National Research And Development Institute For Energy

The present paper is part of a larger project whose purpose is to develop a new hydrokinetic turbine-generator assembly, suitable for very low head water courses. It presents the experimental results of a turbine–generator physical model, installed on the tailrace of Mihailesti Hydropower Plant. In order to carry out the measurements, a floating structure and an anchoring system was installed on the power plant tailrace. This system also allowed the translation of the assembly between the two shores. A first set of measurements followed the water velocity and depth in the channel at various load values of the hydropower plant units, in order to determine the proper conditions for testing the model. The turbine gives the possibility of blades adjustment at three different angles, 0, 9 and 14 degrees respectively. Therefore, a set of measurements has been performed for each position of the blades. The measured parameters were the electric parameters of the generator such as voltage, current and the power variation with rotation speed. For the blades adjustment of 9 degrees and 1.76 m/s water velocity, the generator reached its maximum power of 500 W. The results retrieved will be used for the optimization and design of a new enlarged scale turbine–generator assembly. They will also be used as input data for the numerical modeling of the generator. Also, the exact knowledge of the channel geometry and flow parameters is valuable in studies preceding testing a prototype in the site.

Rezumat: În lucrare este prezentată metoda Gibson (metoda presiune – timp) o metodologie de măsură utilizată pentru determinarea debitului turbinat la o centrală hidroelectrică. Metoda Gibson nu este foarte cunoscută în România, deoarece această metodă nu a fost aplicată până în prezent pentru determinarea debitului respectiv a randamentului turbinelor hidraulice la centralele hidroelectrice din România. […]

Creating the correct maintenance of the strings that form the electric generators, from a photovoltaic park, it requires scanning of the equipment with thermal vision cameras, in the visible and infrared field, at an optimum angle determined precisely for each location depending on the geographic position and the architecture of the power station. In general, this angle is difficult to maintain from the ground so it is necessary to mount the cameras on a support, or most efficiently on a multi-rotor drone that is very stable and easy to handle. Maintenance using multi-rotor drones and heat sensitive cameras is no longer a novelty and has multiple advantages: low costs, minimization of work accidents, and the data acquired can be analyzed in real time or can be stored for later analysis. But this process also has disadvantages: limited flight autonomy of drones, generated by the hard development of battery technology and a small number of specialized personnel in this field. To minimize these disadvantages, we have developed an automatic recharging system of batteries, without disconnecting them, which allows the automation of the scanning process and offers the possibility of taking control of the drones and from a distance.

The research focus was to develop an off-grid hybrid RES mobile containerized system, combining the energy from the photovoltaic and micro-wind turbine source in order to directly providing the energy via DC-DC power supply. The applicability of the system was intended for irrigation and fertigation, in semi-dry and dry-sub-humid arid climates. The project tackled the most common technologies used in solar photovoltaic and small wind turbine applications combining them in an autonomous hybrid RES system that can be used in agriculture to power directly DC power supply (without the need of DC–AC conversion). During the development of the project an experimental model of the hybrid RES mobile system was deployed using a 2.16 kWp photovoltaic and 600 Wp wind turbine power source combined with a 5.3 kWh battery pack for extended use period. For the photovoltaic panels a mobile mechanical system of the photovoltaic source was developed and patented (no. A00730/12-11-2019) in order to increase the flexibility and maximize power production in real life conditions. Further testing in real file conditions is planned for a yearlong irrigation period in order to validate and further improve the energy management algorithm for the for irrigation and fertigation periods.

The FINEAMIN polyamine treatment is currently being used more and more throughout the world in water-steam-condensate circuits from power and industrial plants using conventional fuels. FINEAMIN is a continuous treatment with volatile amines and film forming polyamines. The product has the role of dispersing existing deposits and protecting the metal from the action of oxygen and carbon dioxide through a film of polyamines. The scientific studies developed by the European Agency for Safety and Health at Work (EU-OSHA) and the American Federal Agency (NIOSH), which is part of the Centers for Discase Control and Prevention (CDC) - the Department of Health and Human Services have included hydrazine in the List of Substances with carcinogenic potential, thus requiring replacement.

The influence of the electromagnetic field on the human body, although still heavily studied, can have long-term negative effects. The static electromagnetic field is generated by a continuous current source and has a current flow characteristic conventionally set + from -. The variable electromagnetic field is produced by the alternating current and has the ability to change its direction over time with a frequency of 50 or 60 Hz. It is considered that the non-hazardous limit value for the magnetic field (according to Federal Office for Radiation Security in Germany) is 100 microT for 50 Hz and 83 microT for 60 Hz. For the electric field, the exposure limit value is 5kV/m. Electromagnetic fields are not attenuated by obstacles The consumption of electricity is accompanied by their prevalence. The paper aims to determine the values of the magnetic field around the conductors traveled by AC and DC and proposals for its mitigation.

The paper shows the importance of trending of partial discharge activity in assessing the insulation condition. It is presented the principle of the measurement method and the quantities that characterize partial discharges and also the criteria utilized for the assessement of the insulation condition of the hydrogenerators. Results of the measurements made on several hydrogenerators are presented, like the variation with time of the two main quantities that characterize the partial discharges, maximum magnitude, Qm and the normalized quantity, NQN over a period of about 10 years. Further, a classification of the insulation condition by 3 main and 2 intermediary categories and the definition of these categories are given. The criteria used for the assessment of the insulation condition are presented in the form of a table: quantitative criteria by the ± NQN and ± Qm values and qualitative criteria for the analysis of the 2D and 3D diagrams. At the end of each set of measurements, an analyze of the insulation condition annual evaluation is made, also a verdict is put, and of course, the recommendations made relating to the maintenance and the decisions that have been taken. The paper ends with several considerations on the method of on-line partial discharges and especially, on the conditions for valid trending activity in time.