Capacity Expansion of Distribution Network with Control of Multi-function Battery Storage

With the rapid development of social economy and industry, electricity requirement of customers has greatly increased. Thus, huge power demands and peak-valley characteristic of load make much trouble to distribution network. To expand the capacity of distribution network, many existed methods have been proposed such as rebuilding transmission lines, expanding transformer capacity, using energy storage device. Battery storage has the advantages of low cost, easy to control, small size and high utilization rate. Besides, unbalance loads and loads with reactive power have a negative impact on the power quality of distribution network. Therefore, research on capacity expansion and power quality governance is urgently needed. In this paper, multi-function control strategy for battery storage is proposed, which expand the capacity of distribution network and ensure the power quality. According to peak-valley characteristics of loads, battery storage can expand the capacity. By compensation for negative sequence current and reactive power, power quality is ensured. Meanwhile, in some extreme cases, the battery storage can be used as an emergency power supply, providing power for important loads and sufficient response time for other power failure protection measures of the system. The principle and topology of the control strategy are verified in simulation. The simulation results show that multi-function control strategy we propose can expand capacity of distribution network, ensure power quality and serve as power supply in emergency. Experiment is in progress.