Research On Shunt Active Power Filters With Selective Harmonic Compensation Of Key Technology

With power electronic equipment and nonlinear load increasing widespread in the power system, power quality problems caused by harmonics also become more prominent. Recent years, the Parallel Active Power Filter (APF) with its superior compensation performance has been extensive research and attention. Combining engineering applications Thesis studied shunt APF related technologies.The thesis analyzed the classification of APF and studied the working principle of APF. Mathematical model of three-phase three-wire shunt APF was established. Thesis studied based on the generalized integrator digital phase-locked technology, harmonic current extraction algorithms. Summarizes the advantages and disadvantages of various harmonic current extraction algorithms, we proposed a multi-synchronous coordinate direct harmonic extraction algorithm. Thesis studied the APF current modulation techniques, compared the advantages and disadvantages of current modulation techniques used widely, and in-depth studied of the spatial vector pulse width modulation algorithm. Related technologies under study conducted MATLAB simulation and experimental verification.Because of the poor performance of PI controller to the AC signal tracking, dynamic response of repetitive controller is slowly, A double-loop compound current controller was proposed, which repetitive controller as the outer loop, the PI controller as the inner loop. Thesis finished the design method of controller, analyzed the dynamic response and steady-state characteristic. The controller through repetitive controller ensures static error tracking, and PI controller ensures dynamic response tracking currents. It has compensated high accuracy, fast dynamic response advantages. On the basis of theoretical research, the controller superiority was verified by simulation and experiment. The thesis studied the DC voltage control strategy, and analyzed the impact for the DC side voltage stability when using indirect extraction algorithms and multi-harmonic synchronous rotating coordinate direct harmonic extraction algorithm and when the load changes. In engineering applications, for APF inrush current is too large when APF starting, we designed a DC voltage soft-start control technology, and through the experiments to verify the feasibility of technology.Combining with the phase-locked technology based on the generalized integrator digital, selective harmonic current extraction technology, double-loop current control technology, space vector pulse width modulation technology and the DC voltage control technology, the Thesis studied and proposed a control strategy of three-phase three-wire shunt APF. MATLAB simulation and experimental results shown that the control strategy applied in the design of the APF which can quickly track harmonic currents and compensation has no static error, and the APF has selective harmonic compensation function and high reliability.