Research On Harmonic Current Detection Algorithm In Shunt Active Power Filter

With the development of Technology, A large scale of nonlinear loads are applied to the power system. Meanwhile, with the rapid development of new technologies such as smart and renewable energy integration, they has lead to harmonic pollution problems and caused various types of power quality issues. This paper presents the background of harmonics appearance, the harm to power supply system and the solution of harmonics first, In the paper, The three-phase and three-wire shunt active power filter(SAPF) that most widely used is researched because of advantage and wider interest of active power filter(APF), a power electronic device, as a kind of efficient solution.One of the critical factors to the working performance of the APF is the real-time and accuracy of harmonic current detection algorithm. This paper mainly studies the harmonic detection algorithm based on instantaneous reactive power theory, the simple theory is introduced in the first place, due to the inductance parameter of inverter reactor changes correspondingly when operating condition of APF changes, it leads to decoupling of inner current-loop, which contains inductance parameter, in the dual closed-loop decoupling controller inaccurate or disabled, so a decoupling controller based on synthetic vector is presented to overcome the defect and improve the anti-interference ability of the system. It designs a complex fuzzy PI controller which combines fuzzy control and PI control on control method of active power filter DC voltage. The controller overcome the large overshoot and slow speed of dynamic response, What is more, it achieve the purpose of modifying the parameters online.In order to improve compensation current tracking performance of SAPF, this paper make a brief analysis about the advantages and disadvantages of hysteresis current control and the space vector pulse width modulation(SVPWM) control first and then adopts the strategy of double hysteresis current control based on SVPWM. The control side improves the DC voltage utilization ratio, reduces switching frequency, at the same time, it can improve the dynamic response ability of the system. Eventually, the model of the whole APF system is built in the MATLAB/Simulink, the results show the feasibility and effectiveness of the improved algorithm which enhance the anti-interference ability of the system.