Preface

This book entitled Power System Operation and Control has been intended for use by undergraduate students in Indian universities. With a judicious mix of advanced topics, the book may also be useful for some institutions as a first course for postgraduates. The organization of this book reflects our desire to provide the reader with a thorough understanding of the basic principles and techniques of power system operation and control. Written to address the need for a text that clearly presents the concept of economic system operation in a manner that kindles interest, the topics are dealt with using a lucid approach that may benefit beginners as well as advanced learners of the subject. It has been designed as a functional aid to help students learn independently.

Chapter 1 introduces the economic aspects of power system and provides definitions for the various terms used in its analysis. It explains reserve requirements, the importance of load forecasting, and its classification.

Chapter 2 describes system variables and their functions. The characteristics of thermal and hydro-power units are illustrated in this unit. Non-smooth cost functions with multi-valve effect and with multi-fuel effect are briefly discussed. This chapter explains the mathematical formulation of economic load dispatch among various units by neglecting transmission losses, and it also gives an overview of the applications of various computational methods to solve the optimization problem. The flowchart required to obtain the optimal scheduling of generating units is also described here.

Chapter 3 looks at the derivation of the expression for transmission loss and explains the mathematical determination of economic load dispatch taking transmission loss into consideration. The theory of incremental transmission loss and penalty factor is clearly discussed. It also analyzes the optimal scheduling of generating units, determined with the help of a flowchart.

Chapter 4 expounds on the optimal unit commitment problem and its solution methods by taking a reliable example. Reliability and start-up considerations in optimal unit commitment problems are effectively discussed.

Chapter 5 explains the optimal power-flow problem and its solution techniques with and without inequality constraints. In this chapter, inequality constraints are considered first on control variables, and then on dependent variables. Kuhn–Tucker conditions for the solution of an optimal power flow are presented in this unit.

Chapter 6 spells out the important principle of hydro-thermal scheduling and its classification. It discusses the general mathematical formulations and methods of solving long-term and the short-term hydro-thermal scheduling problems.

Chapter 7 deals with single-area load frequency control. It describes the characteristics of the speed governor and its adjustment in case of parallel operating units. Generator controllers, namely, P–f and Q–V controllers, the speed-governing system model, the turbine model, and the generator–load model and their block diagram representations are clearly discussed. Steady- and dynamic-state analyses of a single-area load frequency control system are also explained. The chapter also discusses the analysis of integral control of a single-area load frequency control system.

Chapter 8 deals with the response of a two-area load frequency control for uncontrolled and controlled cases very effectively. A dynamic-state variable model for a two-area load frequency control and for a three-area load frequency control system is derived.

Chapter 9 delineates reactive-power compensation along with the objectives of load compensation. This chapter discusses uncompensated transmission lines under no-load and load conditions, and compensated transmission lines with the effects of series and shunt compensation using thyristor-controlled reactors and capacitors. It also elucidates the concept of voltage stability and makes clear how the analysis of voltage stability is carried out using P–V curves and Q–V curves.

The relationship among active power, reactive power, and voltage is derived in Chapter 10. This chapter also speaks about the methods of voltage control and the location of voltage-control equipments.

Chapter 11 deals with the principles of modeling hydro-turbines and steam turbines. It also looks at the modeling of synchronous machines including the simplified model with the effect of saliency. The determination of self-inductance and mutual inductance, and the development of general machine equations are discussed in this chapter. Park's transformation and its inverse, the derivations of flux linkage equations and voltage equations of synchronous machines, and the steady-state and dynamic-state model analysis are elucidated.

Chapter 12 offers an insight into the modeling of speed-governing systems for steam- and hydro-turbines. Mechanical–hydraulic-controlled speed-governing systems, electro–hydraulic-controlled speed-governing systems, and the general model for speed-governing systems for steam turbines are explained in detail. It throws light on excitation system modeling in various aspects such as methods of providing excitation, classification of excitation systems, and various components with their transfer functions. Standard block diagram representations for the different excitation systems are illustrated in this chapter.

Chapter 13 explains the steady-state security analysis and the transient security analysis of a power system. The concept of state estimation is developed in this chapter, and the method of least squares estimation of a system state has been clearly explained.