Overall test and construction method of differential protection system of large-scale transformer

Abstract

The invention discloses an overall test and construction method of a differential protection system of a large-scale transformer, which comprises the steps of: firstly, short-connecting an appropriate position at the low-voltage side of the transformer with a bus bar by using a short circuit clamp and utilizing the characteristic of short-circuit impedance of the transformer, and arranging a low-voltage power supply at the high-voltage side of the transformer so as to obtain short-circuit large current in a primary circuit of the differential protection system of the transformer; then, clamping the current of all phases in a differential current secondary circuit of a relay protecting screen by a double-pincerlike phase meter, recording the phase differences and values of all phases, and comparing with all phases of current of the differential circuit of a synthetic microcomputer protection device; and displaying the numerical value on the double-pincerlike phase meter, and outputtinga tripping signal when the numerical value reaches a certain operating value so as to realize the overall test of the whole differential protection system of the transformer. In the test method, lines do not need to be disassembled or assembled, and any primary circuit or secondary circuit is not changed; and the test method is characterized by simpleness, convenience and high efficiency.

Description

technical field [0001] The invention relates to a method of testing electrical protection systems for transformers. Background technique [0002] In the power system, the whole set of tests on the electrical protection system of large transformers is a key link in the installation and commissioning of large transformers. At present, the load test method usually used in the differential protection test of large transformers, that is, when the system is put into the system for the first time, the differential protection tripping function of the microcomputer protection device is withdrawn, and after the transformer is powered on, it is deactivated after it is fully charged (to avoid malfunction) , and then let the transformer take part of the load required for the test, measure the hexagonal diagram, and measure the unbalanced voltage or current of the differential current circuit at the same time. Use this to confirm that the wiring, polarity, and setting values ​​of the sec...

AI Technical Summary

Problems solved by technology

This test method has obvious limitations and defects for the whole set of tests on the differential protection system of large main transformers: first, it is necessary to obtain a large fault current of thousands of amps, the capacity of the test equipment is limited, and the capacity of the conventional large current generator Only 6KVA / 1000A; Secondly, the differential protection requires the protection range between the three-phase current transformers on the high-voltage side and low-voltage side of the main transformer, and the three-phase current transformers on the high-voltage and low-voltage sides must simultaneously output a certain phase and amplitude value of current

However, this method has the following disadvantages: First, it is limited to the operation test of the secondary circuit of the transformer, and does not reflect the test method for the large current of the primary circuit; it has considerable limitations for large-scale transformer systems, because the current is large, so reliable short circuit And convenient short circuit is an important feature to achieve good and fast

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