Design Of Excitation Rectification Device For Power Plant And Application Study Of Runner Electromagnetic Extinguisher Method

The Gezhouba Power Plant was built in 1970s and its first generating units generated in 1980. The generating units have already been in a period of aging after twenty years operation and the equipment malfunction increased significantly. Although some of excitation devices have been rebuilt in some aspects, they sill existed many deficiencies due to the limited level of domestic equipment manufacture. With fewer and fewer staff required corresponding per kilowatt generating capacity for modern grid enterprises whereas the staff's quality demand is increasingly higher and higher as well as the equipment. It is difficult for Gezhouba Power Plant excitation system to meet the increasingly growing operation demands and an urgent solution which is more stable and reliable and less maintaining amount of task is needed to be rebuilt. With the completion of the Three Gorges Power Plant and the joint operation between the Gorges Reservoir and Gezhouba Reservoir, Yangtze Power Co., Ltd. decided to rebuild its generating units by increasing capacity.After the generator units be modified, the excitation system has changed as well and the original excitation system can not meet the function requirement after the system enlarged its capacity and need to be redesign and rebuilt. Based on the current situation of Gezhouba Power Plant excitation system, several excitation methods are briefly analyzed and compared. Combined with the excitation methods popularly adopted at present in large and medium-sized hydropower generator, the rebuilt excitation methods are adopted. Considered the issue exposed in Gezhouba Power Plant excitation-rectifier devices when it running, a novel heat pipe radiate self-cooling excitation rectifier device, which can meet the function requirements after the generator units enlarged its capacity, is designed. The excitation rectifier device take the function requirements involved in all of other generator units into account and has already utilized in practice. How to compute and choose the device in excitation rectifier system and the measure of current sharing against parallel rectifier bridge and how to choose the way of heat dissipation as well as the phase-shifting overvoltage in the three phase fully-controlled bridge are discussed and computed in this paper.The issue of demagnetization of generator rotor has been always a tough question for us. The stand-lone capacity of the generator is increasing and so its exciting current, and rotor voltage is also becoming higher and higher. In this condition, the energy stored in the rotor while it running is also becoming larger and larger. The demagnetization rating of rotor is also becoming more and more difficult. Take Gezhouba Power Station as an example, there were many failure incidents involved in demagnetization of the generator rotor and resulted in the devices burning. Based on the principle of demagnetization of the generator rotor, the failure reason on demagnetization is analyzed and some counterpart schemes were proposed. Some other demagnetization methods were also analyzed in this paper and a novel scheme on demagnetization is proposed. The products and the experiments according to this control scheme were also realized. This verified that the control strategy is reasonable and feasible.