CONTROL AND REDUCTION OF SWITCHING SURGES IN POWER SYSTEM

Abstract

At the EHV and UHV levels the cost of.insulation forms the major part of the cost of the equipment. Hence, an acci•reto estimation of the form and magnitude of expected overvoltages on the system has become more and more important with increasing complexity in power systems for an optimum system design. In this dissertation the method of characteristics combined with nodal analysis has been used for the-calculation of switching surges• In the present dissertation the results of a study of swit ching overvoltages on'Dehar 400 kv system are presented. In the study, the expected magnitudes of switching overvoltages due to energization, reclosing, load rejection, fault initiation and fault clearing operations were evaluated. The effectiveness of various means of overvoltage control was evaluated. It is demonstrated that the overvoltages can be reduced to a practical level depending on the type and complexity of the' control technique utilized. Various types of overvoltages that may arise in a power system, the effect of line connected apparatus on switching surges and their reduction and control methods are discussed in chapter—II. The methods for determining switching surge overvoltages and their merits and demerits are given in Chapter—III. The solution method for determining switching 5,23_ overvoltages using the method of characteristics with nodal analysis alongwith the modeling of transformer, circuit breaker, shunt reactor and lightning arrester is given in Chapter—IV. The results of the study and their discussion- are given..in chapter—VI. The concluding chapter, namely chapter—VII, discusses concAsions and the future scope of work in the related field.