Optical partial discharge (PD) detection is an efficient means of diagnosing the insulation status of power equipment. C4F7N/CO2 gas mixture is a very potential environmentally-friendly SF6 substitute gas, and its PD optical characteristics need to be studied to guide the PD diagnosis of novel C4F7N/CO2 equipment. Therefore, this article proposes a multispectral microarray detection technology, which can achieve high-sensitivity detection and PD diagnosis by simultaneously collecting the spectral characteristics of multiple bands. By setting up an experimental platform, the PD experiments of four typical defects in the C4F7N/CO2 gas mixture with five different proportions and pure SF6 are carried out. Based on the analysis of PD multispectral features, the correlation between different gases and the difference between different defects are obtained. Finally, by combining multispectral detection with a t-distributed stochastic neighbor embedding (T-SNE) feature extraction algorithm, a PD diagnosis method that can adapt to both C4F7N/CO2 gas mixture and SF6 is proposed, which provides a reference for the PD detection of novel C4F7N/CO2 equipment application.

With the widespread application of power electronic switching technology, power equipment is facing new electrical stresses brought about by multilevel staircase voltages during testing and operation. Therefore, the partial discharge (PD) behavior of five typical defects in power equipment under the staircase waveform needs to be investigated. This article mainly analyses the phase-resolved PD (PRPD) pattern and pulse repetition rate (PRR) of five typical defects under sinusoidal voltage and multilevel staircase voltage with different number of levels. Also, the PD behavior under staircase voltage with different step responses are investigated. By analyzing the reasons behind the PD behavior between different cases, the PD characteristics and the transformation of PRPD patterns under different staircase voltages are obtained. Moreover, this research finds that the sensitivity of different defects to the staircase voltage is different. These results provide experimental and theoretical support for the testing and diagnosis of PD under new electrical stress present in the future flexible electric grid.