Research On The Impact Of HTSC Quench On Relay Protection

The resistance of high temperature superconducting cable (HTSC) is zero in superconductive state, which can improve the transmission capability and reduce net loss. However, the characteristic of HTSC has also brought some problems. When a short-circuit failure happens in power system with HTSC, the short-circuit impulse current will lead to HTSC quench, the resistance of HTSC will change non-linearly, and the electrical parameters will vary. This will affect the current relay protection, especially the distance relay protection. The worst situation is when the distance protection reject-action and does damage to the power system operation.This paper analyzed the non-linear couple relations among the factors which affect the varying of HTSC resistance. The critical current, N-value curve of superconductor, copper volumetric specific heat capacity, superconductive strip volume heat capacity, coefficient of heat conduction and cross sction temperature distribution are considered in the model.This paper analyzed the relation of the phase and amplitude of shielding layer current and conductor layer current when short-circuit fault happens in HTSC shielding layer and conductor layer. The amplitude difference and phase difference detection method are proposed for HTSC quench detection. The accuracy of the two methods are validated through several short-circuit fault simulation. The advantage of the method is that the non-fault phase shielding layer quench caused by fault phase can also be detected.This paper presented a three-stage distance protection setting based on the characteristic of HTSC according to existing distance protection setting principle, and simulation was made on power system with different short-circuit fault situations. Simulation results shows that the distance protection of HTSC can be setted using existing distance protection setting principle. Combining the HTSC distance protection and the quench detection method proposed in this paper, the system fault and cable fault can be differentiated quickly and accurately.Based on the shor-circuit transient simulation of HTSC, this paper analyzed the relation of resistance and temperature of HTSC, summarized the existing automatic reclosing strategies, and the feasibility of automatic reclosing was demenstrated by performing simulation in different timing. The most fitted automatic reclosing strategy of HTSC has universal significance.