A DC line protection method in a DC distribution network

Abstract

The invention discloses a direct current line protection method in a direct current power distribution network. The method comprises the steps of firstly, extracting currents at two ends of a line, calculating a modulus current, selecting an appropriate modulus current, performing S-transformation, and setting a protection start criterion; secondly, judging whether an internal fault exists or notaccording to the polarity of a modulus current integral, and calculating a fault distance according to the time when the high-frequency modulus current reaches the two ends; thirdly, according to a control signal, instructing a direct current circuit breaker to operate, and isolating the fault interval; and finally, repairing in time according to the fault distance result to eliminate the fault. The fault current contains a large number of high-frequency components and includes a lot of fault information, thus the interval where the fault occurs can be judged by use of high-frequency characteristics of the fault current and the distance of a fault point is calculated. According to the direct current line protection method in the direct current power distribution network disclosed by the invention, the time at the two ends is required to strictly synchronize, GOOSE communication is utilized, and meanwhile a sampling device is required to have a high sampling frequency.

Description

technical field [0001] The invention relates to a DC line protection method in a DC distribution network. Background technique [0002] Compared with the AC distribution network, the DC distribution network has many advantages as follows: [0003] 1. The DC distribution network does not need to transmit reactive power, and has no capacitive effect and skin effect, so the DC distribution network has a large power supply radius and large transmission capacity; [0004] 2. When the DC distribution network accepts devices such as distributed photovoltaics and energy storage and DC loads, the energy utilization efficiency is improved due to the reduction of converter devices; [0005] 3. The power quality problem of the DC distribution network is easier to solve; the DC distribution network is less affected by the failure of the AC side and does not increase the short-circuit capacity of the AC side. [0006] However, the protection of DC distribution network hinders its furthe...

AI Technical Summary

Problems solved by technology

[0009] The problem to be solved by the present invention is to provide a DC line protection method in the DC distribution network for the problems existing in the existing DC distribution network fault identification method, and provide technical support for the safe and stable operation of the DC distribution network

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