Wind turbine asymmetrical load reduction with pitch sensor fault compensation

Abstract

Offshore wind turbines suffer from asymmetrical loading (blades, tower, etc), leading to enhanced structural fatigue. As well as asymmetrical loading different faults (pitch system faults etc.) can occur simultaneously, causing degradation of load mitigation performance. Individual pitch control (IPC) can achieve rotor asymmetric loads mitigation, but this is accompanied by an enhancement of pitch movements leading to the increased possibility of pitch system faults, which exerts negative effects on the IPC performance. The combined effects of asymmetrical blade and tower bending together with pitch sensor faults are considered as a ''co-design'' problem to minimize performance deterioration and enhance wind turbine sustainability. The essential concept is to attempt to account for all the ''fault effects'' in the rotor and tower systems, which can weaken the load reduction performance through IPC. Pitch sensor faults are compensated by the proposed fault-tolerant control (FTC) strategy to attenuate the fault effects acting in the control system. The work thus constitutes a combination of IPC-based load mitigation and FTC acting at the pitch system level. A linear quadratic regulator (LQR)-based IPC strategy for simultaneous blade and tower loading mitigation is proposed in which the robust fault estimation is achieved using an unknown input observer (UIO), considering four different pitch sensor faults. The analysis of the combined UIO-based FTC scheme with the LQR-based IPC is shown to verify the robustness and effectiveness of these two systems acting together and separately. KEYWORDSfault-tolerant control, individual pitch control, pitch sensor faults, wind turbine asymmetrical load reduction INTRODUCTIONAs a sustainable energy source, wind energy is taking an increasing share of the energy market to meet the growing demand for marine renewable energy. Wind energy has a significant potential for overcoming environmental pollution-related problems by reducing dependence on declining fossil fuel reserves. Wind turbines (WTs) can operate on land or offshore. Offshore WTs have large rotor diameters and high towers for high energy capture. The significant development of offshore wind power in recent years has led to a significant decrease in the levelized cost of energy (LCoE) of this form of renewable energy. However, there are two major challenges that the offshore WTs industry must face for Region 3 operation (above rated wind speed):1. Unexpected malfunction and failures of WT components will result in expensive repairs and typically months of machine unavailability, thus increasing the operation and maintenance (O&M) costs and threatening to increase the LCoE. However, offshore WT O&M are also challenged by the fact that wind farms are sometimes located 100 km offshore.

Quantifying the impact of sensor precision on power output of a wind turbine: A sensitivity analysis via Monte Carlo simulation study

“…While recent research has explored sensorless strategies, exemplified by works such as Aldin et al (2023), Shen et al (2009), Morfin et al (2021), and Benzaouia et al (2021), the WT industry today extensively utilizes sensors for control and monitoring purposes. Researchers like Tian et al (2023), Liu et al (2020), Kini et al (2023), da Silva et al (2022, Biazar et al (2022b), and Maheshwari et al (2023) have utilized sensors in their studies due to Department of Systems and Control Engineering, K. N. Toosi University of Technology, Tehran, Iran the benefits they offer, encompassing superior precision, low algorithmic control complexity, and rapid convergence speed.…”

Fault‐tolerant individual pitch control of floating offshore wind turbines via subspace predictive repetitive control

“…Furthermore, a control allocation‐based approach 13 was developed to compensate for the effect of non‐severe faulty actuators by implementing a reconfiguration law. More recently, adaptive sliding mode observer, 14,15 unknown input observer, 16 and model‐based FTC scheme 17 were utilized to design the fault‐tolerant individual pitch control (FTIPC) in the literature. In addition, other techniques such as barrier Lyapunov functions, 8 back propagation neural networks, 18 fuzzy models, 19 and sliding mode observer 20 were proposed for detecting and accommodating pitch faults in the last few years.…”

Adaptive Observer Based Fault Tolerant Control for Sensor and Actuator Faults in Wind Turbines

“…A vital step of the AFTC scheme is to online estimate the fault for the fault tolerant controller. Liu et al designed an unknown input observer in [12], where the fault signal and the modeling uncertainty were combined as the unknown input of the observer. However, the coupling between the state estimation error and the disturbance should be addressed by H ∞ optimization, which increased the complexity of the design.…”