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1. A High-Power Active Filtering System With Fundamental Magnetic Flux Compensation.

Author

Dayi Li, Qiaofu Chen, Zhengchun Jia, and Changzheng Zhang

Subjects
ELECTRIC transformers, ELECTRIC currents, ELECTRIC filters, ELECTRICAL engineering, ENGINEERING
Abstract

In this paper, a novel transformer structure is proposed in order to manufacture a high-power active filtering device. The novel transformer structure contains one primary and multiple secondary windings. The system configuration and compensation principle are addressed in detail. The fundamental magnetic flux compensation in the case of the transformer with multiple secondary windings is fulfilled. In addition, a three-phase active power filter topology consisting of three independent transformers with multiple secondary windings is presented so that the filter can run under unbalanced loads. The parameters of hysteresis current control are also analyzed in detail. A simple and practical fundamental detecting approach is discussed. Transient response and fault protection schemes are explained. A set of automatic three-phase active power filtering devices has been constructed and operated in the field. The field test results verify the validity of the novel transformer structure and the active power filtering system. [ABSTRACT FROM AUTHOR]

Published
2006
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2. Modeling of replacement alternatives for power transformer populations

Author

J.M. Wetzer, A.W.M. van Schijndel, P.A.A.F. Wouters, Electrical Energy Systems, and Power grid studies

Subjects
Engineering, education.field_of_study, business.industry, Load modeling, Population, Probabilistic logic, Electrical engineering, Energy Engineering and Power Technology, Statistical model, SDG 3 – Goede gezondheid en welzijn, Reliability engineering, law.invention, SDG 3 - Good Health and Well-being, law, Power electronics, Statistical analysis, Electricity, Electrical and Electronic Engineering, business, Transformer, education
Abstract

The age of the majority of power transformers installed in the western electricity network reaches 30 to 60 years and replacement on short term seems eminent. A technically sound policy concerning the replacement of these assets requires a model that estimates the life expectancies of individual components and from that calculates parameters related to the behavior of a population of assets as a whole. A probabilistic approach is adopted and is applied to thermal degradation of the transformer paper insulation. In this paper, we will focus on the determination of the population reliability from individual reliabilities. These individual reliabilities are based on Arrhenius modeling of paper insulation degradation, including the inherent uncertainty in the parameters involved. A statistical failure model is used to obtain the population reliability figures. The modeling method is demonstrated on two populations of power transformers in The Netherlands to evaluate the different replacement alternatives. Using the model, strategies can be defined to maximize transformer utilization and postpone replacement. The downside is the need to replace the complete fleet in a relatively short time afterwards.

Published
2012