Evaluación de diseños de un Convertidor de Turbina de Viento considerando el comportamiento térmico

Evaluar el diseño de un convertidor de electrónica de potencia de turbinas de viento considerando el comportamiento térmico cuando está en servicio. Cuando se diseñan convertidores de electrónica de potencia para turbinas de viento, muy frecuentemente solo la tempetratura de unión máxima entre semiconductores es considerada. Para la aplicación de una turbina de viento, el ciclo térmico debido a la fluctuación de potencia puede también retardar el tiempo de vida de los semiconductores de potencia. De ahí que un sobre diseño sea necesario para incrementar su periodo de vida y para determinarlo, es necesario realizar una estimación del periodo de vida de las unidades semiconductoras de potencia

Enhancement of reliability in condition monitoring techniques in wind turbines

The majority of electrical failures in wind turbines occur in the semiconductor components (IGBTs) of converters. To increase reliability and decrease the maintenance costs associated with this component, several health-monitoring methods have been proposed in the literature. Many laboratory-based tests have been conducted to detect the failure mechanisms of the IGBT in their early stages through monitoring the variations of thermo-sensitive electrical parameters. The methods are generally proposed and validated with a single-phase converter with an air-cored inductive or resistive load. However, limited work has been carried out considering limitations associated with measurement and processing of these parameters in a three-phase converter. Furthermore, looking at just variations of the module junction temperature will most likely lead to unreliable health monitoring as different failure mechanisms have their own individual effects on temperature variations of some, or all, of the electrical parameters. A reliable health monitoring system is necessary to determine whether the temperature variations are due to the presence of a premature failure or from normal converter operation. To address this issue, a temperature measurement approach should be independent from the failure mechanisms. In this paper, temperature is estimated by monitoring an electrical parameter particularly affected by different failure types. Early bond wire lift-off is detected by another electrical parameter that is sensitive to the progress of the failure. Considering two separate electrical parameters, one for estimation of temperature (switching off time) and another to detect the premature bond wire lift-off (collector emitter on-state voltage) enhance the reliability of an IGBT could increase the accuracy of the temperature estimation as well as premature failure detection

Estimation of the power electronic converter lifetime in fully rated converter wind turbine for onshore and offshore wind farms

A comparison has been made of the converter lifetime for a 3MW fully rated converter horizontal axis wind turbine located onshore and offshore. Simulated torque and speed of the turbine shaft were used to calculate voltage and current time series, that was used to calculate the junction temperatures of the diode and IGBT in the generator-side converter by a thermal-electrical model. A rainflow counting algorithm was applied to the junction temperature in combination with an empirical model of the lifetime estimation, to calculate the lifetime of the power electronic modules in the turbine. The number of parallel modules for each location to achieve 20 years life time has also been found. Simulations show the lifetime consumption rate of the diode and IGBT is decreased exponentially by increasing number of parallel modules, lowering the average temperature. The offshore wind turbine has a higher lifetime consumption rate, requiring a slightly higher converter rating to achieve a 20-year lifetime, but this difference is small, and both turbines will use the same number of modules

Holistic Physics-of-Failure Approach to Wind Turbine Power Converter Reliability

As the cost of wind energy becomes of increasing importance to the global surge of clean and green energy sources, the reliability-critical power converter is a target for vast improvements in availability through dedicated research. To this end, this thesis concentrates on providing a new holistic approach to converter reliability research to facilitate reliability increasing, cost reducing innovations unique to the wind industry. This holistic approach combines both computational and physical experimentation to provide a test bench for detailed reliability analysis of the converter power modules under the unique operating conditions of the wind turbine. The computational models include a detailed permanent magnet synchronous generator wind turbine with a power loss and thermal model representing the machine side converter power module response to varying wind turbine conditions. The supporting experimental test rig consists of an inexpensive, precise and extremely fast temperature measurement approach using a PbSe photoconductive infra-red sensor unique in the wind turbine reliability literature. This is used to measure spot temperatures on a modified power module to determine the junction temperature swings experienced during current cycling. A number of key conclusions have been made from this holistic approach. -Physics-of-failure analysis (and indeed any wind turbine power converter based reliability analysis) requires realistic wind speed data as the temporal changes in wind speed have a significant impact on the thermal loading on the devices. -The use of drive train modelling showed that the current throughput of the power converter is decoupled from the incoming wind speed due to drive train dynamics and control. Therefore, the power converter loading cannot be directly derived from the wind speed input without this modelling. -The minimum wind speed data frequency required for sufficiently accurate temperature profiles was determined, and the use of SCADA data for physics-of failure reliability studies was subsequently shown to be entirely inadequate. -The experimental emulation of the power converter validated a number of the aspects of the simulation work including the increase in temperature with wind speed and the detectability of temperature variations due to the current's fundamental frequency. Most importantly, this holistic approach provides an ideal test bench for optimising power converter designs for wind turbine, or for other industries with stochastic loading, conditions whilst maintaining or exceeding present reliability levels to reduce wind turbine's cost of energy, and therefore, society