Backwater Effect over Tailrace Water Level in Cascade Hydropower Plants

Abstract. Hydropower energy, the main renewable energy source in West Africa, contributes to more than half of the Togo and Benin National electrification. This resource highly depends on water availability in rivers or reservoirs. The water availability heavily relies on climate patterns of the area. In the climate change context, the sustainability of hydropower plants is at risk. This work aims to assess the sensitivity of the Nangbeto hydropower plant to multiyear climate variability using statistical analysis. The results show that energy generation at Nangbeto hydropower is more modulated by four main variables namely inflow to reservoir, water level, rainfall of the actual and the previous year. The energy generation is found to be strongly and significantly correlated to inflow to reservoir, water level, and rainfall. Overall, the Nangbeto hydropower generation is more sensitive to inflow which is controlled by climate variables (rainfall, temperature) and land use/cover change. Therefore, the probable future change in these variables is suggested to be deeply investigated.

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Hydropower Plants Frequency Regulation Depending on Upper Reservoir Water Level

Energies ◽

10.3390/en12091637 ◽

2019 ◽

Vol 12 (9) ◽

pp. 1637 ◽

Cited By ~ 3

Author(s):

Platero ◽

Sánchez ◽

Nicolet ◽

Allenbach

Keyword(s):

Water Level ◽

Power Quality ◽

Frequency Regulation ◽

Reservoir Water ◽

Reservoir Water Level ◽

Hydro Power ◽

Control Frequency ◽

Hydropower Plants ◽

Power Injection ◽

Current Water

This paper presents a novel method of hydro power plant operation, based on the control of the injectors’ or wicked gates opening time as a function of the upper reservoir level. In this way, a faster power injection, depending on the current water level on the upper reservoir, could be achieved. When this level is higher, the opening time could be shorter; hence, hydropower ramps could be steeper. Due to this control, frequency excursions and load shedding trips are smaller, thus the power quality is enhanced. This method has been tested and validated by computer simulations in a case study located in El Hierro island, Canary Archipelago (Spain). The simulations made show significant improvements, dependent on upper reservoir water level, in power quality.

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Dynamic Water-Level Regulation at Run-of-River Hydropower Plants to Increase Efficiency and Generation

Water ◽

10.3390/w13212983 ◽

2021 ◽

Vol 13 (21) ◽

pp. 2983

Author(s):

Stephan Heimerl ◽

Niklas Schwiersch

Keyword(s):

Water Level ◽

Discharge Rate ◽

Energy Transition ◽

Operating Regime ◽

Hydropower Plant ◽

Optimization Approach ◽

Hydropower Plants ◽

Discharge Duration ◽

Run Of River ◽

Water Level Regulation

In times of the energy transition and the intensified expansion of renewable energy systems, this article presents an optimization approach for run-of-river power, i.e., dynamic water-level regulation. Its basic idea is to use river sections influenced by backwater more evenly via the operating regime of a hydropower plant. In contrast to conventional dam and weir water level management, the head of the reservoir is not shifted toward the weir while the discharge rate increases but is kept in position by temporarily raising the water level. This generates a greater head for higher discharge rates of an operating regime. As can be shown using an example, this has a direct effect on the performance and, in interaction with the discharge duration curve, on the annual work of the plant. The dynamic water-level regulation, thus, represents an environmentally compatible, energy-efficient optimization for run-of-river hydropower plants.

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