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A coupled electromagnetic circuit method for converter transformer was proposed. The magnet circuit based on the topological structure and the saturation characteristics of core is established. The circuit-magnetic circuit model is achieved by coupling the magnet circuit with the circuit equation of primary side and secondary side of converter transformer. The research method is applied to a finite element model of a converter transformer and the exciting current of normal working condition and under DC bias is calculated together with the loss of structural component. The result shows the exciting current and loss can be predicted and analyzed accurately using this method. © 2016, Xi'an High Voltage Apparatus Research Institute Co., Ltd. All right reserved. Source

Jiang Z.,Xian XD Transformer Co.
Gaoya Dianqi/High Voltage Apparatus | Year: 2011

Reliability of DC barrier system is one of key points of converter transformer's R&D. DC barrier systems are imported over the years. Optimization of insulation structure of barrier system has significant influence on further speeding up localization manufacture of converter transformer in China. The operation characteristic of converter transformer was summarized, and the insulation structure of barrier system was studied. Furthermore, the calculation of electric field of insulation structure for DC barrier system was made. Converter transformer has features as high short circuit impedance, DC bias current influence, serious influence of harmonic and complicated insulation structure. Electric field analysis and calculation was carried on the basis of typical insulation structure of DC barrier system for different models under different testing condition, such as long duration AC applied voltage withstand test, DC voltage withstand test with PD measurement and polarity reversal test to summarize design concept and main points to structure of DC barrier system. Test results show that the developed insulation structure of DC barrier system is reasonable, which has been approved by the test. The same theory and method will be applied to insulation structure electric field analysis of DC barrier system of converter transformer with higher voltage level to optimize the sound insulation structure of DC barrier system. Source

Deng Y.,Xian XD Transformer Co.
Gaoya Dianqi/High Voltage Apparatus | Year: 2011

The insulation structure of converter transformer is its core technology, and it relates to the safety operation of converter transformer and DC transmission system. The special operation condition of converter transformer in DC system determine its main insulation and the valve side barrier system will withstand the voltage which is different from the AC transformer. This paper firstly presents the voltage withstood by insulation structure of converter transformer and then analyzes the voltage distribution in the insulation structure as well as the coordination of insulation material under different voltages. With the development and application of technology for UHV DC transmission, the insulation structure of converter transformer shall meet the electric, mechanical and thermal requirements, so the research of AC and DC combination electric field are the key of converter transformer. Source

Deng Y.,Xian XD Transformer Co.
Gaoya Dianqi/High Voltage Apparatus | Year: 2011

Drying treatment of self-bonding transposed conductor exerts significant influence on the insulation performance and short-circuit resistance capability of transformers. However, conventional drying treatment process does not distinguish different types of windings. The author lists diverse drying treatment processes for different windings by comparing the drying treatment processes and parameter requirements of two distinct windings in order to help manufactures select right drying treatment processes. Source

Zhang Q.-M.,Xian XD Transformer Co. | Zhang L.-X.,Xian Jiaotong University | Chen M.-S.,Xian Jiaotong University
Gaoya Dianqi/High Voltage Apparatus | Year: 2013

The polarity reversal is a special working condition of equipments in high voltage direct current (HVDC) transmission. A three-layers dielectrics composite insulation structure was taken as an example, and the mathematical model under polarity reversal was established in this paper with field-circuit coupling method, the characteristics of space charge at the interfaces of the different dielectrics as well as temporal variation laws of the electric field distribution, current characteristics and heat generation rate were analysed. The results in this paper could provide references for the insulation design of HVDC equipments. Source

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