Output Power Modeling of Wind Turbine Based on State Curve Analysis

Background: In wind power generation, the power curve can reflect the overall power generation performance of a wind turbine. How to make the power curve have high precision and be easy to interpret is a hot research topic. Objective: Because the current power curve modeling method is not comprehensive in feature selection, the simplified model and state curve of a wind turbine are introduced to avoid feature selection and make the model interpret easily. Methods: A power modeling method based on different working conditions is proposed. The wind turbine system is simplified into three physical models of blades, mechanical transmission and generator, and the energy transfer is expressed by mathematical expressions. The operation process of the wind turbine is divided into three phases: constant power (CP), constant speed (CS), and maximum power point tracking (MPPT), and the power expression of each phase is given after the analysis of state curves. Results: The effectiveness of the proposed method is verified by the supervisory control and data acquisition (SCADA) data of a 2MW wind turbine. The experimental results show that the mean absolute percentage error (MAPE) index of the proposed power modeling method based on state curve analysis is 11.56%, which indicates that the power prediction result of this method is better than that of the sixth-order polynomial regression method, whose MAPE is 13.88%. Conclusion: The results show that the proposed method is feasible with high transparency and is interpreted easily.

Reliability assessment of the behavior of reinforced and/or prestressed concrete beams sections in shear failure

The object of this article is to be able to simulate the behavior of reinforced and/or prestressed concrete beam’s section in the shear loading through a model allowing the evaluation of nonlinear strains caused by shear, while taking into account the real behavior of the materials. In this approach, we are often confronted with problems of modeling uncertainties linked to some insufficiencies of the mechanical model allowing to describe the physical phenomena in a realistic way. For that, it is necessary to use a reliability model making it possible to evaluate their probability of failure, by establishing failure curves according to the different transition zones of the limit state curve of the nonlinear behavior in the shear loading up to at section failure of reinforced and/or prestressed concrete beams. In this work, we also propose a coupling of the reliability method by response surface to carry out the reliability optimization on complex mechanical models, where the mechanical and reliability models developed have been implemented on the Fortran. This allows the estimation in an efficient way of the different reliability characteristics according to each transition zone from the limit state curve to the real behavior until failure in the shear loading.

Improvement of the Laser-Welded Lap Joint of Dissimilar Mg Alloy and Cu by Incorporation of a Zn Interlayer

During pulsed laser welding of AZ 31B magnesium (Mg) alloy and T2 pure copper (Cu), Cu2Mg and Mg2Cu are generated, but the bonding ability of the two compounds is usually weak, resulting in low strength. In order to improve the joint of two dissimilar metals, a zinc interlayer was inserted between the Mg alloy and Cu, and the effects of the thickness of the Zn interlayer on the microstructure and properties of the joint were studied. The fused zone consisted of Cu2Mg and MgZn, and, according to first-principles calculation, in the same energy range, the area enclosed by the density of the state curve of MgZn was larger than that of Cu2Mg. Hence, the bonding ability of MgZn was better than that of Cu2Mg, and MgZn improved the strength of the welded joint. The most advantageous thickness of the Zn interlayer was 0.1 mm, and the shear strength was 48.15 MPa that was 161% higher than that of the directly welded Mg/Cu joint.

Buckling analysis of rod structure of the two-tier dome

The paper deals with the problem of calculating the rod structure of a two-tier dome for stability. Such structures consisting of straight rod elements are widely used in practice and have a number of significant advantages. First of all, it is a high rigidity with a low mass. Also, this type of construction is well resistant to dynamic loads. At the same time, the dome model allows for the bifurcation of points on the equilibrium state curve of the system. The problem of the dynamic stability of double dome is solved by the principle of stationarity of total potential energy of the system. The analysis of the obtained solution is carried out, and the equilibrium state diagram for a two-tier core dome is constructed.

Objective Analysis of the Stability of an Extralegal Weight Tractor-Trailer Combination during a Rapid Air Loss Event

ABSTRACT In the California Transportation Permits Manual, the minimum overall tire-to-tire axle width (overall width) of a vehicle in the extralegal weight configuration is 2.44 m. Commercial truck tractor and trailer tandem 1.82-m-wide axles fitted with new-generation wide base single (NGWBS) tires measure 2.34 m in overall axle width; thus, they are not compliant with the current California Department of Transportation requirement. Because of the growing application of NGWBS tires in the market, it is important to understand the vehicle stability characteristics of a tractor-semitrailer fitted with both dual and NGWBS tire configurations. In this research, a comparison of dual to NGWBS with both a 50.8-m outset wheel and a 25.4-mm outset wheel is presented. A rapid air loss (RAL) event was initiated to represent a severe scenario in each of the three following maneuvers: straight line, steady-state curve, and lane change. The data were evaluated, and differences between NGWBS and dual tire–fitted vehicles were compared. While a tire RAL event can be perceived as a dramatic event, previous studies and driver-training events have shown that such an RAL event is manageable. The conclusion of this work is that an RAL event with NGWBS tires is as manageable as a dual tire–fitted vehicle and does not make the system unstable.

Power Loss Analysis of Matrix Converter Based on RB-IGBT

The power loss analysis of matrix converter based on RB-IGBT is discussed in this paper. The on-state performance and switching process of RB-IGBT are tested; the on-state curve is obtained by the mathematical fit of the experimental data; On the basis, a method of power loss calculation for matrix converter under the input line-to-line voltage control strategy and four-step commutation strategy is investigated; Finally, the simulation result obtained by MATLAB/Simulink verifies the correctness and validity of the proposed method.