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All Journal IAES International Journal of Artificial Intelligence (IJ-AI) TELKOMNIKA (Telecommunication Computing Electronics and Control) Indonesian Journal of Electrical Engineering and Informatics (IJEEI) Indonesian Journal of Electrical Engineering and Computer Science
Norhafiz Azis
Universiti Putra Malaysia
Computer Science & IT Electrical & Electronics Engineering Engineering

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Adaptive ANN based differential protective relay for reliable power transformer protection operation during energisation Azniza Ahmad; Mohammad Lufti Othman; Kurreemun Khudsiya Bibi Zainab; Hashim Hizam; Norhafiz Azis
IAES International Journal of Artificial Intelligence (IJ-AI) Vol 8, No 4: December 2019
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (431.332 KB) | DOI: 10.11591/ijai.v8.i4.pp307-316

Abstract

Power transformer is the most expensive equipment in electrical power system that needs continuous monitoring and fast protection response. Differential relay is usually used in power transformer protection scheme. This protection compares the difference of currents between transformer primary and secondary sides, with which a tripping signal to the circuit breaker is asserted. However, when power transformers are energized, the magnetizing inrush current is present and due to its high magnitude, the relay mal-operates. To prevent mal-operation, methods revolving around the fact that the relay should be able to discriminate between the magnetizing inrush current and the fault current must be studied. This paper presents an Artificial Neural Network (ANN) based differential relay that is designed to enable the differential relay to correct its mal-operation during energization by training the ANN and testing it with harmonic current as the restraining element. The MATLAB software is used to implement and evaluate the proposed differential relay. It is shown that the ANN based differential relay is indeed an adaptive relay when it is appropriately trained using the Network Fitting Tool. The improved differential relay models also include a reset part which enables automatic reset of the relays. Using the techniques of 2nd harmonic restraint and ANN to design a differential relay thus illustrates that the latter can successfully differentiate between magnetizing inrush and internal fault currents. With the new adaptive ANN-based differential relay, there is no mal-operation of the relay during energization. The ANN based differential relay shows better performance in terms of its ability to differentiate fault against energization current. Amazingly, the response time, when there is an internal fault, is 1 ms compared to 4.5 ms of the conventional 2nd harmonic restraint based relay.
Design and Experimental Results of Universal Electric Vehicle Charger Using DSP Ali Saadon Al-Ogaili; Ishak bin Aris Aris; Mohammed Lutfi Othman; Norhafiz Azis; Dino Isa; Yap Hoon
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 16, No 4: August 2018
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v16i4.7308

Abstract

Owing to the growing concerns over energy depletion and environmental issues around the world, more and more attention is given on replacing the fuel-based automobiles with electric vehicles (EVs) which have the characteristics of zero-emission and low noise. As a result, various countries have taken specific initiatives to de-carbonize their transport sectors by developing their own EV industry. Regardless of the environmental and economic benefits, substantial scales of grid-connected EVs impose incredible difficulties to the power grid. The main issues caused by EV charging to the power grid include harmonics, voltage drop, system instability, system losses and grid overloading. Therefore, this paper presents design and development of a novel method, which is by applying voltage-oriented control (VOC) algorithm in battery charging of electric bus.The power system of this work consists of three-phase PWM rectifier. The proposed method is based on mathematical analysis. Simulation and experimental works are performed to investigate behavior and performance of the proposed algorithm. This paperclearly described implementation of low and medium power laboratory prototype and operation of digital signal processor (DSP) via MATLAB / Simulink for the proposed method.
Modeling frequency response of transformer winding to investigate the influence of RLC S Al-Ameri; M. F. M. Yousof; Norhafiz Azis; S. Avinash; M. A. Talib; Ali. A. Salem
Indonesian Journal of Electrical Engineering and Computer Science Vol 14, No 1: April 2019
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v14.i1.pp219-229

Abstract

Frequency response measurements are used for power transformer winding failures detection. The variation between frequency responses indicate mechanical changes in the transformer winding. One method to investigate winding failures in transformer is to develop a reliable circuit model which can simulate the frequency response of an actual winding. The main reason to use the model is because it is expensive to create damages on an actual winding. This paper proposes n-stages circuit ladder network to simulate the response of a winding which has unique design. It presents a new technique to calculate the resistance, inductance and capacitance of the winding. Then, the relationship between the RLC parameters and the frequency response is studied. The winding chosen in this investigation is a single phase 33kV transformer winding. The simulated frequency response was compared with the measured response to verify the proposed model. The model can give a comprehensive understanding about the effect of RLC parameters on the frequency response.
Examination on the physical properties of untreated kenaf insulation paper at different beating degrees Muhammad Umair; Norhafiz Azis; Rasmina Halis; Jasronita Jasni
Indonesian Journal of Electrical Engineering and Computer Science Vol 17, No 2: February 2020
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v17.i2.pp759-766

Abstract

This paper examines the physico-mechanical properties of untreated kenaf based insulation paper with consideration on different beating degrees. Kenaf bast fibers were first processed through soda pulping process. Different beating degrees were subjected to the processed pulps. Physical parameters of the paper were measured for each of the beating degrees. It is found that as the beating revolution increases, the kenaf based insulation paper’s density, tensile index and burst index increase while thickness and tear index decrease. 
Electromagnetic force distribution computations due to switching surge in disc-type winding Nurul Farahwahida Md Yasid; Norhafiz Azis; Mohd Fairouz Mohd Yousof; Jasronita Jasni; Mohd Aizam Talib; Avinash Srikanta Murthy
Indonesian Journal of Electrical Engineering and Computer Science Vol 30, No 2: May 2023
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/ijeecs.v30.i2.pp659-669

Abstract

This manuscript discusses the computation of electromagnetic forces on a disc-type winding due to a standard switching impulse (SSI). First, the resistances, inductances and capacitances (RLC) of a 30 MVA, 33/11 kV disc-type distribution transformer were estimated to obtain the winding equivalent circuit. The transient voltage waveforms for each of the disc layers and corresponding resonances of the windings under the SSI were then obtained in time domains. Next, the axial and radial force distributions in the disc winding due to the SSI were computed. The forces on each disc layer and along the disc windings due to the SSI were computed based on the analytical and numerical methods via the finite element method (FEM) respectively. The non-uniform switching impulse voltage distribution results in non-uniform force distribution along the disc winding. The magnitude of the axially directed force on the disc winding is found to be higher as compared to the radially directed force.
Examination on the Denoising Methods for Electrical and Acoustic Emission Partial Discharge Signals in Oil Ahmad Hafiz Mohd Hashim; Norhafiz Azis; Jasronita Jasni; Mohd Amran Mohd Radzi; Masahiro Kozako; Mohamad Kamarol Mohd Jamil; Zaini Yaakub
Indonesian Journal of Electrical Engineering and Informatics (IJEEI) Vol 11, No 3: September 2023
Publisher : IAES Indonesian Section

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.52549/ijeei.v11i3.4463

Abstract

Partial discharge (PD) measurements either through electrical or acoustic emission approaches can be subjected to noises that arise from different sources. In this study, the examination on the denoising methods for electrical and acoustic emission PD signal is carried out. The PD was produced through needle-plane electrodes configuration. Once the voltage reached to 30 kV, the electrical and acoustic emission PD signals were recorded and additive white Gaussian noise (AWGN) was introduced. These signals were then denoised using moving average (MA), finite impulse response (FIR) low/high-pass filters, and discrete wavelet transform (DWT) methods. The denoising methods were evaluated through ratio to noise level (RNL), normalized root mean square error (NRMSE) and normalized correlation coefficient (NCC). In addition, the computation times for all denoising methods were also recorded. Based on RNL, NRMSE and NCC indexes, the performances of the denoising methods were analyzed through normalization based on the coefficient of variation (𝐶𝑣). Based on the current study, it is found that DWT performs well to denoise the electrical PD signal based on the RNL and NRMSE 𝐶𝑣 index while MA has a good denoising NCC and computation time 𝐶𝑣 index for acoustic emission PD signal.
Co-Authors Ahmad Hafiz Mohd Hashim Ali Saadon Al-Ogaili Ali. A. Salem Avinash Srikanta Murthy Azniza Ahmad Dino Isa Hashim Hizam Ishak bin Aris Aris Jasronita Jasni Jasronita Jasni Kurreemun Khudsiya Bibi Zainab M. A. Talib M. F. M. Yousof Masahiro Kozako Mohamad Kamarol Mohd Jamil Mohammad Lufti Othman Mohammed Lutfi Othman Mohd Aizam Talib Mohd Amran Mohd Radzi Mohd Fairouz Mohd Yousof Muhammad Umair Nurul Farahwahida Md Yasid Rasmina Halis S Al-Ameri S. Avinash Yap Hoon Zaini Yaakub