Frequency-conversion differential protection method for output transformer of static frequency converter system
US9640981B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Jul 1, 2013 |
| Grant date | May 2, 2017 |
| Priority date | — |
| Expiry date | Oct 17, 2033 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H7/045
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A frequency-conversion differential protection method for an output transformer of a static frequency convertor system. The method comprises: a protection device measuring a three-phase current at each side of an output transformer of an SFC system; according to the connection manner of the output transformer, using a triangle side as a reference to conduct phase correction on a star side; at the same time, taking into account different secondary rated currents at each side of the transformer to adjust a balance coefficient of each side, so as to form sampling values of a correcting current and a differential current at each side, and using a startup and shut-down protection algorithm free from frequency influence in generator protection to calculate amplitude values of the correcting current, the differential current and a restraint current; and according to the magnitudes of the differential current and the restraint current, using the ratio restraint differential characteristic to achieve the frequency-conversion ratio differential protection of the output transformer. The present protection method is suitable for large-scale frequency change. Compared with the current quick-bre…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.