The hydraulic power unit (HPU) is used as an oil supply unit, which is connected to several hydraulic cylinders through an external piping system to control the action of multiple sets of valves. The fuel tank, oil pump and accumulator form an independent and airtight power oil source system. The station can be equipped with a PLC control system that controls all internal hydraulic functions and generates signals to be exchanged with the control room (DCS). The control element such as hydraulic servo valve is directly installed on the hydraulic cylinder, through which the high-pressure oil is pressed into the cylinder, or the high-pressure oil is released from it.

Under normal conditions, the oil pump supplies oil to the system, automatically maintains the rated pressure of the system, and realizes the position-preserving function of the valve at any position through the locking of the control valve. In the working state, the hydraulic actuator is controlled by the solenoid valve, the system command signals make the solenoid valve action, control the oil pressure and the energy release of the accumulator, and then control the oil cylinder slide valve, drive the valve through the mechanical transmission mechanism, the implementation of quick closing, normal opening and closing and test control. The high pressure cylinder can be fixed on the stem or can be used directly as an actuator. The excess hydraulic oil is returned to the hydraulic station so that the piping system can control several parallel valves with one feed and one return pipe.