Advanced Materials Research Vols. 724-725

Abstract: This research investigates causes of the low performance of the first commercial wind farm in Thailand. The measured data suggests that this wind farm is uncompetitive. We found that this is due to poor turbine-site matching. In contrary to a traditionally held belief, the hub-height and turbine capacity are not the contributing factors. Key performance indicators are obtained for use as benchmarks in future wind farm appraisal. Then a turbine selection method is proposed to increase the capacity factor (CF) of the wind farm. CF is used as the main performance indicator, which can be compared to other wind farms. The real capacity factor (CF_R) determined using measured data is 14.90%. This CF_R is considerably lower than the estimated capacity factor (CF_E) of 21.53%. The low CF_R is due to grid instability. In addition, the CF_R is lower than the CF_E by a factor of 0.69. This information is valuable to investors and wind farm developers in a wind farm feasibility study. A graphical wind turbine-site matching is proposed. Wind turbine-site matching is achieved by using normalised power output plots and power density plots on a probability density graph of the wind site. This process consumes a short period of time. An improved turbine-site matching is achieved.

Abstract: This paper presents a multi-functional wind power generation apparatus, which is suitable for doing fundamental experiment in university laboratories. The laboratorial apparatus has features of being stable, visualized and convenient in exhibiting the entire process of wind power conversion and its utilization. Moreover, the experimental device can display the relationships between its output powers and several characteristic parameters, including wind speed, blade number, wings shape, wings length, pitch angle, load and tip-speed ratio, etc. The wind wheels adjustable performance was emphasized by changing the blade length, blade angle and blade number within the same hub. The wind power generation apparatus provides various options for many experimental projects and corresponding experimenters. Meanwhile, it meets different levels of experimental teaching requirements.

Abstract: Numerical Weather Predication (NWP) is the main way to forecast the surface-layer wind of wind power farm. In order to improve the accuracy of the forecast with the existing observations, the WRF-3DVAR is used in two-way nested simulations with the data from National Centers for Environmental Prediction (NCEP) Final (FNL) Operational Global Analyses as initial and boundary conditions. Conventional data (sounding and surface observation) are assimilated through 3h assimilation cycles. The impacts of assimilation are examined through direct verification of the forecasts against the observations from conventional stations and the wind tower. It is found that the data assimilation can improve the accuracy of the forecast of surface-Layer wind up to 36h, and the improvement at conventional stations is more prominent than that at the wind tower.

Abstract: This paper analyses the mechanism of large scale cascading trip-off failures of wind turbine generators in China, focuses on the reasons of trip-off caused by overvoltage. It analyses the model of Doubly Fed Induction Generation (DFIG) and builds a model of a wind farm that is composed of Doubly Fed Induction generators in DIgSILENT. The wind farm A with capacity of 175MW and wind farm B with capacity of 175MW is accessed to the nine bus system. The simulation reproduces the processes of the cascading trip-off of wind turbine generators caused by undervoltage and overvoltage. The trip-off caused by undervoltage is due to the lack of Low Voltage Ride Through (LVRT). And that the capacitive reactive power compensation device is not timely removed leads to a large surplus of reactive power, then the voltage rises, so the wind turbine generators trip off because of overvoltage. By setting the contrast scenario, the result shows that if capacitive reactive power compensation device is promptly removed after the loss of a large amount of active power, the wind turbine generators will not trip off because of overvoltage.

Abstract: A novel driver concept has been developed to meet the grid requirements. A regulation speed device was connected to a variable speed gearbox with a constant speed synchronous generator.A brushless double rotor motor based on a novel wind power generation system is proposed. The motors structure , principle and mathematic model are studied.The simulation results show that brushless double rotor motor is suitable as a regulation speed device to apply to the novel wind power generation system.

Abstract: Due to wind power generation system (WGS) is strongly nonlinear, multi-input multi-output and with high turbulent disturbance, we build a offset-free model considering system noise and measurement noise and its predictive controller for all operating area from cut-in speed to the cut-out wind speed. Finally we predict the optimum generator torque and pitch control signal. By add damping mode in drive train using torque control, the purpose of smoother power and less torsional torque pulsation on drive train are achieved. Simulation results shows that this predictive controller is able to reduce the impact of noise and interference on the system, ensuring constant power output and reducing the torque pulsation.

Abstract: As the wind power penetration continues to increase, one of the main challenges faced in power operation is to maintain the system reliability when committing an appropriate amount of power from a wind farm in the lead time. This paper presents an approximate model for estimating offshore winds in the domain of meteorology, raising the accuracy and comparability between offshore and onshore wind power. And then, considering the discrepancy in wind speed fluctuations between offshore and onshore sites and difference in operation characteristics between double-fed induction generators and permanent magnet synchronous generators, this paper studied the different influences on the reserve capacity due to the offshore and onshore wind farms committing the power system. Comparing with the onshore wind farms, offshore wind farms have more positive effective on the reliability of the grid and are suitable for more economic operation scheme.

Abstract: This paper mainly introduces the dynamic interactional model of SVC and DFIG to ensure the stability of the voltage when wind power generator access to grid massively. Firstly, we analysis the control characteristics based on the dynamic model of SVC and DFIG. Based on the characteristics we establish the dynamic interactional model of them. By using a simplified model of wind power access to the grid, we prove that the voltage of the access point to the grid will stay in the reasonable range through the interaction of SVC and DFIG providing reactive power when the wind power output fluctuates. The conclusion is proved by simulating calculation of a real regional power grid.

Abstract: With the incentive and supporting policy of the government, wind power industry has experienced swift development and gradually moved towards maturity in China. In this paper, we review the status of the wind power industry in China from a supply chain perspective, there is mismatching between upstream and downstream. In the upstream the production capacity takes the lead but the R&D capability is weak in the world. In the downstream the speed of wind farm development is fastest in the world but the capacity of wind power integration and absorption is restricting the utilization and development of wind farm. We analyze the issues with the supply chain from a macroscopic view and the policy recommendations for optimizing the development of wind power in China are proposed.

Abstract: The rigid-flexible coupling model of wind turbine was established in ADAMS to study the vibration characteristics, which was based on the working principle of megawatt wind turbine. The natural frequencies and vibration modes of the tower have been obtained by dynamic simulation analysis and vibration analysis of the wind turbine. The comparison of the first-order bending natural frequency by raley analysis algorithm and the first-order bending natural frequency by the software, which has validated the correctness of rigid-flexible coupling model of wind turbine, the analysis of vibration characteristic has verified the rationality of the structure of the wind turbine.