Power transformer winding fault online monitoring device and diagnosis method

Abstract

The invention relates to a power transformer winding fault online monitoring device and a diagnosis method, and belongs to the technical field of power transformer fault diagnosis. The power transformer winding fault online monitoring device is characterized in that the output end of a voltage sensor and the output end of a current sensor are connected to the input end of a synchronous signal sampling circuit, the output end of the synchronous signal sampling circuit and the output end of an ultrahigh frequency sensor are connected to the input end of a signal conditioning circuit, the output end of the signal conditioning circuit is connected to the input end of a DSP (Digital Signal Processor) through an A / D conversion circuit, the output end of the DSP is connected with a PC (Personal Computer) through a CPLD (Complex Programmable Logic Device), and the PC is connected with an alarm. The diagnosis method comprises the steps of acquiring ultrasonic signals at the wall of a transformer oil tank, and finally acquiring coordinates of partial discharge through signal conditioning and A / D conversion and through DSP denoising; acquiring voltage signals and current signals, processing the signals, building an online short-circuit reactance model, acquiring a short-circuit reactance value of each phase winding, comparing the acquired short-circuit reactance value with a corresponding historical fault-free short-circuit reactance value so as to acquire the short-circuit reactance change rate, judging a range, in which the change rate is located, of an upper limit threshold and a lower limit threshold, and judging the winding operating state.

Description

technical field [0001] The invention belongs to the technical field of power transformer fault diagnosis, and in particular relates to an online fault monitoring device and a diagnosis method of a power transformer winding. Background technique [0002] As one of the most important hubs of the power system, the power transformer's safe and reliable operation is directly related to the safety and reliability of the power generation and power supply system. Therefore, the fault detection, maintenance and repair of the transformer are important tasks to ensure the normal operation of the power supply system. . Among all kinds of power equipment, the winding of the power transformer is one of the parts that cause more faults in the power transformer, and the structure and electromagnetic environment of the transformer are particularly complex, and the problem of partial discharge monitoring is also more prominent. Therefore, in-depth research on the detection of transformer faul...

AI Technical Summary

Problems solved by technology

There are also many on-line partial discharge monitoring methods currently used. For example, the ultrasonic detection and positioning method is used to monitor the partial discharge location of power transformers online. This method has certain limitations: when the discharge source is located on the surface of the transformer winding, the test is effective. When it is located deep in the insulation of the transformer, the signal will be difficult to receive; for simultaneous multi-point discharges, how to judge the size of the ultrasonic signal and how to distinguish the ultrasonic signals still needs further work; in addition, this method has strong electromagnetic interference. The accuracy of on-site positioning is not high

The main reasons are: the internal insulation structure of the transformer is complex, and various acoustic media have different attenuation of sound waves and different effects on sound velocity.

The currently used partial discharge monitoring ultrasonic sensors have poor anti-electromagnetic interference ability and low sensitivity; the algorithms in various calculation and positioning methods are not perfect

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