Study Of Loss Of Excitation Asynchronism For Powerformer

Powerformer, using XLPE (cross-linked polyethylene) as the stator windings, is a new kind of high voltage generator, this innovational structure enable it to generate high voltage and connect to the power grid directly. So, it is very necessary to study the operation of Powerformer systematically. In this paper, the Loss of excitation of Powerformer is studied thoroughly.Firstly, the developing background and the feature of design are introduced, and contrast benefit of power station which one is made up of Powerformer and the other one is made up of tradition generator, and study states at home and abroad are outlined, in addition, the performance and the harmful effects of loss of excitation are analyzed.Then, the electromechanical transient process, the process from loss of excitation to out of synchronism, the process from transient asynchronous enter steady-state asynchronous and resynchronization process are detailed analysis, and the features of loss of excitation is analysis either.At the same time, in order to analyze the performance of Powerformer under loss of excitation(LOE) condition more effectively, based on MATLAB/Simulink, the simulation model is constructed, the direct short-circuit LOE, partial LOE fault, The direct short–circuit LOE at 40% input power, open-circuit LOE and the excitation winding forms short–circuit LOE with de-excitation resistance are simulated by the model, and the waveforms of excitation current, rotor speed, active power, reactive power, stator current are given, then the results are analyzed detailed, the waveforms show that Powerformer can enter steady-state asynchronous after LOE fault quickly. Besides, three phase shorted fault are simulated either, and the results are compared with LOE fault.Finally, because the Powerformer is a new type generator, so its protect way is different from the other tradition generators, in the paper, several new protect ways for Powerformer are introduced, besides, the loss of (LOE) excitation protection program is done.The conclusion in the paper provides some basis for the reliable design and operation of Powerformer, having certain theoretical significance and practical value.