Excitation Systems Coordination for Back-to-Back Starting for Pumped Storage Units

In the process of back-to-back starts,the excitation systems coordination between two units is a key issue.Using the state equations of synchronous motor,a mathematical model of back-to-back starting was established in this paper.Based on above research,back-to-back starting process for pumped storage units under different conditions were simulated,which includes the normal starting and starting processes with motor de-excitation and braking and so on.With the research of simulations,the problems of excitation systems coordination between two units were recognized,and an appropriate solution for this problem is proposed.By adding a hard-wire circuit between LCU and the tripping circuit and each of these circuits is added with an additional relay,two excitation systems can be removed simultaneously.