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To obtain a large number of infrared images of insulators, we designed and carried out infrared imaging tests on 35kV line insulators facing environmental interference. Based on these tests, an improved adaptive median filter method is proposed to eliminate the noise in the grayscale. For image enhancement and segmentation, double-threshold Ostu with histogram equalization are combined. A genetic algorithm is introduced to optimize the calculations, and a BPNN recognition model for a zero-value insulator was designed and tested. Overall, we conclude that the algorithm and the BPNN model proposed in this paper are effective.

This research aims to analyze transient processes during loop closing and opening operations in distribution grids with DGs. The realization of load transfer without blackouts can improve the reliability of a power supply, reducing economic loss. Hence, we summarize the problems appearing during loop closing and opening processes. Based on this analysis, a loop closing operation was executed at one 110 kV substation, and the voltage and current waveform were recorded. A theoretical analysis of field experiments results yielded the spectral characteristics of the system. A loop closing operation was simulated using EMTP-ATP software. The simulation and the field experiment results matched closely, thus validating the simulation model. We conclude that closing and opening operation are influenced by voltage difference, including the amplitude and phase angle difference. The system capacitance and inductance have impact not only on the transient over- voltage, but also on the frequency characteristics of the system.

We demonstrate a simple chromatic dispersion (CD) monitoring method using amplitude ratio of asynchronous delay-tap sampling plot. By utilizing amplitude ratio in the delay-tap sampling plot, the residual CD values in the range of 0∼75 ps/nm can be measured for 40-Gbit/s 67% carrier-suppressed return-to-zero (CSRZ) differential quadrature phase-shift keying (DQPSK), 50% return-to-zero (RZ) DQPSK and 60-Gbit/s 50% RZ differential eight phase-shift keying (D8PSK) signals. The simulated results in VPItransmission 7.0 show that the amplitude ratio of delay-tap sampling plot decreases monotonously with residual CD in 67% CSRZ DQPSK, 50% RZ DQPSK and 50% RZ D8PSK systems. Since no synchronization or modification on transmitter/receiver is required, the proposed scheme is simple and cost effective.