José R. Wilhelmi

Optimal short-term operation and sizing of pumped-storage power plants in systems with high penetration of wind energy

In this paper the short-term optimal operation of an electric system comprising several thermal power plants and one pumped storage plant is studied in several scenarios of power demand and wind penetration in order to draw conclusions about the contribution of the pumped storage plant to system operation costs. A mixed integer linear programming model is used to obtain the optimal hourly thermal, hydro and pumping powers so that the production cost of the entire system is minimized. An aggregated piecewise linear hourly production cost curve is used to represent the thermal generation; the marginal production cost varying as a function of the power generated according to the slope of each piecewise linear segment. Main design parameters of the pumped storage plant are not considered fixed in the model but rather they are obtained in the solution with the purpose of drawing conclusions about the plant optimal sizing.

Control of a run of river small hydro power plant

Nowadays, new small hydro power plants are being built all over the world. In most cases, these power plants lack significant storage capacity; therefore the more adequate control strategy is to keep constant the water level at the intake basin to capture the maximum amount of energy from the river flow. In this paper, the control of a diversion run of river hydro plant is considered. A practical criterion for tuning the gains of the PI controller is proposed. The influence of turbine operating point on controller gains is analyzed. Finally, the results are applied to a model of a typical hydropower plant to verify that the tuning of the PI controller allows a stable and suitable control of the power plant.

Stability Analysis of a Run-of-River Diversion Hydropower Plant with Surge Tank and Spillway in the Head Pond

Run-of-river hydropower plants usually lack significant storage capacity; therefore, the more adequate control strategy would consist of keeping a constant water level at the intake pond in order to harness the maximum amount of energy from the river flow or to reduce the surface flooded in the head pond. In this paper, a standard PI control system of a run-of-river diversion hydropower plant with surge tank and a spillway in the head pond that evacuates part of the river flow plant is studied. A stability analysis based on the Routh-Hurwitz criterion is carried out and a practical criterion for tuning the gains of the PI controller is proposed. Conclusions about the head pond and surge tank areas are drawn from the stability analysis. Finally, this criterion is applied to a real hydropower plant in design state; the importance of considering the spillway dimensions and turbine characteristic curves for adequate tuning of the controller gains is highlighted.

Contribution to load-frequency regulation of a hydropower plant with long tail-race tunnel

In this paper, a hydroelectric power plant with long tail-race tunnel has been modelled for assessing its contribution to secondary regulation reserve. Cavitation problems, caused by the discharge conduit length, are expected downstream the turbine where low pressure appears during regulation manoeuvres. Therefore, governors gains should be selected taking into account these phenomena. On the other hand, regulation services bidden by the plant operator should fulfil TSO (Transmission System Operator) quality requirements. A methodology for tuning governor PI gains is proposed and applied to a Hydro power plant in pre-design phase in northwest area of Spain. The PI gains adjustment proposed provides a proper plant response, according to some established indexes, while avoiding cavitation phenomena.