Method for distinguishing failure and tripping of high-voltage short-distance double-circuit chain-type power network

Abstract

The invention relates to a method for distinguishing the failure and tripping of a high-voltage short-distance double-circuit chain-type power network; after the over-current criterion of a circuit and the power direction criterion act, the circuit is tripped and the tripping is protected by a set time limit and after a bus coupler protection over-current criterion LJM acts, the bus coupler is tripped and the tripping is protected by a set time limit; and the method is also characterized by using the power direction criterion and the over-current criterion LJM phase which are protected by the bus coupler that is closest to a grounding point for accelerating the time limit protection of the circuit which is directly connected with a bus coupler branch after acting. When short-circuit failure happens to some point of the power network, the power direction criterion and the over-current criterion which are protected by the bus coupler branch that is closest to the failure point immediately act to accelerate the current time limit protection on the direction of a circuit which is connected with the bus coupler branch, thereby achieving the purpose of being capable of quickly removing the fault with high selectivity by adopting a relatively simple method.

Description

technical field [0001] The invention belongs to the field of relay protection automation in the field of electric power engineering, and in particular relates to a new method for judging short-circuit faults and accelerating high-selectivity and fast tripping of line protection in a high-voltage short-distance double-circuit line chain power network. Background technique [0002] At present, there are many short-distance double-circuit chain power networks in the high-voltage (such as 110kV) power systems in urban areas and suburbs of large and medium-sized cities (see figure 1 ), most of its protection devices adopt multi-stage phase-to-phase distance protection, directional current protection, zero-sequence directional current protection or longitudinal differential protection. Due to the short length of each line, the first section of distance protection and directional current protection can only be withdrawn, and only the second and third sections with longer delays (su...

AI Technical Summary

Problems solved by technology

Due to the short length of each line, the first section of distance protection and directional current protection can only be withdrawn, and only the second and third sections with longer delays (such as figure 1 The time delays of the protections shown above) make it impossible to quickly remove the short-circuit fault

Furthermore, the calculation of the setting value of the second section of the protection of the short-distance double-circuit chain network is more difficult, and the branch coefficient under various operating modes needs to be taken into account. It is difficult to ensure that the fault is removed under all operating modes with a fixed setting value. It is difficult to prevent the misoperation of the protection of the other circuit when one circuit fails; in order to prevent the malfunction, it is usually necessary to disconnect each bus tie circuit breaker, that is, to artificially separate the two buses of the same substation from each other independently Operation, so that the original double-circuit parallel-connected power supply line is changed into two separate single-circuit lines for operation. What's more, the scheduling may need to be split into two single-side power supply somewhere in the network during operation. When the radial network operation of the single-circuit line will inevitably cause a short-circuit fault, even if it is selectively removed, such as figure 2 As shown, it will also cause the power supply of the next-level non-faulty line and the bus load to stop together, and there will be a vicious accident of cutting a string and stopping a piece. Advantages of flexibility

If the longitudinal differential protection of short lines is used, fiber optic channels need to be installed, the cost of the protection device will increase and the operation and maintenance of the protection will be more complicated, and the selective removal of bus faults cannot be guaranteed.

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