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Traveling wave consists of the frequencies ranging from tens of kHz to hundreds of kHz in distribution network with single-phase fault, S-transform is implemented to detect the fault line in distribution network from the tens of kHz high frequency transient component of the fault traveling wave. The moment depending on the maximum component in the highest frequency row of the S-transform magnitude matrix of zero modal bus voltage corresponds to the real mutation moment of zero modal bus voltage. Then the moment of the first fault traveling wave front is calibrated and recorded as the beginning moment of single-phase fault occurrence. At this moment, the phases of initial current traveling wave front detected by TA at the protection relay device between fault line and sound lines are opposite. The S-transform is implemented to fault zero modal currents. The argument difference of the highest frequency row between fault line and sound line is 180o after fault, which makes fault line detectible. The proposed method detects the phase characteristics of traveling wave signal from the level of relatively low high-frequency transient component, which can not only reduce the requirements of traveling wave acquisition and processing speed, but also enhance the capacity of high resistance tolerance and anti-noise ability. The simulation results verified the feasibility and validity of this method.

The conclusion draws from traditional power supplying capability evaluation method can not reflect the actual supplying capability of gridby quantitative index, so evaluating the overall power supplying capability by means of fuzzy method has its advantage. Fuzzy analysis method has been employed to create a city gridpower supplying evaluating model in respect of the reality of power supplying condition of KunMing network, in which weighting is assigned by effect value of data reflected by information entropy to avoid the influence of subjective elements in weighting assigning. Seven elements which reflect the power supplying capability of KunMing grid objectively and comprehensively have been chose to construct corresponding membership degree function curve according to their different reflecting dimensionalities of power supplying capability, then the membership degree value of each elements is deduced. Each of the seven evaluating elements is judged to obtain quantitative fuzzy evaluating results, and then these 7 elements are combined to judge the power supplying capability synthetically to derive the fuzzy evaluating result of power supplying capability of KunMing network.

As one of the most important equipments to guarantee power gird operating safely and stably, the fault diagnosis of transformer has most important sense. Since the general diagnosis methods such as DGA and attributes' reduction of rough set haven't enough precision for transformer's fault diagnosis, Extenics and rough set theory are brought into diagnosing the fault of transformer. Using attribute predigesting method in rough set theory to classify the attribute term which needed by each fault diagnosis. Then building matter element model for transformer's fault diagnosis. Using DGA testing datum to be attribute set and the transformer's standard fault model to be the decision set for transformer's fault diagnosis. Utilize association function from Extenics to count each fault degree. Define the fault accepting rule to get transformer's fault. Use this method to diagnose one fault transformer and the diagnosis result matched case of fact fault. Apply this method to diagnose 76 DGA testing data and the right ratio of diagnostic result is better than IEC method.

The reliability can be enhanced by using single-phase reclosing, but when reclose to permanent faults, it is another surge on system. So there is necessity to study on the influence of reclosing sequence on transient stability margin. In the case that transient and permanent fault is not effectively identified, the influence of sequence and time of single-phase reclosing on transient stability margin in Southern China Power Grid of 2005 year is studied using software FASTEST when single-phase fault is occurred on 500 kV Anshun - Tianshengqiao transmission line in this paper. Simulation results indicate that when the terminal without fault uses non-voltage detecting and recloses first instead of the two terminals use non-voltage detecting in turn, the transient angle, voltage and frequency stability margin can all be enhanced and the working condition of breaker can be improved. A method combined with fault location algorithm to modify the sequence of single-phase reclosing online to enhance transient stability and lower the surge when reclose to permanent fault is proposed.