Current Issue : April - June Volume : 2020 Issue Number : 2 Articles : 5 Articles
This paper presents a methodology based on the failure mode and effect analysis (FMEA)\nto analyze the failures in the power stage of wind-fuel cell hybrid energy systems. Besides, fault tree\nanalysis (FTA) is applied to describe the probabilistic failures in the vital subcomponents. Finally,\nthe reliability assessment of the system is carried out for a five-year operation that is guaranteed by\nthe manufacturer. So, as the result, the reliability analysis proves that the metal oxide semiconductor\nfield effect transistor (MOSFET) and electrolytic capacitor are the most critical components that\nintroduce damages in the power circuit. Moreover, a comparative study on the reliability\nassessment by the exponential distribution and the Weibull distribution show that the B1 lifetime\nobtained by the Weibull distribution is closer to reality....
A modified antipredatory particle swarm optimization (MAPSO) algorithm with evasive adjustment behavior is proposed to solve\nthe dynamic economic dispatch problem of wind power. The algorithm adds the social avoidance inertia weight to the conventional\nantipredatory particle swarm optimization (APSO) speed update formula. Thesize of inertia weight is determined by the\ndistance between the global worst particle and other particles. After normalizing the distance, the inertia weight is controlled\nwithin the ideal range by using the characteristics of sigmoid function and linear decreasing method, which improves the ability of\nparticles to avoid the worst solution. Then, according to the characteristics of the acceleration coefficient which can adjust the local\nand global searching ability of particles, acceleration coefficients of nonlinear change strategy is proposed to improve the searching\nability of the algorithm. Finally, the proposed algorithm is applied to several benchmark functions and power grid system models,\nand the results are compared with those reported using other algorithms, which prove the effectiveness and superiority of the\nproposed algorithm....
The two-edge box girder has been widely used as a stiffened girder in cable-stayed bridges. However, such girders have weakness in\naerodynamic stability. To improve its aerodynamic stability, some previous researchers have given slope to the edge box instead of\ninstalling additional attachments to aerodynamically stabilize the bridge. For wind load design, an angle of attack (AOA) has to be\nconsidered. However, the effect of AOA has not been studied for sloped box girder yet. In the present study, the effect of AOA on\nthe static wind load coefficient was investigated for 2-edge sloped box girder. A series of wind tunnel tests was performed by\nvarying the box slope angle from 0Degreeto 17Degreewhere AOA was set from - 10Degreeto 10Degree. Results showed that the lateral wind force is\nconsiderably reduced with the increase of the box slope angle except the case with the physical angle of 8Degree-11Degree. For practical AOA\nrange, the box slope should be larger than 15Degreeto minimize the aerodynamic static lateral force on the girder....
Subsynchronous resonance (SSR) can bring significant negative effects on the grid system like stability, security, and even generator\nshaft damage. This work presents a new method of using a doubly-fed induction machine (DFIM) based system of variable speed\npumped storage plant (VSPS) to mitigate SSR in the power system with high penetration of wind generation. The mitigation is\nreached based on the principle of balanced shaft mechanical input power and electromagnetic power. The fundamental concepts\nand phenomena of SSR with wind farm are discussed in brief in this work. For the sake of analysis and verification of performance\nof the proposed system, the network model including wind farm, VSPS, HVDC, and synchronous machine is built based on Ningxia\ngrid for the SSR study using PSCAD platform. The result shows that VSPS brings significant effect to dampen the SSR in the power\nsystem with high penetration of wind generation....
The nonuniform distribution of snow around structures with holes is extremely unfavorable for structural safety, and the\nmechanism of wind-snow interaction between adjacent structures with holes needs to be explored. Therefore, a wind tunnel\nsimulation was performed, in which quartz particles with an average particle size of 0.14mm as snow particles were used, and\ncubes with dimensions of 100mmÃ? 100mmÃ? 100mm each containing a hole with the size of 20mmÃ? 20mm were employed as\nstructures. Firstly, the quality of a small low-speed wind tunnel flow field was tested, and then the effects of hole orientation (hole\nlocated on the windward side, leeward side, and other vertical sides) and absence of holes on the surface of a single cube were\nstudied. Furthermore, the effects of different hole locations (respectant position, opposite position, and dislocation) and relative\nspacing (50 mm, 100 mm, and 150 mm) on the surfaces of two cubes and the snow distribution around them were investigated. It\nwas concluded that the presence and location of hole had a great influence on snow distribution around cubes. Snow distribution\nwas favorable when hole was located on the other vertical sides of the test specimen. The most unfavorable snow distribution was\nobtained when the holes on the two-holed sides of the cubes were respectant with a maximum snow depth coefficient of 1.4. A\nsignificant difference was observed in the snow depths of two sides of cubes when holes were dislocated. When two holes were\nrespectant, surrounding snow depth was decreased, and the maximum snow depth on model surface area was increased with the\nincrease of spacing. Wind tunnel tests on holed cubes provided a reference for the prediction of snow load distribution of typical\nstructures with holes....
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