Double-end direct current power distribution network protection method

Abstract

The invention discloses a double-end direct current power distribution network protection method, comprising the following steps: using the current variance value to replace the current difference value and serving as the starting threshold to constitute the inverse time current variance protection and reduce the fluctuation impact caused by transition resistance and load changes; using the voltage as an acceleration factor to speed up the removal rate of reverse time over-current protection on near-end fault of a line; and introducing a current differential direction to realize the distinction between the inside area of a faulty line and the outside area of the faulty line so as to accelerate the speed of direction judgment to prevent the protection malfunction. The invention is based on the local measurement quantity, does not need communications, can act quickly, and has certain ability to withstand transition resistance.

Description

technical field [0001] The invention belongs to the field of relay protection for DC distribution networks, and in particular relates to a method for protecting a double-terminal DC distribution network. Background technique [0002] At present, the protection scheme of DC distribution network is still in the stage of theoretical research. There are certain problems in the application of traditional protection schemes in DC distribution networks, such as overcurrent, voltage, and differential protection. The applicability of the distribution network, especially the double-terminal or multi-terminal DC distribution network is poor. For example, when the distance protection is applied in the DC distribution network, due to the limitation of the algorithm, the converter will be blocked when a fault occurs, and the nonlinear changes of voltage and current will cause transient oscillation, making it difficult to improve the accuracy of impedance calculation. For example, when d...

AI Technical Summary

Problems solved by technology

There are certain problems in the application of traditional protection schemes in DC distribution networks, such as overcurrent, voltage, and differential protection. Poor applicability in distribution network, especially in double-terminal or multi-terminal DC distribution network

For example, when the distance protection is applied in the DC distribution network, due to the limitation of the algorithm, the converter will be blocked when a fault occurs, and the nonlinear changes of voltage and current will cause transient oscillation, making it difficult to improve the accuracy of impedance calculation

For example, when differential protection is applied in DC distribution network, it is greatly affected by data synchronization when the fault current changes at a high rate

[0003] It can be seen that the applicability of the traditional protection scheme to the DC distribution network is poor, and it is necessary to study the protection scheme suitable for the DC distribution network

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