DESIGN OF SUITABLE CONTROLLER FOR AUTOMATIC GENERATION CONTROL OF MULTI-AREA POWER SYSTEM

Abstract

The prime objective of automatic generation control (AGC) is to adjust the active power generation in response to variable power demands and hence AGC is required to maintain scheduled system frequency and scheduled tie-line power flows with neighboring control areas at desired tolerance values. A sizeable fall in frequency might badly affect the timing of electric clocks, magnetizing currents in transformers/induction motors, constant speed of AC motors, continuous operation of processes and synchronous operation of various units in power system. Additionally, power system may face a serious instability problem at substantial drop in the frequency. In steady state, automatically these variations must be zero. Enhanced power system stability is achieved with the proper design of supplementary controller adopted in an AGC system. However, continuous growth in size and complexity, stochastically changing power demands, system modeling errors, alterations in electric power system structures and variations in the system parameters over the time has turned AGC task into a challenging one. Consequently, conventional control strategies may be incompetent to handle such unpredictable variations in an AGC system. Hence, the researchers over the world are trying to propose several novel control strategies that fuse knowledge, techniques and methodologies from varied sources to tackle AGC problem of power system effectively. The literature survey indicates that several researchers tried to tackle AGC issue in traditional system. It presents various types of controllers optimized using various conventional and intelligent soft computing techniques. The literature survey also unveils that the performance of AGC system depends chiefly on the sort of intelligent technique exploited and structure of the controller. Hence, the goal of the present study is to propose different types of new supplementary controller structures for various types of traditional power systems. The presented work is divided into ten chapters. Chapter 1 presents the introduction of AGC topic. Chapter 2 deals with a critical review of AGC schemes in power system. Chapter 3 stresses on the modeling of power systems under the study. The simulation work is presented in Chapter 4. vii In Chapter 4, the AGC study is initially implemented on a single-area single-source thermal system. From the results attained in the study, it is authenticated that the single-area single-source non-reheat thermal system shows superior performances in comparison to the single-area single-source reheat thermal system. ALO and GNA tuned PI/PID controllers are employed in the thermal system and compared for the dynamic response. The values of overshoots, undershoots, settling times, and performance index, validated the dominance of GNA tuned controllers for single area thermal system. In Chapter 5, the study is conducted on two-area reheat/non-reheat thermal systems. GNA tuned PI/PID/2DOF-PID controllers are employed. The performance of GNA tuned controller is revealed significantly superior in terms of lesser numerical values compared to conventional controllers based on DE/TLBO/hSFS-PS optimization algorithms. In Chapter 6, the study is conducted on single-area multi-source thermal-hydro-gas interconnected system and two-area multi-source thermal-hydro-gas interconnected system. In first attempt, a new fractional order proportional tilt integral derivative (FOPTID)+1 controller optimized using GNA is proposed for different electric power system. The results of FOPTID+1 controller are found to be superior compared to FOPID/PID controller optimized with GNA algorithm. Yet, FOPTID+1 controller has resulted superior performance compared to the published results with conventional controllers PI/PID. The performance of FOPTID+1 controller is revealed significantly superior in terms of lesser numerical values of settling times (STs), undershoots/overshoots and ITAE compared to conventional controllers based on DE/TLBO/hSFS-PS optimization algorithms. Next, in Chapter 7, the study is conducted on single-area single-source nuclear system, single-area multi-source hydro-nuclear system, single-area multi-source hydro-nuclear-gas system. A new GNA optimized, FOPI-FOPTID controller is proposed for power system. It is observed that proposed controller shows superior results in terms of lesser values of STs/USs/OSs compared to GNA optimized FOPI FOPID/FOPID/PID controllers. To show the effectiveness of the method, the viii approach is further extended to two-area multi-source hydro-nuclear system and two area multi-source hydro-nuclear-gas system. The proposed controller has revealed the superior performance in terms of lesser values of STs/ USs/OSs compared to GNA optimized FOPI-FOPID/FOPID/PID controllers. Next, in Chapter 8, the study is conducted on single-area multi-source and two-area multi-source interconnected traditional thermal-hydro-gas power system without nonlinearities. A new WHO optimized, FOID-FOPTID controller is proposed for power system. It is observed that proposed controller shows superior results in terms of lesser values of STs/USs/OSs compared to WHO optimized FOTID/TID/PID controllers. Further, results are superior with the proposed controller compared to the recently published DE/TLBO/hSFS-PS optimized conventional controllers. To show the effectiveness of the method, the approach is further extended to two-area multi source thermal-hydro-gas systems with nonlinearities. The analysis of the simulation results discloses the efficacy of WHO optimized FOID-FOPTID controller for power systems. In the next step of the study in Chapter 9, an attempt is made to propose efficacy of energy storage systems (ESS), for traditional single-area multi-source thermal-hydro gas system and two-area multi-source thermal-hydro-gas system. The critical analysis of the obtained results revealed the worth of ESS for the enhanced performance of dynamic responses in terms of less numerical value of STs/USs/OSs. It is also experienced that WHO optimized FOID-FOPTID controller is robust since it satisfies the AGC requirements when the system parameters are varied in regulated environment. Finally, Chapter 10 presents an overview of the major contributions made out of, the research work presented in the thesis. The scope for future work in the area of AGC of power systems is also presented.