Research On Stator Winding Internal Faults Transient Simulation In Synchronous Generator And Its Application

With the development of power system, the capacity of single generator is growing, and this demands higher performance for large generator protective relay. The theory of protective relay lies on clear understanding of fault characteristics. To improve the performance of large generator protective relay, it is necessary to study more deeply and comprehensively the internal faults of large generator. Based on clear understanding the fault law of generator, it may be easy to propose new protection criterion and improve protective relay, and enrich and perfect large generator protective relay theory. Based on above, firstly the paper presents some research achievement on internal fault transient simulation of stator windings in large generators. The transient simulation program the paper presents is proven by a test on an analog synchronous generator. After careful studying the fault transient characteristics, the paper presents a new sampling value differential protection based on correlation coefficient, and a new ( power direction component. At last the paper proposes a scheme of generator protective relay testing. The details of this paper are below:Based on multi-loop theory, the paper presents the mathematical model of synchronous machine internal fault transient simulation that adopts a general branch voltage matrix function to establish circuit current matrix function very conveniently and directly. The paper also presents a fault transient mathematical model of generator and transformer unit. Based on above mathematical model, the fault transient simulation program is developed which includes internal fault parameter preparation and transient equation calculation.This paper simulates a salient-pole synchronous machine stator winding internal fault transients, especially when the synchronous machine is loaded. The comparison results between simulation and field tests is very similar, and proves that the theory and ways the paper adopted is able to simulate salient-pole synchronous machine stator winding internal faults correctly. Based on the transient simulation program of stator winding internal faults in synchronous generator, this paper presents the effect of stator winding and damper bar resistance on transient and steady currents. It is very necessary to calculate precisely the resistance of stator winding and damper bar resistance in order to simulate fault correctly.It also analysis the sensitivity of single transverse differential protection, separate phase transverse differential protection, differential protection and incomplete differential protection in stator winding internal faults transient period when synchronous generator is connected to power system. The analytical results show that the sensitivity of single transverse differential protection improves in the transient period, and the sensitivities of separate phase transverse differential protection, differential protection and incomplete differential protection may improve or decrease on different fault conditionsThe paper presents some fault transient simulation of a large turbo-generator, and studies on the protective relay of the large turbo-generator, for example vertical base frequency zero-sequence over voltage protection and ( negative-sequence power direction protection.This paper presents a new generator differential protection criterion based on correlation coefficients of sampling currents values. Theory and simulation results have proven that the new criterion can clear internal fault very fast and reliably and wouldn't misoperate when external fault occurs, especially when one TA is saturated. The paper presents a new ( three phases power direction component. Theory and simulation results have proven that the new direction component can distinguish the internal and external fault on different conditions. The paper also discusses several blocking components that cooperate with the new direction component.The paper presents a relay testing scheme based on off-line power system transient simulation program,...