Experimental Test And Analysis Of Current Limiting Characteristics Of HTS Current Limiter

With the rapid development of interconnected power network and the rapid improvement of transmission efficiency,there are more and more high-voltage transmission lines,resulting in more and more short-circuit fault current problems.In the developed coastal areas of China,the short-circuit fault current has exceeded the breaking capacity of existing circuit breakers.In recent years,scholars have proposed to limit the short-circuit current to a lower level and then open the circuit breaker.At present,the most promising method to solve the problem is the high-temperature superconducting current limiter combined with superconducting materials.High temperature superconducting current limiter(HTS FCL)is gradually known for its advantages of self triggering,fast response and self recovery.The steady-state and transient characteristics of high-temperature superconducting fault current limiter are the key research contents.Firstly,the structure of a new type of high temperature superconducting current limiter is introduced,and the topology and working principle of the current limiting circuit of the new type of high temperature superconducting current limiter are analyzed.The self triggering magnetic bias superconducting current limiter connects the superconducting current limiting components in series with one branch of the double splitting reactor,and then the current limiting is carried out through the characteristics of the superconducting tape,and then the secondary current is conducted through the branch reactance of the double split reactor So as to achieve the step-by-step current limiting effect of superconducting current limiter.Then,a numerical analysis model is established based on the superconductivity characteristics of the second generation high temperature superconducting tape.According to the resistivity model and heat conduction model,the V-I relationship of the SFCL is calculated by impedance analysis method.Combined with the design parameters of the superconducting current limiter,the variation rules of the steady-state operation process and the transient operation process of the SFCL are analyzed.The simulation model of SFCL is built.The robustness analysis of SFCL is carried out under alternating current,and the operation characteristics are simulated and analyzed with 0 degree fault angle and 90 degree fault angle.The variation curves of loop current,voltage and resistance are mastered,and the change curve of limiting flow rate is obtained.Finally,the critical current,AC loss and flow rate limiting performance parameters of the new HTS FCL are tested and verified.The experimental platform of critical current is built,and the critical current of superconducting tape is tested by four lead method;the AC loss experimental platform of superconducting current limiter is built,and the AC loss of different frequencies of 30 Hz,50Hz,70 Hz and 100 Hz under 20 a,30a,40 A and 50 A current is tested respectively,so as to analyze the AC loss under different current and frequency A flow limiting experimental platform is built to test the loop current of the two states of current limiter and no current limiter,and then calculate the step-by-step limiting flow rate of the superconducting current limiter.The experimental results show that the hybrid magnetic bias superconducting current limiter proposed in this paper can realize the function of self touch ground current limiting step by step,and can meet the current limiting requirements of short circuit fault impulse current.