INDUCTION MOTOR LOAD FLOW SIMULATION WITH DIGSILENT POWERFACTORY

Abstract

currently there is a growing interest in load modeling. This has gained momentum globally as an area of research by power industry engineers and academic researchers. The interests have been in the simulation of voltage stability and planning by utilizing static loads to represent the relationship between power and voltage. As, most load of the power systems are dynamic, there is need to diversify the study to capture dynamic load characteristics from the measured voltage disturbance. It is a reality that, 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 in power system load modeling and analyze their characteristics both under steady state and dynamic performance. The paper proposes to solve the load flow equations of a power system with DigSilent induction motor (IM) 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 and 3- phase faults. The simulation results indicate 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.