Wind Power Electric Systems

This Chapter is intended as an introduction to the subject. First, we present the global structure of a conversion wind system. Then the wind process is defined, introducing the main meteorological elements, the wind velocity, and electrical generators used in wind energy conversion system (WCES). An overview of wind systems (stand-alone systems and grid-connected systems) is also presented with the different electrical generators used. In a wind farms, generally an integrated online condition monitoring system can serve as an effective tool for managing day-to-day maintenance routines for a wind turbine and consolidating risky, costly maintenance activities. This chapter includes presizing and maintenance of wind systems. The two types of maintenance are described. Total costs for wind turbine installation depend on different parameters which are presented at the end of this chapter.

This chapter focuses on wind energy conversion and power electronics modeling. In the first part, the global structure of a wind energy conversion system is presented. The modeling of the different parts is given with some simulation results obtained under Matlab/Simulink and the different structures of converters used in wind systems are presented. The second part of this chapter is devoted to power electronics modeling and some applications are given under Matlab/Simulink.

Due to the nonlinear characteristic of the wind turbine, it is difficult to maintain the maximum power output of the wind turbine for all wind speed conditions. In research survey, several methods are used to track the maximum power point of the wind turbine. The most used method are the Hill climb searching or P&O, the Tip Speed Ratio (TSR), Power Signal Feedback (PSF),… The P&O is a popular method due to its simplicity and independence of system characteristics. The TSR direction control method is limited by the difficulty in wind speed and turbine speed measurements. And the PSF method requires the knowledge of the wind turbine’s maximum power curve, and tracks this curve through its control mechanisms. Other advanced methods are used to solve the problem of power maximization. The most used are Sliding Mode Control (SMC), Fuzzy Logic Controller (FLC), Adaptive Fuzzy Logic Controller (AFLC), Particle Swarm Optimization (PSO), Radial Basis Function Network (WRBFM), Artificial Neural Networks (ANN), Adaptive Neuro-Fuzzy Inference System (ANFIS),…Each method perform with its own proprieties (precision, stability, simplicity, robustness, model,…). Generally, they are used in the design of adaptive and intelligent systems since they are able to solve problems from previous examples.

Energy storage is a dominant factor. It can reduce power fluctuations, enhance system flexibility, and enable the storage and dispatch of electricity generated by variable renewable energy sources such as wind and solar. Different storage technologies are used with wind energy system or with hybrid wind systems and each one of them have its proper proprieties as lifetime, costs, density and efficiency. It can be electrical, chemical or electrochemical (Nickel-cadmium, Lead-acid, Sodium-sulfur, Lithium ion, Vanadium-Redox Flow batteries…). It can also be hydrogen storage and in this case different modes are used (compressed, liquefied, metal hydride, etc.). Thermal storage is generally used for wind energy management applications and its applications are around industrial cooling, building cooling and industrial heat storage. Mechanical storage (flywheel energy, pumped hydro energy, compressed air energy) is the most storage applied in wind energy conversion system for power quality and short duration.

In this chapter, several nonlinear controls of wind turbine systems are presented. The mechanical and the electrical part of wind turbine are detailed. We have presented three applications under Matlab/Simulink of the no linear control by static state feedback, the no linear dynamic control by state feedback and the Indirect Speed Control. To highlight the most effective controls, we make a comparison between the three methods under two different perturbation torque. The electrical part is studied using different control strategies as scalar and vector control, Direct torque and modulated hysteresis direct torque control, direct power control, sliding mode control and Fuzzy logic controllers.

This chapter is devoted to hybrid wind systems. It describes the different configurations and the different combinations of hybrid wind systems. Different synoptic schemes and simulation applications are also presented. Different synoptic schemes and simulation applications are also presented. We have presented a study of an hybrid wind/PV//Diesel system with battery storage. The application is under Matlab/Simulink during three different profiles of insolation and wind speed (low, medium and high conditions). This study seems interesting and can be applied to electrification or a pumping system for example.

In this chapter, we present some wind examples of wind turbines with simulation and experimental tests. Identification of the of the generator parameters is an important step before doing any simulation, and some tests are also important to confirm that the wind generator was not damaged in shipment and is ready to install on the tower. The two presented examples can help students to graduation and post graduations in the fields of electrical engineering quickly understand the identification of wind turbine, and make easily the simulation of the studied system.