The Research On Detection And Control Method Of Active Compensation Signal For Reactive Harmonic Frequency Division

Power electronic devices have been applied and promoted in the development of industry and commerce.These nonlinear devices cause serious pollution to the power system and bring serious power quality problems to the power grid.Active power filter(APF),which can dynamically compensate reactive power and harmonic current at the same time,has received extensive attention and research.Aiming at the research of reactive power and harmonic active compensation,this thesis adopts the command signal frequency division detection algorithm based on generalized DQ0 transform to analyze the output control of frequency division compensation for multiple APF parallel systems.Firstly,the thesis introduces the research background and significance of the subject,the research status at home and abroad,the research status of reactive power and harmonic active compensation.Secondly,the generalized harmonic theory of single-phase circuit and threephase circuit is elaborated,and the characteristics of the generalized harmonic in the generalized DQ0 coordinate system are analyzed in detail.The real-time detection algorithm of instantaneous reactive harmonic current frequency division based on the generalized DQ0 transform is studied,that is,the detection algorithm of the positive sequence reactive current using the preset matrix without phase-locked loop,and the detection algorithm of the specified second harmonic using the improved phase-locked loop to reduce the delay.Then the structure of reactive harmonic multi-APF active compensation system is described.The parameter tuning of PI current controller in harmonic rotation coordinate system is described in detail.Then the adaptive hysteresis current control strategy based on frequency division active compensation is emphatically studied.The influence of the stability of DC voltage on the output compensation current is summarized,and the parameters of PI controller for DC voltage are set.Then the whole simulation model is built in Matlab/Simulink.The positive sequence reactive current of the fundamental wave and the specified sub-harmonics are detected by frequency division.The PI current control and the adaptive hysteresis current control are simulated and compared in two cases of reactive power compensation and three-phase nonlinear load symmetry.The simulation analysis of adaptive hysteresis current frequency division active compensation control is carried out under three conditions of three phase nonlinear load asymmetry,load mutation and module switching.The simulation results show that the adaptive hysteresis current control has better real-time performance than PI current control,the output compensation current has higher precision,and the system can quickly track the change of instruction signal.Multiple shunt active power filters have good dynamic performance,high frequency division compensation accuracy,and can purify the power grid well.Finally,the system of reactive harmonic frequency division active compensation is designed and verified by prototype experiment.The results show that the compensation has high real-time performance and good voltage equalizing performance of DC side.