SOME ASPECTS OF HARMONICS EXTRACTION AND MITIGATION IN POWER DISTRIBUTION SYSTEM

Abstract

This thesis presents work on some power quality issues and mitigation techniques. It consists of six chapters. Chapter one presents a review of power quality issues and selfexcited induction generator systems. Chapter two consists of techniques for harmonic extraction in presence of non-linear load. Techniques used for harmonic extraction include d-q transformation, notch filter and p-q theory. Chapter three presents a number of conventional control algorithms for estimation of reference of supply currents and compensation of harmonics in presence of non-linear load in a three-phase-three-wire distribution system. This chapter discusses modeling and control of DSTATCOM which is operated in closed loop feedback for mitigation of power quality problems. The algorithms discussed in this chapter include Synchronous Reference Frame Theory, Instantaneous Reactive Power Theory, Modified Instantaneous Symmetrical Component Theory and Notch Filter. These algorithms have been modeled and the performance of system is discussed and compared. Chapter four presents harmonic extraction and mitigation techniques based on conventional and modified versions of pq theory in presence of non-linear load under distorted grid. Results have been presented for power factor correction and voltage regulation in presence of non-linear load. Chapter five discusses the modelling and control of Self-Excited Induction Generator for voltage regulation.