An Adaptive Vacuum Forced Zero-Crossing DC Breaking Method Based on Superconducting Current Limiting

Abstract

The invention discloses an adaptive vacuum forced zero-crossing DC breaking method based on superconducting current limiting. When the system fails, the quenching resistance rising rate K of part of the superconducting strip in the superconducting current limiter is obtained. 0 , compare K 0 and threshold Y size, if K 0 >Y, then according to the K-t comparison table, select the charging time t 0 ; On the contrary, the current is concentrated on the single superconducting coil, and the rate of rise of the quench resistance of the coil is obtained K 1 , and choose t 1 ; Then turn on the IGBT group, use the quench voltage to charge the capacitor, after completion, trigger the reverse current supply branch to generate a reverse current, superimpose with the current flowing through the vacuum switch to generate a zero-crossing point, and break the fault current; the energy absorption branch Absorb residual energy; finally, if there is no reclosing command, the process ends; otherwise, the vacuum switch is closed, and it is judged to repeat the above process or end the process according to whether the fault is eliminated. The invention solves the problem that the small current of the forced zero-crossing vacuum direct current circuit breaker is difficult to break, and has the ability of automatic reclosing.

Description

technical field [0001] The invention relates to the technical field of superconducting applications and DC breaking, in particular to an adaptive vacuum forced zero-crossing DC breaking method based on superconducting current limiting. Background technique [0002] The high-voltage flexible DC grid can reliably realize long-distance, large-capacity, and high-efficiency power transmission, and is one of the key technologies for renewable energy consumption in the open sea. However, the method of fault removal on the DC side is a difficult point in the construction of the HVDC flexible grid. On the one hand, the DC current has no natural zero-crossing point, and the equipment cannot break the circuit with the help of the natural zero point of the current. The energy stored in the system inductance of several megajoules to tens of megajoules must be released through the high-voltage DC circuit breaker. On the other hand, the short-circuit fault current rise rate in the high-vo...

AI Technical Summary

Problems solved by technology

However, this patent does not automatically adjust the capacitor charging voltage of the reverse current supply branch when breaking the short-circuit current, because when breaking a small short-circuit current, it will still provide a large reverse current, resulting in too high di / dt, resulting in disconnection failure

Poor reliability under small short-circuit current breaking conditions

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