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In this study, a PD defect identification system based on linear discriminant a nalysis and adaptive neural fuzzy inference system is developed. in this study, the par tial discharge signs of typical defects of the GIS measurement were measured with a measuring device. the corresponding characteristic parameters extracted from the GIS measurement were filtered according to the optimization algorithm and stored in the form of three-dimensional discharge mode (q-φ-t). On this basis, the 3d discharge mode is converted into statistical parameters. statistical pd features can be used for defect classification purposes, but it is clear that for this goal, the treatment of sovolume data base will be inefficient. therefore, it would be very helpful to select those features t hat are more effective and more efficient to identify and distinguish potential pd defects through their relevant statistical parameters. Select feature extraction techniques for dimensionality reduction. In solving pattern classification problems, feature extraction methods are usually used as preprocessing techniques, which cannot only reduce the computational complexity, but also achieve better classification performance by reducing irrelevant and redundant information in the data.

In order to study the influence of the test current on the dynamic resistance measurement of the SF6 circuit breaker with different erosion degrees, simulated erosion experiment was carried on 126 kV SF6 circuit breaker. The result shows, that the higher the test current is, the smaller the resistance of arcing contact when the circuit breaker is of any degree of erosion, but there is always no obvious link between the arcing contact travel and the test current. In addition, the dispersion of the test results decreases with the increase of the test current. However, when the erosion of the circuit breaker is very serious, the dispersion of results will be great regardless of the value of the test current. Therefore, considering the influence of test current on contact resistance, in order to obtain actualarcing contact resistance and to reduce the dispersion of test results considering the influence of test current on contact resistance, the larger dynamic resistance test current should be chosen as much as possible, and the dynamic resistance test must be carried on many times when contact erosion is extremely serious, so that the state of arcing contact can be obtained according to the distribution of test results.

Since most of replaceable resources generate the DC power or retrieve the most energy by converted to DC power and more DC loads are appearing on the market, the feasibility of low-voltage DC distribution has been discussed again recently. By applying DC distribution, conversions stages can be saved accompanied with benefits of high stability and the ease of designing UPS system. However, for nearly all distribution system is AC-powered at present, the feasibility of DC distribution system should be discussed. Moreover, AC/DC converters and DC breakers which are two important components in DC distribution system are also the issues to be discussed. Therefore, in this thesis, the feasibility of DC distribution will be investigated. In addition, the feasible topologies and design rules of converter and breakers are proposed with the verification by simulation results.