A fast algorithm of critical power flow for reactive power balance and and its application in UHV grid

With the planning and constructing of the UHV grid of China, it is urgent to analysis the reactive power balance and its critical power flow for UHV grid. In the paper, firstly, the feasible reactive power balance principles are proposed; secondly, the quantitive relationship between the var demand and active power flow through the reactance element is analyzed in depth. Furthermore, only based on active power flow, the fast algorithm of substation-centered reactive power balance and its critical power flow is proposed. The algorithm can not only be applied into the fast quantitive analysis of the given power flow pattern, but also be used to obtain the sensitive relation curves between the critical power flows and the transformer load rates. Finally, the demand and the deployment of CSR(controllable shunt reactor) in a UHV transmission project are studied with the proposed algorithm, and the conclusions and recommended deployment schemes are given.