Applied Mechanics and Materials Vols. 448-453

Abstract: Distributed wind power will bring great impact on transient voltage of distribution network. Based on the characteristics of distributed wind power, this paper presents a doubly-fed induction Generator with four wind speed model and Crowbar protection model in DigSILENT/PowerFactory. The analysis is carried out for a test distribution system representative of the Benchmark 20kv grid. Firstly, this paper respectively provide simulation results showing the effects of distributed wind power on the dynamic voltage in wind fluctuation and a faulted system. Then, a static synchronous compensator (STATCOM) is used to improve the voltage profile of the distribution system.

Abstract: In order to maintain the maximum output power of the WGS (Wind generation system) for all wind speed conditions, a boost converter is used as the power interface between the WGS and DC microgrid. Traditional method is to directly measure the real-time output voltage and current of WGS by sensors. Considering the DC bus voltage is actually stable, the output voltage can be computed by the duty cycle of boost converter and the stable DC bus voltage. A MPPT method is proposed, which only measures the output current of WGS. The output scale power can be obtained by the output current and the duty cycle, and then the perturbation and observation method is executed. A number of voltage sensors and associated circuitry are cancelled. It reduces the interference and system cost and improves the system reliability. Simulation results with PSIM prove the validity of the proposed method.

Abstract: The characteristic of maximum power tracking was required in brushless doubly-fed generator (BDFG) distributed wind power system. This paper analyzed the mathematical model on synchronous coordinates of BDFG, and a vector transformation control strategy is put forward based on flux linkage oriented of the stator technology. It also established the vector transformation and the BDFG model in the Matlab/Simulink, and conducted the maximal wind energy capturing simulation research for the distributed wind power system with this algorithm. The theory analysis and simulation results indicated that this proposed control is feasibility and superiority in this field.

Abstract: For high-wind-speed wind power development and problems, propose development and application of low-wind-speed wind power (LWSP). Analysis of the characteristics of LWSP , advantages and necessity of development and application of it. Research the key technologies of LWSP development. It ultimately lay the foundation for research, development and application of LWSP technologies.

Abstract: LVRT technology is currently a hot research of wind power, but the impact on the wind turbine of grid voltage swells and HVRT technology have not been given sufficient attention. This article analyzed the converter problems of full power wind turbine on grid voltage swells and used the control strategy of reactive power control, dynamic voltage and over-modulation to enhance the full power wind turbines HVRT capability.

Abstract: Wind turbines are required by gird codes that active and reactive power should be fed into power grid during gird faults such as voltage sags. Power output capability is important for DFIG wind turbine to provide active and reactive power support. Constraints of stator, rotor maximum current and maximum output voltage of rotor-side converter (RSC) of DFIG are considered to analyze stator power output limit of the DFIG under unbalanced voltage sags, and newton-raphson method is used to solve the power limits, then the power control strategy based on power limit analysis is proposed. Simulation, calculation and comparison are carried out by a 1.5MW DFIG wind turbine model, and the effectiveness of the analysis and the proposed control strategy is verified.

Abstract: In order to improve the rate and accuracy of wind power forecasting, the Least-Square Support Vector Machine method (LSSVM) is presented. LSSVM adopts equality constraints and defines the least-square system as the objective function, which can simplify the forecasting method to a large extent, as well as accelerate the rate of wind power forecasting. Through the analysis of the original load data, a reasonable choice on training set and test sample set is made in the simulation. Besides, many factors, such as, the temperature, wind direction, wind speed and power previous, are taken into consideration. The result shows that LSSVM is more effective than that of SVM.

Abstract: Wind power industry has been attracting the attention of various countries from the very beginning because of the energy shortage in recent years and Chinese wind power industry has made a rapid progress in the past five years. However, a further study is required to evaluate investment efficiency of wind power industry under the current investment pattern. By sorting out the input and output data of Chinese wind farms from 2005-2010 and constructing and measuring DEA input and output model, this paper finds that efficiency of government-led investment pattern is not high and also analyzes the reasons. Finally, the paper points out enterprises-led investment pattern will create a healthy and sustainable development for wind power industry.

Abstract: Due to the significant instability, anti-peak-regulation and intermittency of wind power, wind power integration needs an accurate prediction technique to be a basis. At present, the difficulty of wind power integration has resulted in a large number of wind curtailment phenomena and wasted a lot of renewable energy. Grey prediction model has many advantages such as requiring little historical data and the simple model, with high prediction accuracy and convenient calculation, and without regard to regularities of distribution, etc. This paper puts forward the method for short-term wind power prediction using gray model GM (1, 1) and carries out simulation study and empirical analysis using the data from a wind farm of Jilin province, which shows the science and operability of the proposed model. It provides a new research method for the wind power prediction.

Abstract: Utilization of the otherwise curtailed wind to produce heat is considered an effective solution to combating wind curtailment. This paper studies the technical potential of wind heating in facilitating wind power integration in China. Technical schemes of wind-heating are proposed and their potential of facilitating wind power integration is studied both theoretically with probability methods, and quantitatively with case examples. The prospects of promoting wind-heating in China are also discussed. Results show that wind heating does help to facilitate wind power integration, but with limited roles. Other measures are still needed to thoroughly solve the wind integration issue. Analysis of wind-heating in wind rich areas such as Inner Mongolia, Liaoning, Jilin and Heilongjiang shows that it help enhance wind integration by 35%-45%.