Robust non‐fragile approach to resilient design of PID‐based blade pitch control for wind energy conversion system

Abstract

The design of a blade pitch controller (BPC) for wind energy conversion system (WECS) applications is load-dependent and has to be adjusted for each operating condition. Thus, BPC robustness is important for coping with the endless variations in operating conditions. The boundaries of a robust stability region are determined in regards to the controller parameters plane using their relevant set of polynomial inequalities via Referential Integrity between Routh-Hurwitz criterion and Root-Locus (RI-RH/RL) approach. Constrained and unconstrained stability regions respectively are defined through a novel hybrid control technique based on the combination of both RI-RH/RL and Kharitonov (Kh) theorem. The hybrid RI-Kh method is used for globally analyzing all vertex plants to ensure the proposed controller robustness, nonfragility, and resilience by selecting its parameters at the center of the robust stability region. The optimal BPC-PID parameters estimated using different optimization techniques are always located within the specified stability region. Thus, the capability of the RI-Kh approach in determining the most robust, non-fragile and resilient controller is verified. Through simulation results, the effectiveness of the proposed approach and its applicability to WECS' global stabilization are validated.

Kharitonov Theorem Based Robust Stability Analysis of a Wind Turbine Pitch Control System

“…In the work of Ahmed et al [29], the Kharitonov robust stability theorem is used to analyze the stability of the pitch control system of a wind turbine. Nevertheless, in the cited paper, a rather simple model of a wind turbine, with no consideration of the dynamics of the tower and the low speed shaft has been used.…”

“…Despite the observed performance limitations when using high order complex dynamic models, adequate results could be obtained by either reducing the order of the model (the dynamic behaviour is kept unchanged) or considering smaller uncertainty levels. In comparison to other Kharitonov theorem based robust stability analyses found in the literature, such as the one presented by Ahmed et al [29], the analysis presented in this paper presents a method to ensure the closed loop stability of the pitch control system in the whole range of operating conditions in which the pitch control loop is active (above rated power) in a real wind turbine. Moreover, a complex and realistic wind turbine model is used.…”

“…Moreover, a complex and realistic wind turbine model is used. In the previously cited work of Ahmed et al [29], the Kharitonov theorem is applied to a simplified wind turbine model operating in mainly under rated power conditions.…”

“…In the same way, in the work of Raouf et al [28], the Kharitonov theorem is used to evaluate the stability of a controller in a hybrid wind-diesel generation system. Finally, in the work of Ahmed et al [29], the Kharitonov robust stability analysis is used to evaluate the absolute stability of the pitch control loop of a wind turbine simplified model. Nevertheless, no robust stability analysis based on the Kharitonov theorem and applied to a complex and realistic wind turbine model has been found in the literature.…”

Fault Detection of WECSs With a Delayed Input and an Unknown Part Based on SVO

“…Therefore, research on the fault detection of WECSs has practical significance. At present, the research objectives of WECSs are mainly focused on single components, such as a blade pitch [1][2] , doubly fed induction generator [3][4] , or permanent magnet synchronous generator [5] . The research targets of fault detection are mainly focused on a variety of models, such as a permanent magnet synchronous motor drives [6] , polytopic linear parameter-varying system [7] , heterogeneous multiagent LPV system [8] , linear discrete time-varying system [9] , and T-S fuzzy system with local nonlinear models [10] .…”