A Generator-Transformer Overexcitation Protection Method Based on Half-Wave Integral Algorithm

Abstract

The invention discloses a generation-transformer group overexcitation protection method based on a half-wave integral algorithm. The generation-transformer group overexcitation protection method basedon a half-wave integral algorithm uses a half-wave integral accumulation algorithm to directly connect the secondary side voltage of a voltage transformer to a CPU, and then calculates the overexcitation multiple. The generation-transformer group overexcitation protection method based on a half-wave integral algorithm no longer uses a complicated and cumbersome analog circuit susceptible interference, and can completely avoid the problems caused by the pre-engineering analog circuit. The half-wave integral accumulation method implemented by software is realized by a computer program, thus being convenient and flexible, and being easy to modify in the field. The generation-transformer group overexcitation protection method based on a half-wave integral algorithm improves the sensitivity ofoverexcitation protection to voltage frequency variation, ensures the accuracy and stability of the overexcitation multiple calculation when the frequency variation in the protection measurement frequency range is large, and improves the reliability of the overexcitation protection.

Description

technical field [0001] The patent of the invention relates to the realization of the software method of the over-excitation protection technology of the generator-transformer unit, and is especially suitable for occasions where electromagnetic signal interference is relatively large, and belongs to the technical field of relay protection. Background technique [0002] The over-excitation protection method of the generator transformer set used in the prior art is to transmit the secondary phase-to-phase voltage of the voltage transformer at the generator end or the high-voltage side of the transformer to the unique U / f measurement circuit in the relay protection device. This circuit is usually integrated on the CPU of the relay protection device, including intermediate correlations, voltage transformers, rectification circuits, etc. The over-excitation multiple measured from this is used as the over-excitation protection criterion, which is a low-pass filter-based Over-excita...

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Problems solved by technology

[0004] 1. The protection device separately configures the circuit and the corresponding sampling channel for over-excitation protection signal collection. The hardware is cumbersome, and it is not easy to replace when the circuit fails; usually it needs to be shut down for replacement, and the cost is relatively high.

[0005] 2. After the device is put into operation on site, the electromagnetic interference of the protection device, the aging of components and other factors will cause the measured value of n to deviate or shake greatly, which may easily cause protection misoperation

[0006] 3. The sensitivity to the voltage amplitude change transmitted by the voltage transformer is high, and the calculation accuracy of n is high, but the sensitivity to frequency changes is poor, and the calculation accuracy of n is poor, especially when the frequency deviates from the rated value. The measured over-excitation multiple error increases significantly, and it is easy to cause protection malfunction

[0007] 4. In the projects that have been put into operation, the frequency tracking measurement method mainly uses hardware circuits, which are realized through filter shaping circuits and phase-locked loops. The cost is relatively high, and the implementation process is relatively complicated, which is contrary to the development direction of miniaturization of microcomputer protection devices.

[0008] Therefore, the existing low-pass filter over-excitation protection method cannot fully and effectively protect generators and transformer equipment

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