Power Stability Analysis and Control of Micro-grid Storage system under Voltage Asymmetric Fault

Load asymmetric or asymmetric fault will cause output power fluctuation and three-phase current imbalance of micro-grid storage system, which affects the power quality and distribution network system stability. A control strategy of voltage stability and power balance based on novel current decoupled is presented to deal with the problem in this paper. The energy storage converter mathematical model in the state of voltage unbalanced is established, and the mechanism of power fluctuation and three-phase current variation is revealed. The complex coefficient filter is proposed to control the positive sequence voltage and negative sequence voltage independently, and current vector control is realized by the quasi-PR controller. On the basis of decomposing positive and negative sequence current into active and reactive components, the command current values with negative sequence current suppression and power fluctuation suppression as control objectives are given respectively, and the expression of three-phase current is deduced. Case analysis on typical Micro-grid energy storage systems is shown to confirm the feasibility of this method.