Dynamic Characteristics Analysis Of Auxiliary Control Of Generater Excitation System

Recent years,the synchronization of giant units and wind and hydraulic power generation and the weak link between interconnected system,and all these making the electric network much more complex,cause some problems such as the local power grid collapse,long period low frequency concussion,and sub-synchronous resonance.In these cases,improving the stability of the system,to ensure the safe and stable operation of the power system is particularly important.The generator excitation control system has been regarded as the most economic and effective measures in a variety of adjusting methods for enhancing and improving the stability of power system.Relies on Research,Exploitation and Application of North China Grid Machine Net Cooperation Operating Data Analysis Platform project,the excitation control system and its auxiliary links were used for research.This paper using PSS/E simulation software build up a user defined model of bus fed static excitation system main circuit.The following dynamic simulation on one machine infinity bus system employed this model,and comparison of the results with real time digital simulator data indicates the proved effectiveness of this model.On this basis,power system stabilizers(PSS)and under excitation limiters(UEL)are researched respectively.On one machine infinity bus system and North China grid system,two different PSS models PSS2B and PSS4B were dynamically simulated.The comparative simulation result shows that both PSS2B and PSS4B are able to inhibit generator and interconnecting ties oscillation,and PSS4B performed better inhibiting capability of generator oscillation than PSS2B,while both models performed similar effect on the oscillation of interconnecting ties.In this paper,we also studied the situation when UEL coordinates with PSS with theoretical analysis and simulating research,and mainly discussed the parameters for oscillation mechanism under improper system state.The results show that the main reason that improper UEL parameters setting causing system oscillation is because that,1)UEL providing a electromagnetic torque lagging 180° in?? direction,and 2)UEL and PSS mismatched in function frequency band.