Coordinated Control Strategy for Multimachine Power System to Enhance Dynamic Stability

Power systems are currently operating closer to their static and dynamic stability limits due to an increase in the power transfer demands on existing transmission systems, given the significant growth of loads and generation, lack of new transmission lines, and competitive electricity market pressures. Stability problems associated with voltage collapse and undamped oscillations are currently the leading causes of major blackouts, FACTS controllers are becoming more relevant, since due to their fast response, these controllers can improve the stability of a power system, thereby allowing a more efficient use of existing transmission grids Various types of FACTS controllers, particularly SVCs, TCSCs, STATCOMs, SSSCs, and UPFCs are being used in practice.
Controllers based on ac-ac vectorial converters have been proposed demonstrating that it is possible to attain similar control objectives and performance as those based on VSC converters. SVeC (Series Vectorial Compensator) to control active power on a transmission line with a simple structure, injecting a series capacitive reactance that is adjusted automatically through a duty cycle control. SVeC present a smoother control alternative than the TCSC, since the TCSC “jumps” from capacitive to inductive operating regions due to problems associated with open-circuit operating conditions and harmonics.
Based on the aforementioned comparisons, it can be argued that direct PWM, vectorial-converter-based controllers may be a reasonable alternative to thyristor- and VSC-based options for similar applications. Therefore, other features on applications of such controllers must be analyzed to evaluate its performance in some multi-machine power systems. Hence my research work focuses on analytical modeling of SVeC for a dynamic stability analysis. This book aims at exploring the issue of this dynamic stability problem in multimachine power systems and its mitigation by applying power system controllers Traditional and efficient ways to mitigate these problems are to derive additional signals for generator excitation systems and to compensate the fluctuations of power flow through the transmission networks. Power system stabilizer (PSS) and flexible alternating current transmission system (FACTS) devices have remarkable capability to perform these tasks. The objective of this book is to present a detailed study, simulation, and analysis of the dynamic stability problem and its mitigation by applying PSS, Coordinated Control of series FACTS device SVeC with PSS, linear feedback controller based on LQR concept and nonlinear feedback control based on sliding mode concept. The simulation results have been presented employing eigenvalue and time domain analysis in MATLAB.