The LVRT of the BESS under both balance and unbalance grid fault

In order to meet the requirement of low voltage ride through (LVRT) in the situation of both the balance and unbalance voltage fault in the energy storage system (ESS), considering the shortage of power conversion system (PCS), the LVRT control methods are studied, a positive-negative sequence composite mathematical model is built, a double d-q unbalance control strategy is designed and the positive-negative sequence current is controlled effectively. Based on that, the active and reactive current during the LVRT is distributed and limited through reference switching. At last simulation of a battery module (84 kW) in the case of grid fault based on the PSCAD is conducted, and the results show that the mathematical model built and the control method studied can meet the needs of the LVTR under both balance and unbalance grid fault.