Research On Digital Control System For Active Power Filter Based On DSP

The substantial increase in the use of power electronic equipment results in harmonic pollution and reactive burden above the tolerable limits. Many conventional solutions to the power quality issues can't meet the conditions of modern power system. Active power filters are known as a dynamic, adjustable and potential solution to the power quality problems. This paper presents the operation principle and configuration of a shunt active power filter in detail, and analyzes the harmonic detecting methods and control strategies systematically. Currently harmonic detection method based on instantaneous reactive power theory has been widely used. Here a simulation model for ip-iq method is presented and the low-pass filter is analyzed. This paper presents an improved current controller that combines the instantaneous active and reactive current component ip-iq method and the sine-triangle PWM voltage modulation. In the α–βreference frame, instantaneous active and reactive currents are respectively controlled with a proportional integral (PI) regulator and then the true compensating currents can track the harmonic signals well. Compared with the conventional control method whose control objects are three-phase feedback currents, the improved current controller can realize decoupling control. Simulation results verify the validity of the proposed controller. To verify the proposed algorithm, this paper designs an experimental system for a 5-kVA shunt active power filter in which the control circuit is realized using digital signal processor TMS320LF2407A. In the assembly language program, cross-zero compare and digital low-pass filter is realized...