Method for solving line-protection false tripping when overloading

Abstract

The invention discloses a method for solving line-protection false tripping when overloading. The method comprises the steps of: for a ground distance relay III, discriminating whether the ground distance relay III is in overloading state or a fault state through a degree of asymmetry m, wherein the degree of asymmetry m is defined in formula (2), when m is smaller than and equal to k1,as the ground distance relay III is judged in the loading state and the limit condition is not open, when m is larger than and equal to k2, the ground distance relay III is judged in a light loading state, the limit condition is open, and when m is smaller than k2 and larger than k1, the ground distance relay III is judged in a heave loading state, additional limit conditions are increased and finally if the limit condition is open is judged; and for a phase spacing relay III, increasing the limit conditions in formula (6), wherein when the formula (6) is satisfied, the limit conditions are open, otherwise, the limit conditions are not open. The invention can ensure performance of distance protection in conditions of overloading as well as overloading and fault so as to avoid distance protection false tripping caused by overloading and eliminates a constant value adjusted by users of a loading limiting relay in a protector so as to avoid the problem brought by the wrong adjustment of the constant value.

Description

technical field

[0001] The invention relates to a method for solving misoperation of line protection caused by overload and a device using the method. Background technique

[0002] The AC interconnection of the large power grid and the improvement of the transmission capacity of the ultra-high voltage line make the overload of the line particularly prominent. In the case of overload, the action performance of the protection device in the system will be restricted to a certain extent, especially the distance III section of the distance protection. In the case of no fault, the action cuts off the line. This backup protection action before the safety automatic device may lead to the expansion of the accident and bring a bad impact on the stable operation of the power grid.

[0003] The existing overload solutions generally start from the action characteristics of distance protection, without changing the original setting principle of distance relays, only adding grounding and p...

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