Analysis and Simulation oftheAVR Systemand Parameters VariationEffects

Theprimary roleofanautomatic voltage regulator (AVR)istoregulate thereactive powerandvoltage magnitude. Thesystem modeled consists oftheamplifier, exciter, sensor and stabilizer orproportional-integral-derivative (PID)controller. Thestate-space technique isusedtomodelthesystem. Their characteristics andbehavior arealsobriefly discussed. Results of thesimulation studies ontheAVR system using Matlabareprese- nted.By examining theparameters ofthestabilizer and controller, thegenerator terminal voltage variations are predicted. I.INTRODUCTION Thereactive powerisoneofimportant factors forexploitati- onanddesigning inthepowersystem. Thebalance ofreactive powerinthesystem implies constant output voltage. Themost commonstrategies forthereactive powerandvoltage control canbeclassified asinjection ofreactive powerbyshunt com- pensator, displacement ofreactive powerinthesystem bytap changing transformers andreducing inductive reactance ofthe lines by series capacitor. TheAVR systems areused extensively inexciter control system. Theprimary meansof generator reactive powercontrol isthegenerator excitation control byAVR.Therole ofanAVR isholding thegenerator terminal voltage constant under normal operating conditions at various loadlevels (1). TheAVR loop oftheexcitation control system employs terminal voltage error foradjusting thefield voltage tocontrol theterminal voltage (2). Thebasic compone- ntsofanexciter control system comprises four maincompone- ntsnamely amplifier, sensor, exciter andgenerator. Control principles fortheAVR system havebeendescribed inafew publications (2-5). A design methodfordetermining the optimal proportional-int egral-derivative (PID) controller para-