METHOD OF CONTROLLING REACTOR-THYRISTOR CONTROL DEVICE OF POWER TRANSFORMER Russian patent published in 2025 - IPC H02M5/257 H02P13/06 

FIELD: electrical engineering.

SUBSTANCE: invention relates to electrical engineering, in particular to electric power systems. Voltage regulation is divided into three levels – nominal, intermediate and maximum, where the rated voltage level at the power transformer input and at the substation load is set by the power transformer transformation ratio with the high-voltage switch turned on and both the main and additional thyristor keys completely closed, as well as with switched off three-phase contactor, main, intermediate and additional reactors at rated voltage in network and rated load. Intermediate level of voltage control on the high side of the power transformer is set by the total resistance of the intermediate and additional reactors during combined operation of both the main and additional thyristor switches, which bypass three-phase contactor and high-voltage switch at intermediate voltage level in network and rated load. Maximum level of voltage regulation is set by total resistance of the main, intermediate and additional reactors with the three-phase contactor switched on and completely closed main and additional thyristor keys, as well as switched off high-voltage circuit breaker at this level of network voltage and rated load. Intermediate level of voltage regulation is divided into two ranges – upper and lower. Retention of rated voltage at consumers at upper voltage control range can be divided into two subranges – upper and lower voltage control subranges. Maintaining voltage at consumers at the specified value at the lower range of voltage regulation is performed by additional thyristor keys and inductive resistance of the additional reactor with switched off three-phase contactor and high-voltage switch, as well as completely closed main thyristor keys. At three levels and two ranges of voltage regulation, a dead zone is introduced to change the conducting state of both the main thyristor keys and additional thyristor keys, at which the positive voltage deviation on the load does not exceed one percent of the degree of voltage regulation of one or another level or voltage regulation range.

EFFECT: improvement of energy indicators of power transformer and electric power consumers in stationary and dynamic processes due to expansion of method of switching on and off of power transformers, level and range of voltage regulation, as well as improvement of non-sinusoidal voltage at upper and lower ranges of voltage regulation on the high side of power transformers of the substation.

1 cl, 4 dwg