Investigating the Impact of Power System Stabilizers in a Multi Machine System with an Induction Motor Load

Abstract

Current trends indicate that modern power systems are continuously working under stressed conditions. Power demand is rising constantly while several generators are connected to work synchronously to meet the demand. Occasionally, faults within a system occur, which induce electromechanical oscillations of the electrical generators. These oscillations, also called power swings, must be effectively damped to maintain the system stability. Additionally, due to these faults, bus voltages are reduced. The high reactive power demand by the induction motor load during fault condition due to reduced bus voltages may cause a generator to behave like a voltage source behind the synchronous reactance and its terminal voltage reduces leading to the possibility of a voltage collapse scenario. For reliability of these systems, and in an attempt to reduce system oscillations, Power System Stabilizers (PSS) have used to add damping by controlling the excitation system. Studies on a SMIB and those using static loads have shown that a well-tuned PSS can effectively improve power system dynamic stability. This paper investigates the impact of the various PSS in maintaining voltage stability in a system with induction motor loads. A large induction motor is introduced as a load in a multi machine system and the impact of the various PSS are investigated by introducing a temporary three phase fault.