Generator local discharge on-line monitoring device and monitoring method thereof

Abstract

A generator local discharge on-line monitoring device comprises a ceramic capacitive transducer 1, a ceramic capacitive transducer 2, and a high frequency transducer 3 which are connected with a signal conditioner unit 4, the signal conditioner unit 4 is connected with an acquisition card 5, the acquisition card 5 is output via optical fiber and is connected with a network card of an industrial personal computer (IPC) 6, and the IPC 6 is connected with a Web server 7. The monitoring method thereof comprises: taking a signal at location of a neutral point, dividing coupled signal into 1000 segments by the high frequency transducer 3, calculating the maximum value of each segment and the average value, taking the average value as signal dynamic threshold value, then comparing with the absolute value of the neutral point signal, eliminating if smaller than dynamic threshold value, otherwise, comparing again, judging as a discharge point if the polarities are identical, and judging as an interference signal if the polarities are opposite. The invention has the characteristics of good anti-interference effect, high security and easy and convenient application.

Description

[0001] Field [0002] The invention belongs to the field of on-line monitoring of electrical equipment insulation, and in particular relates to an on-line monitoring device for partial discharge of a generator and a monitoring method thereof. Background technique [0003] Partial discharge measurement systems have been used for over 40 years to monitor the insulation condition of generator stator windings. In the past 25 years, the further development of generator partial discharge on-line monitoring technology has gradually become the most extensive and effective insulation condition monitoring method after temperature monitoring. As of 2001, in North America, more than 50% of generators / motors operating above 20MW have installed partial discharge on-line monitoring systems for insulation diagnosis. The reason why there is so much focus on partial discharge monitoring is that partial discharges can damage stator winding insulation. The operation department has organized exp...

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Problems solved by technology

[0006] 2) The designed measurement bandwidth is generally relatively low, up to 30MHz

[0007] 3) The anti-jamming method is relatively simple

[0008] The neutral point of the generator alone is not an ideal monitoring point, because the high-frequency component has been seriously attenuated when the discharge pulse in the stator winding is transmitted to the neutral point through a complex capacitance / inductance network, and the discharge mainly occurs in the high-voltage end winding In addition, at the neutral point, the sensitivity and reliability of the measurement results are greatly reduced due to the aliasing of three-phase discharge signals and the aliasing of discharge signals from other high-voltage equipment.

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