Now showing 1 - 10 of 14
  • Publication
    Partial discharge signal measurement based on stand-alone and hybrid detection technique for power transformer
    Partial discharge (PD) is a phenomenon that causes failures in high voltage (HV) components due to the degradation of insulation. Before an interruption or fault occurs, early detection of insulation degradation is essential. However, the long-term effect of PD will lead to the failure of the power system. This is important to control and diagnose the health of the HV power equipment such as power transformer. The main issue when measuring PD is the accuracy and sensitivity of the PD detection technique. This paper consists of two parts which are classification of the PD detection technique and hybrid detection technique. In this paper, an overview of the detection technique for power transformer including optical detection, chemical detection, electrical detection, electromagnetic detection, acoustic emission detection and hybrid detection technique is presented. The hybrid detection technique is based on combining two or more stand-alone detection technique. Based on this review, the hybrid detection technique showed that the advantages of performance in terms of sensitivity and accuracy for detecting the PD in power transformer.
      1  36
  • Publication
    A review: Partial discharge detection using acoustic sensor on high voltage transformer
    Partial discharge (PD) is an electrical discharge which is one of the most critical breakdown factor that is affecting the electrical equipment. The loss of the power will affect consumers and system operation. High voltage (HV) transformer is one of the equipment's subjected to phenomena PD. In this paper reviews an application of acoustic methods in transformer and piezoelectric sensors application on PD detection in HV transformer. Based on this review, the new design in acoustic sensor is required in order to improve the sensitivity and bandwidth for PD detection at HV transformer. The valuable parameter such as materials, size, and PD frequency range were discussed in this paper and can be used for early stage on designing new acoustic sensor. This detection method given some benefits on preventing the power electrical system from breakdown.
      1  28
  • Publication
    Electrical Tree Image Segmentation Using Hybrid Multi Scale Line Tracking Algorithm
    Electrical trees are an aging mechanism most associated with partial discharge (PD) activities in crosslinked polyethylene (XLPE) insulation of high-voltage (HV) cables. Characterization of electrical tree structures gained considerable attention from researchers since a deep understanding of the tree morphology is required to develop new insulation material. Two-dimensional (2D) optical microscopy is primarily used to examine tree structures and propagation shapes with image segmentation methods. However, since electrical trees can emerge in different shapes such as bush-type or branch-type, treeing images are complicated to segment due to manifestation of convoluted tree branches, leading to a high misclassification rate during segmentation. Therefore, this study proposed a new method for segmenting 2D electrical tree images based on the multi-scale line tracking algorithm (MSLTA) by integrating batch processing method. The proposed method, h-MSLTA aims to provide accurate segmentation of electrical tree images obtained over a period of tree propagation observation under optical microscopy. The initial phase involves XLPE sample preparation and treeing image acquisition under real-time microscopy observation. The treeing images are then sampled and binarized in pre-processing. In the next phase, segmentation of tree structures is performed using the h-MSLTA by utilizing batch processing in multiple instances of treeing duration. Finally, the comparative investigation has been conducted using standard performance assessment metrics, including accuracy, sensitivity, specificity, Dice coefficient and Matthew’s correlation coefficient (MCC). Based on segmentation performance evaluation against several established segmentation methods, h-MSLTA achieved better results of 95.43% accuracy, 97.28% specificity, 69.43% sensitivity rate with 23.38% and 24.16% average improvement in Dice coefficient and MCC score respectively over the original algorithm. In addition, h-MSLTA produced accurate measurement results of global tree parameters of length and width in comparison with the ground truth image. These results indicated that the proposed method had a solid performance in terms of segmenting electrical tree branches in 2D treeing images compared to other established techniques.
      1  29
  • Publication
    Hilbert fractal UHF sensor based on partial discharge detection signal for on-line condition monitoring in power transformer
    ( 2020-01-01)
    Roslizan N.D.
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    ; ; ; ;
    Akashah N.A.
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    Mukhtaruddin A.
    PD detection is an effective method of inspecting insulation defects and identifying potential faults in a power transformer. Electromagnetic waves generated due to PD can be detected by ultrahigh-frequency (UHF) sensor in the frequency band greater than 300 MHz. However, the size and the frequency bandwidth of a UHF sensor for PD detection are the concern for practical installation inside a transformer. High sensitivity and wide bandwidth of sensors are needed in order to detect the PD signal in an early stage. This paper presents an array 4th order Hilbert fractal UHF sensor for PD detection inside a power transformer. This UHF sensor was modeled to capture PD signal in a range of frequencies between 300 MHz to 3 GHz. The sensor is designed by using CST software where the transmission lines combined 2 sensors become 1 output by setting the dimension of 100 x 200 mm for length and width with FR4 epoxy substrate of thickness 1.6 mm. Based on the simulation result, the proposed sensor is obtained a PD signal measurement with a reflection coefficient below-10 dB with VSWR ≤5. The advantages of this sensor have a wide bandwidth, high sensitivity and suitable size for easy installation. Thus, this sensor has been qualified as UHF PD detection in the power transformer.
      10  30
  • Publication
    Partial discharge detection performance using multi-cylindrical slots antenna with parasitic suppression patch for power transforme
    ( 2022-01-01)
    Bohari Z.H.
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    ; ;
    Soh P.J.
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    Sulaima M.F.
    This paper focused on analyzing multi-cylindrical slots performance combining with parasitic suppression patch for partial discharge detection. Both proposed slots antenna and conventional monopole are simulated using CST Microwave Studio software before being fabricated and tested with real partial discharge signal. Performance comparison will be focused on scattering parameter, radiation pattern and surface current distribution. Both antennas are subjected to a partial discharge signal from lab scaled power transformer for the field test. Based on the result, the proposed performed better in both simulation and field testing with the dual-frequency operation, with better gain improvement by 14%. For the field test, the proposed antenna generated better detection result with reduced noises by 50%.
      10  31
  • Publication
    Selective harmonic elimination pulse width modulation for five-phase cascaded multilevel inverter using non-notch and notch switching technique
    As in this era, the conversion of DC power to AC power is a necessity in the power system in order to make useful of renewable energy. The most commonly used switching mechanism is known as inverter or multilevel inverter. However, this switching may cause harmonics. Harmonics usually occur in a power system due to distortion, which can cause a lot of unwanted problems. It could appear either in voltage or in current waveforms. Minimization of Total Harmonic Distortion (THD) is necessary in order to maintain a good power system. This paper introduces selective harmonic elimination pulse width modulation for five-phase cascaded multilevel inverter. The proposed switching technique for five-phase cascaded multilevel inverter used in this research is non-notch and notch switching technique. Particle Swarm Optimization (PSO) algorithm was used as an optimization technique to find switching angles for non-notch and notch switching techniques. In addition, the simulation of a seven-level five-phase cascaded multilevel inverter for both switching operations is carried out in the PSIM environment. The results show that the non-notch switching was able to eliminate lower order harmonics up to the 7th harmonic. In addition, the notch switching technique managed to eliminate lower order harmonics up to the 21st harmonic for 3/3/3 switching distribution.
      4  40
  • Publication
    Modelling of piezoelectric sensor based on ZnO material for partial discharge detection on power transformer
    Detection of partial discharge (PD) in early stages able to reduce the risk of decommissioning of high voltage (HV) equipment. However, the conventional method for PD detection are not suitable for on-site measurement due to electrical disturbance. One of the method in detecting PD signal is piezoelectric based acoustic emission (AE) sensors. In this project, an AE sensor is modelled to obtain a PD signal in the range of 10 – 300 kHz occurred in HV transformer and been found out by simulation and analytical approach. Two models of a piezoelectric sensor with different types of cantilever and different dimension variation starting from 4 mm to 15 mm are designed in the Finite element Method (FEM) in order to investigate the resonant frequency which is matched to the range of AE detection. Zinc oxide (ZnO) as a piezoelectric material is proposed in this project due to its high piezoelectric coupling and environmentally friendly compared to the others material which is harmful. Based on the simulation result, ZnO piezoelectric sensor with the length of 5 mm and thickness of 0.451 mm generates 0.0537 mV electrical potentials under the resonant frequency of 155.30 kHz which is in the range of AE detection technique.
      31  3
  • Publication
    Development of detachable Rogowski Coil current sensor using PCB for High Voltage cable partial discharge measurement
    Insulation failure in High Voltage (HV) cables is evaluated using a variety of monitoring techniques. Previous silicon technologies were outperformed by wide-bandgap semiconductor power devices with faster switching speeds. Their precise current management or current protection measures must be upgraded. As a result, their precise current control or protection measures have become more sophisticated. The traditional Rogowski Coil (RC) with the magnetic core, on the other hand, has low measurement accuracy, a short measuring range, and is difficult to fabricate. This paper presents and discusses the development of a Rogowski Coil using a detachable Printed Circuit Board (PCB) as a current sensor for Partial Discharge (PD) measurement. Furthermore, the development of this innovative current sensor concentrated on the detachable PCB Rogowski Coil's capability to measure as a high-voltage (HV) current sensor and its sensitivity in fault diagnosis, over-voltage current sensing, and high-impulse current sensing on HV cables. The experimental design, techniques, and measurement parameters used in models were discussed. Finally, a brief analysis of the detachable PCB RC current sensor such as sensitivity, maximum voltage and current detection is presented. This paper can also be used as a guideline for other researchers to develop an advanced RC current sensor using PCB as a HV current sensor in the future. The measurement results of the detachable PCB RC current sensor such as the sensitivity and current detection signal can also be used as a guideline by another researcher. As a result, the goal of this project is to measure PD on HV cables using an RC current sensor by utilising PCB technology.
      2  44
  • Publication
    Dynamic Partial Discharge Characteristic for Onsite Measurement Based on Zero Crossing in Power Cable
    This paper analyzed the dynamic Partial discharge (PD) characteristic for onsite measurement based on zero crossing in high voltage power cable. According to IEC60270, high voltage measurement characteristic is required to identify correct PD signal. There is currently limited research operating on the trait, especially zero crossing, and because of this, comprehensive PD detection characteristics need to be further established in certain severe conditions. This occurrence has an erratic and sporadic characteristic that is challenging to identify. This paper explored the time of zero crossing for onsite measured PD signal for power cable through MATLAB simulation. This task is crucial to choose the range of zero crossing time based on the highest peak of detected PD signal. Based on the detailed analysis, it is substantially identified that there is an specific time only for PD signal with the highest amplitude, and based on detected times, a range of zero crossing characteristic was described for PD signal. It provided a useful analysis result for the guideline during onsite PD measurement for power cable.
      37  2
  • Publication
    Development and Performance Analysis of the Rogowski coil sensor for Arcing Fault Measurement
    Arcing fault is an overvoltage that usually occurs in the power system network, and it is necessary to monitor this phenomenon in electrical equipment. This paper presents the Rogowski coil (RC) as an arcing fault sensor. Finite element method (FEM) software used for analysing the RC magnetic flux density with two types of RC with the different turns and size demonstrated. The sizing of RC based on the 240 mm2 cross-link polyethene (XLPE) 11 kV underground cable. The prototypes of the RC sensors were designed using Solidworks software and three-dimensional (3D) printer for fabrication purposes. The main objective of the experiment is to investigate the RC effect with high magnetic flux density by implementing in real measurement. An experimental setup for real arcing fault with various voltages (up to 15 kV) was conducted to verify the RC performance, such as sensitivity and bandwidth range. The result has shown that the bandwidth of RC 1 is higher than RC 2 in all measurement by 22.6%.
      2  56