Estudo de estabilidade transitória em sistemas multimáquinas

Abstract

Electric Power Systems may be subject to a wide variety of disturbances. Depending on type and magnitude, a disturbance may cause serious damage to power systems, leading to structural changes after the operation of protective elements and consequent mitigation of the fault. When considering a severe disturbance, such as a three-phase short-circuit, the stability studies are called “Transient Stability” (or stability on great disturbances). Such studies focus on analyzing the synchronism of the various synchronous generator on parallel operation, which may suffer acceleration or deceleration of the rotor angles due to the unbalance between electrical and mechanical power, finding or not a new balance point afterwards. In this context, the operation of relays and circuit breakers should be quick enough to eliminate the defect and avoid severe damage to equipment and loss of synchronism between the generators. Therefore, finding the critical opening time for the circuit breakers becomes crucial for the correct configuration of the protection equipment, and, consequently, for keeping the system stable. Considering all this information, the main goal of this monograph is to analyze the transient stability of power systems with several generators, considering three-phase disturbances and finding the critical opening times for the breakers. In order to clarify the theme and contemplate the final objective, the equations and modelling that define the behavior of the system elements are presented. Besides, the results of simulations on a system with three buses and three generators, simulated through a stability program developed on the software MATLAB, which solves differential equations through Euler’s method, are presented.