Online Detection Of Battery SOC And Application In Optical-storage Coordination Control

With coal energy shortages and the intensification of atmospheric pollution, Micro-grid consisted of renewable energy has become the main direction of development of the industry. Energy storage system is an important part of the Micro-grid and battery energy storage system is the core equipment in the energy storage system, so the battery’s manufacturing process and group application technology has become the key factor of micro-grid development. The remaining battery power(SOC)is the core of the battery management system, reflecting the main parameters of battery operation state, providing the basis for judging the control strategy for energy storage system.At first, this paper based on the general battery model established the equivalent circuit model of the battery. Then the parameters of circuit model were obtained by the charge and discharge experiment. At last, the battery SOC model based on state observer was established.Then, the principle of the low pass filter to stabilize the photovoltaic power fluctuations was analyzed, and the PV power range of compensation was confirmed through Fourier analysis. In order to control the SOC in an ideal range in different SOC conditions, we rationally adjusted the filter time of the low pass filter. To prevent battery charging overvoltage, according to the battery polarization phenomenon, the smooth control strategy that low-pass filter smooth control and constant voltage control strategy switched smoothly was put forward, that can protect the storage battery.Finally, based on the battery charge discharge experimental, we built test corresponding control system. The system that used a Bi-directional DC/DC as the controller and photovoltaic power generation system composed of the optical storage coordination control to realize stabilize photovoltaic power fluctuation.