Abstract:
This thesis presents a problematic analysis of the undefined occurrence of malfunction in Rayong Combined Cycle Power Plant during the black-out test of the power system operation.
The strategy of the analysis is collecting the parameter of the electrical equipment in the system in order to simulate such system using PSCAD/EMTP and compare to the experiment field tests. This will proceed to a solution of a systematic problem. By observing, it is found that over-voltage and the waveform distortion are occurred due to ferro-resonance phenomena in such system. This phenomena is overcome due to a grading capacitance of the circuit breaker and a non-linear reactance from an auxiliary transformer. The ferro-resonance phenomenon is not affected in damage to the transformer directly, but degrading such transformer. However, the fault trip of the circuit breaker come from the stray capacitance in the transmission line systems which is resulted in an over-current in the generators transformer protection system and affected into an open circuit operation of such circuit breaker. Therefore, this specific problem can be solved by reducing of the stray capacitance in the system during the black-out test.
The results from simulation test and experiment field test show that the increasing of inductive reactance in the system by connecting the reserved transformer and the increasing of generator load result in the decreasing of system capacitance. In which, it leads to the completely correct operation of the circuit breaker during the black-out test.