Load Frequency Control in Multi Machine Systems Using PID Controller
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بسم هللا الرحمن الرحيم Sudan University of Science and Technology College of Graduate Studies Load Frequency Control in Multi Machine Systems Using PID Controller التحكم في تردد الحمل في اﻷنظمة متعددة الماكينات باستخدام الحاكمة التناسبية- التكاممية- التفاضمية A Thesis Submitted in Partial Fulfillment of the Requirements of M.Sc. Degree in Electrical Engineering (Microprocessor and Control) Prepared by: Yahia Amir Yahia Gamal Supervised by: Ust. Abdullah Salih Ali اﻵية بسم اهلل الرمحن الرحيم َ َ َ َ َ َ َ ق ََال ََو َاَ َس َب ََحَا َن ََكَﻻ ََ َع َم ََمَل َ َنَاََإ َﻻَ ََمَاَ ََعَم ََمت َ َنَاََإ َن ََكَأ ََن ََتََا َل ََعَمَي ََمََا َل ََحَكَي َمَ َ صدقَاهللَالعظيم َ سورةَالبقرةَاﻵية)23( َ I Dedication For my father Dad, thanks for knowing exactly when to stop holding my hand and begin watching my back. You carried me in your arms when I was little and you held my hand while I was growing up. Dad, I am going to be your pillar when you are old and I will carry you in my heart until I die. Thanks for everything Sweet Bucket for my Mother Mother! A vast, revered, honored word; full of love, feelings, emotions and care that cannot be expressed in words. Mother is not only a parent for her children but a friend, helper, guider and a well-wisher. She is the one who brings us up, gives courage to face the world, confidence to achieve, teaches perseverance, moral ethics and to stand along. Mother is the name from where you begin; she remains with you in her life and even after her life, her prayers surround you everywhere. I love you for ever A brother and sister shares my childhood memories and grown-up dreams Brothers and sister don't necessarily have to say anything to each other- they can sit in a room and be together and just be completely comfortable with each other. II Acknowledgement I would like to thank Prof. my supervisor, Ust. Abdullah Salih for his highly appreciable and valuable supervision and advice throughout the study. I am deeply indebted to the teaching staff of School of Pharmacy, for their guidance, advices and efforts throughout the course of our graduation. Finally, my deep appreciation goes to anyone who supported us in this research until it reached its final steps. III Abstract Modern power systems networks consist of a number of utilities interconnected together. Power is exchanged between utilities over tie- lines by which they are connected. Automatic generation control (AGC) plays a very important role in power system. Its main role is to maintain the system frequency and tie-line flow at their scheduled values during normal period and also when the system is subjected to small step load perturbations. The most commonly used controller is the PID controller, which requires a mathematical model of the system. It is a good tool for the control of systems that are difficult to model. In this study, a power system with two areas connected through tie-line is considered. The objective of AGC, based on PID controller, is to damp the transient deviations (frequency and power) and to provide zero steady-state error of these variables in a very short time. The simulation is implemented by using MATLAB Simulink program. IV مستخلص ذحرىي َظى انقذسج انكهشتائٍح انحذٌثح عهى عذد يٍ انشثكاخ انكهشتائٍح ذشذثػ يع تععها انثعط و ذ ر ث ا د ل ا ن ط ا ق ح ا ن ك ه ش ت ا ئ ٍ ح ع ٍ غ ش ٌ ق خ ط ى غ ا ن ش ت ػ ا ن ك ه ش ت ا ئ ً . ٌ ه ع ة ا ن ر ح ك ى اﻻ ن ً ن ه ر ى ن ٍ ذ د و س ا سئٍسٍا فً ذثثٍد انرشدد نهُظاو انكهشتائً وكزنهك اَسٍاب انقذسج خﻻل خػ انشتػ انكهشتائً تانقٍى انًثشيدح أثُاء دوسج انرشغٍم انعادٌح وأٌعا خﻻل اهرضاصاخ انحًم انكهشتائً انخفٍفح. أصثر انًرحكى انرُاسثً- انرفاظهً- انركايهً ٌطثق تُداذ فً عذد كثٍش يٍ ذطثٍقاخ أَظًح انرحكى. وٌعرثش أداج خٍذج نهرحكى فً اﻷَظًح انرً ٌصعة وظع ًَىرج سٌاظً نها. ف ً ه ز ِ ا ن ذ س ا س ح ، أ خ ز ف ً ا ﻻ ع ر ث ا س َ ظ ا و ق ذ س ج ك ه ش ت ا ئ ٍ ح ٌ ر ك ى َ ا ٌ يٍ يُطقرٍٍ ذشذثطاٌ عٍ غشٌق خ ػ س ت ػ ك ه ش ت ا ئ ً . ا ن غ ش ض ي ٍ ا س ر خ ذ ا و ا ن ر ح ك ى اﻻ ن ً ن ه ر ى ن ٍ ذ- انزي ٌعرًذ عهى)انًرحكى انرُاسثً- انركايهً-انرفاظهً( - هىاخًاد اﻻَحشافاخ انعاتشج نهرشدد وانقذسج وكزنك أٌ ٌعطً هزا انًرحكى خطأ صفشي نهحانح انًسرقشج نهزِ انًرغٍشاخ فً صيٍ وخٍض. ذى عًم انًحاكاج وانرحهٍم تاسرخذاو نغح يعًم انًصفىفاخ )ياذﻻب( عٍ غشٌق تشَايح ساتػ انًحاكاج. V Table of Contents Content Page NO I اٌَح Dedication II Acknowledgement III Abstract IV V يسرخهص Table of Contents VI List of Figures IX List of Tables XI Chapter One Introduction 1.1 General 1 1.2 Problem Statement 2 1.3 Objectives 2 1.4 Methodology 2 1.5 Layout 2 Chapter Two Literature and Theoretical Background 2.1 Power Plants 3 2.2 Types of Steam Turbine 4 2.2.1 Non-reheat steam turbine 4 2.2.2 Reheat steam turbine 4 2.2.3 Tandem Compound 5 2.2.4 Cross Compound 6 2.2.5 Hydro-turbine 6 2.3 Generation 7 VI Content Page NO 2.4 Electromagnetic Generators 7 2.4.1 Dynamo 8 2.4.2 Alternator 9 2.4.3 Induction generator 10 2.4.4 Magneto-hydro-dynamic generator 10 2.5 Control Theory 10 2.6 Automatic Generation Control 11 2.7 Proportional Integral Derivative Controller 12 2.7.1 Droop 15 2.7.2 Loop tuning 17 2.7.3 Stability 18 2.7.4 Optimum behavior 18 Chapter Three Mathematical Model of the System 3.1 Introduction 20 3.2 Generator Model: 20 3.3 Load Model 21 3.4 Prime Mover Model: 22 3.5 Governor Model: 23 3.6 Isochronous Governors 24 3.7 Governors with Speed-Droop Characteristic 25 3.8 Percent Speed Regulation or Droop 26 3.9 Load Sharing by Parallel Units 27 3.10 Control of Generating Unit Power Output 28 3.11 AGC in A Single Area System 29 3.12 AGC in the Multi Area Power System 30 VII Content Page NO 3.13 Tie-Line Bias Control 32 Chapter Four System Design and Simulation 4.1 Introduction 34 4.2 Two Area Power System 35 4.2.1 System response without AGC 35 4.2.2 AGC using Conventional PID Controller 37 4.3 Comparative Results 39 Chapter Five Conclusion and Recommendations 5.1 Conclusion 40 5.2 Recommendations 41 References 42 VIII List of Figures Figure Title Page No 2.1 A simple non-reheat steam turbine 4 2.2 A simple reheats steam turbine 5 2.3 Tandem compound, single reheat 6 2.4 Cross compound, single reheat 6 2.5 A simple hydro-turbine 7 2.6 PID controller 14 2.7 PV versus time, for three values of Kp 15 2.8 PV versus time, for three values of Ki 16 2.9 PV vs time, for three values of Kd 16 3.1 Generator block diagram 21 3.2 Generator and load block diagram 22 3.3 Block diagram for a simple non reheat steam turbine 22 3.4 Speed governing system. 23 3.5 Schematic of an isochronous governor 24 3.6 Governor with steady state feedback 25 3.7 Block diagram of a speed governor with droop 26 3.8 Ideal steady state characteristics of governor with 26 speed droop 3.9 Load sharing by parallel units with drooping governor 27 characteristic 3.10 Governor with load reference control for adjusting 29 speed load Relationship 3.11 Effect of speed changer setting on governor characteristic 29 IX Figure Title Page No 3.12 AGC for an isolated power system 30 3.13 Equivalent network for a two-area power system 32 3.14 AGC block diagram of two-area power system 33 4.1 Simulation block diagram for two area systems 35 without AGC 4.2 Frequency deviation step response without AGC 36 4.3 Power deviation step response without AGC 36 4.4 Simulation block diagram for two-area using 37 conventional PID 4.5 Frequency deviation step response using conventional 38 PID 4.6 Power deviation step response using conventional PID 38 X List of Tables Table Title Page No 2.1 Effects of increasing a parameter independently 19 4.1 Power system parameters 34 4.2 Time response specifications for two area power 39 system 4.3 Power deviation values in the steady state for two 39 area power system XI Chapter One Introduction Chapter One Introduction 1.1 General Automatic Generation Control (AGC) has been an important issue in power system operation and control since last several decades. The objective of the AGC is to enable each generator to control its generation independently to achieve zero state value of area control error and economic loadings of its generators against unpredictable changes in the load demand which occur continuously in a power system. If the load on the system increased, the turbine speed drops before the governor can adjust the input of the steam to the new load. As the change in the value of speed diminishes, the error signal become smaller and the positions of the governor fly-balls gets closer to the point required to maintain constant speed.