NOVELTY - The medium has instructions for monitoring a voltage of a set of auxiliary buses (26a, 26b), and controlling power factor of an auxiliary power system to have a preset power factor value. The control of the power factor of the system is stopped and the voltage on the affected bus is controlled to move the voltage back into the preset range when the bus is affected by a voltage disturbance. The voltage is controlled by increasing/decreasing the reactive power of a set of adjustable speed drives, respectively when the voltage of the bus is below/above the preset range.    USE - Computer readable medium for storing computer-readable instructions for controlling power in an auxiliary power system of a thermal power plant. Uses include but are not limited to coal-fired power plant, nuclear power plant, solar power plant and geothermal power plant.    ADVANTAGE - The adjustable speed drives (ASDs) are controlled by a dynamic voltage controller to suppress transient over-voltages or under-voltages. The reference value of the overall power factor of the auxiliary power system is changed manually by an operator through a human machine interface (HMI) or automatically by the auxiliary power control program, so that the overall reactive power of the auxiliary power system improves the leading phase operation of the generator during peak load hours and during off-peak load hours the overall reactive power of the auxiliary power system improves the lagging phase operation of the generator, thus eliminating the losses and increasing the overall transmission efficiency.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for an apparatus for controlling power in an auxiliary power system of a thermal power plant comprising a set of adjustable speed drives.    DESCRIPTION OF DRAWING(S) - The drawing shows a circuit block diagram of an auxiliary power control program that controls the power factor of an auxiliary power system of the power generation plant by providing steady state voltage regulation and dynamic voltage support.    Auxiliary buses (26a,26b)    Auxiliary power control program (62)    Power factor controller (64)    Dynamic voltage controller (66)    Disturbance detector (68)    Active rectifier unit interface unit (70)