollution, however, its instability and intermittent of power supply brings new challenges to power quality and reliability of microgrid. In order to improve the defects of distributed power generation, we combine power-type energy storage device and capacity storage device type into a hybrid energy storage system, which could ease the impact of distributed generation on microgrid to improve power quality and ease power shortage at rush hours to improve the reliability of electricity supply. This paper firstly established super capacitor and lithium iron phosphate battery monomer model; Then, researched the power allocation strategy of the hybrid energy storage system after grouped the monomers; Finally, used PSO and power allocation strategy to optimize the output of wind turbine. The main contents are as follows:1) This paper takes LiFePO4 lithium iron phosphate battery (Capacity storage device) and super capacitor (Power energy storage device) as the object of study, builds monomer equivalent circuit model of lithium battery and super capacitor respectively based on physical network approach. After analyzing the traditional method of obtaining the model parameters, we propose a new method to obtain model parameters by processing experimental data. It proves that this method can obtain parameters quickly by comparing and analyzing the experimental and simulation data, meanwhile, it can obtain high precision model. This paper puts forward a new ultra capacitor model based on this method, compared with former model, this one is still in high accuracy with a variety of current in the simulation.2) This paper establishes mathematical model through the analysis of the steady state and small signal model of bidirectional DC converter.By using circuit model of lithium iron batteries and super capacitor equivalent and mathematical model of bidirectional dc converter,hybrid energy storage semi-active control system simulation model is set up.The moving average method is adopted to do power distribution for hybrid energy storage system.The research results of the established model of hybrid energy storage systemthe under passive control and semi-active control show that the semi-active hybrid energy storage system is not only have the same advantages of high cycle life and large power density as a super capacitor, but also prolong the cycle life of lithium batteries.3) Taking the output data of a wind generator Yunnan Province as the object of optimization, an energy storage system capacity configuration model based on PSO algorithm optimal was established in this paper in order to effectively reduce the power fluctuation amplitude and shorten the duration of the high power. This paper also presented the capacitance value of supercapacitors and the nominal capacity of lithium-ion batteries with the control strategy in hybrid energy storage.