The traditional high voltage switchgear (HVS) state evaluation model mostly adopts electrical test, live detection and historical data, neglecting the influence of real-time operation data of HVS composition equipment on the state evaluation results. This paper proposes a HVS operation state evaluation model based on fuzzy set-valued statistics method and kernel vector space model based on electrical test data and on-line monitoring data. First of all, according to the components of high voltage switchgear, the operation state of HVS is described and the evaluation index system is established. Secondly, the fuzzy set-valued statistics method is used to construct the mathematical model of evaluation index weight. Then, the kernel vector space model is introduced, and the Gaussian kernel function is used to map the sample to the features of the high-dimensional feature space. The indicator vector of the sample data and the ideal indicator vector of the high-voltage switchgear operation status level standard are defined in the high-dimensional feature space, and the angle-weighted cosine between the two vectors is calculated as the closeness of the sample to the standard status level, and then the high-voltage switchgear operation status level is obtained. Finally, the real data of a power supply company in western China are simulated. The results show that the greater the closeness degree is, the closer the HVS corresponding to the sample is to the normal state, on the contrary, the smaller the closeness degree is, the closer the HVS is to the fault state.

This paper mainly studied the circuit parameter calculation theory and the methods based on damped oscillations in transient signals. The methods can be used for the location and origin of faults by calculating the circuit parameters of transient fault signals' path when the fault occurs in the power system transmission lines. It is important in theoretical and practical engineering to locate faults in powerlines by calculating circuit parameters based on damped oscillations which are the main component of the transient signals. In R-L and R-C circuits, relations of the characteristic parameters in damped oscillation voltage and current in time domain, with the circuit parameters as well as the component parameters are deduced. And the impedance characteristic of the circuit under damped oscillation is analyzed, which is defined as a pseudo-impedance based on the definition that impedance is steady and sinusoidal. Relations between the pseudo-impedance and circuit parameters are also found. Relations between component parameter and pseudo-impedance in series or parallel are also analyzed. So methods for circuit parameter calculation are proposed separately based on the characteristic parameters and pseudo-impedance, each of which is a kind of characteristic of the damped oscillation signal. Specific calculation methods are also proposed combining with the state-of-the-art signal analysis for damped oscillation signal. Analyses in this paper may lay an important foundation for practical engineering application. The proposed theory and methods are verified based on simulation of fault signals produced by MATLAB. The equivalent circuit of an actual distribution system is simulated by using PSCAD/EMTDC. Actual fault signals reappear in the simulation. Location of single-line-to-ground fault using damped oscillation signal proposed in the paper is proved feasible.

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