Patent ID: 7134834

Claim:
A method of reducing flow disturbance in a turbine including N input control valves caused by the closing and reopening of one of said valves during periodic operational testing, the method comprising the steps of: determining total mass flow through said N valves for varying valve stem settings; determining total mass flow through N- 1 of said N valves for said varying valve stem settings; determining the difference in total mass flow for said N valves and total mass flow for said N- 1 valves; determining a stem lift flow compensation for each of said N- 1 valves not being tested, where said one test valve is being closed and reopened during operational testing using said difference in flow characteristics between total mass flow for said N valves and total mass flow for said N- 1 valves; as said one test valve is operatively tested, applying to each of said N- 1 valves not being tested, said stem lift flow compensation on an increasing basis as said one test valve is being closed, and on a decreasing basis as said one tested valve is being reopened, the valve lift of said one test valve being used as feedback to control the amount of said stem lift flow compensation applied to each of said N- 1 valves to minimize said flow disturbance, whereby the total mass flow through said N- 1 valves remains substantially the same as the total mass flow through said N valves.