Advanced Materials Research Vols. 1008-1009

Abstract: This article focuses on the topics of cascaded wind power generation system with Variable Speed Constant Frequency (VSCF). It consists of four key components, including the wind turbine, dual-rotor motors, low-speed synchronous motor and inverter. This paper summarizes and compares multiple topology form of cascade wind power system, and through the study of the relevant working mechanism, structure and layout of the form, the applicable conditions and scope of the new system are expounded in detail. In particular, as the superiority of cascade system, it makes a synthesis of variable speed and constant speed power generation into reality, thereby the cascaded systems comprehensive operational efficiency are improved.

Abstract: Microgrid are LV or MV electric networks which utilize various distributed generators (DG) to serve local loads.In this paper an equivalent model of a hybrid system including wind power and solar power generating units has been built based on the mathematical models of wind turbine(WT) and photovoltaic(PV).Control strategies of the converters have been also developed. The short-circuit current and voltage levels of the microgrid have been calculated respectively based on the IEC 60909 standard corresponding to the occurrence of a three-phases short-circuit at the Point of the Common Coupling(PCC). Simulation results verified that the micro sources and microgrid built in this paper can simulate the actual system operation very well, and it can provide a simulation platform for further study of operation characteristics of system-integrated microgrid.

Abstract: This paper analyses the subsynchronous resonance (SSR) phenomena in doubly-fed induction generator (DFIG)-based wind farms interconnected with series compensated Networks. The study system is derived from IEEE first benchmark model. Small-signal analysis is conducted on the basis of detailed mathematical model being set up. Time domain simulations are performed in DIgSILENT/Power Factory to confirm the small-signal analysis results that IGE instead of TI is the major reason for SSR in such systems.

Abstract: This paper analyzes three main factors (turbulence intensity, air density, annual average wind speed ) that influence the low wind speed wind turbine fatigue loads, In order to analyze the influence of each main parameters how to affect the fatigue load of low wind speed wind turbine, using a 2000kW wind turbine as an example on the simulation test , 3 turbulence, 4 air density and 7 annual average wind speed were employed. The results show that, with the air density, turbulence intensity and the annual average wind speed increases, the wind turbine of fatigue load increase in rule approximately. Based on the above rule, it can reduce fatigue loads and prolong the life of wind turbine in design optimization of low wind speed wind turbine and sit choice.

Abstract: According to requirements of lubrication points and characteristics of grease, a distributed intelligent lubrication system of wind turbines is presented in this paper. PLC+SCU is the major control part in this system. It is adopted communication mode between PLC and SCU, so the system has better expansibility, which can simultaneously lubricate more classified points of wind turbines. PLC has more reserved interface sources and can completely supply grease at long distance. Monitor and protect circuits are devised in this system, and these parts can inspire, locate and alert the fault when the failure in pipelines or operator system is occurred. This paper introduces the structure, principle and its’ control system of lubrication system for wind turbines in detail, and the usability of the system is analyzed and some practical equipments are shown on.

Abstract: According to the impact of the wind power prediction uncertainty on the power system reserve capacity, the idea of scenario is introduced to the stochastic programming model. The method of scenario is used to simulate the uncertainty model of the wind power generation, load and the conventional units. The scenario-reduction methodology is combined to reduce the large scenario set to a simpler one, then the probability statistics on these scenarios is given in order to obtain the probability density of the system power difference, and the expected energy not supplied (EENS) and expected wind waste risk (EWWR) are presented. The reserve capacity is determined by the two aspects, which are the reliability shown by EENS and EWWR, and the economy of reserve capacity cost. Finally, simulations on a ten-unit system are given to demonstrate the method is effective to reduce the cost of reserve and the abandoned wind power in the context of system reliability.

Abstract: Our planet gives us many mineral sources, but they have a big disadvantage. They are finite. Non-renewable energy sources are enough only for decades, exceptionally for centuries. Current generation is aware of the importance of using other energy sources, such as sunlight, wind, rain, tides, waves and geothermal heat. These energy sources are renewable. It means that they come from sources, which are naturally replenished on a human timescale. One of these sources is wind energy. Use of this kind of energy source needs an initial investment, but it can reduce cost of running a household and other sectors. This article is about Savonius wind turbine and its use for the needs of public lighting.

Abstract: In order to improve the prediction accuracy of wind power, this research is based on time series and improved BP-ANN algorithm. The basic idea is described as follows: wind speed forecasting model is established by using time series method; wind speed-wind power model is built by utilising improved BP-ANN algorithm; wind speed data from time series forecasting is used as input of neural network model, and the prediction results for wind power are obtained. In order to analyse the availability of wind power prediction model, the mean absolute error and correlation coefficient are compared to analyse the predictions results. The results show that the prediction model can effectively improve the forecasting accuracy of wind power.

Abstract: Harnessing wind energy for power generation involves first achieving a preliminary study to understand the wind characteristics for the chosen location. In this way, the results are useful for understanding performace of an project that is connected with wind energy. The purpose of this article is to determine global estimates and different energy reports (ER). This is necessary because we do not always have a lots of meteorological datas. For the determination of these reports (ER) it used different kinds of energies calculated for a period of six years, hourly, daily and monthly data. Therfor, it was calculated the energy monthly, seasonally and annually report between monthly energy calculated with daily wind date and monthly energy calculated with instantaneous wind date (R _{m, Z/I}); energy monthly, seasonally and annually report between monthly energy calculated with monthly wind date and monthly energy calculated with instantaneous wind date (R _{m, L/I}); energy monthly, seasonally and annually report between monthly energy calculated with instantaneous wind date and monthly energy Betz (R _{m, I/B}). All these reports were determined for a certain family of wind turbines used for a functional home using wind and solar energy. From the obtained results that are quite significant differences between seasonal and annual energy reports values determined with different types of energy.

Abstract: The paper have described the vibration and damping analysis of carbon fiber wind turbine blade with viscoelastic damping treatment using commercial ANSYS program. The wind turbine system including a carbon fiber layer and a viscoelastic damping layer was attached on inside of carbon layer. Firstly, the natural frequencies and mode shape of pure carbon fiber turbine blade were compared with viscoelastic damping treated turbine blade using modal analysis. There were 1mm, 2mm, 3mm thickness damping layer finite element model to be constructed. The results show the little changes in lower first mode but getting smaller with higher modes. Finally, the frequency response functions of damped and undamped turbine blade were calculated for investigating the damping effect of viscoelastic damping layer. As shown in the results, the viscoelastic damping layer has good damping effect for vibration control of carbon fiber wind turbine blade.