Applications and Modeling Techniques of Wind Turbine Power Curve for Wind Farms - A Review

In the wind energy industry, the power curve represents the relationship between the “wind speed” at the hub height and the corresponding “active power” to be generated. It is the most versatile condition indicator and of vital importance in several key applications, such as wind turbine selection, capacity factor estimation, wind energy assessment and forecasting, and condition monitoring, among others. Ensuring an effective implementation of the aforementioned applications mostly requires a modeling technique that best approximates the normal properties of an optimal wind turbines operation in a particular wind farm. This challenge has drawn the attention of wind farm operators and researchers towards the “state of the art” in wind energy technology. This paper provides an exhaustive and updated review on power curve based applications, the most common anomaly and fault types including their root-causes, along with data preprocessing and correction schemes (i.e., filtering, clustering, isolation, and others), and modeling techniques (i.e., parametric and non-parametric) which cover a wide range of algorithms. More than 100 references, for the most part selected from recently published journal articles, were carefully compiled to properly assess the past, present, and future research directions in this active domain

Piston driven yaw mechanism

Masteroppgave i mekatronikk MAS 500 Universitetet i Agder 2014The current thesis presents a piston driven yaw mechanism for wind turbines. Traditionally the yaw mechanismhas been one of the mayor contributors to down time and repair has been costly. The proposed designaims to improve the reliability of the yaw mechanism by reducing the point loads and by using hydrauliccylinders instead electrical motors to generate torque. In addition the design is modular allowing the mechanismto be disassembled and components to be replaced without the requirement of complicated or costlymachinery. The current thesis presents an analysis of the state of the art and discusses concepts which maysolve some of the challenges with existing yaw mechanisms. Further on a conceptual model of the mechanismis developed. Modelling and simulation is carried out to verify the suitability of the concept. It is found thatthe proposed yaw mechanism may be suitable for modern wind turbines and that the design may increasethe reliability and reduce cost of repair compared to current solutions

On mooring line tension and fatigue prediction for offshore vertical axis wind turbines: A comparison of lumped mass and quasi-static approaches

Despite several potential advantages, relatively few studies and design support tools have been developed for floating vertical axis wind turbines. Due to the substantial aerodynamics differences, the analyses of vertical axis wind turbine on floating structures cannot be easily extended from what have been already done for horizontal axis wind turbines. Therefore, the main aim of the present work is to compare the dynamic response of the floating offshore wind turbine system adopting two different mooring dynamics approaches. Two versions of the in-house aero-hydro-mooring coupled model of dynamics for floating vertical axis wind turbine (FloVAWT) have been used, employing a mooring quasi-static model, which solves the equations using an energetic approach, and a modified version of floating vertical axis wind turbine, which instead couples with the lumped mass mooring line model MoorDyn. The results, in terms of mooring line tension, fatigue and response in frequency have been obtained and analysed, based on a 5 MW Darrieus type rotor supported by the OC4-DeepCwind semisubmersible

Fault Diagnosis of a Variable-Speed Wind Turbine via Support Vector Machines

In recent years, wind energy is considered as the most practical substitute energy to replace the fossil fuels. Wind turbines are massive and installed in locations, where a non-planned maintenance is very costly. Therefore, a fault-tolerant control system that is able to maintain the wind turbine connected after the occurrence of certain faults can avoid major economic losses. To keep the wind turbine operational or at least safe, in severe cases, a reliable fault diagnosis methodology has to be exploited. It must detect, in the required time, any deviation of the system behaviour from its ordinary case, identify the location and type of the fault and reconfigure the control system to accommodate the so-called discrepancy. To achieve the above goals, a vast number of methods have been suggested by many researchers all around the world. In this thesis, the promising classification framework of the Support Vector Machines is applied to fault detection for variable speed turbines, highlighting its features. In this regard, different fault scenarios are imposed on a benchmark model of a horizontal-axis wind turbine to check the functionality of the mentioned fault detector and the control reconfiguration module

Detection of Mass Imbalance Fault in Wind Turbine using Data Driven Approach

Optimizing the operation and maintenance of wind turbines is crucial as the wind energy sector continues to expand. Predicting the mass imbalance of wind turbines, which can seriously damage the rotor blades, gearbox, and other components, is one of the key issues in this field. In this work, we propose a machine learning-based method for predicting the mass imbalance of wind turbines utilizing information from multiple sensors and monitoring systems. We collected data and trained the model from Adwen AD8 wind turbine model and evaluated on the real wind turbine SCADA data which is located at Fraunhofer IWES, Bremerhaven. The data included various parameters such as wind speed, blade root bending moments and rotor speed. We used this data to train and test machine learning classification models based on different algorithms, including extra-tree classifiers, support vector machines, and random forest. Our results showed that the machine learning models were able to predict the mass imbalance percentage of wind turbines with high accuracy. Particularly, the extra tree classifiers with blade root bending moments outperformed other research for multiclassification problem with an F1 score of 0.91 and an accuracy of 90%. Additionally, we examined the significance of various features in predicting the mass imbalance and observed that the rotor speed and blade root bending moments were the most crucial variables. Our research has significant effects for the wind energy sector since it offers a reliable and efficient way for predicting wind turbine mass imbalance. Wind farm operators can save maintenance costs, minimize downtime of wind turbines, and increase the lifespan of turbine components by identifying and eliminating mass imbalances. Also, further investigation will allow us to apply our method to different kinds of wind turbines, and it is simple to incorporate into current monitoring systems as it supports prediction without installing additional sensors. In conclusion, our study demonstrates the potential of machine learning for predicting the percentage of mass imbalance of wind turbines. We believe that our approach can significantly benefit the wind energy industry and contribute to the development of sustainable energy sources

Optimization of Stand-Alone Hybrid Solar-Wind System by Using General Morphological Analysis

At the beginning of this chapter is a brief introduction to the issue of renewable energy sources. Next, aspects that should be considered when choosing a location of both solar photovoltaics panels and wind turbines are discussed. Afterwards, there is a brief theoretical introduction to the General Morphological Analysis (GMA), followed by practical application of GMA to optimize the structure of hybrid solar-wind system, which is preceded by a description of the adopted design assumptions. At the end of the chapter is a numerical model of a hybrid solar-wind system developed in the MATLAB/Simulink environment and analysis of the results of numerical simulations

TIDAL STREAM DEVICES: RELIABILITY PREDICTION MODELS DURING THEIR CONCEPTUAL & DEVELOPMENT PHASES

Tidal Stream Devices (TSDs) are relatively new renewable energy converters. To date only a few prototypes, primarily horizontal-axis turbine designs, are operational; therefore, little reliability data has accumulated. Pressure to develop reliable sources of renewable electric power is encouraging investors to consider the technology for development. There are a variety of engineering solutions under consideration, including floating tethered, submerged tethered, ducted sea-bed bottom-mounted and sea-bed pile-mounted turbines, but in the absence of in-service reliability data it is difficult to critically evaluate comparative technologies. Developing reliability models for TSDs could reduce long-term risks and costs for investors and developers, encouraging more feasible and economically viable options. This research develops robust reliability models for comparison, defining TSD reliability block diagrams (RBD) in a rigorous way, using surrogate reliability data from similarly-rated wind turbines (WTs) and other relevant marine and electrical industries. The purpose of the research is not to derive individual TSD failure rates but to provide a means of comparison of the relative reliabilities of various devices. Analysis of TSD sub-assemblies from the major types of TSDs used today is performed to identify criticality, to improve controllability and maintainability. The models show that TSDs can be expected to have lower reliability than WTs of comparable size and that failure rates increase with complexity. The models also demonstrate that controls and drive train sub-assemblies, such as the gearbox, generator and converter, are critical to device reliability. The proposed developed models provide clear identification of required changes to the proposed TSD system designs, to raise availability, including duplication of critical systems, use of components developed for harsh environments and migration of equipment onshore, wherever practicable

Energy Security and Resiliency for the Texas National Guard

The Texas Military Department (TMD) faces energy security issues due to the dependency of electricity from the grid that can be disrupted in case of a natural disaster like Hurricane Harvey hitting Texas. This motivates us to generate electricity at the location using locally available renewable sources, reducing TMDs dependency on the grid and giving a sense of energy security. The fall in the price of renewable energy over the last few years makes them a suitable candidate for harnessing greener energy and establishing an independent micro grid. Most of these renewable energy sources are intermittent in nature which takes our focus on storage options, along with greater reliance on more reliable energy sources such as biomass and natural gas. This study targets the electricity consumption of Camp Swift on an annual basis. From the optimization results we can learn that we can produce over 40% of the energy through renewable sources which is which is higher than the state average of 18%. This results in a total cost of about 2.7 million USD out of which about 62000 USD is kept for running costs while 2.33 million USD is the expected cost of setting up this grid. By using Biomass and Natural Gas, in conjunction with Solar and a Diesel Generator, the system is able to produce 5.5 million kWh of electricity against annual demand of less than 2 million kWh which can be used to sell electricity back to the grid in the event of a grid failure or via net metering enabled smart meters

Design and Testing of Power Cycle Concepts for the WPI Kite-Powered Water Pump

The goal of this MQP was to continue the design and testing of the Rotary WPI Kite-Powered Water Pump using concepts for airborne wind energy systems. An ascending kite pulls on a tether attached to a rotating wheel, gear mechanism, and water pump axle. The kite is retracted to its original altitude using a retraction system. First, we designed a support for the water pump that could be incorporated into the existing A-frame design. We improved the housing for the power spool to allow for a stall spool and brakes. We improved the vertical pump shaft connecting the windmill pump to the underground pump cylinder. Solidworks was used to design all parts and a program was developed to calculate variables within the airborne wind system. The final design was lab and field tested