Моделювання перехідних процесів в синхронному генераторі при витковому замиканні обмотки статора

Abstract

The purpose of this study is to develop a mathematical model of a synchronous generator to study its modes of operation in the case of asymmetric damage to the phases of the stator winding, namely twisting, the use of which will make it possible to improve relay protection systems against twisting of the stator winding of a synchronous generator. Transverse differential protection is used to protect synchronous generators from winding circuits. However, such protection can be used only on generators with parallel branches in the phase of the stator winding. In the work, a mathematical model of a synchronous generator was developed, which allows to study the transient processes of the generator in case of the appearance of turn short circuits in the stator winding. This mathematical model is based on differential equations written for the stator phase axes a, b and c. An algorithm for calculating transient processes in a synchronous generator is proposed. In turn-to-turn circuits of the stator winding, which is based on the fourth-order Runge-Kutt numerical integration method. With the help of the developed mathematical model, the values of currents and voltages of the generator were calculated in the case of short-circuits of the stator winding for the TVB-200-2 turbogenerator. The results of mathematical modeling of the transient processes taking place in the TVB-200-2 generator when closing a different number of turns of the stator phase showed that the reduction of the fundamental harmonic voltage at the terminals of the generator in the damaged phase when closing 10 %, 40 %, and 60 % of the winding turns is, respectively, 21 %, 77 % and 89 %. At the same time, there is an increase in the amplitude of the first harmonic of the current of the damaged phase by 3.7 to 7.8 times. The obtained research results make it possible to improve relay protection systems for synchronous generators, namely protection against turn-to-turn circuits in stator windings without parallel branches.