Bi-level Dispatching Strategy for HESS in Distribution Networks with High PV Penetration Considering Voltage Regulation and Price Arbitrage

A bi-level multi-timescale dispatching strategy for hybrid energy storage system (HESS) is proposed to smooth the PV output fluctuation as well as to solve voltage rise/drop issues and to make profits from the peak and valley price. The exponential smoothing method is adopted at the lower-level to produce PV output reference and ultra-capacitors are utilized to compensate the PV fluctuation within every minute. The smoothed PV output are employed at the upper-level to control lithium batteries within hourly timescale, which includes voltage regulation and price arbitrage. In the voltage regulation part, performance indices such as batteries’ remaining lifetime, State of Charge (SoC), operating costs and voltage sensitivity factor (VSF) are taken into consideration to optimize the control strategy. In the price arbitrage part, to minimize the effects on the node voltage and to achieve optimality based on the real-time price, the battery with the minimal VSF and operating costs will be selected with the highest priority to realize the control strategy. A case study is shown in this paper to verify the effectiveness of the proposed strategy.