Harmonic Mitigation Techniques for Shunt Active Power Filter using Synchronous Reference Frame | Original Article
A shunt active filter injects a suitable non-sinusoidal current (compensating current) into the system at the point of common coupling and makes the source current sinusoidal. This paper presents a method for obtaining the desired reference current for Voltage Source Converter (VSC) of the Shunt Active Power Filter (SAPF) using Synchronous Reference Frame Theory. The method relies on the performance of the Proportional-Integral (PI) controller for obtaining the best control performance of the SAPF. To improve the performance of the PI controller, the feedback path to the integral term is introduced to compensate the winding up phenomenon due to integrator. Using Reference Frame Transformation, reference signals are transformed from a − b – c stationery frame to 0 − d − q rotating frame. Using the PI controller, the reference signals in the 0 − d – q rotating frame are controlled to get the desired reference signals for the Pulse Width Modulation. The synchronizer, the Phase Locked Loop (PLL) with PI filter is used for synchronization, with much emphasis on minimizing delays. The system performance is examined with Shunt Active Power Filter simulation model. The use of active power filters is widely accepted and implemented as a solution to the power quality problems in utility, industry and commercial applications. In this paper, three of the three-phase shunt active filtering algorithms in time-domain have been compared for a non-linear load. The non-linear load chosen here is a soft start for a three-phase induction motor. The comparison of the simulation results show the effectiveness of both the algorithms although the time domain current detection modified algorithm is more complex in terms of its implementation aspects.