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Abstract

The degradation process of wind turbines is greatly affected by external factors. Wind turbine maintenance costs are high. The regular maintenance of wind turbines can easily lead to over and insufficient maintenance. To solve the above problems, a stochastic degradation model (SDE, stochastic differential equation) is proposed to simulate the change of the state of the wind turbine. First, the average degradation trend is obtained by analyzing the properties of the stochastic degradation model. Then the average degradation model is used to describe the predictive degradation model. Then analyze the change trend between the actual degradation state and the predicted state of the wind turbine. Secondly, according to the update process theory, the effect of maintenance on the state of wind turbines is comprehensively analyzed to obtain the availability. Then based on the average degradation process, the optimal maintenance period of the wind turbine is obtained. The optimal maintenance time of wind turbines is obtained by optimizing the maintenance cycle through availability constraints. Finally, an onshore wind turbine is used as an example to verification. Based on the historical fault data of wind turbines, the optimized maintenance decision is obtained by analyzing the reliability and maintenance cost of wind turbines under periodic and non-equal cycle conditions. The research results show that maintenance based on this model can effectively improve the performance of wind turbines and reduce maintenance costs.
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Bibliography

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Authors and Affiliations

Hongsheng Su
1
Xuping Duan
1
ORCID: ORCID
Dantong Wang
1

  1. Lanzhou Jiaotong University, China
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Abstract

The paste content in the self-compacting concrete is about 40% in unit volume. The rheological properties of paste directly determine the properties of self-compacting concrete. In this paper, the effect of silica fume (2, 3, 4, and 5%), limestone powder (5, 10 and 15%), and the viscosity modified admixture (2, 3, 4, 5, 6, and 7%) on the rheological properties were investigated. The effect of admixtures on shear thickening response was discussed based on the modified Bingham model. The results indicate that yield stress and plastic viscosity increased with increased silica fume and viscosity modified admixture replacement. The paste’s yield stress increases and then decreases with limestone powder replacement. The critical shear stress and minimum plastic viscosity are improved by silica fume and viscosity modifying admixture. The critical shear stress first increases and decreases as the limestone powder replacement increases. A reduction in the shear thickening response of paste was observed with silica fume and viscosity modified admixture replacement increase.
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Authors and Affiliations

He Liu
1
ORCID: ORCID
Guangchao Duan
1
ORCID: ORCID
Jingyi Zhang
2
ORCID: ORCID
Yanhai Yang
1
ORCID: ORCID

  1. Shenyang Jianzhu University, School of Transportation and Geometics Engineering, No. 25 Hunnan Zhong Road, Hunnan District, 110168 Shenyang, China
  2. Shenyang Urban Construction University, School of Civil Engineering, No. 380 Bai Ta Road, Hunnan District, 110167 Shenyang, China
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Abstract

Commonly, the Park model is used to calculate transients or steady-state operations of synchronous machines. The expanded Park theory derives the Park equations from the phase-domain model of the synchronous machine by the use of transformations. Thereby, several hypothesis are made, which are under investigation in this article in respect to the main inductances of two different types of synchronous machines. It is shown, that the derivation of the Park equations from the phase-domain model does not lead to constant inductances, as it is usually assumed for these equations. Nevertheless the Park model is the most common analytic model of synchronous machines. Therefore, in the second part of this article a method using the evolution strategy is shown to obtain the parameters of the Park model.

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Authors and Affiliations

Christoph Schmuelling
Christian Kreischer
Marek Gołebiowski

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