Reliability analysis and condition monitoring of a horizontal axis wind turbine

Abstract

Wind is one of the cheapest and cleanest sources of energy. However, large and frequent fluctuations in wind intensity and directions cause serious problems in harvesting this energy. Wind turbines are subjected to many harsh environmental conditions, which lead to their failure or degraded performance. Hence an assessment of total lifetime and reliability of wind turbine components is required. Moreover a condition monitoring system is also needed to keep an eye on ever changing effects of environment on different components. This thesis comprises of two main objectives. -- First objective of research deals with component based reliability analysis, which involves four steps. To accomplish first objective an assessment of failure modes using Failure Mode and Effect Analysis (FMEA) approach is first conducted. Subsequently, based on working and environmental conditions and failure characteristics, the reliability of each individual component is computed. Standard procedures like fault tree and markov analysis are also carried out. -- The second goal of research makes use of the results of reliability analysis, to design a safety system for wind turbines. Based on sensitivity of all the components, a number of parameters are selected for monitoring the most venerable components. A monitoring system is suggested using a single board computer (SBC), signal conditioning electronics and sensors. This SBC is responsible for monitoring of selected parameters. This computer as proposed in thesis will interact with system's built in PLC to initiate shutdown of the system if an alarming changes in parameters are detected. -- This research brings in to focus the need for a component based reliability analysis of small wind turbine systems. These systems appear to be reliable for some portion of the year and remain in stand by or for maintenance rest of the time. The need for condition monitoring system is also proved by lower reliability of specific components that require constant monitoring.