Power regulation of wind turbines using torque and pitch control

Abstract

Power generation control in variable-speed variable-pitch horizontal-axis wind turbines operating at high wind speeds is considered in this work. A torque and pitch control strategies are proposed, implemented and validated using the National Renewable Energy Laboratory wind turbine simulator FAST (Fatigue, Aerodynamics, Structures, and Turbulence) code. Numerical results show that the proposed controllers are effective for power regulation. The performance of the contributed controllers is compared to some state-of-theart methodologies showing its improvements.

Nonlinear adaptive power tracking control of variable-speed wind turbines

“…When performing the control action, it is important to consider the loads behavior. Among the most important to consider are: 16,18 the tower base roll (or side-to-side) moment shown in Figure 5(a), the low-speed shaft (LSS) bending moment at the shaft’s strain gage shown in Figure 5(b), the LSS bending moment at the shaft tip shown in Figure 5(c), the tower-top/yaw bearing roll moment shown in Figure 5(d), the tower-top/yaw bearing side-to-side shear force shown in Figure 5(e), and the blade edgewise moment (i.e. the moment caused by edgewise forces) at the blade root shown in Figure 6.…”

“…As shown, the proposed controller depends on the rotor acceleration w · r . Following literature, 18 a way to compute this derivative is to use the estimator (transfer function in the Laplace domain) s / ( 0 . 1 s + 1 ) , where the input is w r and the output is an estimation of w · r . Another alternative to compute w · r is through the exact differentiator given in Levant, 30 which has finite-time convergence, does not depend on the system model, trivially satisfies the separation principle, and incorporates an algorithm for sampled signals.…”

“…Thus, variable-speed control has shown to be a better option to optimize the operation of these systems. 16–20…”

“…In studies by Rajendran and Jena 5 and Boukhezzar et al, 19 a variable-speed wind turbine is considered for power control, and the controllers depend on the knowledge of the turbine parameters, which could represent a drawback in practice. Vidal et al 16 and Pozo et al 18 proposed a controller based on the first-order sliding mode technique, and few parameters are required for solving the power regulation (PR) problem; however, the generator acceleration is needed. Others controllers based on sliding modes are reported by Beltran et al 21,22 Beltran et al 21 used an approximation of the signum function to avoid chattering in order to reduce mechanical stresses due to the high-frequency torque variations.…”

Development of small-scale wind energy systems adaptable to climatic conditions using chattering torque control - PI pitch control and CAES strategy

“…For the variable-speed variable-pitch horizontal axis wind turbines, we have proposed control techniques based on the combination of a nonlinear dynamic chattering torque control strategy and a proportional integral (PI) control strategy for the blade pitch angle [12], in both controllers the generator speed measurement is used as the input information. The above control structure allows for a rapid transition of the wind turbine generated power between different desired values, which implies that it is possible to adjust the wind turbine power production taking into account the power set-point or power consumption.…”