Flexible direct-current distribution line protection device and method based on direct-current circuit breaker

Abstract

The invention discloses a flexible direct-current distribution line protection device based on direct-current circuit breakers. The flexible direct-current distribution line protection device comprises (M+N) direct-current circuit breakers, a circuit breaker control unit, M bus fault detection units and N line fault detection units; the circuit breaker control unit combines the magnitudes of current on all direct-current buses and the magnitudes of current on a power distribution line, the current break variable and the current direction are taken as protection characteristics to construct a fault criterion, a fault occurrence position is judged, whether a fault action signal is sent out or not is judged, and a corresponding direct-current circuit breaker is tripped off according to the obtained fault action signal. According to the method, the break variable and the power direction of the fault current can be comprehensively considered, and the action characteristics of the novel direct-current circuit breakers are combined, so that the bus fault and the line fault of a net-shaped direct-current power distribution network are quickly protected and distinguished.

Description

technical field [0001] The invention relates to the technical field of flexible DC power grid protection, in particular to a DC circuit breaker-based flexible DC distribution line protection device and method. Background technique [0002] Due to its flexible and controllable transmission power, low power transmission loss, and the ability to supply power to passive systems (without the need to transmit reactive power), the flexible DC grid has become a key technology for today's smart grid construction. [0003] Due to the special structure and operation mode of the flexible DC grid itself, the protection and isolation technology of DC faults has always been a hot research issue. When a fault occurs on the DC side, the rising speed and peak value of the fault current are much higher than that of the traditional AC grid, which will have a great impact on the safe operation of the flexible DC system. As the most effective way to clear DC side faults, DC circuit breakers have...

AI Technical Summary

Problems solved by technology

At present, some researchers have proposed a DC power grid partition coordination protection strategy based on DC circuit breakers. This protection strategy solves the problem of DC fault differentiation, but the reliability of the DC power grid has been affected.

The researchers also designed a fault identification method based on the rate of change of fault voltage (ROCOV) and short-term energy for the unipolar ground fault of the star DC grid, but the adaptability of this protection scheme to the radial DC grid remains to be studied.

[0004] In addition, the DC circuit breakers used in the above protection schemes are all bidirectional circuit breakers that can cut off bidirectional fault currents, but there are few studies on protection schemes using unidirectional DC circuit breakers.

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