Series-compensation parameter determination method of transmission lines with consideration of unbalance degree

This paper discusses the formation of unbalance current when series-compensated transmission lines operate normally, studies the principle of improving unbalance degree by adjusting the series-compensation capacity within relatively tight bounds of each phase, proposes the method of series compensation parameters based on Nelder-Mead algorithm. A simulation model of 750kV transmission lines was constructed. The results show that this method can minimize zero sequence unbalance degree and negative sequence unbalance degree respectively. Moreover, the transfer capability of transmission lines almost stays the same before and after the adjustment.