Research On New Criterion Of Loss Of Excitation Protection

With the power industry develops and the capacity of single generator grows, the large generator-transformer units play more important roles in power system and the safe running of generator is an important factor for power system.The loss of excitation is a serious fault for synchronous generator and the effect on the generator and the power system becomes more and more serious because of the loss of excitation. In order to avoid the impact of surge, the exit loss of excitation protection needs delay, so the time of eliminating fault will lengthen. In this paper, the loss of excitation and the exit loss of excitation protection have been emphasis analyzed. By use of the selected blocks from Power System Library in Matlab, the author simulates the loss of excitation fault, surge fault and short circuit fault. The exit loss of excitation protection is improved by the result of calculation and simulation, so a new project for loss of excitation protection is proposed. The new project can distinguish between the loss of excitation and oscillation before the generator losses steady stability, so the negative effect on generator caused by delay can be avoided and the protection can operate more quickly.