Providing Reliable Operation of Electric Networks

This book presents theoretical and practical aspects of providing reliable electrical network operation by 6 500 V voltage. The topics covered includes semiconductor systems for de-icing overhead transmission lines, dispatching solutions in power systems by expert systems, partial discharge diagnostics, electrodynamic testing of reactors, an investigation of technological breakdowns with damage to power transformers, perspectives for using photothyristors, IGCT and IGBT for electrodynamic, programmable static converters for intelligent electrical networks, and digital current transformers for digital substations. Chapter 1 describes the serious problem of glacial deposits on overhead transmission lines during the autumn-winter period. One of the methods to combat this is melting the glacial deposits on alternating current lines by creating short circuits, or direct currents using uncontrolled or controlled rectifier blocks. Chapter 2 discusses the expansion of the Automatic Dispatch Control System for substations and electrical networks using intelligent subsystems based on the technology of expert systems. Chapter 3 presents an application's experience with monitoring the electric activity of the partial discharges into the insulation of transformers, data on electrical tests in autotransformer windings, and testing XLPE cables. Chapter 4 shows the thermal and electrodynamic tests of reactors on the reliability and durability of windings during the passage of short-circuit currents, serving as a tool for improving the reliability of their design. Chapter 5 investigates a technological breakdown with damage to power transformers, which is a difficult task, and is performed to improve the reliability of the power supply. Chapter 6 shows diagnostic and mathematical models of the windings of the high-voltage transformers and reactors. Mathematical models of winding radial and axial deformations are also calculated. Chapter 7 provides the comparative characteristics of switching capabilities of photothyristors, lockable thyristors IGCT, and high-power transistors IGBT, taking into account the specific operating conditions in the composition of the high-voltage high-current semiconductor key (HHCSK) during electrodynamic tests. In Chapter 8, the author considers the basic operations of implicative algebra for the choice of the logical-algebraic modeling of static converters, provided that the objective and predicate variables are identified with the parameters of the energy and information processes. Chapter 9 presents controlled reactor-transformers with reduced high current harmonics and the calculation of parameters of the active parts of transformers. Finally, chapter 10 presents the results of designing a device for calculating the current on digital current transformers, based on the Faraday Effect. This book is based on the authors previous research, including more than 240 scientific and technical publications.