METHOD OF DIFFERENTIAL PROTECTION WHEN CONVERTING FREQUENCY FOR OUTPUT TRANSFORMER SYSTEM WITH STATIC FREQUENCY CONVERTER Russian patent published in 2016 - IPC H02H7/45 

FIELD: electrical engineering.

SUBSTANCE: invention can be applied to electrical engineering. According to the method of differential protection when converting frequency for output transformer system with static frequency converter (SFC) protective device measures the three-phase current on each side of the output transformer system with SFC. According to the output transformer winding connection circuit side windings which are connected in triangle is used as a reference for performing phase correction on the side of the winding of which are connected in star. Considering the fact that the secondary rated currents of transformer on each side are different, balance coefficient on each side is adjusted to calculate the discrete values of correcting current of each side and imbalance current. Algorithm of protection of start-up and shutdown of the generator, not depending on frequency, is used for calculation of correction current amplitude values, imbalance current and brake current. Differential protection when converting frequency for output transformer is carried out by means of braking of differential characteristics in compliance with values of imbalance current and brake current.

EFFECT: technical result is improvement of reliability and sensitivity of protection.

4 cl, 4 dwg