Modeling and elimination of load buses in power flow solutions

This paper presents a method to solve the power flow problem after eliminating load buses from the system. Loads are first modeled and reflected in the admittance matrix and then their respective buses are eliminated. The obtained model is a reduced model of the original system. The admittance matrix is of the same order as the number of voltage-controlled buses in the system. The variables of the reduced model are the voltage-controlled buses voltage angles only. The Newton Raphson method is used to calculate the voltage angles of the reduced model and then the voltage and angles of the original system are calculated by a direct method. The simulation is carried out on two systems, the IEEE 118 bus test system and a 131 bus actual system. It is shown that solution time is significantly reduced when compared to the conventional Newton Raphson method using the original system