To solve the influence of photovoltaic connected to the station on the power quality of the low-voltage distribution network under extreme weather conditions, the two key points of harmonic and flicker are researched, and the analysis model of harmonic and flicker of the low-voltage distribution network is established according to the characteristics of the low-voltage distribution network in the station area. The characteristics of harmonics and flicker in low-voltage distribution networks with photovoltaic grid-connected inverters as grid-connected interfaces are studied in this paper. Through simulation, it can be concluded that the meteorological factors in the operating environment of distributed grid-connected photovoltaic power supply will have a certain impact on the harmonics and flicker of the low-voltage distribution network in the station area. The main reason is that extreme weather affects the output of the photovoltaic power supply, and the reduction of the PWM duty cycle under low output conditions leads to a significant increase in the number of odd harmonics. At the same time, the low output operation condition also leads to the occurrence of flicker. Finally, a method of controlling the generation of harmonics and flicker by using BP artificial neural network to predict the photovoltaic output and optimize the operation of photovoltaic is proposed. This method has certain practicability for improving the power quality of distributed photovoltaic power supply after connecting to the low-voltage distribution network in the station area.

Based on the Multi-body dynamics, the dynamics equation of the flexible blade in wind turbine is established by discretizing the rotating blade using finite element method. The simulation analysis of the single blade and the vibration modes of a 5MW wind turbine rotor are carried out by MATLAB. The first six natural frequencies and modes of the single blade and the rotor are figured out, and whose results are analyzed. The simulation results indicates that the coupling effect of the rotor can lead to dynamic stiffening. In comparison to the results in FAST, these simulation results show an outstanding agreement with the results calculated by FAST and hence approve the simulation method is valid and meanwhile give reference for large wind turbine design and running.

In this paper, we demonstrate the design and simulation of a baseline PID rotor collective pitch controller with a gain scheduling for WindPACT) operation. We use a FAST-Simulink model of the closed-loop system to describe simulating this controller.Through the simulation analysis and comparing the result, control effect with the control strategy of gain scheduling results in better power regulation. At the moment of wind speed make more close to the rated wind speed, the changes of pitch angle is more sensitive, and the output power is larger and more smoothly.

Blade is one of key parts in wind turbine. Its shape design and airfoil selection directly affects the performance of wind turbine. This paper presented reverse redesign method of blade of large wind turbine and developed a blade airfoil automatically generating system. The redesign of blade is achieved through such processes as reverse measurement, reverse CAD modeling and blade reverse model analysis as well as determining the formula of blade section parameters. The blade airfoil automatically generating system has been applied.

This paper uses modern control based on DAC control to numerically simulate a 1.5MW wind turbine. Through linearized modeling of 1.5MW wind turbine, this paper illustrates state-space control design and simulation for a 1.5MW wind turbine. This paper emphasizes on the use of DAC control to alleviate loads when the turbine is operating at maximum power. Loads diagrams of 1.5MW wind turbine including generator, low-speed shaft and high-speed shaft are obtained. The simulation results show that the collective pitch control based on DAC has certain effects on load alleviation compared to PI control.