Synthesis of nonlinear controller for wind turbines stability when providing grid support

Abstract

SUMMARYThis paper presents a new nonlinear polynomial controller for wind turbines that assures stability and maximizes the energy produced while imposing a bound in the generated power derivative in normal operation (guarantees a smooth operation against wind turbulence). The proposed controller structure also allows eventually producing a transient power increase to provide grid support, in response to a demand from a frequency controller. The controller design uses new optimization over polynomials techniques, leading to a tractable semidefinite programming problem. The ability of the wind turbine to increase its power under partial load operation has been analysed. The above optimization techniques have allowed quantifying the maximum transient overproduction that can be demanded to the wind turbine without violating minimum speed constraints (that could lead to unstable behaviour), as well as the total generated energy loss. The ability to evaluate this shortfall has permitted the development of an optimization procedure in which wind farm overproduction requirements are divided into individual turbines, assuring that the total energy loss in the wind farm is minimum, while complying with the maximum demanded power constraints.

Maximum Power Point Tracking Strategy for Large-Scale Wind Generation Systems Considering Wind Turbine Dynamics

“…is assumed to be the measured or estimated value at a given site and over a certain time period, and is designed as a Gaussian distribution, e.g., ( , ) d~μ Σ  [11], [12]. In this paper, the empirical design is replaced by a model called Norm-Bounded uncertainty.…”

“…Thus, the proposed WECS control problem can be solved by SDP approaches and the optimal control input can be obtained with the transformation In many previously used WECS controls, the wind speed disturbance is commonly assumed to be Gaussian [11], [12]. This assumption may not hold in many cases and in the real world the disturbance does not always follow a regular probability distribution.…”

Co-design ofH∞jump observers for event-based measurements over networks

“…n y ). In order to make the problem numerically tractable we use the sum of squares (SOS) decomposition (Chesi (2010); Peñarrocha et al (2013Peñarrocha et al ( , 2014; Dolz et al (2015)) to define sufficient conditions to accomplish with the previous guaranteed performance. The idea is to consider the probabilities β i [t] on the previous LMI constraint as new variables of the problem and thus transform it into a polynomial matrix inequality (PMI).…”

Combined feedback linearization and MPC for wind turbine power tracking

“…Wang and Seiler (2014), Khezami et al (2010), Camblong et al (2012)). Peñarrocha et al (2013) present a nonlinear control to let transient power increase with respect to maximum aerodynamic power to sustain the grid in the case of low wind speed and fixed pitch angle. Concerning nonlinear control techniques applied to the turbine control for MPPT mode of operation or power limiting at high wind speed, plenty of strategies have been proposed.…”