Wear-optimized partial stroke test for all-electric actuation systems

Abstract

Offshore production industry is continuously growing. Access to unexplored resources at the seabed represents a challenge for current technologies to fulfill the demanding standards to guarantee safe and pollution-free solutions. All-electric actuation systems arise as an alternative for the actuation of Emergency Shutdown valves in subsea x-mas trees. Partial Stroke Test (PST) corresponds to a diagnosis test that actuates all-electric actuation systems by partially opening/closing the valve. The novelty of this paper lies in a wear-optimized PST approach to diagnose all-electric actuation systems, evaluated through experimental tests. The PST software is designed and implemented in the actuators controller, keeping the system complexity level unaltered. Torque vs position graphs are live generated while varying parameters such as valve travel, operation modes, and process fluid. As conclusion, the PST approach implemented on all-electric actuation systems has a higher diagnostic coverage over the state of the art for a Normally Closed operation mode by detecting valve leakage through pressure estimation. For a Normally Open operation mode, the diagnostic coverage reaches the state of the art without additional hardware. The results are obtained with a PST that does not unseal the valve, avoiding the most critical moments that add wear to it.