Research on Transient Electromagnetic Field and Eddy Current Losses Reduction in End of Large-Capacity Synchronous Condenser During UHVDC System Faults

During the fault process of the ultra-high voltage direct current (UHVDC) system, the winding of the large-capacity synchronous condenser (SC) generates strong impulse current, leading to excessive eddy current losses and easily causing local overheating in the end structure. In this paper, the machine-network coupling transient model of the SC is established, and the transient characteristics of stator current and excitation current of the SC are revealed when three-phase short-circuit fault occurs at the sending end of the UHVDC system. Then, the 3-D nonlinear transient electromagnetic field calculation model of 300MVar SC is established, and the end magnetic field and the eddy current losses in the end structure at different times are analyzed. According to the distribution law of electromagnetic field, a new end topology structure which can effectively reduce the eddy current losses in the clamping ring and clamping finger is proposed. The end magnetic field and eddy losses in the traditional model (TM) and the improved model (IM) are compared, and the superiority of the improved model is verified.