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About this book

This book is focused on the development of Phasor Measurement Units (PMUs) as a tool to analyse and control power systems. The book develops a nonlinear system-wide approach to control using PMU signals and provides numerous examples of different power systems to demonstrate the robustness of the approach in comparison to heuristic optimization. Some of the applicable controls include:
· Excitation systems;· Wind power;· Static VAR compensators;· High evoltage DC; and· Inverter dynamics.
For the operation of transmission and distribution systems, the book explains the dynamics of power systems and explores how well-established tools such as energy-based control and Kalman filters can address many of the existing and developing issues in their operation. By providing a thorough guide to PMUs, this book enables readers to fully understand the potential benefits their implementation can bring.

Table of Contents

Frontmatter

Chapter 1. Phasor Measurements for Identification and Control

Abstract
Power Systems relying on synchronous generators have been traditionally monitored and controls using measurements of voltage, current and power.
Gerard Ledwich, Arash Vahidnia

Chapter 2. Load Modelling

Abstract
For engineering analysis of power systems many different models are required covering
Gerard Ledwich, Arash Vahidnia

Chapter 3. Identification of Power System Dynamics

Abstract
To identify oscillations and damping system identification is required but to develop control processes low order models and a control approach applicable to nonlinear systems are desired. This chapter introduces the model reduction process and the foundations of energy based control.
Gerard Ledwich, Arash Vahidnia

Chapter 4. Direct Control of Power System Dynamics

Abstract
Large power systems can be visualized as a set of masses connected by nonlinear springs.
Gerard Ledwich, Arash Vahidnia

Chapter 5. Indirect Control of Power System Dynamics

Abstract
One of the main causes of power system instability is low-damped inter-area oscillations. It is important to damp out low-frequency oscillations effectively and to provide necessary precautions in order to avoid major separations of power systems and cascading blackouts. Development of reliable control strategies to keep the system in a stable condition is a way to prevent system blackouts or brownouts.
Gerard Ledwich, Arash Vahidnia

Chapter 6. Inverters Operating in Power System in Weak Grids

Abstract
When connecting inverters to a weak grid, one significant concern is the interaction between the phase locked loops of each inverter and thus with system stability.
Gerard Ledwich, Arash Vahidnia

Chapter 7. Travelling Waves

Abstract
In the train model introduced in Chap. 2 if there is a sudden disturbance on Carriage 1 the jolt will travel down the train in much the same way a continuous spring would have propagating waves. In a similar way the sets of generators in a power system have nonlinear springs but still the jolt at one generator will propagate down the power system. Ideally a long spring would carry any frequency disturbance down the train. The discrete case of distinct carriages means that only low frequency transients will propagate well down the train.
Gerard Ledwich, Arash Vahidnia

Chapter 8. Identification of DynamicsDynamics of Inverters and Loads in Power Systems

Abstract
When adding new inverters to an area the interaction with existing inverters needs to be considered. When the number of existing inverters is limited and perfect models are available then simulation of the new system with all inverters is feasible and control designs able to be refined. However when existing models are not well specified an identification route is highly desirable.
Gerard Ledwich, Arash Vahidnia

Chapter 9. Phasors for Distribution

Abstract
Phasor measurements have mainly been applied for transmission systems partly because of cost. There is a continuing reduction in the cost and distribution applications are growing. One of the developing issues is the impact of solar panels in the distribution network causing voltage rises and the potential for battery use to expand. If all customers simultaneously exported power from their battery that would have even more potential for overvoltage problems. The growth in these Distributed Energy Resources (DER) is driving a greater need to observe the flows and voltages in distribution. It has been proposed that estimation of the state of voltages on a distribution line would be a lower cost path rather than extensive measurements and communication. This is examined in Sects. 9.2, 9.3, 9.4, 9.5.
Gerard Ledwich, Arash Vahidnia

Chapter 10. Conclusions

Abstract
The high accuracy of PMU measurements makes fast estimation of the state and the dynamic response of a power system readily available. The motor content of loads can be identified as well as interarea dynamics. Nonlinear state estimators can tell us whether a section of the network has critical issues. Nonlinear control design based on Kinetic Energy can provide both first swing improvements as well as overall nonlinear damping control.
Gerard Ledwich, Arash Vahidnia

Backmatter

Additional information