Research On Voltage-Loss Protection On The Customer High-Voltage Power System

In the power system there are many industrial loads especially the factory and mine which are in the harsh environment containing some insurant such as coal dust, gas, dripping, etc. Furthermore the loads fluctuate much in the underground baroque power grid and the failures occur frequently. The common failures include the interphase short circuit fault, single phase ground short circuit fault and inter-turn short circuit fault of the transformers and the motors that lead to frequently short time blackouts, most of which are due to the voltage-loss release protection tripped by the voltage fluctuation.According to the demand that the breaker should disconnect once the bus loses voltage, the high-voltage breakers install voltage-loss protection which drive the breaker disconnect after the voltage loss to avoid the auto reclosing. Since the breakers mostly adapt voltage-loss release which would release without delay once the line voltage drops to 65% normal voltage, the voltage fluctuation and the voltage loss of the bus could not be distinguished. Therefore sometimes the voltage fluctuation lead to large area blackout in the high-voltage line caused by lightning, short circuit, etc., while there is no real voltage loss in the bus line.The main work of the thesis is on the theory and arithmetic to resolve the practical problem of malfunction of the,then to distinguish the responsibility of power quality pollution and to try to identify and to locate the disturbance source as early as possible in order to reduce the loss.The achievements in this thesis are as followings:(1) By the analysis of the fundamental characters of types of voltage loss in the factory and mine, including system fault voltage loss, impact load voltage loss, lightning voltage loss and so on, the mechanism of the voltage-loss protection action.(2) By taking advantage of the p-q-r algorithm, a new method to determine the voltage sags and swells was verified by simulation using matlab which shows fine rapidity and reliability.(3) A design was put forward which describes the principle and architecture. It settled the problem that when the integrated supervisory control system malfunctions the voltage-loss protection could not achieve an the problem of the energy saving component has low capacity so that the delay could not last long.