Transient stability analysis of multi-machine power system and first swing stability analysis using SVC

Transient stability analysis is an indispensible part of utility system planning. The industry standard for transient stability evaluation varies from region to region, but in a broader sense it requires the system to withstand severe disturbances. Since the inception and identification of stability problem in multi-machine power system, numerical method of iteratively solving the system Differential and Algebraic equations has been the conventional solution for stability analysis. Exploiting the features of digital computation several direct methods of stability analysis were developed successively. The energy function based methods of stability evaluation, has been a milestone in stability assessment of multi-machine power system. This paper deals with the stability analysis of a multi-machine power system using energy functions of individual machine and group of machines. The simulations carried out reaffirm the concept of critical machines in stability analysis. The use of energy functions to determine the Critical clearing time (of fault), an important parameter in design of circuit breakers and various other protection equipment, has been reviewed. Power systems worldwide are undergoing transformation into complex entities with the introduction of various fast controllers such as FACTS. Stability analysis incorporating one of the FACTS devices - SVC is the need of the hour. Some preliminary effort in this regard has been carried out in this paper.