Advanced Materials Research Vols. 608-609

Abstract: In this paper, the optimal schedule for power output of a wind farm with storage units and forecasting system has been studied. Optimal schedule for wind power output aims at maximizing expected schedule income and minimizing cost over the required period. We present a practical method to solve the problems based on forward dynamic programming algorithm. It is demonstrated by simulation that the method presented in this paper can ensure one to get a feasible and profitable schedule for wind farm.

Abstract: An Emergency power supply unit is of great importance to an electric pitch control system especially in MW turbines. Based on a basic parallel-series shift circuit, the paper proposes a novel topology of an emergency power supply unit consisting of ultracapacitors in electric pitch system. Capacitance configuration is obtained and the percentage of efficiency improvement using parallel-series circuit is calculated. Then a control strategy involving three operating modes is established and specific parameters are shown with a flow chart. Finally a simulation of an emergency power supply unit is established and the result confirms the theory.

Abstract: The output characteristics of wind energy conversion system are affected by the wind speed stochastic nonlinearity and uncertainty. To improve conversion efficiency, the method of realizing maximum power point tracking (MPPT) based on fuzzy control is proposed. Through adjusting the speed of the wind turbine by output power, the system approximates the maximum power operating point without wind speed sensor. The method constantly revises the system parameter in operation so that the parameter can be constantly optimized. Simulation results are given and discussed with MATLAB/SIMULINK to validate that the proposed control strategy has the good performance in terms of dynamic response and steady property.

Abstract: This paper presents an embedded control system for wind power generation based on DFIG (Doubly-fed Induction Generator). DSP was used as the core of the control system, which can meet the requirement of high precision and real time. An embedded real-time operation system (RTOS) was transplanted into the hardware platform and some function blocks in common use were added into the RTOS. The control system software in the computer was programmed with LabVIEW, which perform the control function and can process the data came from the A/D in the platform. By using this experiment platform, many control arithmetic of wind power generation can be tested in the laboratory.

Abstract: The integration of wind farms has a significant impact on the power system reliability. An appropriate model used to assess wind power system reliability is needed. Establishing multi-objective models (wind speed model, wind turbine generator output model and wind farm equivalent model) and based on the non-sequential Monte Carlo simulation method to calculate risk indicators is a viable method for quantitatively assessing the reliability of power system including wind farms. The IEEE-RTS 79 test system and a 300MW wind farm are taken as example.The calculation resluts show that using the multi-objective models can improve accuracy and reduce error; the higher average wind speed obtains the better system reliabitity accordingly.

Abstract: In order to build an aggregated wind farm model to research on the effect large scale wind power has on the transient performance of the power system, firstly, it is necessary to build an effective WTGs model. Based on the electro-magnetic transient simulation platform PSCAD/EMTDC, this paper built models of all the parts of Doubly-fed type VSCF wind generator, including wind model, wind turbine model, rotation system model, detailed converters model, and emphatically expounded the implementation process of the control strategy based on the stator flux vector oriented principle. Then through the change of wind speed and setting three-phase short-circuit fault on the net side, the model is verified on the decoupling control of active and reactive power for maximum point power tracking (MPPT) and the ability of low voltage ride-through.

Abstract: Use software Pro/E to build a blade model based on 1.5MW wind turbine, analyze stress characteristics of different regions including spar cap, webs and trailing edge of the dangerous section of blade at related loads by using different strength criteria to make finite element analysis to check the strength, through comparing the F.I.(fatigue index) and stress bringing about the idea that using different strength criteria to analyze different material of different regions can ensure the security and reliability of the designed blade at large extent.

Abstract: The impact of wind power integration on power market is complex and time-dependent, and can be reflected by some key factors with causal feedback relationships. First, the System Dynamics feature of the impact of wind power integration on power market is analyzed; second, according to the causal feedback relationships among the key factors, the System Dynamics model of the impact of wind power integration on power market is established; on this basis, under the scenario of wind power integrated capacity increasing, the impacts of wind power integration on the power supply and demand, power price and costs in power market are dynamically simulated, and the validity of the System Dynamics model in this paper is verified.

Abstract: This paper uses neural network combined with time series to establish rolling neural network model to predict short-term wind speed in the wind farm. In order to improve wind speed prediction accuracy, this paper analyzes effects of wind direction on wind speed by gray correlation analysis and obtains the correlation coefficient between wind speed at next moment and current wind direction is the largest by calculating. Then wind direction at current moment, historical wind speed and residuals which determined by time series are used as input variables to establish wind prediction model with rolling BP neural network. The simulation results show that neural network combined with time series which considers wind direction could improve the prediction accuracy when wind speed fluctuation is large.

Abstract: Switched reluctance generator (SRG) has a promising prospect for variable speed wind energy application because of its ruggedness, advantage cost, simplicity and ability to work over wide speed ranges. This paper presents the application of a single neuron adaptive PID algorithm to the problem of maximum power point tracking (MPPT) control in the wind power system using SRG, and a 750W, three phase (6/4) SRG prototype is chosen for the study. The nonlinear characteristics of the SRG and the wind turbine are described firstly, then the optimal speed tracking strategy based on the single neuron adaptive PID control for MPPT of the wind power system using SRG is investigated in the paper. Based on the developed model in MATLAB environment, simulation studies are performed in various conditions including a step change in the wind speed or in the load of SRG. Simulation results show the control system can quickly and steadily track the optimal curve to realize the MPPT with excellent dynamic and static performances, which verify the effectiveness of the control strategy investigated in the paper.