Maintenance decision on steam turbine digital electro-hydraulic control system based on risk

As the substitute of mechanical hydraulic governing system, steam turbine digital electro-hydraulic (DEH) control system presents different maintenance characteristics. If the traditional maintenance strategy is still adopted, that is the replacement or inspection time determined just according to overhaul or minimal maintenance standard items, the result is either maintenance cost increasing due to excessive maintenance or reliability decreasing due to deficient maintenance. For the problem, a frame of risk-based maintenance (RBM) decision of DEH system is put forward, the expression method of failure effect and risk is determined, and the optimal maintenance interval of equipment in system is decided by using fault tree algorithm. Take the DEH system of a certain 300 MW steam turbine as example, the maintenance decision is made. It is shown by the instance that this method is feasible and effective, and the decision results can be used as a support for maintenance plan.