Design of Passive High Pass Filter for Hybrid Active Power Filter Applications

Abstract

In recent years there has been considerable concern over power quality, at both distribution and consumer levels, and the need to control reactive power and voltage stability at transmission levels. Active filtering of electric power has now become a mature technology for harmonic and reactive power compensation in two-wire (single phase), three-wire (three phase without neutral), and four-wire (three phase with neutral) ac power networks with nonlinear loads. Active power filter and passive filters (APF & PF) are the traditional ways of compensating for harmonics. However, both of the two ways have some disadvantages, namely resonance and tuning problems in passive filters, and capacity, initial and running cost in APF. Hybrid Active Power Filter (HAPF) has been proposed to overcome the disadvantages of APF and PF. It is a combined system of PF and APF. Appropriate choice of PF and detailed design method for the same is being presented in this thesis, which when combined with APF will eliminate the higher order harmonics. A simple mathematical design procedure is derived for the passive high pass filter. In this thesis, power quality improvement based on HAPF is analyzed for a nonlinear RL-load connected to a 1-phase ac supply which can simultaneously improve the power quality and control the reactive power requirement of the load. The switching algorithm for the APF is presented. The design procedure is limited to the design of passive HPF. However using the designed PF along with existing system consisting of APF is improving the power quality. The obtained results of the proposed HAPF is compared with the existing system with only APF in terms of source current and source voltage spectrums, active & reactive power flow from the filter side to the power system at the point of common coupling (PCC). The studied system is modeled and simulated in the MATLAB/Simulink environment. The performance indices included are THD analysis of source voltage, source current.