4 research outputs found
Performance Evaluation of Edge-Based Segmentation Methods for Electrical Tree Image Analysis in High-Voltage Experiments
Get PDFThis research evaluates the performance of edge-based segmentation methods in analysing two-dimensional (2D) electrical tree images obtained during high-voltage (HV) electrical tree experiments. Non-uniform illumination in 2D optical images poses challenges in accurately extracting and measuring the original treeing image. Edge segmentation emerges as a promising solution to precisely distinguish tree structures from the insulation background within the image. Cross-linked polyethylene (XLPE) samples were subjected to HV stress for real-time propagation observation, followed by extraction and segmentation of treeing images using edge-based operators. The findings emphasize the superiority of the Roberts edge operator in accurately detecting electrical trees, showcasing the highest average accuracy of 97.01% and 99.58% specificity, while also demonstrating relatively high sensitivity. Moreover, the Roberts method provide much precisely measures the propagation length and width than conventional measurement method, closely approximating the actual tree measurements. This research emphasizes the significance of accurate segmentation for investigating electrical tree propagation in XLPE materials and provides recommendations for future research, especially in HV XLPE cable manufacturing
Frequency dependence of electroluminescence measurement in LDPE
Get PDFA good insulator for high voltage cable has low dielectric loss, reasonable flexibility and thermo-mechanically stable. However, prolonged application of electrical stresses on the cable will degraded the cable; physically and morphologically. Electrical degradation in high voltage cable can be detected using electroluminescence (EL) method. Electroluminescence is a phenomenon that occurs when the atoms of a material are being excited due to the application of and external high electrical stresses. There are several external factors that affect the behaviour of electroluminescence emission such as, applied voltage, applied frequency, ageing of material and types of materials. In this paper, the EL measurement is employed to determine the effect of applied frequency on virgin LDPE at fixed and varying applied voltage. It can be observed that EL emission increases as applied frequency increases with increasing voltage applied. However, interesting EL behaviour is observed when varying frequency is applied from 10 Hz to 100 Hz
A Quasi oppositional smell agent optimization and its levy flight variant: A PV/Wind/battery system optimization application
No full textIn this study, two novel algorithms are developed: the quasi oppositional smell agent optimization (QOBL-SAO) and its levy flight variation (LFQOBL-SAO), and their performance is compared to that of the conventional smell agent optimization (SAO). Two investigations were carried out. First, the capabilities of the novel algorithms were tested in solving ten benchmarked functions and five CEC2020 real world optimization problems. Second, they are applied to optimize the hybrid photovoltaic (PV)/wind/battery, PV/battery and wind/battery power system for a healthcare centre in a Nigerian village. Load demand, PV and wind profiles of the aforementioned location were used to developed the hybrid system. All simulations were carried out in MATLAB software and the results show that the novel algorithms are capable of solving both the benchmarked functions and the CEC2020 real world constrained optimization competition. In particular, the performance of the QOBL and the LF-QOBL are as good as the top performing functions like the IUDE, í µí¼MAgES and the iLSHADε algorithms. However, in terms of convergence time, lowest cost of energy (LCE), and total annualized cost (TAC), the novel algorithms outperformed the SAO for the PV/wind/battery optimization application. The hybrid PV/wind/battery system is the most cost-effective when using LFQOBL-SAO and QOBL-SAO, with a TAC value of $15100. Furthermore, the results demonstrate that the LFQOBL-SAO method is accurate and outperforms the QOBL-SAO and SAO algorithms. Keywords: Quasi oppositional smell agent optimization, levy flight quasi oppositional smell agent optimization, smell agent optimization, photovoltaic, wind, renewable energy sources, lowest cost of energy, net present cost and hybrid system.
Electrical Tree Image De-Noising using Threshold Wavelet Transform and Wiener Filter
Get PDFElectrical treeing occurred in solid dielectric materials, especially in electrical application with high voltage. The occurrence of electrical tree happens when high electric fields applied, causing tiny channels or paths to form. The main issue during the data collection process is the changes of lighting, making it difficult to study the tree's propagation length, fractal dimension, and growth rate due to corrupted images. This research aims to analyse electrical tree structure images in XLPE material using a CCD camera and develop image de-noising techniques to suppress noise on the electrical tree image. The performance was then analysed using the Otsu thresholding algorithm for accurate segmentation. The methodology was divided into four phases: sample preparation, experimental setup, image pre-processing in MATLAB, and testing four de-noising filters: Wiener, median, NLM, and Gaussian. The Wiener filter with higher PSNR, SNR, and RMSE was selected and using superimposed method, both threshold wavelet transforms and wiener was combined to eliminate the noise. Finally, the proposed method of superimposed was tested with the Otsu thresholding method to evaluate accuracy, sensitivity, and specificity of the combination filter. Based on the analysis of PSNR, SNR, and RMSE, the performance of the threshold wavelet and Wiener filter (TWWF) de-noising technique improves the image quality of the electrical tree structure. Thus, for the Otsu thresholding segmentation algorithm analysis, it also had the highest values in terms of accuracy, sensitivity, and specificity
