Abstract
The paper presents a model-based control strategy for optimal asset management of hydroelectric units in run-of-river hydropower plants. The proposed control strategy aims to operate the unit at the best efficiency while improving water flow management and minimise components wear during frequency containment reserve provision. This approach is designed for a double regulated turbine (Kaplan) with adjustable guide vanes angle and runner blades angle and can be extended to other turbines adopted in run-of-river hydropower plants. The optimal discharge set-point is computed for maximising the frequency containment reserve provision while controlling the head of the river. The best efficiency is achieved by solving a suitably defined convex optimisation problem leveraging a regressive model of the hydraulic characteristics of the turbine and dynamics of the guide vanes and blades servomotors. The discharge set-point combines three terms: the dispatch plan set-point, the regulating discharge, proportional to the grid frequency deviation, and an offset term computed to control the average flow through the machine. Furthermore, a method to forecast the energy required in the following hour for the provision of grid frequency regulation is exploited to enhance the unit’s frequency containment reserve action. The control strategy is validated by simulating a month of operation for the full-scale run-of-river hydropower plant located in Vogelgrun (France) and by comparing the results with operational statistics. Results show the effectiveness of the proposed control strategy able to increase the provision of frequency containment reserve while decreasing the number of movements of the machine components and maximise the efficiency.
Highlights
The need for integrating renewable energy sources in the European power mix has long been ascertained as a fundamental step of the decarbonisation process
By targeting the fulfillment of this gap, this paper proposes a multilevel control strategy that embeds a discharge control framework capable to: (i) select the maximum frequency droop that allows the Hydropower Plants (HPPs) to operate while respecting the discharge set-point, (ii) contain the discharge error during operation, and At the same time, the proposed framework targets efficiency maximisation for the HPP
The simulation results are compared with measured data of the full-size RoR HPP Vogelgrun, owned by Électricité de fullscale run-of-river hydropower plant located in Vogelgrun (France) (EDF), on the Rhine river (France)
Summary
The need for integrating renewable energy sources in the European power mix has long been ascertained as a fundamental step of the decarbonisation process. As volatile renewable sources continue to grow in number and generated power, HPP can support this evolution especially by contributing to the provision of Frequency Containment Reserve (FCR) [2] Part of this reserve can be offered by Run-of-River (RoR) power plants, accounting for 5.93% of the total generated electricity in the ENTSOE area [7]. RoR HPPs are often equipped with double regulated machines (i.e. machines able to control guide vanes and blades opening angles), namely Kaplan turbines These turbines are used thanks to their ability to guarantee high-efficiency values through a wide range of water discharge conditions. The need for tracking the discharge set-point with good accuracy assumes great importance in RoR HPPs [10,11] This results from the necessity of complying with the day-ahead dispatch, and of controlling the river head for safety reasons. The increase of frequency control actions could enlarge the discrepancy between discharge set-point usually established by day-ahead markets and real value of the discharge
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