Distance protection method and system applicable for grid-connected grid system of new energy stations

Abstract

The invention provides a distance protection method and system applicable for a grid-connected grid system of new energy stations. The method comprises the following steps: according to the running current and running voltage data actually measured at the occurring time of a ground fault on a new energy station grid-connected point side, using a Kirchhoff voltage law to calculate the equivalent impedance of the corresponding new energy station grid-connected point side, and comparing the equivalent impedance with preset protective setting impedance value so as to carry out starting judgment for distance protection relay protection actions on the new energy station grid-connected point side. Under the condition that the protective setting impedance value is not adjusted, effective control for the distance protection relay protection actions on the new energy station grid-connected point side can be realized, the accuracy of the protection actions is improved, the distance protection forthe new energy station grid-connected point side can be realized preferably, and the damages on a power grid and users due to false actions or refuse operation of a distance protection relay are reduced.

Description

technical field [0001] The invention relates to the technical field of new energy grid protection, in particular to a distance protection method and system suitable for grid-connected grid systems of new energy stations. Background technique [0002] Relay protection is the first line of defense among the three lines of defense for the safe operation of the power system, and it is of great significance to the reliable operation of the power system. In order to meet the characteristics of relay protection, the fixed value of each line distance protection must be set according to the protection regulations, and the distance protection of each line also needs to be coordinated. [0003] According to the latest requirements and specifications of the power grid, when the power system including new energy stations fails, the new energy stations must have a certain low-voltage ride-through capability. That is, when the grid voltage drops, the new energy station can operate without...

AI Technical Summary

Problems solved by technology

If the line distance protection is still set without considering the new energy power generation device, it will cause the protection to malfunction or refuse to operate; if the distance protection is set according to a certain operation mode of the new energy power generation, that is, a certain output, then Because the equivalent impedance of the new energy power generation device varies with its output data and is uncontrollable, it may still cause malfunction or refusal of the protection

Malfunction or refusal of distance protection will easily lead to the expansion of the fault range, and even cause large-scale power outages, causing serious losses to the power grid and users. It can be seen that the research on relay protection of power grids containing new energy stations is very necessary

[0004] In the prior art, there are two main methods of line distance protection suitable for grid-connected power grid systems of new energy stations, including: 1. The distance protection is set according to the rated output data of the power generation device, but when the output data of the power generation device changes , the protection may malfunction or refuse to operate; 2. Adjust the protection setting impedance value according to the real-time operation situation. Although it can better meet the protection requirements, in the actual application process, the protection setting impedance value cannot be arbitrarily Changes, otherwise it will be difficult to comply with the management regulations and operation and maintenance system of the current power grid system relay protection

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