Locking method of preventing generator stator grounding protection misoperation caused by transmission voltage
A stator grounding protection, generator stator technology, applied in the direction of emergency protection circuit devices, electrical components, etc., can solve the transmission voltage blocking logic can not effectively eliminate the transmission voltage, stator grounding error tripping and other problems, to prevent economic benefits and Loss of social benefits, preventing misoperation of stator grounding protection, ensuring rapidity and sensitivity
Active Publication Date: 2015-11-18
ELECTRIC POWER RESEARCH INSTITUTE OF STATE GRID SHANDONG ELECTRIC POWER COMPANY +1
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Problems solved by technology
[0007] According to the statistics of on-site protection actions, for generator sets with grounded arc suppression coils, the current transmission voltage blocking logic adopted by the stator ground protection cannot effectively eliminate the influence of the transmission voltage, and it will still cause false tripping of the stator ground protection
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example 1
[0045] Example 1: Take the misoperation event of a 300WM unit grounded through the arc suppression coil as an example to describe the discrimination process of this method in detail. image 3 It is a logical schematic diagram of the inventive method.
[0046] When a ground fault occurs in the system, the zero-sequence voltage 3U0 on the system side will be greater than the fixed value. At this time, the zero-sequence voltage will be generated in the generator due to the transmission voltage, that is, the transmission voltage. At this time, the stator grounding protection will be blocked.
[0047] When the system ground fault is removed, according to theoretical analysis, the zero-sequence voltage at the generator terminal will enter a free oscillation process, and its frequency is the mixed frequency of the characteristic frequency of the generator system and the system ground fault zero-sequence voltage source frequency (50Hz), which has It is obviously different from the 50H...
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The invention discloses a locking method of preventing generator stator grounding protection misoperation caused by a transmission voltage. For a grounding set via an arc extinguishing coil, the method performs transmission voltage identification and locking according to the difference between a zero sequence voltage frequency and a system power frequency, and the delay reset after the disappearance of a system side zero sequence voltage 3U0, and locks stator grounding protection within set delay time after a system grounding fault is removed, and when the zero sequence voltage frequency is vastly different from 50 Hz, otherwise, the method starts stator grounding protection. Compared with a current method in which a set protective device avoids misoperation only by increasing protection fixed values, the method of the invention can effectively avoid stator grounding protection misoperation when a transmission voltage enters a free oscillation process after a system fault is removed, require no cooperation between the protection fixed values and the amplitude and time of the transmission voltage, ensure the rapidity and sensitivity of stator grounding protection motion, reduce set shutdown caused by misoperation prevention, and effectively avoid electric power plant economic benefit and social benefit loss.
Description
technical field [0001] The invention relates to a blocking method for preventing misoperation of generator stator grounding protection caused by transmission voltage. Background technique [0002] The quick action of the stator grounding protection plays an important role in curbing the development of generator electrical faults and reducing the degree of damage to the generator. With the standardization of stator ground protection setting calculation and the improvement of protection logic, the false operation rate of the fundamental zero-sequence voltage stator ground protection caused by the transmission voltage of the main transformer has been reduced. The protection misoperation of the arc suppressing coil grounding unit accounts for a large proportion. At present, in the generator-transformer protection devices produced by mainstream manufacturers, although the transmission voltage blocking logic is adopted in the stator grounding protection, according to field statis...
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IPC IPC(8): H02H7/06
Inventor 王昕苏欣李乃永井雨刚张国辉孙运涛唐新建杨超赵斌超王军张婉婕黄秉清李玉敦王宏王大鹏苏文博
Owner ELECTRIC POWER RESEARCH INSTITUTE OF STATE GRID SHANDONG ELECTRIC POWER COMPANY