A new three phase transformerless shunt active power filter with reduced switch count for harmonic compensation in grid-connected applications / Wajahat Ullah Khan Tareen

Wajahat Ullah Khan, Tareen (2017) A new three phase transformerless shunt active power filter with reduced switch count for harmonic compensation in grid-connected applications / Wajahat Ullah Khan Tareen. PhD thesis, University of Malaya.

	PDF (The Candidate's Agreement) Restricted to Repository staff only Download (1705Kb)
Preview	PDF (Thesis PhD) Download (5Mb) | Preview

Abstract

The demand for electricity in the modern industrial world is rapidly increasing, from household utilities to commercial industries. In the power utilization industry, an increasing number of renewable energy devices, as well as linear and nonlinear loads, are being introduced; these devices include the nonlinear rectifier and static Var compensator (SVC), which affect daily life. Integrated grid-connected energy systems produce certain harmonics, heat, and other complicated power-quality issues. Therefore, proper current harmonic and power-quality mitigation methods are required to enhance the reliability of the grid-connected systems. Various solutions have been proposed to solve the power-quality issues, the active power filter (APF) is the most dominant and liberal solution against problems of power quality, with reactive power and current harmonics compensation. The shunt active power filter (SAPF) topologies for harmonic compensation use numerous high-power rating components and are therefore disadvantageous. Hybrid topologies combining low-power rating APF with passive filters (PFs) are used to reduce the power devices (IGBTs) rating of voltage source inverter (VSI). Hybrid APF (HAPF) topologies for high-power rating system applications use a transformer with large numbers of passive components. When connected to the electrical grid, the increased number of semiconductor switch components produces higher switch losses, which contributes to harmonics in the output voltage waveform, degrades the system efficiency, and causes the overall system performance to deteriorate. In this thesis, a novel APF circuit based on reduced switch count and transformer-less configuration is presented. A new four-switch two-leg VSI topology is proposed for a three-phase SAPF that decreases the number of power switching devices in the power converter, hence minimizing the system cost and size. It comprises a two-arm bridge structure, four switches, coupling inductors, inductors and capacitors sets of LC PFs. The third leg of the three-phase VSI is removed by eliminating the set of power switching devices, thereby directly connecting the phase with the negative terminals of the DC-link capacitor. The feasibility of the power distribution system is improved by eliminating the transformer and reducing power component to provide accurate performance, small volumetric size, and less cost compared with other existing topologies. The proposed topology enhances the harmonic compensation capability and reactive power compensation compared with conventional APF topologies in grid-connected systems. The series ac coupling inductors overcome the fixed reactive power compensation limitation, due to fixed value of the LC filters (inductors and capacitors set). The series LC PF tuned at the 5th and 7th order harmonic frequencies improves the active filtering capability and the reactive power compensation performance. The control algorithm ensures the regulated sinusoidal voltage, phase amplitude, and low THD in the power distribution system along with constant DC-link voltage. The new hardware prototype is tested in the laboratory to validate the results in terms of total harmonic distortion, reactive power compensation and harmonic mitigation, following the IEEE-519 standard. All the experimental and simulation results verify the feasibility performance of proposed transformer-less shunt active power filter (SAPF) with comparison to conventional full-bridge APFs and hybrid active power filter (HAPF) topologies.

Actions (For repository staff only : Login required)