Induction Motor Load Flow Simulation with Digsilent Powerfactory

Abstract

In recent times, interest in load modeling has gained momentum globally as an area of research by power industry engineers and academic researchers for simulation of voltage stability and planning by utilizing static loads to represent the relationship between power and voltage. It is a reality that, much attention has been given to models for generation, transmission and distribution equipment. However, load representation that contributes significantly to voltage instability of the power system has received relatively less attention and continues to be an area of greater ambiguity. Therefore, there is a need for studies into the behavior of power system load modeling and analyze their characteristics both under steady state and dynamic performance. The paper proposes to solve the load flow equations with DigSilent induction motor models whose active and reactive power are estimated at each iteration. Simulations were carried out to demonstrate the effects of small and large faults in the system on the induction motor loads. In addition, the dynamic behavior of the IM with reference to various parameters was investigated. The results include system responses to sudden load changes, 3-phase faults and open line fault. The simulation results indicated that the effect of the load model and their aggregation on system performance is reasonable and practical. It was also found that representing the system loads by a single dynamic equivalent load reflects the actual stability of the power system. However, representing these loads by constant impedance load gives false indication of the system stability under dynamic behavior.