¡À 800kv Uhvdc Transmission System Converter Transformer Internal Fault Identification And Positioning Research

The advantage of the technology of UHVDC power-transmission is of high voltage and transmission capacity, suit for long distance transmission and so on, the first UHVDC transmission lines in the word, "Yun-Guang±800kV UHVDC Transmission Line" has been run into operation. With the technology become more and more sophisticated, the technology of UHVDC power-transmission will be widely used. Converter transformer is one of the most important main electrical equipmen in UHVDC transmission system, it is a power-transfor hub in the system, whose safe operation directly affect the safe operation of the DC transmission system safe and stable operation.Converter transformer is a special type of transformer in converter station, since the voltage added on the valve side winding of converter transformer is AC voltage,DC voltage and polarity reversal voltage, and a series of harmonic winding current is in both sides winds, so there is a lot of difference in design, manufacture and operation between converter transformers and common AC transformer.Recognizing to variation of electrical quantity of converter transformer internal fault is the premise of developing new protection principle, so it is necessary to simulate and analyse the onverter transformer internal fault in detail. The paper take±800kV UHVDC transmission system converter transformer as an example, use electromagnetic transient simulation software PSCAD/EMTDC as the simulation platform, based on the multi-transmission line model of transformer, established a new converter transformer internal fault High-frequency distributed parameter transient circuit simulation mode. Using wavelet transform accurate the wavelet energy relative entropy, (WERE), and analyse the distribution along the scale of WERE on the various fault conditions in detail. At last established internal fault identification BP neural sub-networks and internal fault location BP neural sub-network, and make converter transformer fault diagnosis and fault location. Through simulating the converter transformer internal fault model, provide basis for the study and exploration of speed movement, reliable and high sensitivity of new transformer protection principle and repairing and maintenance of converter transformer.