Reserves of Turbine Generator of Power Unit for Compensation of Magnetization Power of Unit Transformer

The impact of increasing geoinduced currents on the mode of reactive power output of the “turbine generator (turbogenerator) - unit transformer” power unit of a thermal power plant into an adjacent electrical grid has been studied. The authors show that the main harmonic of the magnetization current of a unit transformer is in charge of overloading the turbogenerator with reactive power. The dependences of the reactive power of the turbogenerator of the power unit at different active loads and the setpoint of the automatic voltage excitation controller are defined; it makes it possible to estimate the turbine generator reserves for compensating the magnetization power of the unit transformer when the magnetic system is saturated. The quantitative estimates of the reactive power reserve have been obtained using the example of the TVV-320 turbogenerator to compensate for the magnetization power of a unit transformer with increased geomagnetic activity. It is shown that it is possible to additionally increase the reactive power of the turbogenerator by correcting the setpoint of the automatic voltage excitation controller and unloading the turbogenerator by active power. It is concluded that the stator current overload of the turbogenerator is possible during increased geomagnetic activity, which can result in the activation of the maximum current protection of the power unit “unit turbogenerator - unit transformer” for the disconnection and disruption of the stability of the adjacent electrical grid.