Statistical properties of current, energy conversion, and electron acceleration in flux ropes in the terrestrial magnetotail

2021 ◽  
Author(s):  
K. Jiang ◽  
S. Y. Huang ◽  
Z. G. Yuan ◽  
X. H. Deng ◽  
Y. Y. Wei ◽  
...  
Keyword(s):  
Energy Conversion ◽  
Electron Acceleration ◽  
Statistical Properties ◽  
Flux Ropes ◽  
Current Energy

scholarly journals Performance Characteristics in Runner of an Impulse Water Turbine with Splitter Blade

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 303
Author(s):  
Lingdi Tang ◽  
Shouqi Yuan ◽  
Yue Tang ◽  
Zhijun Gao
Keyword(s):  
Energy Conversion ◽  
Flow Direction ◽  
Mechanical Energy ◽  
Experimental Tests ◽  
High Energy ◽  
Negative Energy ◽  
Water Turbine ◽  
Conversion Performance ◽  
Water Turbines ◽  
Current Energy

The impulse water turbine is a promising energy conversion device that can be used as mechanical power or a micro hydro generator, and its application can effectively ease the current energy crisis. This paper aims to clarify the mechanism of liquid acting on runner blades, the hydraulic performance, and energy conversion characteristics in the runner domain of an impulse water turbine with a splitter blade by using experimental tests and numerical simulations. The runner was divided into seven areas along the flow direction, and the power variation in the runner domain was analyzed to reflect its energy conversion characteristics. The obtained results indicate that the critical area of the runner for doing the work is in the front half of the blades, while the rear area of the blades does relatively little work and even consumes the mechanical energy of the runner to produce negative work. The high energy area is concentrated in the flow passage facing the nozzle. The energy is gradually evenly distributed from the runner inlet to the runner outlet, and the negative energy caused by flow separation with high probability is gradually reduced. The clarification of the energy conversion performance is of great significance to improve the design of impulse water turbines.

scholarly journals An FTC Design via Multiple SOGIs with Suppression of Harmonic Disturbances for Five-Phase PMSG-Based Tidal Current Applications

2021 ◽  
Vol 9 (6) ◽  
pp. 574
Author(s):  
Zhuo Liu ◽  
Tianhao Tang ◽  
Azeddine Houari ◽  
Mohamed Machmoum ◽  
Mohamed Fouad Benkhoris
Keyword(s):  
Fault Tolerance ◽  
Energy Conversion ◽  
Tidal Current ◽  
Fault Tolerant ◽  
Tidal Current Energy ◽  
Electromagnetic Forces ◽  
Model Free ◽  
Energy Conversion Systems ◽  
Power Scale ◽  
Current Energy

This paper firstly adopts a fault accommodation structure, a five-phase permanent magnet synchronous generator (PMSG) with trapezoidal back-electromagnetic forces, in order to enhance the fault tolerance of tidal current energy conversion systems. Meanwhile, a fault-tolerant control (FTC) method is proposed using multiple second-order generalized integrators (multiple SOGIs) to further improve the systematic fault tolerance. Then, additional harmonic disturbances from phase current or back-electromagnetic forces in original and Park’s frames are characterized under a single-phase open condition. Relying on a classical field-oriented vector control scheme, fault-tolerant composite controllers are then reconfigured using multiple SOGIs by compensating q-axis control commands. Finally, a real power-scale simulation setup with a gearless back-to-back tidal current energy conversion chain and a small power-scale laboratory prototype in machine side are established to comprehensively validate feasibility and fault tolerance of the proposed method. Simulation results show that the proposed method is able to suppress the main harmonic disturbances and maintain a satisfactory fault tolerance when third harmonic flux varies. Experimental results reveal that the proposed model-free fault-tolerant design is simple to implement, which contributes to better fault-tolerant behaviors, higher power quality and lower copper losses. The main advantage of the multiple SOGIs lies in convenient online implementation and efficient multi-harmonic extractions, without considering system’s model parameters. The proposed FTC design provides a model-free fault-tolerant solution to the energy harvested process of actual tidal current energy conversion systems under different working conditions.

scholarly journals Status of Marine Current Energy Conversion in China

2021 ◽  
Vol 4 (1) ◽  
pp. 11-23
Author(s):  
Hongwei Liu ◽  
AbuBakr S. Bahaj
Keyword(s):  
Energy Conversion ◽  
Policy Framework ◽  
Chinese Government ◽  
Renewable Energy Systems ◽  
Technology Deployment ◽  
Prototype Development ◽  
Marine Energy ◽  
The Status ◽  
Marine Current ◽  
Current Energy

Marine current energy conversion (MCEC) technologies are promising renewable energy systems with some full scale and semi-commercial turbines constructed and deployed in several countries around the world. In this work, we present the status of marine current energy and systems in China and policies geared to support these. Over the past ten years the Chinese government has provided a policy framework and financial supports for the development of MCEC technologies of various design philosophies which has resulted in significant technology deployment at sea. A review of these technologies – which have turbine capacities in the range 20 kW to 650 kW, mostly tested at sea – is presented in the paper. In addition, the paper also discusses Chinese plans for marine energy test sites at sea to support prototype development and testing and concludes with a view of future prospects for the marine energy technology deployment in China.

Ocean Current Energy Conversion

2016 ◽  
pp. 1147-1162
Author(s):  
Howard P. Hanson ◽  
James H. VanZwieten ◽  
Gabriel M. Alsenas
Keyword(s):  
Energy Conversion ◽  
Ocean Current ◽  
Current Energy ◽  
Ocean Current Energy

Marine current energy conversion: the dawn of a new era in electricity production

2013 ◽  
Vol 371 (1985) ◽  
pp. 20120500 ◽  
Author(s):  
AbuBakr S. Bahaj
Keyword(s):  
Energy Conversion ◽  
Resource Assessment ◽  
Electricity Production ◽  
Planetary Motion ◽  
The Status ◽  
Marine Current ◽  
Marine Currents ◽  
Wind Energy Development ◽  
Current Energy ◽  
Flow Velocities

Marine currents can carry large amounts of energy, largely driven by the tides, which are a consequence of the gravitational effects of the planetary motion of the Earth, the Moon and the Sun. Augmented flow velocities can be found where the underwater topography (bathymetry) in straits between islands and the mainland or in shallows around headlands plays a major role in enhancing the flow velocities, resulting in appreciable kinetic energy. At some of these sites where practical flows are more than 1 m s −1 , marine current energy conversion is considered to be economically viable. This study describes the salient issues related to the exploitation of marine currents for electricity production, resource assessment, the conversion technologies and the status of leading projects in the field. This study also summarizes important issues related to site development and some of the approaches currently being undertaken to inform device and array development. This study concludes that, given the highlighted commitments to establish favourable regulatory and incentive regimes as well as the aspiration for energy independence and combating climate change, the progress to multi-megawatt arrays will be much faster than that achieved for wind energy development.

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