Stability Study Of Cold Dielectric High Temperature Superconducting Cable

Compare to the normal cable, the transmitting capacity of Cold dielectric high temperature superconducting (CD HTS) cable is3～5times larger as well as reducing the transmission loss to ten percent. It has the advance of low losses, large capacity, light weight, small size, without fire hidden trouble and electromagnetic pollution. It is a good way to transmit electricity with high efficiency, large capacity and low losses. Because the transmission capacity of the HTS cable the is large, when the HTS cable is quench, it is maybe destroyed and even the stability of the power system is seriously affected. So the stability study is one of the key technical researches of the HTS cable.The steady state and transient state stability of a1km,110kV/3kA YBCO-based CD HTS cable is studied. The steady state equivalent circuit is constructed according to the structure of HTS cable, the method of calculating the steady state current distribution is given based on the equivalent circuit, each layer of self and mutual inductances are calculated. The numerical model of steady state radial temperature distribution is proposed, to check the correctness of the model, the simulation of steady state radial temperature distribution is performed used ANSYS, the results fit with the numerical model results well. The influence of the current distribution on operating performance of HTS cable is analyzed, the results show that a uniform current distribution can not only enhance the current capacity but also reduce the steady state operating temperature and improve the steady state stability.The transient state equivalent circuit of HTS cable is constructed according to its operating characters, according to the transient state temperature of HTS cable, the current distribution is divided into two types:I>IC,T<TCand I>IC,T≥TC. The transient state temperature of former and conductor layers are calculated with adiabatic model and the transient state temperature of shield layers are calculated with one-dimension transient heat transfer model. The magnetic-thermo coupling influence of the current and the temperature is analyzed by an example calculation. The factor of affecting the transient stability of HTS cable is analyzed, according the designing target, the area of the fault current and the fault time that the HTS cable can endure is conformed.The critical current of two types of the YBCO tapes are tested, the influence of the direction and intensity of background magnetic field on critical current is analyzed; the influence of DC background magnetic field and AC background magnetic field on critical current is analyzed. The steady state performance of a HTS cable is tested, the tested data of current phase, current amplitude, operating temperature are analyzed, the data fit well with the theoretical value.