Research On Combined System For Harmonic Suppression And Reactive Power Compensation Based On APF And TSC

With the wide application of power electronic equipment in the industry and civilization occasions,lots of reactive power and harmonic current pour into electrical network,which bring titanic peril for power grid and disturb the operation of high accuracy equipment.Thus,superior power quality of power grid are demanded by many users.Recently,reactive power and harmonic current dynamic hybrid compensator,such as active power filter,have caused widely attention.In this paper a reactive power and harmonic current hybrid compensator which composes of shunt active power filter and thyristor-switched capacitor have been designed.The compensation character and the pros and cons of TAPF under different control strategies for current-source type nonlinear load were well studied theoretically and quantitatively by establishing mathematic model.Operating performance of the compensator produced by different control strategies were simulated as power network parameters change.The design and character of TAPF hardware platform were also discussed.The mathematic model and stabilizing factor of TAPF under load-current detection and double-current detection were introduced in this paper.Reactance ratio and harmonic compensation ratio of TAPF are well analyzed.On this basis,a hybrid control strategy of harmonic and reactive power compensation which utilizes reactance ratio and fractional frequency detection was proposed in this paper.This control strategy can also stabilize TAPF when different TSC are operating.The current tracking algorithm is the core part of TAPF.In this paper PI and parallel resonant controllers under dq rotating coordinate are adopted to track the harmonic current.Each resonant controller represents two harmonic components under stationary coordinate,which can improve the efficiency of the system,achieving good dynamic performance and high tracking accuracy of the system.In order to make the discrete-time subsystem of TAPF,thyristor-switched capacitor(TSC)cooperate with the continuous-time subsystem of TAPF,active power filter(APF)in the reactive load power fluctuation,the algorithm of tracking signal of TAPF have designed in this paper.Finally,a controller of TAPF based on discrete and continuous variables have designed in this paper.