准同期并网中三相不平衡问题的优化

Optimized strategy of three-phase unbalance in synchronized grid-connected

基于对并网装置运行状况的调研,提出了准同期并网时三相不平衡问题的优化方案。从准同期并网的条件入手,然后由并网冲击电流的等效电路图和并网相位不相等时的相量图,对合闸瞬间的相角差与冲击电流的关系进行分析,并推导出并网冲击电流的计算公式。分析网侧变压器电压相角不对称的主要原因,最后由冲击电流的大小选择并网的操作相,该方案有效提高了并网时的可靠性和安全性。

According to the analysis of synchronization device, this paper advances an optimal method of three-phase unbalance in synchronized grid-connected. First, it introduces the qualification of grid-connected. Then, from equivalent circuit diagram of surge current and vector diagram of unequal vectors, it analyzes the relation between angular phase difference and surge current. Furthermore, the expression of surge current is deduced out. The reasons of three-phase unbalance of transformer are analyzed. At last, the operational phase of grid-connected is based on the value of the surge current. This optimized strategy is helpful to improve the reliability and stability of grid-connected.