Advanced Materials Research Vols. 608-609

Abstract: The application of maglev flywheel in wind generator is investigated. The dynamics analysis of maglev flywheel rotor has been performed including the critical speed analysis and unbalance response analysis, which took into account the gyroscopic effect by using of finite element analysis method. Based on the model reduction method, the modeling and LQR control of maglev flywheel rotor is presented, the simulation results show stable levitation and good levitated rotation.

Abstract: Wind turbine’s Low Voltage Ride Through(LVRT) ability must be verified by site-test, safety design was key factor of wind turbine’s mobile LVRT test device design and development. Based on research of protection scope, design principal of safety design, this paper realized five aspects of safety design: switchgear selection, relay configuration and setting value, routine operation, self-check failure lock, operation regulations. Safety design realized by this paper did not affect normal test process, colud provided perfect protection to operator, wind farm facilities and test device. Test device complied with this design had been used in wind turbine site-test and perfected well.

Abstract: Fault of gearbox is one of the significant causes which lead to high cost of wind farm, so early fault prediction of gearbox is meaningful for ensuring reliable running and reducing maintenance costs. With condition monitoring data, the relation between gearbox temperature and potential faults was researched and a new method for online fault prediction of wind turbine gearbox was presented. First, the temperature prediction model for normal behavior of gearbox was built up by non-linear regression analysis. Then, a detecting function which can indicate the deviation between actual running state and prediction state of gearbox was introduced. The condition of gearbox could be monitored by comparing the real-time value of detecting function with the chosen threshold. Theoretical analysis and simulation results demonstrated that this method could predict the abnormality of gearbox in time, and it can be applied to monitor the running condition of gearbox.

Abstract: Wind power converter device and its control system is the main research part of wind turbine. This paper, combining the technology developing trend of DFIG(double-fed induction generator) and FPWT (full power wind turbine), describes the implementation of converter devices and the strategies for LVRT, under unbalanced voltage, and gives the zero voltage ride through waveforms for DFIG

Abstract: Doubly-fed induction generator (DFIG) wind turbine has become the most widely used wind turbine in wind farms, since it presents noticeably advantages such as decoupled controls of active and reactive powers, and the use of a power converter with a rated power of 25% of total system power. As the penetration of wind power in power system increases, it is required that the wind turbine remained connected and actively contributed to the system stability during and after faults and disturbance. One common approach for a DFIG to obtain such low voltage ride through (LVRT) function is to install a crowbar circuit across its rotor terminals, which short circuit the rotor side converter when over-current is detected in the rotor. A detailed model of LVRT function normally requires electromagnetic simulations. However, the time consuming computational process is prohibitive for the studies of the integration of wind farms into large scale power systems. Electromechanical simulations are more suitable for such engineering applications. GE has incorporated the LVRT function into its recently released DFIG wind turbine model for Electro-mechanical simulations. This paper has implemented this model and verified the effectiveness of the LVRT function.

Abstract: In this paper, the wind resources and planning in Jing-jin-tang grid are firstly introduced. The focus is on the analysis of characteristics of wind power output in Jing-jin-tang grid. The analysis data is from the actual wind running power and load in the whole year. The indicators considered are wind power penetration, proportion of wind output power, guaranteed capacity, effective output, etc. The results studied have the important significance for grid planning and operation.

Abstract: After large-scale wind power integrate into the system, there is a great impact for the system dispatching operation and the unit maintenance and repair of the wind power , so it's extremely necessary to forecast wind power output and assess its level of forecasting. This paper mainly focusing on the containing wind power system, studies the wind power output fluctuation in the demand for system reserve, and analyse the rationality of the wind power forecasting assessment standard in North China area wind power integration operation management implementing regulations by combining with the status of wind power in North China area, that is, whether the assessment mechanism can promote wind farms raising the forecasting level.

Abstract: Low Voltage Ride through (LVRT) technology of Doubly Fed Wind-Power Induction Generator (DFIG) is a very important issue for grid-connection of wind power system. The paper analyzed and simulated dynamic response of DFIG under balanced and unbalanced gird voltage dip. Then proposed a whole set of LVRT control strategies based on finite state machine method for DFIG and carried out a detailed experimental validation on a 22KW DFIG driving system test platform on balanced grid voltage dip, which was connected to a voltage-dip generator. The experimental waveforms indicated that the proposed control strategy could effectively met LVRT requirement under different dip depth and time.

Abstract: The paper collects and analyzes the data of wind power installed capacity, grid integration capacity, and wind power generation from 2008 to 2011, and also researches the proportion of wind power grid-connected in top 10 provinces in China. Based on analysis of wind abandonment in 2011, the paper concludes the difficulties in wind power grid integration from technical and political perspectives. At last the paper proposes some recommendations on the issue of wind power grid integration in China.

Abstract: Extreme learning machine (ELM) is a new and effective single-hidden layer feed forward neural network learning algorithm. Extreme learning machine only needs to set the number of hidden layer nodes of the network, and there is no need to adjust the neural network input weights and the hidden units bias, and it generates the only optimum solution, so it has the advantage of fast learning and good generalization ability. And the back propagation (BP) neural network is the most maturely applied. This paper has introduced the extreme learning machine into the wind power prediction. By comparing the wind power prediction method using the BP neural network. Study shows that the extreme learning machine has better prediction accuracy and shorter model training time.