Applied Mechanics and Materials Vols. 446-447

Abstract: In this paper, the performances of all the three kinds of Axial type Multi-Pole Permanent Magnet Synchronous Generators (PMSG) namely Three-phase, Multi-phase or Five Phase and Double Stator fixed in Vertical Axis Wind Turbine (VAWT) were investigated and compared in order to get an optimal system. MATLAB/Simulink had been used to model and simulate the wind turbine system together with all the three types Permanent Magnet Generators. It was observed from the result that with the increasing number of pole in both low and high wind speed, the five phase generator produced more power than the other two generators. In general, it was observed that the responses of the Multi-phase generator at both high and low speed wind showed promising aspect towards the system followed by Dual Stator. But with the change of the variables such as wind velocity, turbine height, radius, area together with the generator pole pairs and stator resistance, the optimum system should be chosen by considering the trade-off between different configurations which were firmly analyzed and described in this paper.

Abstract: In solar desalination system, solar energy is utilized for heating salt water using parabolic solar concentrator. The steam formed is then condensed to get the pure water. The water is kept in an absorber placed within the focal area of the concentrator. Optimal utilization of solar energy is possible by designing an absorber of proper size. Parabolic dish type concentrator is generally used for cooking but here we discuss its use in steam generation. Paper explains design and manufacturing of absorber and then comparing the results with conventional cooking vessel. Material of the absorber is selected considering the effects of seawater, the ability to resist high temperature, and manufacturability. Heat resistant coating is applied for maximum absorption of the radiation. Absorber designed as a thin walled pressure vessel is then manufactured by rolling, pressing and welding processes. Rate of evaporation of water in the designed absorber is compared with that in the conventional vessel for different sunshine conditions. It is observed that designed absorber is more efficient.

Abstract: Based on a kind of 1.5MW large-scale horizontal axis wind turbine tower, the mechanical modeling of a wind turbine tower-foundation is established, the static and dynamic analysis of the model is carried out by ANSYS software. The top displacement of the system is calculated by the static analysis to meet the design requirements in engineering. In dynamic analysis, each pile foundation is equivalent to a group of springs for the simulation of horizontal and vertical rigidity of the pile. The influence of top mass and foundation elasticity on wind turbine tower modes is analyzed, and calculated the natural frequency of the tower within a certain scope of rigidity in different directions about the piles foundation. The results show that the natural frequency of the wind turbine tower is influenced significantly by the mass on the tower top and foundation rigidity. The study provides a theoretical basis for optimal design of the wind turbine.

Abstract: This paper presents a Takagi-Sugeno (TS) fuzzy state-feedback controller based on a linear matrix inequality (LMI) approach for the permanent magnet synchronous generator of wind energy conversion system (PMSG-WECS). A dc/dc converter is considered to regulate the maximum power output of the system. To show its effectiveness, the dynamic model is replaced by the TS fuzzy model, which the proposed controller can be applied to the PMSG-WECS, while the controller gains can be obtained by solving set of a LMI approach. The proposed controller guarantees the stability of the system. Therefore, the performance of the proposed TS fuzzy state-feedback controller is assessed through the computer simulation.

Abstract: In this paper, a 1.5 MW wind turbine tower in Dali, Yunnan Province is used as the research object, using large-scale finite element software Ansys to carry on the dynamic analysis. These natural frequencies and natural vibration type of the first five of tower are obtained by modal analysis and are compared with natural frequency to determine whether the resonance occurs. Based on the modal analysis, the results of the transient dynamic analysis are obtained from the tower, which is loaded by the static wind load and fluctuating wind load in two different forms. By comparing the different results, it provides the basis for the dynamic design of wind turbine tower.

Abstract: This paper presents the now design, modeling and static analysis of a new two-axis solar tracker (Azimuth and Altitude). The tracker is an electro-hydraulic device that keeps photovoltaic panels in an optimum position perpendicularly to the solar radiation during daylight hours. The tracker of 24 m² panel’s size was designed using the SolidWorks 3D CAD software. The finite element method (FEM) is adopted to ensure the stability and the reliability of the tracker. COSMOSWorks was used to determine displacement, equivalent stress and safety factor of the tracker under its own weight and wind load critical, namely wind speed of 130 km/h. Simulation results show that the maximum displacement of the structure is 1.18 mm, the level of the maximum equivalent stress is 74.43 MPa and the safety factor is about 3. The tracker structure completely satisfies the design requirements.

Abstract: The increasing complexity of rotating machinery and atrocity competitions of current industrial sectors to launch a new designs on markets or to improve products quality and to reduce design cycle and operating cost, request overload use of the computer industrial software. The presence of cracks in the frameworks may lead to a dangerous and catastrophic effect on the static behavior and cause serious damage to the system. However, modeling and static analysis of frameworks is also a crucial stage preliminary to the fabricate process. It is allowed to predicting performances, optimizing system design and checking its rigidity, stress in most significant points. This paper aim to use ¶SolidWorks (SW) and COSMOSWorks (CW) solvers for modeling Savonius aerogenerator with and without cracks and to simulate its static behaviors by Finite Element Analysis (FEA) under its free weight and critical wind load of 30m/s. Statics strain and stress obtained are strongly influenced by the presence of cracks on the weld sides of the wind turbine. However, the presence of one crack sized of 0.5mm in the system increased respectively VonMises stress of 9.26%, displacement of 0.8%, strain of 19.95% and reduced the security factor of 9.24%.

Abstract: The corrosion conditions of in-service aluminum conductor steel reinforced (ACSR) overhead lines in typical climate were studied by using macroscopic and microscopic methods. According to its operating environment, the corrosion causes were also analyzed. It is found that the corrosion of the outer aluminum stranded conductors is more serious than other parts. And partial corrosion pits have been found on the outer layers of aluminum stranded conductors. While there is no obvious corrosion appeared on the steel core matrix. Additionally, corrosion products can reduce the corrosion rate of aluminum stranded conductors but accelerate corrosion of the steel core. Through this research, more attention should be paid to monitor the aluminum stranded conductors.

Abstract: This paper will discuss and demonstrate how FACTS controllers shunt Static Synchronous Compensator (STATCOM) and Static VAR Compensator (SVC) have successfully been applied to power system for effective regulating system voltage. One of the major reasons for installing a STATCOM or SVC is to improve dynamic voltage control and thus increase system load ability. In this paper a STATCOM and SVC are used to regulate voltage in a power system. When system voltage is low they generate reactive power (capacitive). When system voltage is high they absorb reactive power (inductive). In this paper comparison is also performed between SVC and STATCOM under fault condition and it is show that STATCOM have the ability to provide more capacitive power during a fault over SVC. All the simulations for the above work have been carried out using MATLAB/SIMULINK environment.

Abstract: Frequency estimation is a vital tool for many power system applications such as load shedding, power system security assessment and power quality monitoring. Moreover, the complexity and noisiness of modern power system networks have created challenges for many power system applications. Fast and accurate frequency estimation in the presence of noise is a challenging task. Sliding window with the complex form of least mean square (LMS) algorithm has been utilized in this study in order to improve the frequency estimation in noisy power system. Different simulation cases have been examined for signal with different signal to noise ratio (SNR) and to evaluate the performance of sliding window method for better frequency estimation. The results obtained show that the sliding window method with LMS is able to improve and enhance the frequency estimation even when the (SNR) is small compared to the existing LMS method.