A differential protection method for a multi-winding phase-shifting transformer with arbitrary phase-shifting angle

Abstract

The invention discloses a differential protection method for a multi-winding arbitrary phase shift angle phase shift transformer. The method comprises steps that currents of windings at a primary side and a secondary side of a transformer are acquired in real time; reduction from a secondary side multi-winding arbitrary angle current of the transformer to a primary side current is carried out through a phase shift synthesis algorithm; current differential amount and braking amount are calculated according to the current after reduction and the primary side current; in combination with the current differential amount and the braking amount, whether action conditions are satisfied is determined, if yes, a differential protection logic locking mark is invalid, differential protection is valid, and the protected transformer is cut off through tripping. The method is advantaged in that the method is suitable for differential protection on the multi-winding arbitrary phase shift angle phase shift transformer, the method is compatible with differential protection of common transformers, strong universality is realized, and the phase shift synthesis algorithm provides a new solution thinking for reduction from the secondary side multi-winding arbitrary angle current of the transformer to the primary side current.

Description

technical field [0001] The invention relates to the technical field of microcomputer relay protection in electrical engineering, in particular to a differential protection method for a multi-winding arbitrary phase-shifting angle phase-shifting transformer. Background technique [0002] High-voltage and high-power frequency converter is an important equipment for industrial control, speed regulation and soft start of high-power motors. The mainstream scheme adopts the power unit series multi-level scheme, and its input terminal needs to be equipped with a multi-winding phase-shifting transformer to rectify and eliminate harmonics, realize electrical isolation from the power grid, and provide matching input voltage for the power unit. With the country's increasing investment in energy saving and emission reduction, high-voltage and high-power inverters have been more and more widely used in high-energy-consuming industries such as electric power, metallurgy, petrochemical, wa...

AI Technical Summary

Problems solved by technology

Compared with ordinary transformers, multi-winding phase-shifting transformers have a special electrical structure, have too many secondary side windings, and have non-integral phase shifts between windings, and the differential protection scheme suitable for ordinary transformers cannot meet the requirements of multi-windings. Differential protection requirements for phase-shifting transformers

If the traditional differential protection scheme is still adopted, the error of the calculated current differential amount and braking amount will be too large, which will reduce the sensitivity and reliability of the protection, and easily cause the protection to malfunction or refuse to operate.

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