8 research outputs found

    Benefits of battery hybridization in hydraulic turbines. Wear and tear evaluation in a Kaplan prototype

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    Kaplan turbines are nowadays used to provide Frequency Containment Reserve (FCR) to the grid due to their fast capacity to regulate their power maintaining high efficiency. However, this continuous power regulation increases the wear and tear of the regulation system considerably. To reduce the amount of movements in the regulation servomotors, and thus their wear and tear, a new technology is being investigated within the frame of the European project XFLEX Hydro. This new technology is based on hybridizing the hydro unit with a small size battery in parallel, this one being in charge of compensating the small frequency fluctuations in the grid by providing or absorbing power. In this paper, the benefits of the implementation of this new technology are evaluated. A Kaplan turbine prototype located in Vogelgrun, France, has been hybridized and different parameters have been monitored while the unit was working in hybrid mode and in normal standalone hydro mode. Wear and tear of the regulation system have been compared for both hybrid and standalone hydro modes. A reduction of about 25% in servomotors mileage and of 50% in fatigue damage have been obtained by hybridizing the unit.Peer ReviewedPostprint (published version

    Hybridization of a RoR HPP with a BESS—The XFLEX HYDRO Vogelgrun Demonstrator

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    In the XFLEX HYDRO Vogelgrun demonstrator, a run-of-river hydropower plant, the hybridization of one turbine-generator unit with a battery energy storage system is being investigated. This paper describes the integration methodology of the hybrid control algorithm without replacing the existing speed governor of the unit. Furthermore, the comparison of the performances of a non-hybrid and hybrid unit is discussed, and first experiences gained during the operation and monitoring of the hybrid operating mode are presented.This work has been realized with the participation of INES.2S. David ValentĂ­n and Alexandre Presas acknowledge the Serra HĂşnter program. The corresponding author would like to express his gratitude to Nicolas Ruchonnet for his contributions during the revision.Postprint (published version

    CFD simulations of hydraulic short-circuits in junctions, application to the Grand’Maison power plant

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    In the framework of the XFLEX HYDRO H2020 European Project, the pumped storage power plant of Grand’Maison (France), owned by Electricit´e De France, focuses on the implementation of the hydraulic short-circuit (HSC) operating mode. This mode increases the flexibility in pumping mode, which helps the integration of intermittent energies. Grand’Maison is divided into two power houses: the first features four Pelton turbine units and the second eight reversible pump-turbines units. A trifurcation splits the flow into three penstocks, each is then split into two branches that feed each power house. The HSC operating mode, which consists in operating the pumps and the Pelton turbines simultaneously, changes the flow paths in the junctions compared to the pump mode. The power plant was not designed to operate in HSC mode over a long duration, therefore an assessment of its feasibility is necessary. 151 computational fluid dynamic simulations are carried out for two bifurcations and one trifurcation. The numerical simulation results show that the local head losses in HSC mode represent less than 1% of the gross head. No flow instabilities are observed at the bifurcations contrary to the trifurcation. Additional analyses are required to better understand the flow in the trifurcation

    Assessment of Power Swings in Hydropower Plants Through High-Order Modeling and Eigenanalysis

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    POWER plants are subject to introduce disturbances in the power grid, resulting from interactions with the dynamical behavior of the energy source subsystem. In the case of hydropower plants when used to compensate for variations of power generation and consumption, instabilities or undesirable disturbances may arise. They may be caused by phenomena such as part load vortex rope pulsations in the draft tube of Francis turbines. This may affect the dynamical behavior of the power plant and lead to troublesome interactions with the grid. This paper presents a case study of an existing hydropower plant that illustrates the effects of pressure pulsations due to vortex rope precession on the draft tube of Francis turbines. It also showcases possible solutions to the mitigation of the effects of this disturbing hydraulic phenomenon over the operation of the generators and electrical system. The investigated system is a 1-GW hydropower plant (4 Ă— 250 MW units). The assessment of the power swings is performed through modal analysis combined with frequency-domain and time-domain simulations, which are then compared with onsite measurements

    Influence of Starts and Stops on the Aging of Hydroelectric Generator Stators by Thermal Cycling: Empirical Study and Accelerated Lifetime Model

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    International audienceDue to the deregulation of the energy market and the integration of renewable energies, hydropower plant operators are faced with an increasing number of start and stops and load changes that can reduce the life of equipment. This paper proposes to assess the influence of the start and stop cycles on the ageing of stators in hydroelectric generators. In a first step, different modes of generator degradation are identified. The most affected component by start and stop cycles is the stator insulation,because of the thermal stress induced by these cycles, and the insulation default is considered to be the first cause of a premature end-of-life. The stator lifetime is first estimated using a Weibull analysis on the winding replacement dates recorded on a large number of units subject to a variable number of start and stop cycles per day. The results show that there is a significant difference in lifetime between installations subject respectively to a high or a lower number of start and stop cycles. As the degradation of the generators' insulation is mainly due to thermal stress, a model using Coffin Manson's law is then used to explicitly take into account this stress and to determine the acceleration factor that allows predicting the reduction of the stator's lifetime due to thermal cycling. The proposed accelerated model is used on actual temperature monitoring data and the results show that the value of the acceleration factor is greater than one and increases with the cycles frequency which means that the life of the generator stator decreases as the number of starts and stops per day increases

    Effect of start and stop cycles on hydropower plants: modelling the deterioration of the equipment to evaluate the cycling cost

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    International audienceAbstract With the high energy demand, renewable energies emerged and the deregulation of the energy market appeared in the late ’90. These types of energies are intermittent and can produce high fluctuations in the power grid because they are connected only in certain weather conditions (for example: solar energy can be produced only by day and wind energy only when it is windy). Hydropower energy is recognized for its flexibility in responding to the demands of the network in order to maintain a constant level of energy and to guarantee the security of the electrical network. Nowadays, the hydropower plants are the main provider of energy adjustments thanks to a high number of start and stop cycles (which can sometimes be around 6 per day), the fast variations in load and the use of PSH (pumped-storage hydropower). But these rapid changes in the production conditions of hydroelectric power plants lead to high stresses on the components and consequently to faster degradation (mechanical, electrical, thermal, hydraulic, etc.). This work focuses on the design of a methodology that relies on auditable methods to estimate the cost of start and stop cycles and presents three complementary, representative (by equipment), reproductible (can be applied by different operators) methods based on explicit assumptions and validated by experts and in function of the available data in order to estimate the degradation of the main components of the hydropower plant (shut-off valve, runner, generator, transformer and circuit-breaker). These methods are based on the main degradation phenomena. The first method uses on-site measurements to study the fatigue on runners, the second method uses a reliability law to estimate the lifetime of generators and a predictive model using online temperature measurements and the last method uses expert judgement due to the lack of measurements on the equipment