Afifah Shuhada Rosmi
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Preferred name
Afifah Shuhada Rosmi
Official Name
Afifah Shuhada, Rosmi
Alternative Name
Rosmi, Afifah Shuhada
Rosmi, Afifah Shuhada C
Rosmi, A. S.
Rosmi, A. S.C.
Main Affiliation
Scopus Author ID
57193830914
Researcher ID
DNN-7471-2022

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Comparison of Image Restoration using Median, Wiener, and Gaussian Filtering Techniques based on Electrical Tree

2021-01-01 , Abdulah C.S.K. , Mohamad Nur Khairul Hafizi Rohani , Baharuddin Ismail , Isa M.A.M. , Afifah Shuhada Rosmi , Wan Azani Wan Mustafa

Electrical treeing lead to a major cause of a breakdown in solid insulation. Thus reduced solid insulation performance by degrading the insulation. Hence, it is important to study the electrical treeing and learn the root cause of the treeing formation. In this paper, the performances of median, wiener, and gaussian filters in restoring noisy images are studied based on electrical tree images. The electrical tree colour images is being transform into grayscale images, noisy images using impulse noise (salt and pepper), and finally motion blur are applied. Even though, there are several number of filters available, this paper focus on median, wiener, gaussian, and combination of the filters. In the end, comparison between these filters is made to study the efficiency using PSNR, SNR, and MSE in graph form.

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Multiple Partial Discharge Signal Classification Using Artificial Neural Network Technique in XLPE Power Cable

2023-02-01 , Halim M.I.A. , Razaly N.Z.M. , Mohamad Nur Khairul Hafizi Rohani , Norfadilah Rosle , Auni W.N. , Afifah Shuhada Rosmi , Muhammad Zaid Aihsan , Mohd Aminudin Jamlos , Mas’ud A.A.

According to partial discharge (PD) damage in the electrodes that are not entirely bridging, the presence of PD in the high voltage (HV) power cable might lead to insulation failure. PD defects can damage cross-linked polyethylene (XLPE) cables directly, which is one of the most critical electrical issues in the industry. Poor workmanship during cable jointing, aging, or exposure to the surrounding environment is the most common cause of PD in HV cable systems. As a result, the location of the PD signals that occur cannot be classified without identifying the multiple PD signals present in the cable system. In this study, the artificial neural network (ANN) based feedforward back propagation classification technique is used as a diagnostic tool thru MATLAB software in which the PD signal was approached to determine the accuracy of the location PD signal. In addition, statistical feature extraction was added to compare the accuracy of classification with the standard method. The three-point technique is also an approach used to locate PD signals in a single line 11 kV XLPE underground power cable. The results show that the statistical feature extraction had been successful classify the PD signal location with the accuracy of 80% compared to without statistical feature extraction. The distance between PD signals and the PD source affected the result of the three-point technique which proved that a lower error means a near distance between them.

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The magnetic flux density of various geometries of Rogowski Coil for overvoltage measurements

2020-01-01 , Ayob Nazmy Nanyan , Mohamad Nur Khairul Hafizi Rohani , Muzamir Isa , Afifah Shuhada Rosmi , Ahmad Zaidi Abdullah , Baharuddin Ismail , Haziah Abdul Hamid

Overvoltage phenomenon is the common problem that always occurs in the power system and can cause the electrical system network breakdown, and in some cases, it may explode. The frequent overvoltage also can affect and degrade the lifespan of the electrical power system components and network. Thus, the overvoltage sensor is needed to overcome this problem matter. The Rogowski coil (RC) is one of an inductive coil group, and it is suitable for measuring the alternating current (AC) and transient currents or overvoltage. This paper demonstrated the effect of RC magnetic flux density, B with difference cross-section, geometries sizing and the number of turns by using Finite Element Method (FEM). Commonly, there are three types of RC widely used; rectangular, circular and oval. Each of these cross-sections has different characteristics in term of performance. The results have shown that the rectangular cross-section is better than oval and circular cross-section based on the number of magnetic flux density.

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Comparison Study of UHF Sensor Modelling Based on 4th Order Hilbert Fractal Category for Partial Discharge Detection in Power Transformer

2020-12-11 , Roslizan N.D. , Mohamad Nur Khairul Hafizi Rohani , Afifah Shuhada Rosmi , Baharuddin Ismail , Mohd Aminudin Jamlos , Wooi Chin Leong , Che Muhammad Nor Che Isa , Jalil M.A.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 at an early stage. This paper presents an array with partial ground 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 an 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.

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Protection Relay Setting based on Overcurrent Phenomena in Commercial Building

2024-03-01 , Isyraq Faizzi Mohammad , Mohamad Nur Khairul Hafizi Rohani , Afifah Shuhada Rosmi , Baharuddin Ismail , Muhamad Hatta Hussain , Abdullahi Abubakar Mas’ud , Firdaus Muhammad-Sukki

Nowadays, every single distribution system needs to install an appropriate relay to keep the system safe. The operational and commonly recommended relay for distribution systems is the overcurrent (OC) relay. Throughout the distribution system, the protective relay is one of the methods that can detect and protect the location according to its observation from any fault from abnormal activity. Note that time coordination between the protective equipment relay needs to be a minimum of time interruption to prevent faults occurs. The ideal setting for all coordination protection relays is necessary to protect the device against electrical failure and interference. This paper analyzes the real results data collected for the selected commercial building of an OC relay implemented in a distribution board for high voltage and low voltage downward at a commercial building. All the parameters need to be clarified first before testing has been made and measurement is carried out using the MICROTEST 860 set. Based on the analysis, it proves that according to the IEC Standard of 0.10-time multiplier Setting (TMS) is practical to be used to obtain the operation time in seconds for the current curve set. Other than that, the results show that the normal inverse curve from manual calculation results is more accurate compared to the service setting (SS) made based on the incoming setting in a real commercial building. The case study for OC relay setting is related between current injection and time-tripping, which complies with the IEC 60255-3 standard using its formula. This method was applied to determine the characteristics of the curve. Hence, this research successfully determined the proper methods for the OC relay setting for the power distribution system. Besides, the feasibility and efficiency of OC relay data transmission are tested and checked successfully to implement the measurement method in the relay coordination study.

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Influence of PD source and AE sensor distance towards arrival time of propagation wave in power transformer

2020-01-07 , Khairul Nadiah Khalid , Mohamad Nur Khairul Hafizi Rohani , Baharuddin Ismail , Muzamir Isa , Afifah Shuhada Rosmi , Wooi Chin Leong , Yii C.C.

Partial discharge (PD) often begins with cracks or gas-filled voids in solid insulation or with gaseous bubbles in liquid insulation. These presences can degrade the quality of insulator. PD detection can identify these cracks at high voltage equipment such as power cables and power transformer at the early stage. One of PD detection methods is acoustic emission (AE) detection. PD produces an ultrasonic signal that can be captured by an AE sensor. The signal captured is then analysed by capturing the time of the receiving signal onto the sensor. The information related to time can be used for allocating the PD for maintenance purpose. This paper shows the influence of the distance between PD source and the AE sensor towards the arrival time of propagation wave in power transformer. In this study, the four placements of sensors were analysed by having three possible PD sources to represent the variety of distances between the PD source and the sensor. The simulated signal is generated by MATLAB and the arrival time is captured using time of arrival (TOA) method. The time captured and the distance between the PD source and arrival time showed that the relationship is proportional to one another.

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Design of vibration energy harvester for low voltage power supply using finite element methods (FEM) analysis

2018 , Afifah Shuhada Rosmi

The rapid growth of electronic devices miniaturization attract the researchers interest either to save space or for cost reduction. The main purpose of miniaturization is to implement the concept of portable in order to locate the devices everywhere without connected to a power strip. Therefore, the use of battery as a power supply is the only choice to realizing the concepts. However, the improper battery disposal gives the detrimental effects to the environment and human being. Energy harvesting is proposed as the best solution as it provides more comfort and safety to the device compared to the old-fashioned battery. However, the development of lead-free vibration harvester for low frequency of ambient vibration energy is rarely reported. Thus, energy harvester based on zinc oxide (ZnO) piezoelectric material has been chosen as a vibration energy to electrical power transducer as it is compatible with microelectromechanical systems (MEMS) technologies, which can generate power from μW up to mW level power. Powering the devices using energy harvester is really suggested as it can provide clean energy, no need for frequent battery replacement and long-term solution. This research focus on designing and simulating the four different models of micro scale piezoelectric power generator (PPG) cantilever beam type named as PPG 1, PPG 2, PPG 3 and PPG 4 using COMSOL Multiphysics approach. The models with attached proof mass at the end tip were analyses to investigate the capability in converting the ambient vibration energy which is commonly below than 200 Hz and less than 1 g (1 g = 9.81 m/s2) acceleration amplitudes. Two working conditions are considered for the analyses. The first condition is to mount the PPG model to a machinery, while the second condition is to locate the PPG model close to the ambient sound wave energy sources. FEM simulation was done with two types of analysis taken. In order to obtain the required results which are resonant frequency analysis and evaluation of electrical output power, eigenfrequency and frequency domain modules were used. As a result, the frequency resonance for all models is below than 200 Hz. As a highlight of this work, PPG 4 shows the superior capability than other model since able to generate the highest output power which is 17.11 μW when integrated with voltage multiplier. Meanwhile, PPG 2 is more suitable for harvesting low frequency of vibration energy since able to vibrate at lower frequency compared to other models which is as low as 52.77 Hz. Based on these two findings about PPG 2 and PPG 4, PPG 4 is selected as the better model since capable in generating higher output power at resonant frequency less than 200 Hz.

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Electrical Tree Investigation on Solid Insulation for High Voltage Applications

2021-01-01 , Abdulah C.S.K. , Mohamad Nur Khairul Hafizi Rohani , Baharuddin Ismail , Isa M.A.M. , Afifah Shuhada Rosmi , Wan Azani Wan Mustafa , Kamarol M.

Electrical treeing is a major cause of a breakdown in solid insulation cable. This phenomenon reduced aging by degrading the insulation, leading to failure in the high voltage materials. The most common experimental set-up in studying the electrical tree is using a needle electrode to initiate the treeing image. Different types of needle and insulation material had been studied from the previous experiment. This paper review the method used to investigate tree growth and its technique to capture the treeing image. Based on this review, several causes delay the treeing process in the needle embedded experiments. In contrast, 2D image processing is the most frequent image developed in the electrical tree on solid insulation.

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Modelling of piezoelectric sensor based on ZnO material for partial discharge detection on power transformer

2020-01-01 , Akashah N.A. , Mohamad Nur Khairul Hafizi Rohani , Afifah Shuhada Rosmi , Muzamir Isa , Baharuddin Ismail , Kamarol M. , Roslizan N.D. , Khairul Nadiah Khalid

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.

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Hilbert fractal UHF sensor based on partial discharge detection signal for on-line condition monitoring in power transformer

2020-01-01 , Roslizan N.D. , Mohamad Nur Khairul Hafizi Rohani , Afifah Shuhada Rosmi , Baharuddin Ismail , Muzamir Isa , Akashah N.A. , 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.

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