Valve drive device and steam turbine system

A valve drive device that is configured to drive a regulating valve that is configured to regulate a flow rate of steam in a flow path which is configured to supply the steam into a casing of a steam turbine, the valve drive device comprising:

• a hydraulic cylinder that is configured to drive the regulating valve;
• an actuator that is configured to supply hydraulic oil to the hydraulic cylinder;
• and
• a connection pipe through which the hydraulic cylinder and the actuator communicate with each other and the hydraulic oil flows, wherein
• the hydraulic cylinder includes a cylinder body formed in a cylindrical shape and to which the hydraulic oil is supplied, a piston disposed inside the cylinder body and configured to move in a central axis direction of the cylinder body by the hydraulic oil supplied to the cylinder body, and a cylinder base connected to the cylinder body and on which the cylinder body is placed in a state where the central axis direction is coincident with a vertical direction,
• the valve drive device further comprises:
• a hydraulic oil supply line that is configured to supply the hydraulic oil to the actuator;
• a communication pipe connected to the hydraulic oil supply line and communicating with an inside of the cylinder body on a side opposite to a position where the cylinder base is connected to the piston in the central axis direction;
• and
• an on-off valve disposed in a connection portion between the hydraulic oil supply line and the communication pipe and configured to switch a supply destination of the hydraulic oil to the hydraulic oil supply line or the communication pipe, and
• the cylinder base has a hydraulic oil flow path portion connected to the connection pipe and through which the hydraulic oil flows.