A Review On Power Quality Issues And Their Mitigation Techniques

International Journal of Engineering Technology and Management Sciences, 2020

Power quality complications are treated as interrupted voltage, current or frequency which reflects as malfunction of connected elements at end levels. User system models, smoothen loads of industries and crucial, regular operations of all effected by kinds of outcomes & line distortions, they can impact with economy of the whole system. Here the power quality includes the enhancement of voltage quality, source power factor, control of harmonic distortions, voltage sags and swells. The devices selected for power quality improvement are DSTATCOM, Hybrid active power filters, Dynamic voltage restorers, static var compensators TVSS,CVT etc.

From last decade power quality issues has become more complex at all level of power system. It is a major topic of concern due to the sensitivity of the modern equipment which are nonlinear loads and hence results in imbalance of the power system. Power quality parameters consist of harmonic distortions, dips and swells, interruptions, flickers, transients, frequency deviations etc. The aim of this paper is to review the most common power quality issues, the effect of the same on the power quality and various techniques utilizing in the present system for its improvement.

Besides quantity, the quality of power is also equally important. Poor power quality decreases the efficiency and misoperation of electrical and electronic devices, this may result interrupted electrical power supply. Due to recent development of electronics and computer based automated and smart devices in every field e.g. medical, bank, industry, quality of power becomes more and more important as these devices require best power quality. Power quality mitigation becomes very important as we cannot avoid the nonlinear loadings and many more issues which is responsible for poor power quality. In this paper various power quality mitigation techniques are discussed such as Distribution Static Synchronous Compensator (DSTATCOM), Static VAR Compensator (SVC), Dynamic Voltage Restorer (DVR) and Unified Power Quality Compensator (UPQC) for the improvement of power quality in manufacturing industries. Recent developments in mitigation techniques are also discussed. Different techniques are explained in chronological order. Impacts of different techniques for different disturbances are also mentioned. Index Terms: Dynamic Voltage Restorer (DVR), Unified Power Quality Conditioner (UPQC), Distribution Static Compensator (DSTATCOM), Transient Voltage Surge Suppressors (TVSS), Voltage Regulators, Uninterruptible Power Supply (UPS) Solid State Breaker, Static Current Limiter.

Due to the increased use of power electronic converters in domestic, commercial, and industrial sectors, the quality of power in distribution networks is deteriorating at an alarming rate. This is causing a number of problems such as increased losses, poor utilization of distribution systems, mal-operation of sensitive equipment, and disturbance to nearby consumers, protective devices, and communication systems. These problems are also aggravated by the direct injection of non-steady power from renewable energy sources in the distribution system. It is expected that in the next few years, more than 80% of AC power is to be processed through power converters owing to their benefits of energy conservation, flexibility, network interconnection, and weight and volume reduction in a number of equipment such as lighting, HVAC, computers, fans, and so on. In view of these facts, it is considered timely to write this book to identify, classify, analyze, simulate, and quantify the associated power quality problems and thereby provide mitigation techniques to these power quality problems that will help practicing engineers and scientist to design better energy supply systems and mitigate existing ones. This book is aimed at both undergraduate and postgraduate students in the field of energy conversion and power quality in more than 10,000 institutions around the word. The book aims to achieve the following: • Easy explanation of the subject matter through illustrations, waveforms, and phasor diagrams using minimum texts, which is one of the most efficient methods of understanding complex phenomenon. • Simple learning of the subject through numerical examples and problems, which is one of the most favorite techniques of learning by engineering graduates. • To gain an in-depth knowledge of the subject through computer simulation-based problems, which is the most favored skill of today's young engineers. • To get the confidence to find the solutions of latest practical problems, which are encountered in the field of power quality. • To develop enthusiasm for logical thinking in students and instructors. • To gain an in-depth understanding of latest topics on power quality in minimum time and with less efforts. This book is planned in a unique and different manner compared with existing books on the subject. It consists of rare material for easy learning of the subject matter and a large number of simple derivations are included in a simplified mathematical form for solving most of the power quality problems in analytical form and designing their mitigation devices. Aside from this, the book provides essential theory supported by a reasonable number of solved numerical examples with illustrations, waveforms and phasor diagrams, small review questions, unsolved numerical problems, computer simulation-based problems, and references. In addition to undergraduate and postgraduate students in the field of power quality, this book will also prove useful for researchers, instructors, and practicing engineers in the field. This book facilitates simplified mathematical formulations in closed form solution through calculation, computation, and modeling of power quality problems and designing their mitigation devices. This book consists of 11 chapters. Chapter 1 gives an introduction on power quality (PQ), causes and effects of PQ problems, requirement of PQ improvements, and mitigation aspects of PQ problems. Chapter 2 deals with PQ definitions, terminologies, standards, benchmarks, monitoring requirements, financial loss, and analytical quantification through numerical problems. In Chapters 3-6, passive shunt and series compensation using lossless passive LC components, active shunt compensation using DSTATCOM (distribution static compensators), active series compensation using DVR (dynamic voltage restorer), and combined compensation using UPQC (unified power quality compensator) are covered for mitigation of current-based PQ problems such as reactive power compensation to achieve power factor correction (PFC) or voltage regulation (VR), load balancing, and neutral current reduction and mitigation of voltage-based PQ problems such as compensation of voltage drop, sag, swell, unbalance, and so on in the single-phase and three-phase three-wire and fourwire loads and supply systems. In Chapter 7, various types of nonlinear loads, which cause these power quality problems, are illustrated, classified, modeled, quantified, and analyzed for associated power quality problems. Chapters 8-11 deal with different kinds of power filters such as passive filters, active shunt filters, active series filters, and hybrid filters to meet the requirements of various kinds of power quality problems such as current and voltage harmonic elimination, reactive power compensation, and so on caused by harmonics-producing single-phase and three-phase nonlinear loads. Moreover, these power filters are also used for elimination of voltage harmonics present in the supply systems. The major strength of this book is its 175 numerical examples, 250 review questions, 175 numerical problems, 250 computer simulation-based problems, and 600 references in different chapters. and École de technologie supérieure, Montréal, Canada (ÉTS). Professor Singh would like to thank his research students for their contributions to some of the chapters in terms of making diagrams, figures, simulations, numerical verifications, proofreading, and constructive suggestions. Many of them deserve mention, namely

The objective of Electric power system is to generate electrical energy and distribute that energy to the end user appliance at an acceptable voltage. As increasing demand of power there is a need to expand and upgrade the modern power system for the reliability and stability of the power system network. It is essential to maintain good quality of power supply. In the distribution and industrial sector are highly depended on the power electronics device. Which are the greater sources of nonlinear loads and harmonics in power system. Due to nonlinearity of all loads causes disturbances in the voltage waveform. Poor power quality issues can cause voltage sag, swell, generation of harmonics, equipment failure due to large current, voltage, frequency imbalance. The aim of this paper is to review power quality issues, its problems and corrective methods.