Energy Storage Science and Technology ›› 2018, Vol. 7 ›› Issue (4): 726-731.doi: 10.12028/j.issn.2095-4239.2018.0054

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A power allocation strategy of a hybrid energy storage system for a PV grid-connected system

MI Gensuo, MU Yanting   

  1. School of Automation & Electrical Engineering, Lanzhou Jiaotong University, Lanzhou 730070, Gansu, China
  • Received:2018-04-08 Revised:2018-04-25 Online:2018-07-01 Published:2018-07-01

Abstract: A battery-supercapacitor hybrid energy storage system (HESS) is applied to a PV grid-connected system to deal with fluctuation and intermittency of the PV microgrid to achieve smooth photovoltaic system power output, balance and improve grid power quality. Considering the upper limit of the battery power and the state of charge (SOC) of the supercapacitor, a power distribution strategy is proposed for the hybrid energy storage system. The strategy uses the SOC of the supercapacitor and the output of the power allocation unit as a reference value to design the hybrid energy storage system charge and discharge processes. The supercapacitor and the battery are connected to the 500 V DC bus using a Bi-direction DC/DC converter. The supercapacitor controls the DC bus voltage through a double closed-loop control strategy. The simulation results show that the proposed power allocation strategy can rationally distribute the power of the hybrid energy storage system, achieve the grid connection of unit power factor and stabilize the DC bus voltage.

Key words: photovoltaic power generation, battery, super capacitor, state of charge, power distribution strategy

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