A bus differential protection anti-misoperation operation method and device when charging in the t-zone of the bus

Abstract

The invention discloses a misoperation prevention operation method for bus differential protections when a bus T-zone is discharged and a device thereof. The device is characterized in that switches on two sides of lines are identified in hot stand-by conditions; the time from the protective grounding of a line which is opposite to a line to be discharged to part II of phase-to-phase distance is shortened to 0.2 second; two bus differential protections which is on the side of the line to be discharged are kept switching on, the changing ratio of a CT which is corresponding to the line to be charged in bus differential protections is adjusted to 0:1; all of disconnecting links on the side of the bus in the T-zone which is on the side of the line to be charged are opened; a switch which is on the side of the line to be charged is closed; a switch which is on the opposite site of the line to be charged is closed. According to the invention, a method that the changing ratio of the CT which is corresponding to the line to be charged in the bus differential protections is adjusted to 0:1 and meanwhile the backup protection time of the opposite side of the line to be charged is shortened to 0.2 second is adopted. In the method, the removal of the bus under normal circumstance resulted from Misoperation of the bus differential protections can be effectively avoided, operation is simple, reliability is high, a bus fault point can be quickly positioned, continuous power supply is ensured, the security of system performance is enhanced greatly.

Description

technical field [0001] The invention relates to the technical field of microcomputer protection in an electric power system, in particular to an operation method for preventing bus differential protection from malfunctioning and cutting off a normal bus during charging in T zone of a bus. Background technique [0002] The 220kV system generally adopts double-bus or double-bus double-section wiring. When a bus fails, the bus differential protection action trips the bus tie switch and all branches on the faulty bus. The fault grounding point may be on the main body of the busbar, or it may be at the connection between the line switch and the line current transformer (hereinafter referred to as CT) connected to the busbar. The area referred to by the latter is generally referred to as the T zone (such as figure 1 ). In order to find the specific location of the bus fault, it is necessary to narrow down the scope of the fault point. At the same time, before the fault point of...

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Problems solved by technology

However, since the two busbar switches have been opened, the busbar protection cannot determine which busbar the line is connected to, so the fault current of the branch cannot be included in the "small difference"

Finally, the bus differential protection "has a big difference but no small difference". At this time, some models of the bus differential protection will delay and accidentally trip the 220kV bus coupler and busbar, resulting in a power failure of the 2M busbar in normal operation, and the scope of the accident will expand. Therefore, it is necessary to take precautions measure

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