Advanced Materials Research Vols. 860-863

Abstract: With the increasing proportion of distributed generation, higher requirement on power quality of distributed generation system is put forward by utilities. This paper first introduced the main indices and international standards related to power quality, and then built the DFIG dynamic model in which the double PWM converter and variable pitch control strategy were applied. Simulation of power quality of unbalanced system is conducted using PSCAD/EMTDC.

Abstract: In this paper, a rotor flux based variable-structure model reference adaptive system (MRAS) observers is proposed for speed observer in a sensorless controlled doubly fed induction generator (DFIG) aligned with the stator flux. In the strategy, two rotor flux models with different structure are used. The rotor flux voltage model without including rotor position item is used as reference model, and the rotor flux current model including rotor position item as adjustable model. A slide-mode surface is formulated from the errors between the two models, and the rotor speed estimation can be obtained by a sliding mode algorithm. Meanwhile the one order inertial link is used to avoid suffering from integrator drift effects in voltage model. Simulation results confirm the validity of the approach.

Abstract: The aeroelasticity and the flutter of the wind turbine blade have been emphasized by related fields. The flutter of the wind turbine blade airfoil and its condition will be focused on. The eigenvalue method and the time domain analysis method will be used to solve the flutter of the wind turbine blade airfoil respectively. The flutter problem will be firstly solved using eigenvalue approach. The flutter region, where the flutter will occur and anti-flutter region, where the flutter will not occur, will be obtained directly by judging the sign of the real part of the characteristic roots of the blade system. Then the time domain analysis of flutter of wind turbine blade will be carried out through the use of the four-order Runge-Kutta numerical methods, the flutter region and the anti-flutter region will be gotten in another way. The time domain analysis can give the changing treads of the aeroelastic responses in great detail than those of the eigenvalue method. The flap displacement of wind turbine blade airfoil will change from convergence to divergence, and change from divergence to convergence extremely suddenly. During the flutter region, the flutter of wind turbine blade will occur extremely dramatically. The flutter region provided by the time domain analysis of the flutter of the blade airfoil accurately coincides with the results of eigenvalue approach, therefore the simulation results are reliable and credible.

Abstract: In this paper, power characteristics of hybrid wind, photovoltaic generation and energy storage device is studied. Two-stage Smooth Energy Storage Control Strategy is designed in order to effectively inhabit both high frequency and low frequency section of wind and photovoltaic power. A topology of demonstration project of hybrid wind power, photovoltaic, energy storage and power transmission in north China is considered for simulation. Power characteristic of different hybrid generation mode is studied, and the simulation results show reliability and effectiveness of the control strategy. The results studied have the important significance for grid planning and operation.

Abstract: With the increase of its proportion in power system, wind power not only brings economic and environmental benefits but also the potential security risks due to its fluctuation and uncertainty. In order to take the potential security risks into account, an environmental/economic/safe static dispatch (EESD) model of power system with wind power is built. A new multi-objective particle swarm optimization (MOPSO) algorithm with standby selection and micro variation is proposed to solve the model. Two cases with and without wind power are simulated with the standard IEEE-30 system. The simulation results validate the effectiveness of the proposed algorithm.

Abstract: This paper studied the short-term prediction of wind speed by means of wavelet decomposition and Extreme Learning Machine. Wind speed signal was decomposed into several sequences by wavelet decomposition to reduce the non-stationary. Secondly, the phase space reconstructed was used to mine sequences characteristics, and then an improved extreme learning machine model of each component was established. Finally, the results of each component forecast superimposed to get the final result. The simulation result verified that the hybrid model effectively improved the wind speed prediction accuracy.

Abstract: Considering economic effect and low-carbon effect the benefit formation mechanism of wind power was analyzed, and then through integrating the benefits from the two aspects by low-carbon economic elements a concept of low-carbon comprehensive benefit was proposed. Combining with construction cost of wind power , an analysis model of low-carbon comprehensive benefit from wind power was built.

Abstract: Policies of the burgeoning wind power industry in China are sorted out and a comparative analysis on such policies and those in countries advanced in wind power development is made in the perspective of externality theory in the paper; then, disadvantages are summarized and constructive suggestions are proposed combined with foreign experience and these disadvantages in China.

Abstract: In order to insure the safe running of wind turbine in high efficiency under the premise of lowest maintenance cost, preventive maintenance cycles need to be determined reasonable. In this paper, the special operation environment, complicated fault type and diversified situation of wind turbine are full considered, preventive maintenance cycle decision making optimization model is established under the minimum maintenance cost and availability constraints. Finally, gear box system is taken as an example for analysis and calculation to show the feasibility and rationality of model, the results can provide scientific decision basis for planning maintenance of wind turbine.

Abstract: Based on a "wind power remote monitoring system" project, this paper focus on the modeling and simulation of the wind power variant pitch control system, and also the wind generator active power control OPC CLIENT interface programming. Using the VC++ language and MFC, OPC CLIENT interface was designed for the start-stop control of fan and the active power control of wind farms, which enables the wind farm to accurate and rapid response of the wind power grid load instruction of automatic generation control (AGC). Further, based on the MATLAB/SIMULINK platform, we analyzed the variable pitch control system of the variable pitch wind turbine by modeling and simulation with the Denmark's VESTAS V80-2000 (2MV).