Wind power T-type connection line ground fault setting method

Abstract

The present invention relates to a wind power T-type connection line ground fault setting method. The method comprises the following steps: 1) extracting the zero-sequence voltage and the zero-sequence current at the wind power T-type connection line protection installation position, and solving the simulation impedance and the signaling threshold value of a sender according to system parameters; 2) calculating the power direction of each side, and determining the fault direction; and 3) if the faults are the positive direction faults, determining whether blocking signals are received or not, and if the blocking signals are received, determining that faults are the external faults of the T-type connection line, and protecting the closed lock; and if the closed locking signals are not received, determining that the faults are the internal faults of the T-type connection line, and immediately performing the tripping operation. The wind power T-type connection line ground fault setting method can effectively avoid the influence of the T-type connection line topology and the wind power fault features on the T-type connection line protection configuration and considers the economy so as to ensure the selectivity, the sensitivity and the reliability of the T-type connection line protection.

Description

technical field [0001] The invention belongs to the technical field of electric power system relay protection, and in particular relates to a grounding fault setting method of a wind power T-connection line. Background technique [0002] With the increase of wind power penetration, the power grid shows more and more fault characteristics different from the conventional power grid, which leads to great challenges in the selectivity, sensitivity and reliability of relay protection configured according to the conventional system. State Grid Corporation's enterprise standard Q / GDW738-2012 "Technical Guidelines for Planning and Design of Distribution Network and Instructions for Compilation" pointed out that in a 110kV high-voltage distribution network, wind power can be connected to the grid in a T-connection manner. In order to ensure the reliability of power supply, the distribution network often adopts the power supply mode of hand-in-hand ring network or double-terminal powe...

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Problems solved by technology

[0004] (2) If the protection configuration scheme of the T-connection transmission line is directly used, that is, the current differential protection is applied to the T-connection line of the distribution network containing wind power, since each side of the protection needs to exchange current vector information with the other two sides, New fiber optic channels need to be erected, which will greatly increase the investment cost of power grid transformation

However, since the line has three branch lines at point T, the high-frequency signal sent by the transmitter will be shunted when it passes through point T, which is equivalent to an increase in line loss. In severe cases, it may cause the opposite end to fail to receive the blocking signal , to protect against misoperation

[0006] (4) The change of wind turbine equivalent sequence impedance destroys the best application environment of traditional fault component directional elements

There are great differences between wind turbines and conventional power sources, especially for double-fed wind turbines that combine asynchronous generators and power electronic devices, and their fault characteristics are very complicated

During the fault period, the equivalent positive and negative sequence impedance of the wind power supply is controlled by the fault transient strategy of the wind turbine, and the impedance phase angle may change greatly, which may lead to

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