Turbines are used to extract energy from flowing water and convert it using a generator into electricity. Turbines receive a great deal of attention in transient analysis because of potential problems in startup and shutdown [see modeling Hydraulic Transients in Hydropower Plants]. Users also want to estimate the amount of energy that can be generated and the value of that energy. Turbine energy generation is covered in Scenario Energy Cost Manager.

Unlike transient analysis where a great deal of data is required to describe turbine performance, in a steady/EPS model a turbine can be described by a head loss vs. flow curve and an overall (water-to-wire) efficiency. These data are entered using the Turbine flex table.

To create a turbine head loss curve, pick the ellipse button in the column labelled "Turbine Curve". A turbine curve dialog will open. The user should enter at least two points with the head loss increasing with flow. When done select OK.

The other input which is needed only if energy generation is going to be calculated is the overall efficiency of the turbine and generator. While the efficiency does vary slightly with flow and energy generation, most turbine operators try to run at a roughly constant flow so that using an average efficiency is a reasonable approximation. There may be control valves around a turbine such that if the flow is too great, excess flow bypasses the turbine or if the flow is too low, the turbine shuts down and the flow bypasses through a PRV.

The logic in the turbine element is applicable to both single purpose turbines and PAT's (pumps as turbines). If a PAT is to be run in both directions, it is necessary to model it as a separate pump and turbine in parallel in different directions.