Research On Battery Simulator And Its Application

In recent years, as the fossil energy becomes exhausted and the greenhouse effect goessevere, renewable energy power generation has attracted increasing attention. However,electric power generated from renewable resources, such as wind energy and solar energy,is intermittent and fluctuant. This will pose an adverse effect on the stability and quality ofthe power system. Battery energy storage system (BESS) is necessary to be integrated in apower grid and it provides valuable benefits to smooth out the unpredictable fluctuatingpower output, improve stability, quality and reliability of power supply.In this case, battery simulator, which is used for simulating real V-I characteristics ofbatteries, will be necessary and useful. This paper firstly built the improved models ofVanadium Redox Flow Battery (VRB), Li-ion Battery and Lead-acid Battery, which will bemore precise and realistic. Based on the topology of the existed battery simulators and theneed of experiment, this paper proposed the design and implementation of the batterysimulator based on DSP and power electronics technology. Using a three-phase voltagesource PWM converter (VSC) as topology, the device can simulate V-I characteristics ofbatteries of different kinds, different parameters and different operation modes. Thehardware and software design process will be detailed in this paper, and the device isdeveloped. At last, simulation and experiment results proved that the designed batterysimulator has good performance and satisfied effect.For further study, research on the application of battery simulator has done. As to theproblem for wind power connected to power grid using BESS, this paper summarized theexisted control methods of BESS. To smooth wind power output and prolong life of BESS,this paper proposed an optimal control based on variable smoothing time constant andpower limit. Under this optimal control, BESS can be fully protected by adjustingsmoothing time constant based on state of charge (SOC), and can avoid the possibility ofover-charge, over-discharge and over-load. The hardware and software design of thegrid-connected inverter is given in this paper. Finally prototype is developed andexperiments are done combined with the battery simulator. Results show that the optimalcontrol based on variable smoothing time constant is more effective to smooth wind poweroutput as well as prolong life of BESS.