Run-of-the-river hydroelectricity

Run-of-river hydroelectricity (ROR) or run-of-the-river hydroelectricity is a type of hydroelectric generation plant whereby little or no water storage is provided. Run-of-the-river power plants may have no water storage at all or a limited amount of storage, in which case the storage reservoir is referred to as pondage. A plant without pondage is subject to seasonal river flows, thus the plant will operate as an intermittent energy source. Conventional hydro uses reservoirs, which regulate water for flood control, dispatchable electrical power, and the provision of fresh water for agriculture. Concept Run-of-the-river, or ROR, hydroelectricity is considered ideal for streams or rivers that can sustain a minimum flow or those regulated by a lake or reservoir upstream. A small dam is usually built to create a headpond ensuring that there is enough water entering the penstock pipes that lead to the turbines, which are at a lower elevation. Projects with

Optimal CAM Computation of Kaplan Turbines Accounting for Wear and Tear Originated by Frequency Control

Francesco Gerini, Mario Paolone, Elena Vagnoni

Nowadays, the importance of providing frequency stability to power systems with hydropower units is significantly increasing due to the growing proportion of volatile renewable energy sources. However, the provision of such services, as frequency containment reserve, inevitably increases the wear and tear, decreasing the performance of the hydraulic machines, especially the Kaplan ones. In view of a growing demand for frequency containment reserve, it is important to quantify the performance decline and occasionally recompute the characteristic curves of the hydraulic machine to update the control system and reduce the efficiency loss. Since this process is usually expensive, as it requires off-line tests, this paper proposes a data-driven method to estimate the performance decrease of Kaplan turbines by leveraging operational recorded data. The proposed approach is applied to compute a new CAM relation for the run-of-river power plant of Vogelgrun. The new CAM, obtained with the proposed method is finally compared with real operational data.

IEEE2021

Improving frequency containment reserve provision in run-of-river hydropower plants

Francesco Gerini, Mario Paolone, Elena Vagnoni

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.

2021

Assessing the potential increase of seasonal energy storage to mitigate the impact of climate change in Switzerland: Case study of the Grande Dixence dam

Pedro Filipe De Almeida Manso, Jérôme François Sylvain Dujardin, Blaise Monay, Anton Schleiss

The total storage capacity of the reservoirs in Switzerland represents only 42% of their annual production of electricity, but secures approximately 100% of hydropower’s contribution to the winter electricity supply. In order to avoid spilling, the storage power plants therefore need to turbine the supplementary inflows like a run-on-the-river plant when the reservoirs are full at the end of the summer semester. This leads to a significant need to import electricity during the winter semester due to lack of production. The storage capacity of the reservoirs located in Valais contains more than 30% of the total live storage capacity in Switzerland and is strategical for the seasonal energy transfer. This paper presents a methodology to assess the potential to increase seasonal storage and then explores this methodology on a case study. The methodology was first developed and tested using recent hydrology and reservoir operation, and then used to explore alternative ways of operating and adapting the hydropower infrastructure when exposed to predictions of future runoff for the coming decades. In fact, from now to the year 2100, the inflows to these reservoirs are expected to vary considerably both in time and space. For instance, an especially significant increase of the yearly inflows due to glacier recession is expected for the 2045-2074 period. This will lead to new opportunities and new challenges in the operational management of the dams. The application of the methodology to the case study of the hydropower scheme of Grande Dixence illustrates two different options to increase the seasonal storage capacity: the creation of a new reservoir further upstream and the heightening of the Grande Dixence dam. The optimal storage capacity that guarantees the best use of the available future inflows and an adequate balance between water abundance in some years and water scarcity in others is computed considering different ways of using the inflows in a range of consecutive years and runoff predictions obtained for three greenhouse gas emission scenarios.

2017

Assessing the potential increase of seasonal energy storage to mitigate the impact of climate change in Switzerland: Case study of the Grande Dixence dam

Pedro Filipe De Almeida Manso, Jérôme François Sylvain Dujardin, Blaise Monay, Anton Schleiss

2017