Abstract: To solve the practical problem that the PT value of the collected bus cannot be fixed when calculating the real-time power on the high-voltage side of the main transformer of each unit after the unit-connected bus switching in a double-bus power station, a real-time calculation method for the output power on the high-voltage side of the main transformer based on double-bus switching is proposed. The AC module of the UC630 full-synchronization measurement and control device is connected to the current transformer (CT) and the PTs of the two bus sections. The DI module of the UC630 full-synchronization measurement and control device is connected to the position auxiliary node signals of the No.I isolating switch and No.II isolating switch. The UC630 full-synchronization measurement and control device is connected to the telecontrol host through a network switch, and the telecontrol host is connected to the dispatching data network via a network cable. This realizes accurate and rapid calculation of the output power on the high-voltage side of the unit's main transformer using the existing PT equipment on the bus.