Study on Bus-type Extended Load Flow and Its Solvability

There are three types of buses in the ordinary load flow calculation,which are PQ,PV and Vθ.Since load flow calculation is to solve a set of nonlinear algebraic equations,it is necessary that the number of linearly independent equations equal to the number of unknown state variables,without limitation for bus types.A bus-type extended load flow algorithm which could consider all bus types was introduced in this paper.This proposed general method can make some load flow adjusting much easier.A fast decoupled load flow algorithm was used to solve this problem,and a proposed topology-based method was used to identify the solvability of the bus-type extended load flow.Numerical tests with various cases had been done to verify the solvability judgment.