Bridge type superconductive failure current limiter without harmonic distortion

Abstract

The invention relates to a bridge type superconducting failure current limiter with no harmonic distortion, which is characterized by consisting of a single-phase rectification bridge, a superconducting current-limiting inductance (HTS) and a controllable auxiliary magnetization circuit. The current limiter has the following advantages: the circuit structure is simple and easy to be controlled; the current limiting function of the current limiter is not damaged; the failure current can be automatically detected; the controllable magnetization circuit has simple structure and can operate stably; only a small number of components are required to be added to eliminate the current distortion caused by the current-limiting bridges or paths; simultaneously, no influence is caused by the magnetization circuit onto the current-limiting operation of the current limiter; moreover, the magnetization circuit can improve the dynamic response performance of the current limiter; and the magnetization circuit can not be damaged by the high voltage of the electric grid.

Description

(1) Technical field: [0001] The invention relates to a bridge-type superconducting fault current limiter, in particular to a bridge-type superconducting fault current limiter without harmonic distortion. (two) background technology: [0002] Due to the development of the power system, the increase of the load, the investment of large-capacity units, power plants and substation equipment, especially the emergence of large power plants in the load center and the interconnection of the power system, the capacity of the transmission and distribution network has been greatly increased, and the short-circuit current The level is increasing day by day, and even the short-circuit current level in some places has exceeded the breaking capacity of the current circuit breaker. If no restrictive measures are taken to control it, it will not only greatly increase the equipment investment of the new substation, but also have a great impact on the original substation equipment in the syste...

AI Technical Summary

Problems solved by technology

The development of a high-level power grid requires a large investment and environmental pollution problems. Although low-voltage sharding or splitting the power grid is simple and effective, it may reduce the safety margin of the system and limit the flexibility of operation and accident handling. It is a last resort not adopted;

[0005] (2) Using DC networking and DC networking for power transmission, the short-circuit current can be significantly reduced, but the investment in the converter equipment at both ends is large, such as when the connecting line is not long and the switching power is not large, this method is often not feasible;

This measure is commonly used, but its loss is large during steady-state operation;

[0007] (4) The use of series reactors in power transmission and distribution systems will not only increase network losses, but also reduce system stability;

Since the short-circuit protection circuit is rectified, the current flows through the equivalent current source, that is, the single-phase inductor, which makes the inductor current be charged until the fault is cut off, so the capacity of the inductor is very large, and with the increase of the inductor current, the inductor is charged The time in series with the voltage source circuit is getting shorter and shorter, which makes the current limiting effect worse and worse until the current limiting effect is lost, that is, this protection circuit cannot limit the steady-state fault circuit; and, if used in the transmission and distribution network, The short-circuit protection switch SW, whether it is an electronic switch or an electrical switch, the former has a very large capacity, and it needs to break the fault current with a very large current change rate, so the reliability is poor during the initial period; if it is the latter, the breaking time is too long and the current limiting effect is poor. , because the fault current gradually increases, the breaking capacity of the electrical switch is also a big problem

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