Double-feed wind power plant outgoing line three-phase short circuit fault direction determination method and direction element

Abstract

The invention discloses a double-feed wind power plant outgoing line three-phase short circuit fault direction determination method and a direction element; the method comprises the following steps: S1, building a double-feed wind power plant outgoing line fault model; S2, analyzing the fault model in S1, and building wind power plant outgoing line direction element new criteria; S3, calculating an phase angle of the direction element new criteria, and determining a fault direction according to the phase angle calculation result; S4, carrying out simulation verification for the determination result. The advantages are that the method can analyze double-feed wind power plant outgoing line fault characteristics, improvements are made on the basis of a conventional power frequency fault component direction element, thus providing wind power plant outgoing line new direction element criteria; the method employs the direction element new criteria for determination, thus correctly determining the fault direction on line two-side protections when three-phase faults happen in different positions of the outgoing line, and solving the hard determination problems of the wind power plant outgoing line three-phase fault direction.

Description

technical field [0001] The invention relates to the technical field of wind farms, in particular to a method for judging the direction of a three-phase short-circuit fault of an outgoing line of a doubly-fed wind farm and a directional element. Background technique [0002] With the continuous development of wind power generation technology, the installed capacity of wind power has grown rapidly, and large-scale wind power is connected to the system, which has a great impact on the relay protection of the power grid. Large-scale wind farms are mostly dominated by doubly fed induction generators (DFIG). The transmission line of the wind farm is an important channel for transmitting power from the wind farm to the grid. Its operation safety is of great importance to the safe and stable operation of the wind farm and the grid. Therefore, it is necessary to study a reliable relay protection scheme suitable for wind farm sending lines. [0003] The directional element is one of ...

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Problems solved by technology

However, the load current of the system connected to the fan changes frequently, and it is difficult to judge the fault direction only by the current amount.

Document 2 "Petit M, Le Pivert X, Garcia-Santander L. Directional relays without voltage sensors for distribution networks with distributed generation: Use of symmetrical components [J]. Electric Power Systems Research, 2010, 80(10): 1222-1228." Two kinds of directional elements based on sequence components are proposed, one is to directly use the ratio of negative sequence component and zero sequence component, find its fault boundary value according to statistical data, and compare the ratio with the boundary value to judge the fault direction; the other One is to judge the fault direction by comparing the ratio of the fifth harmonic zero-sequence component to the positive-sequence component. These two directional components can work normally under ideal conditions, but because the harmonic component is easily affected by high-order harmonics and aperiodic The interference of components makes the calculation results less accurate, and both algorithms need to use zero-sequence components, so they cannot be applied to ungrounded faults

Document 3 "Ali Hooshyar, Maher Abdelkhalek Azzouz, Ehab F.El-Saadany.Three-phase faultdirection identification for distribution systems with DFIG-based wind DG[J].IEEE Transactions on Sustainable Energy,2014,5(3):747- 756." A fault current classification method is proposed, which judges the fault direction according to the difference of the fault current waveform, which can be used to solve the problem that the three-phase fault of the distributed power access system cannot accurately judge the direction, but the criterion is more complicated

[0005] Aiming at the problem of misjudgment of the directional element when the three-phase fault of the outgoing line of the wind farm, the invention proposes a method for judging the direction of the three-phase short-circuit fault of the outgoing line of the doubly-fed wind farm and the directional element

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