Computational Paradigm Techniques for Enhancing Electric Power Quality

L. Ashok Kumar, S Albert Alexander

• Publisher: CRC Press
• Year: 2018
• eBook ISBN: 9780429809903
• Topic: Mathematics
• Subtopic: Mathematics General
• Index: Mathematics

This book focusses on power quality improvement and enhancement techniques with aid of intelligent controllers and experimental results. It covers topics ranging from the fundamentals of power quality indices, mitigation methods, advanced controller design and its step by step approach, simulation of the proposed controllers for real time applications and its corresponding experimental results, performance improvement paradigms and its overall analysis, which helps readers understand power quality from its fundamental to experimental implementations. The book also covers implementation of power quality improvement practices.

Key Features

• Provides solution for the power quality improvement with intelligent techniques
• Incorporated and Illustrated with simulation and experimental results
• Discusses renewable energy integration and multiple case studies pertaining to various loads
• Combines the power quality literature with power electronics based solutions
• Includes implementation examples, datasets, experimental and simulation procedures

1

Introduction

1.1 General Classes of Power Quality Problems

Many different types of power quality measurement devices exist and it is important for employees in different areas of power distribution, transmission, and processing to use the same language and measurement techniques.

The IEEE Standards Coordinating Committee 22 (IEEE SCC22) has framed power quality standards in the United States. The Industry Applications Society and the Power Engineering Society along with IEEE played a major role in framing standards. The International Electro technical Commission (IEC) classifies electromagnetic phenomena into the sets presented in Table 1.1.

The power quality standard for IEC was developed by monitoring electric power quality for U.S. industries. Sag is a synonym to the IEC term dip. The category short-duration variations includes voltage dips, swell, and short interruptions. The word swell is an exact opposite to sag (dip). The category long-duration variation deals with American National Standards Institute (ANSI) C84.1 limits. The broadband conducted phenomena are under the category of noise. The category waveform distortion contains harmonics, interharmonics, DC in AC networks, and notching phenomena. The IEEE Standard 519–1992 explains the concept related to harmonics.

Table 1.2 shows the electromagnetic phenomena categorization related to power quality community. The listed phenomena in the table can be further listed in detail by appropriate attributes.

The following attributes can be used for steady-state phenomena:

• Amplitude

• Frequency

• Spectrum

• Modulation

• Source impedance

• Notch depth

• Notch area

For non-steady-state phenomena, other attributes may be required:

• Rate of rise

• Amplitude

• Duration

• Spectrum

• Frequency

• Rate of occurrence

• Energy potential

• Source impedance

TABLE 1.1
Principal Phenomena Causing Electromagnetic Disturbances as Classified by IEC

• Conducted low-frequency phenomena 1. Harmonics, interharmonics 2. Signal system (power line carrier) 3. Voltage fluctuations (flicker) 4. Voltage dips and interruptions 5. Voltage imbalance (unbalance) 6. Power frequency variations 7. Induced low-frequency voltages 8. DC in AC networks

• Radiated low-frequency phenomena 1. Magnetic fields 2. Electric fields

• Conducted high-frequency phenomena 1. Induced Continuous Wave (CW) voltages or currents 2. Unidirectional transients 3. Oscillatory transients

• Radiated high-frequency phenomena 1. Magnetic fields 2. Electric fields 3. Electromagnetic fields 4. Continuous waves 5. Transients

• Electrostatic Discharge Phenomena (EDP)

• Nuclear Electro Magnetic Pulse (NEMP)

TABLE 1.2
Categories and Characteristics of Power System Electromagnetic Phenomena

Categories	Typical Spectral Content	Typical Duration	Typical Voltage
Transient Impulsive
Nanosecond	5-ns rise	<50 ns
Microsecond	1-µs rise	50 ns–1 ms
Millisecond	0.1-ms rise	> 1 ms
Oscillatory
Low frequency	<5 kHz	0.3–50 ms	0–4 pu
Medium frequency	5–500 kHz	20 µs	0–8 pu
High frequency	0.5–5 MHz	5 µs	0–4 pu
Short-duration variations
Instantaneous
Interruption		0.5–30 cycles	<0.1 pu
Sag (dip)		0.5–30 cycles	0.1–0.9 pu
Swell		0.5–30 cycles	1.1–1.8 pu
Momentary
Interruption		30 cycles–3 s	<0.1 pu
Sag (dip)		30 cycles–3 s	0.1–0.9 pu
Swell		30 cycles–3 s	1.1–1.4 pu
Temporary
Interruption		3 s–1 min	<0.1 pu
Sag (dip)		3 s–1 min	0.1–0.9 pu
Swell		3 s–1 min	1.1–1.2 pu

Table 1.2 shows each category of electromagnetic phenomena regarding typical spectral content, duration, and magnitude. The categories and their descriptions provide the cause of power quality problems.

1.2 Types of Power Quality Problems

Defining and understanding the diverse power quality problems helps to prevent and solve those problems. The type of power quality problem is identified by the signature or characteristics of the disturbance. The variation in behavior of the sine wave, i.e., voltage, current, and frequency, recognizes the type of power quality problem. The most common type of power quality problem is voltage sag. Table 1.3 shows the sources, causes and effects of typical power quality problems.

TABLE 1.3
Summary of Power Quality Problems

Example Wave Shape or RMS Variation	Causes	Sources	Effects	Examples of Power Conditioning Solutions
	Impulsive transients (Transient disturbance)	• Lightning • Electrostatic discharge • Load switching • Capacitor switching	• Destroys computer chips and TV regulators	• Surge arresters • Filters • Isolation transformers
	Oscillatory transients (Transient disturbance)	• Line/cable switching • Capacitor switching • Load switching	• Destroys computer chips and TV regulators	• Surge arresters • Filters • Isolation transformers
	Sags/swells (RMS disturbance)	• Remote system faults	• Motors stalling and overheating • Computer failures • ASDs shutting down	• Ferroresonant transformers • Energy storage technologies • Uninterruptible Power Supply (UPS)
	Interruptions (RMS disturbance)	• System protection • Breakers • Fuses • Maintenance	• Loss production • Shutting down of equipment	• Energy storage technologies • UPS • Backup generators
	Undervoltages/overvoltages (steady-state variation)	• Motor starting • Load variations • Load dropping	• Reduces life of motors and lightning filaments	• Voltage regulators • Ferroresonant transformers
	Harmonic distortion (steady-state variation)	• Nonlinear loads • System resonance	• Overheating transformers and motors • Fuses blow • Relays trip • Meters malfunction	• Active or passive filters • Transformers with neglecting zero sequence components
	Voltage flicker (steady-state variation)	• Intermittent loads • Motor starting • Arc furnaces	• Lights flicker • Irritation	• Static VAR systems

1.2.1 Voltage Sags (Dips)

IEEE Standard P1564 gives the recommended indices and procedures for characterizing voltage sag performance and comparing performance across different systems. Also, a new IEC Standard 61000-2-8 titled “Environment – Voltage Dips and Short Interruptions” has come recently. This standard warrants considerable discussion within the IEEE to avoid conflicting methods of characterizing system performance in different parts of the world.

Voltage sags are named as voltage dips in Europe. Decline in voltage for a short time is defined by IEEE as voltage sag. The voltage sag lasts for 0.5 cycles to 1 minute. The voltage magnitude between 10%–90% of the normal Root Mean Square (RMS) voltage is stated as voltage sag. The RMS or effective value of a sine wave is equal to the square root of the average of the squares of all the instantaneous values of a cycle and is equivalent to $(1/\text{}\sqrt{2})$ times the peak value of the sine wave, as shown in Figure 1.1.

Figure 1.2 shows that voltage comes back to normal value after a 0.12 second voltage sag. Voltage sag occurs only for short periods.

Voltage sags occurs on transmission and distribution systems by both utilities and end users. For example, the utility power system is affected by transformer failure that results in voltage sag. The energy is supplied by power system for faults. The fault in the utility power system causes voltage sag. As the fault is cleared, the voltage comes to normal. Sags due to transmission system lasts about 6 cycles (or 0.10 seconds). Distribution faults occur for more time than transmiss...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Preface
• Acknowledgments
• Authors
• Abbreviations
• 1. Introduction
• 2. Mitigation Techniques
• 3. A Voltage-Controlled DSTATCOM for Power Quality Improvement
• 4. Power Quality Issues and Solutions in Renewable Energy Systems
• 5. Review of Control Topologies for Shunt Active Filters
• 6. Control Topologies for Series Active Filters
• 7. Control Strategies for Active Filters
• 8. An Active Power Filter in Phase Coordinates for Harmonic Mitigation
• 9. Line Harmonics Reduction in High-Power Systems
• 10. AC–DC Boost Converter Control for Power Quality Mitigation
• 11. Harmonic and Flicker Assessment of an Industrial System with Bulk Nonlinear Loads
• 12. LCL Filter Design for Grid-Interconnected Systems
• 13. Harmonics Mitigation in Load Commutated Inverter Fed Synchronous Motor Drives
• 14. Power-Quality Improvements in Vector-Controlled Induction Motor Drives
• Index