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WECS & T&D 2012 - 04 - LS - Reliability
You are here: EPE Documents > 03 - EPE Seminar Papers > 006 - EPE Joint Wind Energy and T&D Chapters Seminar (2012) > WECS & T&D 2012 - 04 - LS - Reliability
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	Cost of poor Reliability, Do you want to know? Do you dare to know? - Presentation   By P. de Place Rimmen	[View]   [Download]
Abstract: The presentation of "Cost of poor Reliability, Do you want to know? Do you dare to know?"
	FRENS - Lifetime prediction for Power Converters - Presentation   By H. Huang; M. Jennings; Ph. Mawby	[View]   [Download]
Abstract: The presentation of "FRENS - Lifetime prediction for Power Converters"
	Power Electronics for Wind Turbines – Designing for Reliability - Presentation   By L. Helle; T. abeyasekera; T. Lundgren; P. C. Kjaer	[View]   [Download]
Abstract: The presentation of "Power Electronics for Wind Turbines – Designing for Reliability"
	Life assessment methodology for wind turbine power conversion building blocks - Presentation   By P. Hansen; V. Donescu; L. Helle	[View]   [Download]
Abstract: The presentation of "Life assessment methodology for wind turbine power conversion building blocks"
	Transformers internal voltage stress during current interruption in wind farm collection grids - Presentation   By T. Abdulahovic; T. Thiringer	[View]   [Download]
Abstract: The presentation of "Transformers internal voltage stress during current interruption in wind farm collection grids"
	POWER ELECTRONICS FOR WIND TURBINES – Designing for reliability - Paper   By L. Helle; T. Abeyasekera; T. Lundgren; P. C. Kjaer	[View]   [Download]
Abstract: Over the last 5-10 years, turbine reliability and turbine availability have been major focus areas for the wind industry and as indicated by Figure 1 the effort has paid off in terms of a significant increase in turbines availability (given by lost production factor) and in warranty provisions [1]. With the present plans for offshore developments in both Germany [2] and UK [3] the focus on reliability is unlikely to reduce.
	Nonlinear Damage Accumulation for Inverter Lifetime Prediction - Paper   By H. Huang; P.A. Mawby; M.R. Jennings; D. Hamilton	[View]   [Download]
Abstract: This paper introduces an inverter lifetime prediction model which is able to estimate the inverter lifetime from a given mission profile. This model mainly consists of an inverter electrothermal model and an IGBT fatigue damage model. Different damage accumulation methods are examined. A nonlinear accumulation method shows the best fit to the experimental results, hence it is a much improved method for accumulating the damage caused by the fatigue of IGBT modules.
	Transformers internal voltage stress during current interruption for different wind turbine layouts - Paper   By T. Abdulahovic; T. Thiringer	[View]   [Download]
Abstract: The voltage transients generated during the breaker operations in cable systems, for instance, a wind park collection grid, can reach very low rise times. The rise times of these transients can be almost 50 times shorter than the rise time of a lightning pulse. Such transients can generate a very high voltage stress on the internal transformers insulation. In this paper, a test case is studied using verified models of different types of transformers and wind turbine layouts in order to account for typical wind turbine layouts found in modern wind farms. A critical switching scenario is chosen in order to provoke the highest possible voltage transients during a current interruption. Furthermore, internal overvoltages are estimated using model of a similarly sized winding. Simulations show that the magnitude of the voltage transients is higher than the basic lightning impulse insulation level (BIL) defined by present standards. Moreover, it is found that the rise time of the voltage surges is much shorter than the rise time of the lightning pulse. The shortest rise time of 40ns is obtained in a wind turbine layout where the wind turbine breaker is placed near the transformer. Due to very short rise times of the voltage transients, very high internal overvoltages are estimated in dry-type transformer windings. These internal overvoltages are much higher than overvoltages recorded at the basic lightning impulse level. For a wind turbine layout where a breaker is placed in the bottom of a tower and a dry-type transformer in a nacelle, the highest turn-to-turn voltage is estimated of about 1:5pu. This is almost 4 times higher turn-to-turn voltage compared to what is obtained during the BIL test. In a wind turbine layout where a breaker is placed close to the transformer, the amplitude of the turn-to-turn voltages reached 1:8pu due to lower stray capacitances and thus a shorter rise time of voltage strikes.