scholarly journals Assessing Wind Farm Reliability Using Weather Dependent Failure Rates

2016 ◽  
pp. 63-86
Author(s):  
Khashayar Hojjati-Emami ◽  
Balbir S. Dhillon ◽  
Kouroush Jenab

Nowadays, the human error is usually identified as the conclusive cause of investigations in road accidents. The human although is the person in control of vehicle until the moment of crash but it has to be understood that the human is under continued impact by various factors including road environment, vehicle and human's state, abilities and conduct. The current advances in design of vehicle and roads have been intended to provide drivers with extra comfort with less physical and mental efforts, whereas the fatigue imposed on driver is just being transformed from over-load fatigue to under-load fatigue and boredom. A representational model to illustrate the relationships between design and condition of vehicle and road as well as driver's condition and state on fatigue and the human error leading to accidents has been developed. Thereafter, the stochastic mathematical models based on time-dependent failure rates were developed to make prediction on the road transportation reliability and failure probabilities due to each cause (vehicle, road environment, human due to fatigue, and human due to non fatigue factors). Furthermore, the supportive assessment methodology and models to assess and predict the failure rates of driver due to each category of causes were developed and proposed.


Energies ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2682 ◽  
Author(s):  
John Warnock ◽  
David McMillan ◽  
James Pilgrim ◽  
Sally Shenton

In the offshore wind industry, failures are often costlier than those experienced onshore. Through examination of the literature, it is clear that failures occurring in offshore transmission systems are not well documented. As a result of this, many developers and other parties involved in the planning processes associated with offshore wind farms will defer back to existing reliability metrics in the public domain. This article presents a review of European offshore wind farm transmission failures based on fusing information from multiple public domain sources. The results highlight both the spread of the reliability performance of these assets and the reliability performance over time. The results also reinforce the industry view that installation practices could lead to low reliability in the initial years of operation, resulting in increased repair costs and decreased revenue for wind farm owners and operators. The information collated in the review is also compared to metrics from across the literature to evaluate the difference in forecasted failure rates to those experienced within the industry. In general, it is found that the experienced failure rates are subject to a much higher spread in practice than those published until now.


2013 ◽  
Vol 4 (1) ◽  
pp. 25-39 ◽  
Author(s):  
Khashayar Hojjati-Emami ◽  
Balbir S. Dhillon ◽  
Kouroush Jenab

Nowadays, the human error is usually identified as the conclusive cause of investigations in road accidents. The human although is the person in control of vehicle until the moment of crash but it has to be understood that the human is under continued impact by various factors including road environment, vehicle and human’s state, abilities and conduct. The current advances in design of vehicle and roads have been intended to provide drivers with extra comfort with less physical and mental efforts, whereas the fatigue imposed on driver is just being transformed from over-load fatigue to under-load fatigue and boredom. A representational model to illustrate the relationships between design and condition of vehicle and road as well as driver’s condition and state on fatigue and the human error leading to accidents has been developed. Thereafter, the stochastic mathematical models based on time-dependent failure rates were developed to make prediction on the road transportation reliability and failure probabilities due to each cause (vehicle, road environment, human due to fatigue, and human due to non fatigue factors). Furthermore, the supportive assessment methodology and models to assess and predict the failure rates of driver due to each category of causes were developed and proposed.


Batteries ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 39
Author(s):  
Rafael Conradt ◽  
Frederic Heidinger ◽  
Kai Peter Birke

The safety requirements in vehicles continuously increase due to more automated functions using electronic components. Besides the reliability of the components themselves, a reliable power supply is crucial for a safe overall system. Different architectures for a safe power supply consider the lead battery as a backup solution for safety-critical applications. Various ageing mechanisms influence the performance of the battery and have an impact on its reliability. In order to qualify the battery with its specific failure modes for use in safety-critical applications, it is necessary to prove this reliability by failure rates. Previous investigations determine the fixed failure rates of lead batteries using data from teardown analyses to identify the battery failure modes but did not include the lifetime of these batteries examined. Alternatively, lifetime values of battery replacements in workshops without knowing the reason for failure were used to determine the overall time-dependent failure rate. This study presents a method for determining reliability models of lead batteries by investigating individual failure modes. Since batteries are subject to ageing, the analysis of lifetime values of different failure modes results in time-dependent failure rates of different magnitudes. The failure rates of the individual failure modes develop with different shapes over time, which allows their ageing behaviour to be evaluated.


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