System and method for hydraulically actuating main and bypass valves of a steam turbine

A system, comprising:

• a steam turbine system having one or more steam turbines;
• a main control system having one or more first hydraulic actuators coupled to one or more main valves, wherein the one or more main valves are coupled to the steam turbine system to control a steam supply to flow through the one or more steam turbines;
• a bypass control system having one or more second hydraulic actuators coupled to one or more bypass valves, wherein the one or more bypass valves are coupled to the steam turbine system to control a bypass of the steam supply to not flow through the one or more steam turbines;
• and
• a hydraulic power unit coupled to the main control system and the bypass control system, wherein the hydraulic power unit comprises at least one of a tank, a pump assembly, an accumulator assembly, a header, or a combination thereof, wherein the hydraulic power unit supplies a common hydraulic fluid as a pressurized hydraulic fluid at a pressure sufficient to operate the one or more first hydraulic actuators to actuate the one or more main valves and the one or more second hydraulic actuators to actuate the one or more bypass valves, wherein the pressure at least meets or exceeds first specifications of the one or more first hydraulic actuators of the one or more main valves and second specifications of the one or more second hydraulic actuators of the one or more bypass valves, wherein the first and second specifications are different from one another;
• and
• a trip system having one or more trip valves configured to control a supply of the pressurized hydraulic fluid in response to a turbine trip event of the steam turbine system, wherein the turbine trip event comprises a pressure drop in the pressurized hydraulic fluid below a pressure threshold.

A method, comprising:

• storing a common hydraulic fluid in a tank of a hydraulic power unit;
• pumping the common hydraulic fluid from the tank via a pump assembly of the hydraulic power unit to provide a pressurized hydraulic fluid;
• storing the pressurized hydraulic fluid via an accumulator assembly of the hydraulic power unit;
• and
• controlling a supply of the pressurized hydraulic fluid to one or more first hydraulic actuators coupled to one or more main valves of a main control system and one or more second hydraulic actuators coupled to one or more bypass valves of a bypass control system of a steam turbine system via a header of the hydraulic power unit, wherein the header is coupled to the pump assembly and the accumulator assembly, wherein controlling the supply comprises:
• controlling the supply of the pressurized hydraulic fluid to at least meet or exceed first specifications of the one or more first hydraulic actuators of the one or more main valves and second specifications of the one or more second hydraulic actuators of the one or more bypass valves, wherein the first and second specifications are different from one another;
• controlling the supply of the pressurized hydraulic fluid to the one or more first hydraulic actuators to actuate the one or more main valves of the main control system to control a steam supply to flow through one or more steam turbines of the steam turbine system;
• controlling the supply of the pressurized hydraulic fluid to the one or more second hydraulic actuators to actuate the one or more bypass valves of the bypass control system to control a bypass of the steam supply to not flow through the one or more steam turbines of the steam turbine system;
• and
• controlling the supply of the pressurized hydraulic fluid via a trip system having one or more trip valves in response to a turbine trip event of the steam turbine system, wherein the turbine trip event comprises a pressure drop in the pressurized hydraulic fluid below a pressure threshold.

A system, comprising:

• a steam turbine system having one or more steam turbines comprising a high pressure turbine coupled to a high pressure steam line, an intermediate pressure turbine coupled to an intermediate pressure steam line, and a low pressure turbine coupled to a low pressure steam line;
• one or more main valves, wherein the one or more main valves comprise:
• high pressure main valves along the high pressure steam line, wherein the high pressure main valves comprise a high pressure main steam control valve and a high pressure main steam stop valve;
• intermediate pressure main valves along the intermediate pressure steam line, wherein the intermediate pressure main valves comprise an intermediate pressure main steam control valve and an intermediate pressure main steam stop valve;
• and
• low pressure main valves along the low pressure steam line, wherein the low pressure main valves comprise a low pressure main steam control valve and a low pressure main steam stop valve;
• one or more bypass valves, wherein the one or more bypass valves comprise:
• high pressure bypass valves along a high pressure bypass line coupled to the high pressure steam line, wherein the high pressure bypass valves comprise a high pressure bypass pressure control valve, a high pressure bypass spray water isolation valve, and a high pressure bypass spray water control valve;
• intermediate pressure bypass valves along an intermediate pressure bypass line coupled to the intermediate pressure steam line, wherein the intermediate pressure bypass valves comprise an intermediate pressure bypass pressure control valve, an intermediate pressure bypass steam shutoff valve, and an intermediate pressure bypass spray water control valve;
• and
• low pressure bypass valves along a low pressure bypass line coupled to the low pressure steam line, wherein the low pressure bypass valves comprise a low pressure bypass pressure control valve, a low pressure bypass steam shutoff valve, a low pressure bypass spray water control valve, and a low pressure bypass spray water isolation valve;
• a hydraulic power unit, comprising:
• a tank configured to store a hydraulic fluid;
• a pump assembly configured to pump the hydraulic fluid from the tank to provide a pressurized hydraulic fluid;
• an accumulator assembly configured to store the pressurized hydraulic fluid;
• and
• a header coupled to the pump assembly and the accumulator assembly, wherein the header is configured to supply the pressurized hydraulic fluid to one or more first hydraulic actuators coupled to the one or more main valves and one or more second hydraulic actuators coupled to the one or more bypass valves of the steam turbine system;
• and
• a controller coupled to the hydraulic power unit, wherein the controller comprises a processor, a memory, and instructions stored on the memory and executable by the processor to control the hydraulic power unit to:
• control the supply of the pressurized hydraulic fluid to at least meet or exceed first specifications of the one or more first hydraulic actuators of the one or more main valves and second specifications of the one or more second hydraulic actuators of the one or more bypass valves, wherein the first and second specifications are different from one another;
• control the supply of the pressurized hydraulic fluid to the one or more first hydraulic actuators to actuate the one or more main valves to control a steam supply to flow through the one or more steam turbines of the steam turbine system;
• and
• control the supply of the pressurized hydraulic fluid to the one or more second hydraulic actuators to actuate the one or more bypass valves to control a bypass of the steam supply to not flow through the one or more steam turbines of the steam turbine system.