Improving Shunt Hybrid Filter Performance Through Reducing Control System Time Delay

Abstract

This paper presents a new control scheme for shunt hybrid power filters that provides the capability of harmonics mitigation and reactive power compensation. The control system includes two main loops. The first control loop, which is responsible for harmonic mitigation, generates harmonic component of the active power filter reference voltage. In this control scheme no harmonic extracting circuit is used and, hence, it offers better filtering performances as compared with conventional control schemes of hybrid power filters. The second control loop is designed for reactive power compensation of non-linear loads. The magnitude of the fundamental injected voltage is controlled to adjust the reactive current of passive filter according to the reactive demand of loads, thereby making the line current in-phase with the system voltage. Frequency response of the shunt hybrid power filter is investigated by mathematical analysis and it is shown that the reduction of controller time delay improves filtering characteristic at high order harmonic frequencies. Computer simulations results, carried out for a typical distribution system with two non-linear loads, are presented to show fine steady-state and dynamic performances of the proposed controller.

Key Words:

• Shunt hybrid power filter
• harmonic compensation
• non-linear load
• frequency response
• control
• system time delay
• reactive power compensation

Additional information

Notes on contributors

S. Jamali

Sadegh Jamali received his BSc from Sharif University of Technology in Tehran in 1979, MSc from UMIST, Manchester, UK, in 1986 and PhD from City University, London, UK, in 1990, all in electrical engineering. Sadegh is currently an Associate Professor in the Department of Electrical Engineering at Iran University of Science and Technology in Tehran. He is a Fellow of the Institution of Engineering and Technology (IET) and the IET Council Representative in Iran. His fields of interest include power system protection and distribution systems.

S.A. Mousavi

Seyyed Abdollah Mousavi received the BSc degree from KN Toosi University of Technology, Tehran, Iran, in 1999, and MSc degree from Iran University of Science and Technology, Tehran, Iran, in 2002, all in electrical engineering. He is currently a PhD student at Iran University of Science and Technology. His research interests include utility applications of power electronics, such as active and hybrid power filters, unified power quality conditioner and DFACTS devices.

M.A.S. Masoum

Mohammad A. S. Masoum received his BS, MS and PhD degrees in electrical and computer engineering from the University of Colorado, Boulder, USA, in 1983, 1985 and 1991, respectively. His research interests include optimisation, power quality and stability of power systems/electric machines, and distributed generation. Currently, he is an Associate Professor in the Electrical and Computer Engineering Department, Curtin University of Technology, Perth, Australia. He is a senior member of the IEEE.