Simulation Research On Active Power Filter

The rapid development of power electronics technology, on one hand, makes power energy transformation and application conveniently, and on the other hand, leads to the serious power quality problems in the power system, such as harmonic currents pollution, reactive power problem, voltage fluctuation and unbalance. Active Power Filter (APF) is one kind of modern power electronics equipment which can compensate harmonic current and reactive power. It has much more advantages than other passive filters. This paper chooses three phase shunt APF to study. The thesis builds simulation model of APF using Matlab software, and focuses on the harmonic current detection and current tracking control strategy.The thesis researches harmonic current detection of pq, ip-iq and dq based on instantaneous reactive power theory and adaptive harmonic detection method based on neuron adaptive noise canceling concept. Besides, the thesis researches the influence of different cut-off frequency of low pass filter (LPF) on dynamic response and detection precision of APF system. It also carries out simulation analysis and comparison of the steady-state performance and transient performance in ip-iq method and self-adaptive detection through structuring simulation model. Specific to current control problem in APF, the thesis proposes four kinds of current tracking control methods including periodic sampling control, triangle wave comparison control, hysteresis current comparison control and hysteresis control based on space vector. What is more, the thesis simulates triangle wave comparison control and hysteresis current comparison control. It also compares the compensation effects.The thesis researches the selection method of parameters in the main circuit of APF. It deduces the selection methods of voltage and capacitance in DC side through theoretical analysis. Finally, the thesis proposes the PI control method about DC side voltage based on adaptive harmonic current detection method. The simulation results prove its feasibility.