Analysis Of Power System Resonance Phenomenon Based On Modal Analysis Method And Harmonic Control

With the development rapidly of power electronics technology as well as the demand of modern industrial development,a large quantity of nonlinear power electronics devices have been used,resulting in a huge impact on the power grid.Especially the harmonic pollution problem is the most serious.Harmonic is harmful to the normal operation of power system.In some large-scale enterprises which require higher power quality,harmonic pollution is especially serious.Harmonic control is imminent.Harmonic resonance is not only a typical phenomenon of harmonic problems,but also an important problem.It is of great significance to study harmonic resonance for the reliable operation of power system.When harmonic resonance occurs,the harmonic current or voltage magnifies exponentially,resulting in harmonic over voltage and harmonic over current,resulting in overheating,increasing capacitor partial discharge,and accelerating insulation aging.This may lead to equipment damage,protection and automatic device malfunction.Control system will be out of control,and endanger the safe operation of the system.In this thesis,the common methods of harmonic detection and harmonic suppression are introduced first of all.For harmonic detection,the instantaneous reactive power theory and fast Fourier transform(FFT)theory are mainly introduced.For harmonic suppression,the passive harmonic suppression method is mainly introduced.At present,active power filter is widely used in harmonic control.Harmonic detection is the foundation of harmonic control.Secondly,the RLC series-parallel resonance of a circuit model is analyzed mathematically and physically.The simulation results are in full accord with the theoretical analyse.The traditional harmonic resonance analysis methods of power system include numerical simulation method and spectrum analysis method.But these two methods can not meet the requirements of short time-consuming,timeliness and simple steps.This paper analyzes the harmonic resonance modal analysis method.Taking three bus test system and fourteen-bus test system as examples,a simulation model is built on the simulation platform.It is provided by MATLAB to verify the correctness of the method.Then the particle swarm optimization(PSO)algorithm is introduced,and the optimal installation location of SHAPF based on PSO is expounded.The location selection of APF will directly affect whether the power system can achieve safe,stable and economic operation.Finally,APF is used to solve the harmonic problem in distribution network of a key state-owned enterprise.Good results are achieved.