Research On UHV Converter Transformer Harmonic Loss Measurement, Analysis And Calculation Model

As China’s energy resources are spread unevenly across the country, HVDC power grid gets the major development of SGCC, which fits for transmitting electrical power in long distance and large capacity. Along with the development of Ultra High Voltage power grid. As a core component of each HVDC transmission system, the converter transformer has received extensive attention. Especially, HVDC transmission system mostly works under the condition of double 12 pulse converter, large of harmonic which generated from the 12-pulse rectifiers flow through its windings, a huge waste of energy created by the nonlinear load current, serious affects the temperature rise and load capacity of converter transformer. According to statistics, in the converter station such loss due to the converter transformer was estimated at 35%-50% of the total power loss. In this thesis, in order to conquer the difficulty of measuring loss of converter transformer, proposes a method of converter transformer harmonic loss measurement based on harmonic power source through the study, which by applying 10%-50% of the rated harmonic current in grid side of converter transformer, which can accurately measure the converter transformer harmonic loss, and obtain the converter transformer harmonic loss’frequency characteristic. Therefore, all Above-mentioned has great guiding significance in operation, maintenance and improvements for design, manufacturing in the future.The main contents of this thesis are as follows:(1)Considering difficult of the converter transformer harmonic loss measurement, IEC 61378-2 as the most widely used method for calculating is selected as the researched object, We analyzed the harmonic loss theory through the characteristics of converter transformer and its operation condition, and the relationship between different components with frequency. Finally, we correct the calculation model of the harmonic loss after the related simulation, experimental work.(2)On the basis of the works above, a measurement system for measuring and analysis of harmonic loss is presented. We verify the effectiveness and feasibility of the measurement system, and improve the measurement system scheme through measuring a scaled-down converter transformer harmonic loss. Then, complete the harmonic loss measurement system which fits to UHVDC converter transformer.(3)Design the experimental scenario in view of the harmonic loss measuring environment, the measuring results in real converter transformer are given and analyzed with two methods of IEC 61378-2 and proposed in this paper. We further improve the calculation model with the loss data comparative analysis.Using the modified model decouple the converter transformer harmonic loss, gets windings and connections’ stray loss, tank and structural parts’eddy loss under each harmonic, according to the simulation results, which verify the accuracy of the modified model and conclusion of this paper.