Preface

This book contains two sections: Section 1 'Power System Stability - Small Signal Stability and Dynamics' and Section 2 'Power System Stability - Power Oscillations and Electrical Infrastructures'. The book is relevant to academia and industries because it contains information from several authors with sound academic and industrial background in the field of power system technology.

Section 1 *Power System Stability - Small Signal Stability and Dynamics* - This section has three chapters. Chapter 1 introduces the book by giving an overview of power systems and stability criteria. This chapter presents a brief overview of power system structure, power system components and power system stability based on the swing equation. Stability studies considering synchronous generator models are also discussed. Steady state small disturbances and transient stability studies are also covered. The equal area criterion could be used for a quick prediction of stability. In this chapter, the various scenarios for stability analysis in a power network considering the equal area criterion for sudden change of load, maximum power limit, three phase fault at the sending end and three phase fault away from the sending end are presented for a one machine connected system to an infinite bus. Chapter 2 describes the application of the trajectory sensitivity theory to small signal stability analysis. This chapter presents a practical approach for assessing the stability of power system equilibrium points in real time based on the concept of trajectory sensitivity theory. The Mexican power system was used as a case study to evaluate and demonstrate the approach in a general sense and also to show how power systems could be effectively operated and control, considering effective energy management systems. Complementary information to those given by selective modal analysis is also obtained using this approach in order to find how the state variables that are linked with critical eigenvalues are affected by the parameters of the system. Also, this chapter provides solutions for how to evaluate the oscillatory behavior of a power system based on the parameters of the system. In Chapter 3, power system small signal stability as affected by grid-connected Smart Park is investigated. In this chapter, Damping Torque Analysis (DTA) was employed to examine the effects of the integration of smart charging station on the dynamic stability of transmission system. A single-machine infinite bus power system with a smart charging station was used in this work as an aggregate of several charging stations. The results obtained from DTA, according to this chapter, show that the damping ratio and optimal charging capacity should be considered in the design of the smart charging station. This is because the power system that can achieve the best maintained dynamic stability and damping ratio would be able to reach the crest value. The chapter further proposes the Phillips-Heffron model to design the stabilizer through regulation of the active and reactive power of the smart charging station, considering phase compensation methods. The power oscillation in tieline can be suppressed more quickly and accurately with the help of the stabilizer, damping of the system oscillation under certain operating conditions.

Section 2 *Power System Stability- Power Oscillations and Electrical Infrastructures* - This section has two chapters. Power oscillations due to ferroresonance and Sub Synchronous Resonance (SSR) is presented in Chapter 4. Ferroresonance and SSR are the phenomena that cause power oscillation of rotary systems. These ideas are presented in this chapter of the book. Ferroresonance is likely to occur due to traversing capacitance line of the system across non-linear area of transformer saturation curve as a result of several configurations such as; breaker failure, voltage transformer connected to grading capacitor circuit breaker, line and plant outage, and others. This chapter argues that changes in these variables cause misshaping of the waveforms and frequency differences between points in the network. In addition, the chapter addresses the issue of SSR causing an increase of the magnitudes of voltage and current in the network. Consequently, increasing the voltage causes saturation of iron core of the transformers or reactors, which leads to the occurrence of ferroresonance in the presence of series capacitance connected in the network. The effects of climate change in electric power infrastructures are addressed in Chapter 5. The chapter explains several ways in which electric power infrastructure has contributed to climate change, how climate change affects electric power infrastructures, the mitigation options to reduce its effects and adaptation methods to be implemented. The electricity infrastructures considered in this study include; the technologies of power generation, transmission lines, substations and loads. The following climate change categories were used; atmospheric greenhouse gas concentration levels, rising sea levels, changes in precipitation patterns, river flows, and extreme air temperatures. The United States of America desert southwest was considered as a case study. Based on long-term forecasting of infrastructure performance, various supply and demand side strategic options to maintain reliable operations, were considered as quantitative studies, in providing estimated vulnerability from heat waves.

> **Dr. Kenneth Eloghene Okedu** National University of Science and Technology Glasgow Caledonian University Muscat, Oman

Section 1

Small Signal Stability and

Dynamics

Section 1
