Flow Constraints for Maintenance#

To increase the accuracy of electricity generation estimates, certain real-world constraints such as, minimum and maximum flow constraints and annual and 5 yearly maintenance constraints, have been added to restrict the allowable flow through the turbine. Anuual maintenance and 5 yearly can be activated or deactivated using flags, ‘annual_maintenance_flag’ and ’major_maintenance_flag’, respectively.

Flow Constraints for Design#

The ‘minimum_turbineflow’ and ‘minimum_turbineflow_percent’ parameters can be used to declare lower limit of flow, and can be either a cfs value (minimum_turbineflow) or a percentage of the design flow (minimum_turbineflow_percent). If neither of these parameters are defined by the user, Hydrogenerate assumes 10% of design flow as the minimum admissible flow for power generation. The maximum flow through the turbine is limited to the design flow (calculated internally or user-defined using ’design_flow’). By default, the minimum and maximum flow constraints are always active.

Workflow#

Once design flow is calculated and turbine type is determined, the flow and maintenance constraints are executed in the following order:

  1. Maximum flow constraint: Limits the maxmimum permissible flow through the turbine to the design flow value.

  2. Minimum flow constraint: Limits the minimum flow through the turbine to the specified minimum value. If the minimum value is not specified, the program assumes 10% of design flow as the minimum flow.

  3. Major maintenance constraint: Major maintenance is assumed to last for 2 weeks every 5 years. This constraint limits the flow to 0 during the 2 week that have the lowest flow in one year.

  4. Anual maintenance constraint: Annual maintenance is assumed to last for 1 week annualy. This constraint limits the flow to 0 during the week of the lowest flow in one year. If a year is selected for Major maintanence, annual maintenance is not performed.

The modified turbine flow generated by applying the above constraints is then used for power output calculations.