Gotowa bibliografia na temat „Micro-alternator”

Micro-hydro power plants (μHPPs) are a major energy source in grid-isolated zones because they do not require reservoirs and dams to be built. μHPPs operate in a standalone mode, but a continuously varying load generates voltage unbalances and frequency fluctuations which can cause long-term damage to plant components. One method of frequency regulation is the use of alternating current-alternating current (AC-AC) converters as an electronic load controller (ELC). The disadvantage of AC-AC converters is reactive power consumption with the associated decrease in both the power factor and the capacity of the alternator to deliver current. To avoid this disadvantage, we proposed two rectifier topologies combined with symmetrical switching. However, the performance of the frequency regulation loop with each topology remains unknown. Therefore, the objective of this work was to evaluate the performance of the frequency regulation loop when each topology, with a symmetrical switching form, was inserted. A MATLAB® model was implemented to simulate the frequency loop. The results from a μHPP case study in a small Cuban rural community called ‘Los Gallegos’ showed that the performance of the frequency regulation loop using the proposed topologies satisfied the standard frequency regulation and increased both the power factor and current delivery capabilities of the alternator.

The paper presents a laboratory micro hydroelectric power plant destined to applicative activities. The hydraulic turbine is a Pelton turbine, rebuilt by fast prototyping in Geomagic Design X and printed on a 3 D printer. The turbine casing and the afferent elements are made in-house. The hydrogenator is synchronous being an alternator from a Dacia vehicle. The hydrogenerator load is constituted by 3 groups of light bulbs. We analysed the working of the micro-hydroelectric power plant in idle run and for different loads. As a result of the analysis we found out that it stably works for different loads and by its open construction it is useful for developing students’ ability to understand the phenomena. The installation designed and executed is useful for the engineering students as the pandemic forbids the thematical visits in hydro-energetic facilities.

Since the fairly high temperature in fire scenes combined with the high temperature of LED, the water-cooling is proposed to solve the challenge of the existing thermal problem of the flashlights used by fire fighter. A Nozzle Light is lighten by a portion of the hydropower in the water passing through a fire nozzle is harvested. The water is used to drive a micro-turbine alternator and generate electrical power to light up LED lighting. When the water is discharged from the fire nozzle, we find that the maximum temperature on Nozzle Light is only increased 1.3°C compared to the 24°C of that without water. It shows that water-cooling effect of large-amount of water indeed lower the temperature increment. The LED operated under lower ambient temperature has higher relative luminous flux and longer lifetime. It reduces the firefighting loadings of firefighters and raises their safety.

Micro-hydro Power Plant (MHPP) is a small-scale power plant that uses hydroelectric power as its driving force, such as irrigation canals, rivers or natural waterfalls using the height of the waterfall (head) and the amount of water discharge. Yeh Dikis River, Banjar Lebah, Tabanan Regency is a supporting location for the construction of a Micro Hydro Power Plant (MHPP) which is useful in planning tourism development around the river. The results of measurements and calculations of the current are 0.381 m3/s with a head of 8.2 m. Through the analysis and calculation results, a crossflow turbine with a capacity of 18.15 kW is obtained. The generator used is an alternator with a rotational speed of 1500 rpm. The energy potential that can be generated with a turbine efficiency of 0.75 and a generator efficiency of 0.9 is 15,516 kW. The investment cost to build a PLTMH located on the Yeh Dikis River, Banjar Lebah Tabanan Bali is IDR 372,593,629. The NPV discount rate used is 10% and 12%, the value becomes IDR 305,254,944.69 and IDR 241,046,517.53. IRR is 37.8% and 46.0%, BCR is 0.82 and 0.65; BEP per unit is obtained by selling 1,284,609 kWh of energy. The construction of a MHPP on the Yeh Dikis River, Banjar Lebah, Tabanan, Bali is said to be feasible and capable of obtaining a return on capital in at least 5 years.

Renewable energy is a naturally available energy source in nature, including wind, bioenergy, geothermal heat, solar radiation, flowing and high-drop water, as well as oceanic motion and temperature changes. Planning for the Micro Hydro Power Plant (PLTMH) in Yeh Dikis Banjar Lebah, Tabanan Regency, utilizes an AC generator as one of the ways renewable energy can be utilized. The literature review and observation methods were employed in this study to determine the turbine rotation speed required to drive the generator and to select the appropriate generator. Yeh Dikis River in Banjar Lebah, Tabanan Regency has a capacity of 30.62 kW, with a crossflow turbine operating at a rotation speed of 539 rpm and a torque of 321.81 Nm. The calculation results indicate that the generator capacity to be used is 21.55 kVA. Therefore, the chosen generator is the Generator Head Alternator with a rotation speed of 1500 rpm, providing an output power of 15.516 kW, a generator current of 31.75 A, and an efficiency of 90%. Since the turbine and generator rotation speeds are not compatible, a mechanical transmission system is required, achieved by designing pulley and belt ratios.

Cette thèse traite des problèmes de stabilité introduits par l'interconnexion d'énergies renouvelables massives dans un micro-réseau isolé. Cette recherche vise à identifier les problèmes liés au sujet, les indices permettant de mieux comprendre ces problèmes, ainsi que la stratégie visant à améliorer la stabilité des microréseaux du point de vue du réseau électrique. Dans la première partie, un état de l'art sur l'évolution de la stabilité du réseau electrique est abordé. Un bref historique de la stabilité du système électrique depuis sa première identification et son évolution a été présenté. Une revue des indices pratiques d’évaluation de la stabilité du réseau est également présentée, y compris ceux que nous proposons. Cette partie est également utile pour analyser le positionnement de cette thèseLa deuxième partie de la thèse présente les efforts pour améliorer la stabilité dynamique des microréseaux caractérisés par une pénétration massive des énergies renouvelables. Les principaux défis et les efforts en cours sont passés en revue, qui ont montré que les solutions actuelles se concentrent sur le maintien de la philosophie d’un réseau électrique classique. Avec l'avènement des énergies plus intermittentes, les efforts actuels se sont révélés coûteux. Par conséquent, une nouvelle perspective est proposée. Ici, les générateurs et les clients sont exposés à des écarts de tension et de fréquence plus élevés, qui sont nécessaires pour maintenir l'équilibre de puissance et la stabilité du microréseau. Cette perspective convient avec le concept de micro-réseau pour réaliser le rêve de l’électricité universelle.Le concept est ensuite développé en une nouvelle stratégie de régulation dans laquelle le rapport de la fréquence et la tension du système sont maintenues essentiellement constant autour de 1 (en per unit). Cette stratégie peut potentiellement être mise en œuvre sur toutes les technologies de grid forming. Les avantages de cette stratégie sont l’assurance que les machines électriques ne sont pas endommagées, la fonctionnalité plug-and-play, la compatibilité avec les technologies actuelles d’onduleurs et l’absence de systèmes de communication rapides. Enfin, la stratégie proposée est facile à mettre en œuvre et ne nécessite pas de révolution en termes d’équipement et de contrôle du réseau électrique. Cette mise en œuvre de ce concept offre un élément de flexibilité très précieux: le temps, qui améliore la résilience et la stabilité d'un microréseau. Cependant, des écarts de fréquence et de tension plus importants se produisent et doivent être acceptés par tous les acteurs du microréseau. Une validation par des simulations numériques en Power Factory et des expérimentations dans une plateforme hardware-in-the-loop en temps réel ont été réalisées avec des résultats satisfaisant
This thesis deals with the stability issues introduced by the interconnection of massive renewables into an isolated microgrid. This research aims to identify the problems related to the topic, the indices to help understand the issues, and the strategy to enhance microgrid stability from the power system point of view.In the first part, a state of the art on the evolution of power stability is addressed. A short history of power system stability since its first identification and how it has evolved is firstly presented. This part also provides a literature review of the power system stability, including its classification, and how it has evolved due to two reasons: the microgrid concept and the trend towards the integration of more inverter-based generation. A review of the practical indices for grid stability assessment is also reported, including the ones that we propose. This part is also useful for analyzing the positioning of this PhD research.The second part of thesis presents the efforts to enhance the dynamic stability of microgrids characterized by massive renewable penetration. The main challenges and the current efforts are reviewed, which have shown that the current solutions focus on maintaining the philosophy of a classical power grid. With the advent of more intermittent energy, the current efforts have proven to be costly. Therefore, a new perspective is proposed. Here, the generating elements and the customers are exposed with higher deviations in voltage and frequency, which are necessary so that that the power equilibrium and the stability of the microgrid can be maintained. This perspective is suitable with the microgrid concept to realize the dream of universal electricity.The concept is then developed into a novel regulation strategy in which the system frequency and voltage are maintained in such a way to keep their ratio essentially constant around 1 (p.u. voltage to p.u. frequency). This strategy can potentially be implemented on all grid forming technologies. The benefits of employing this strategy include assurance that the electrical machinery is not harmed, plug-and-play feature, compatibility with current grid-tied inverter technologies, and no need for fast communication systems. Finally, this proposed strategy is easy to implement and does not require revolution in terms of power system equipment and control. This implementation of this concept provides a very valuable piece of flexibility: time, which enhances the resilience and stability of a microgrid. However, wider frequency and voltage deviations occur and have to be accepted by all the actors within the microgrid. A validation through computer simulations in Power Factory and real-time hardware in the loop experiments has been carried out with satisfactory results

Studying the dynamic behaviour of non-linear complex power systems in a laboratory is very challenging. Early experimental platforms used micro-alternators to emulate the behaviour of fixed steam and hydro turbine models. The micro-alternator is a three-phase synchronous generator with similar electrical constants (in per unit on machine rating) as those typically found in alternators in large power stations. It is an electrical scaled-down model of machines up to 1000 MW rating and is rated between 1 to 10 kVA. Researchers used these micro-machines up to the 90s to study large electric generators’ transient and steady-state performance. The department of electrical engineering at the Indian Institute of Science (IISc) was also very active in experimental research in power engineering. The department still retained two-three kVA and one ten kVA micro-machine sets, but the control panels of these machines became obsolete as the manufacturer of these machines Mawdsley, London, doesnt exist anymore. Advancements in simulation software packages and real-time simulators have primarily replaced the experimental models of electric power systems worldwide. The push for green energy technologies worldwide due to climate concerns has increased the presence of power electronic converters in the power grids. Reduction of overall inertia, frequent occurrence of electromechanical oscillations, electromagnetic transients, and control interaction modes has become a concern for the power grid operators. The need for understanding the physical insights of the oscillatory modes introduced by fast-acting power electronic converters, the need for developing practically feasible control algorithms for mitigating the interaction modes, and the need for developing dispatchability and grid support features like conventional generation sources have triggered the development of laboratory-scale experimental power grids across the world in the past decade. In this thesis, initially, an attempt is made to revive the old 3 kVA micro alternator controls. An IGBT-based buck converter static excitation system has been developed for the micro-alternator. This exciter also incorporates several limiters which were non-existent in the old analog control panels. An under-excitation limiter, overexcitation limiter, and V/Hz limiter as per IEEE standard 421.5 have been designed to protect the micro-alternator during abnormal conditions such as overloading, overheating, and over-fluxing of the machine. A digital time constant regulator (TCR) is incorporated to modify the micro-alternator field’s time constant to mimic large synchronous machines’ dynamics as micro-machine time constants are very small. The detailed tuning procedure of limiters and TCR is discussed to comply with IEEE STD 421.2 and IEEE STD 421.5. Overheating of old micro-machines was observed due to the creation of multiple shortcircuit faults. Hence, a custom 5 kVA micro-alternator is manufactured through a local vendor having parameters like the old machines. A single micro-alternator can represent only one large alternator dynamics, thereby limiting the scalability of the platform. Emulating machines of different ratings using a single micro-machine would undoubtedly boost the capabilities of experimental platforms for investigating conventional and non-conventional source interactions in laboratories. To the best of our knowledge, only one such attempt was made in the literature, where a model reference control algorithm is proposed to mimic any rating alternator dynamics using a doubly excited laboratory micro-alternator. However, doubly excited micro-alternators are non-existent today. A reconfigurable experimental single machine infinite bus testbed using the 5 kVA singly excited micro-alternator is developed reconfigurable options to emulate different types of IEEE Standard excitation systems, standard turbine governor models and different machine parameters. A non-linear output matching control based on the dynamic inversion technique is proposed for emulating the synchronous generators of different ratings with the IEEE standard excitation system and governor turbine models using a single micro-alternator. IEEE Model 1.1 is used for representing the behaviour of large alternators. The singlemachine infinite bus (SMIB) experimental testbed has been used to validate the proposed emulation approach. The dynamics of the synchronous generator model in per unit corresponding to 128 MVA and 192 MVA machines have been physically emulated on the 5 kVA laboratory micro-alternator. Good tracking performance is obtained with the proposed approach under small and large disturbances in MATLAB simulations and experimental evaluations. Using a systematic scaling procedure the proposed emulation approach has been extended to evaluate the possibility of emulating the WSCC 3 machine 9 bus system in the laboratory using MATLAB simulations. The simulation results are found to be very promising in replicating the dynamics of WSCC system using the 5 kVA micro-machines. Emulation of large machine dynamics with different types of turbines, governors, and excitation controls using a singly excited micro-alternator enabling a generalized synchronous machine emulation platform is a first-of-its-kind effort in the literature to the best of our knowledge.

AbstractThe micro gas turbine (MGT) is considered one of the main solutions for the future power generation system to provide secure and stable energy. Thanks to its multi-fuel capability and high values of power-to-weight ratio, it is a suitable candidate for many applications such as Combined Heat and Power (CHP) systems, range extenders, and auxiliary power units. Among these applications, the micro-CHP system benefits from both the electricity and exhaust heat of the MGT for household or industrial process applications. The MGT could be integrated with a heat exchanger to introduce a CHP boiler to the domestic boiler market. To reduce the cost and size of the package and to compete with a traditional boiler the simple Brayton cycle without the recuperator is considered and all of the useful energy in the exhaust gas is transferred to the heat exchanger to provide hot water. To further reduce the cost of the system to compete in the market, off-the-shelf components were adopted in this project. In this article, the development process of this product is presented including conceptual design based on the type and size of the market. It follows with an evaluation of off-the-shelf compressor and turbine modulus from the automotive turbochargers to match the operating conditions. Here, the MGT is designed in a way that can be adapted to the boilers with minimum components change. A high-speed alternator was powered with a tie grid drive/inverter to enable a bi-directional connection of the power unit to the network. A comparison between the product definition and experimental results of a demonstrator prototype is presented which reveals gaps between design and prototype outcomes. Analysis shows that 23% of the power degradation can be recovered by enhancing the cooling. Potential development and improvement scenarios are addressed for future development.

In the paper the authors will present the design and preliminary test results for a distributed electric generating system that uses renewable energy sources for economical load-following and peak-shaving capability in an oil-free, high-speed micro-turboalternator system using compliant foil bearings and a permanent magnet alternator. The high operating temperatures and speeds required to make the Renewable Energy Turbo-Alternator (RETA) an efficient and cost effect system require that oil-free compliant foil bearings be used and that the alternator section be isolated from the turbine. Preliminary simulator testing compares well with design predictions and shows a stable rotordynamic and thermal environment.

In the paper the authors will present the design and preliminary test results for a high specific power (i.e., kW/kg) fully integrated and completely oil-free gas turbine driven electric generating system that operates with commercially available heavy fuel. The oil-free, high-speed micro-turboalternator system achieves high specific power through operating speeds to 180,000 rpm and the use of compliant foil bearings, high performance compressor and turbine and a permanent magnet alternator. The high operating temperatures and speeds require that oil-free compliant foil bearings be used and that the alternator section be isolated from the turbine engine portion of the system. The selected modular design approach, including compressor and turbine aerodynamic design, system thermal management issues and the corresponding impact on rotor bearing system dynamics, will all be presented. The paper concludes with a presentation of preliminary testing results showing stable full speed operation and peak power generated. Data obtained compares well with design predictions both from a rotordynamic and with regard to the cycle efficiency and performance. Conclusions regarding the ability to scale the technology to even smaller systems will also be presented.

In this paper, a test rig for experimentation on a micro gas turbine is presented. The test rig consists of a micro gas turbine Solar T-62T-32, which, coupled with a 50 kVA alternator, can supply electrical energy to a calibrated resistive load bank. Particular attention is paid to the design of the inlet duct for the mass flow rate measurement. The basic issue was to create the intake duct for a micro gas turbine (MGT) test rig, in order to provide precise data about the mass flow rate and the thermodynamic air characteristics in the MGT inlet section. The inlet duct is also designed in order to allow future tests on inlet cooling technologies. The MGT is incorporated in a chassis for noise reduction, the dimensions of which are 540 mm (height), 570 mm (width) and 940 mm (length). These small dimensions lead to problems with the insertion of the duct. Moreover, the intake of the compressor is not axial but radial, and this means that a volute must be foreseen to convey the flux into the MGT. Several shapes of volute are analyzed in this paper, considering the effects on the pressure loss and the induction of turbulence. The challenge was to develop a fluid-dynamically efficient duct with the hindrance of a very small available space between the compressor casing, the gearbox and the fuel pipes inside the narrow noise-reduction chassis. The mass flow rate will be computed by means of the differential static pressure between the upstream and the downstream section of a Venturi tube. The choice of a Venturi was due to the fact that it produces a pressure loss lower than any other device, such as orifice plates or other nozzle shapes. Furthermore, the expected mass flow rate would lead to high fluid speeds and, as a consequence, the diameter ratio between the duct and the throat of the Venturi was chosen to be as high as possible.

In this paper the authors will present the design and preliminary test results for a distributed electric generating system that uses renewable energy source for economical load-following and peak-shaving capability in an oil-free, high-speed micro-turboalternator system using compliant foil bearings and a permanent magnet alternator. Test results achieved with the prototype system operating to full speed and under power generating mode will be presented. A comparison between predicted and measured electrical output will also be presented up to a power generating level of 25 kWe at approximately 55,000 rpm. The excellent correlation between design and test provides the basis for scale up to larger power levels. Based upon the turboalternator test results a thermodynamic cycle analysis of a system using low grade waste heat water at approximately 100 C will be reviewed. The tradeoff study results for a series of environmentally friendly refrigerant working fluids will also be presented including sensitivity to vaporization and condensing temperatures. Based on the cycle and pinch point analyses predicted maximum output power was determined. Finally a preliminary turbine design for the selected R134a working fluid was completed. The results of this study show that a net output power level of greater than 40 kW is possible for approximately 240 l/m flow of water at 100C is possible.

A pressurized molten carbonate fuel cell (MCFC) and a micro gas turbine (MGT) hybrid power system has been developed to demonstrate high power generation efficiency (target of 55%), very low NOx emissions, and the operation using high-temperature gasification gas (biogas) as its fuel. The MCFC generator is pressurized, and is operating on process air supplied by the compressor of the MGT and reformed fuel. The power system achieves increased power output and higher efficiency thanks to its utilization by the gas turbine generator of thermal energy from the pressurized MCFC exhaust gas. The MGT is a single-shaft gas turbine that powers a high-speed direct-drive alternator. A heat recovery steam generator (HRSG) and the low-temperature heat exchanger of a hot water driven absorption refrigeration machine are also equipped using the heat recovered from the MGT exhaust gas. The MGT combustor plays an important role during system start-up. But the system is able to operate with no combustor firing in the range of 75% to 100% load. Therefore the NOx emissions are almost zero. The demonstration of this system was carried out at the 2005 World Exposition, Aichi, Japan. Wood waste that had to be cut during the construction of the EXPO 2005 site and waste plastic bottles at 1200°C in a high-temperature gasifier produce hydrogen and carbon monoxide. The MCFC/MGT hybrid system can use both high-temperature gasification gas (biogas) as well as Town Gas as its fuel. This system was started in February 22nd, and was operated by controlling from Distributed Power Supply Management System. A maximum efficiency was 52% at 300kW, and the total on-site operating time reached about 5200 hours with no failures. After the end of the half-year term of Aichi Expo., this system will be located to Central Japan Airport City, and the endurance test of next phase will be continued there.