Autonomous MHK Monitoring System for Intelligent Converter Health Management

Marine and hydrokinetic (MHK) energy converters are often installed in remote, harsh environments where access is limited and maintenance is a costly and labor intensive process. The lack of real time information on the status and health of critical structural components prevents the adoption of condition based maintenance strategies, and thus requires the use of preemptory maintenance practices. This creates a deficiency of information on failures, and in turn impedes future design efforts. General statement of how this problem is being addressed: Luna is developing an embedded sensing system that combines sensors, electronics, and structural health and prognostic algorithms to identify the presence, type, and severity of structural damage to MHK devices. This technology will provide results that can inform control strategies and maintenance activities to lower operational costs and improve energy converter availability for energy production. What was done in Phase I: In Phase I, Luna used active electromechanical impedance measurements to obtain structural data and relate this to the onset of discrete damage for composite plates, as well as fatigue induced degradation from manufacturing flaws that are common in MHK devices. Detection and prediction algorithms were developed to perform a damage state analysis of the results to classify system health, with detection accuracies of 85.7 – 93.4% observed for composite specimens tested in the laboratory. What is planned for the Phase II project: The Phase II project will extend research in the Phase I, generating predictions of the remaining useful life for components based on damage state assessments and estimates of future loading conditions. These algorithms will be designed for implementation on embedded sensing hardware, with a preproduction prototype designed and built to provide data acquisition, signal processing, analysis, and communication with MHK control systems. Commercial Applications and Other Benefits: The proposed technology will result in a marketable structural health management system that can be integrated into existing or future MHK systems. The technology provides comprehensive characterization of the structural integrity of critical components in the MHK device throughout its lifecycle, comprised of development, testing, towing, installation, lifting, and normal operation of the energy converter. The information generated by this system will be used to notify operators of upset conditions or impending structural faults based on measured or predicted health states. This will have application to a variety of MHK devices, and derivatives of the technology will extend to other renewable energy platforms such as land based and offshore wind turbines. Key Words: Marine and hydrokinetic, MHK, ocean energy, water power, structural health monitoring, prognostics and health management, PHM, composite structures.