Hydraulic drive valve monitoring device

A hydraulic drive valve monitoring device for monitoring a hydraulic drive valve device including a valve body installed in a flow path of working fluid introduced into a turbine and a valve drive provided to change an opening degree of the valve body by an action of a control oil, the hydraulic drive valve monitoring device comprising:

• a determination part, the determination part including an arithmetic unit and a memory, the memory configured to store a program that, when carried out by the arithmetic unit, causes the determination part to determine whether there is a sign of failure in the hydraulic drive valve device;
• a failure cause identifier configured to identify, when the determination part determines that there is a sign of failure in the hydraulic drive valve device, a cause of the failure determined by the determination part;
• and
• a failure cause display configured to display the cause of the failure identified by the failure cause identifier, wherein:
• the valve drive comprises:
• a piston provided at an operation rod which operates the valve body part;
• an oil cylinder housing the piston in an internal space, the internal space being divided by the piston into a first hydraulic chamber and a second hydraulic chamber;
• and
• a closing spring urging the valve body part in a closing direction, and
• is configured to execute an opening action of the valve body by supplying the control oil to the first hydraulic chamber and execute a closing action of the valve body by draining the control oil as a drain oil from the first hydraulic chamber;
• the valve body includes a parent valve element and a child valve element, and is configured so that the child valve element starts to open when the parent valve element is in a fully-closed state and the parent valve element starts to open when the child valve element becomes a fully-open state;
• the determination part is configured to make the determination based on a pressure of the control oil applied to the first hydraulic chamber when starting to open the valve body part, and on a result of comparison between a transition of a working fluid pressure measurement value obtained by measuring a pressure of the working fluid flowing into the valve body and a transition of a working fluid pressure reference value set for the pressure of the working fluid flowing into the valve body, when the opening degree of the valve body is changed;
• and
• the failure cause identifier, in a case where the pressure of the control oil applied to the first hydraulic chamber when starting to open the valve body is lower than a first correct value,
• (A) identifies that a decrease in spring force of the closing spring is the cause of the failure when a value by which the working fluid pressure measurement value varies when starting to open the valve body is a second correct value, and
• (B) identifies that the child valve element has the cause of the failure when the value by which the working fluid pressure measurement value varies when starting to open the valve body is lower than the second correct value.