Study On Control Strategy Of Hybrid Energy Storage System In Microgrid

This article studies control strategy of hybrid energy storage system inmicrogrid, in order to solve power disturbance and power quality in thetransient process, which mixes and coordinate control various energystorage devices to make sure safety and steady operation. Then the stabilityanalysis mathematical model of microgrid based on hybrid energy storagesystem. At the basis of single energy storage power source control system,the proposed control strategy is evaluated combined with power systemstability analysis.The main research contents is as following:(1) The control strategy of microgrid is briefly explained, includingthe control strategy of single distributed generation and integrated controlstrategy of microgrid. The energy storage systems are taken as theregulation power source of the voltage and current on busbar. According tothe droop characteristic of different energy storage systems, the coordinatecontrol strategy, including that the control strategy of Vanadium RedoxBattery(VRB) is droop control, for stabilizing the voltage and frequency ofbusbar for long term. And the control strategy of supercapacitor is inversedroop control, for compensating the gap of power,voltage and frequencyquickly during island mode.(2)The mathematical model of a3-phase full-bridge converter hasbeen built. And the transfer function of droop control for Vanadium RedoxBattery (VRB) energy storage system has also been derived and designed,which is foundation of the control algorithms research for compositeenergy storage system. In addition, both the theoretical design of VRB droop control and its simulation verification using PSCAD has beencompleted.(3) In order to analyse and assess the control algorithm stability ofcomposite energy storage in micro-grid, the steady-state analysis model ofmulti-source-storage power system has been built. In terms of thetheoretical research and stability analysis result of the composite energystorage control algorithm, the PSCAD software was used to verify thecontrol algorithm for micro-grid composite energy storage in simulation.And the simulation result shows that, comparing with the single energystorage system, the composite energy storage micro-grid using VRB andSuper Capacitor has faster response when the disturbance or abnormityhappens in the micro-grid system. Therefore, it improves the transientstability of the whole system.(4) Under the experimental platform of a company’s Microgridexperiment platform, a series of experiment are carried out, includingsupercapacitor stabilizing the power fluctuation, restraining VRB overloadand improving power quality during transfer mode of microgrid. Theexperimental results verify the theoretical analysis and simulation result.