Method for solving line-protection false tripping when overloading
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A line protection and solution technology, which is applied in the field of anti-misoperation of line protection during overload, and can solve the problems of influence on the stable operation of the power grid, high sensitivity of fault phase opening, and misoperation.
Active Publication Date: 2010-05-19
CENT CHINA GRID +1
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[0011] The purpose of the present invention is to: improve the action performance of the distance element in line protection under overload conditions, avoid secondary accidents caused by incorrect actions of line protection during overload, and seriously affect the stable operation of the power grid; at the same time solve the existing The problem that the load limit relay is difficult for users to set, avoiding the possibility of misoperation due to setting errors
This limit condition ensures that it will not open when overloaded, and open correctly under fault conditions. At the same time, the opening sensitivity of the fault phase is higher than that of the non-fault phase, which can solve the problem of overload and fault conditions.
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Embodiment approach 1
[0069] 1. Implementation mode 1: increase the grounding distance of the restrictive condition III segment relay
[0070] 1. According to figure 1 The logic shown judges the restrictive conditions of section III of the grounding distance to determine whether it is open;
[0071] Judgment of asymmetry m range
[0072] if m≤k 1 The restrictive conditions are not open, the output is false "0", and the grounding distance section III relay is blocked;
[0073] if m≥k 2 The restriction condition is open, the output is true "1", and the grounding distance section III relay is opened,
[0074] if k 1 2 , and satisfy the formula (3) and formula (4) in the description at the same time, the restriction condition is open, otherwise the restriction condition is closed.
[0075] 2. According to image 3 In the logic shown, the restrictive conditions are combined with the grounding distance relay, and after the delay of the third section of the grounding distance relay, it is finally d...
Embodiment approach 2
[0080] 2. Implementation Mode 2: Increase the phase-to-phase distance III relay of the restriction
[0081] 1. According to figure 2 Shown to judge the restrictive conditions of phase-to-phase distance III to determine whether it is open;
[0082] satisfy Then the phase-to-phase distance restriction condition is open, otherwise the phase-to-phase distance section III relay restriction condition is not open.
[0083] 2. According to image 3 In the logic shown, the restrictive conditions are combined with the phase-to-phase distance relay section III, and after the delay of the phase-to-phase distance relay section III, it is finally determined whether the phase-to-phase distance relay section III is activated.
[0084] When the phase-to-phase distance restriction conditions are opened and the action equation of the phase-to-phase distance relay of section III is satisfied at the same time, the action will trip after the phase-to-phase distance delay t2 of section III.
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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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Application Information
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