Muzamir Isa

Comparison between Parameter of Single Core Unarmoured Aluminium Conductor 6.35/11 kV Underground Cable for Partial Discharge Measurement Using EMTP-ATP Software

Partial Discharge (PD) is one of a symptom in the underground cable before the fault happens.This paper concerned with estimation and detection problems related to PD phenomena in buried underground cables. The Rogowski coil has been implemented to analyze this symptom. The various sizes of nominal cross-sectional area cross-linked polyethylene (XLPE) cable with 6.35/11 KV single core unarmored aluminum conductors that follows Nexans manufacturer datasheet based on design standard IEC 60502 has been used in the simulation using Electromagnetic Transient Program-Alternative Transient Program (EMTP-ATP) software. The Lumped parameter is used for the Rogowski coil sensor model. Meanwhile, for Double-end measurement using J-Marti model is designed to evaluate the parameter changing in the measurement.Based on the measurement, the value of amplitude voltage and current is proportional increase depends on the size of cross-sectional area of conductor XLPE cable.

Effect of unshielded and shielded Rogowski coil sensor performance for partial discharge measurement

This paper presents the analysis of constructed shielded Rogowski coil (RC) sensor for partial discharge (PD) measurement. The RC sensor with rectangular shape has been designed in order to compare the performance unshielded and shielded type in term of sensitivity. Solidwork 3D CAD software has been used to design the core of RC sensor with their casing. Marker Board Replicator 2X 3D printer is used to print the design. An experiment has been conducted to evaluate the difference performance of unshielded and shielded RC sensor with amplitude range PD signal between 1 V to 5 V respectively and the frequency is fixed to 1 MHz. The difference terminating resistance has been installed to the RC sensor too. From the experiment, the percentage average losses of unshielded and shielded RC sensor from 1 V to 5 V at 14.48 % is achieved. The low level of PD signal is challenging to be detected by the RC sensor. The terminating resistance of the coil is a part of parameter which can improve the performance of RC sensor.

Three-Point Technique for Partial Discharge Location on XLPE Armoured Underground Cable

Recently, a new partial discharge location technique called three-point technique had been introduced to locate partial discharge on underground cable. It is the improvement of double-end technique. In this paper, the mathematical formula of three-point technique had been simplified from previous research. Alternative Transient Program (ATP) was being used to simulate both double-end and three-point technique. The results of the simulation were compared and analysed based on the accuracy, cost of implementation and algorithm complexity of the technique. Three-point technique had shown significant improvement in the accuracy of partial discharge location on underground cable.

Multi-end PD location algorithm using segmented correlation and trimmed mean data filtering techniques for MV Underground Cable

Medium voltage underground cables are widely used in urban area as distribution power lines due to their advantages over overhead cables. Underground cables may suffer from partial discharge because of insulation degradation after certain period of time. In this paper, an improved multi-end partial discharge location algorithm called segmented correlation trimmed mean algorithm is proposed. The algorithm uses segmented correlation technique and trimmed mean data filtering technique to enhance the accuracy of partial discharge location algorithm. The algorithm had been tested in MATLAB environment which consists white Gaussian noise. First, discrete wavelet transform is carried out to suppress noisy signals. Next, segmented correlation technique is applied to the de-noised segmented partial discharge signals. Segmented correlation technique has manipulates partial discharge signals by performing cross correlation process on segmented partial discharge signals in order to reduce memory usage and algorithm execution time. Lastly, trimmed mean data filtering technique is applied to the estimated partial discharge location values to estimate new partial discharge location value. Trimmed mean data filtering technique does statistical process control on estimated partial discharge location values in order to minimize the error of estimated partial discharge location. The segmented correlation trimmed mean algorithm had been compared with the existing multi-end correlation-based algorithm. The result shown that the segmented correlation trimmed mean algorithm has better accuracy than multi-end correlation-based algorithm.

Techniques on partial discharge detection and location determination in power transformer

Insulation failure has been identified as one of the main reasons for transformer breakdown. As one the most important assets in the high voltage system, the loss of a power transformer will cause significant effects to consumers and on the system. The condition of the insulation can directly be correlated to the presence of Partial discharge (PD). Therefore, the ability to accurately detect and analyse the information from PD could be the answer to avoid catastrophic breakdown. On top of that, the capability to pinpoint the location of the PD source would enable swift preventive action to be taken. Several methods have been researched and developed in those two areas. This paper will discuss such techniques. Included in the discussion is an introduction to some less conventional techniques such as optical and ionising emission detection.

Multi-end partial discharge location algorithm based on trimmed mean data filtering technique for MV underground cable

A remarkable challenge in online partial discharge monitoring is to extract desired partial discharge signal from excessive noise caused by the operating cable. Wavelet based de-noising technique can be utilized for noise suppression. However, the wavelet based de-noising techniques ability to fully suppress the non-constant level of noise is limited. Therefore, trimmed mean data filtering technique is applied in partial discharge location algorithm for statistical analysis. In the process of creating trimmed mean partial discharge location algorithm, multi-end partial discharge location algorithm is restructured by adding trimmed mean data filtering technique. Both multi-end partial discharge location algorithm and trimmed mean partial discharge location algorithm had been tested for their performance. In the performance test, noise is modeled and added into the simulated partial discharge signals to enhance the similarity of simulated partial discharge signals with real detected partial discharge signals. Discrete wavelet transform de-noising technique is used for suppressing various level of simulated noise in partial discharge signals. The test result showed that trimmed mean partial discharge location algorithm enhances the accuracy in estimating partial discharge location under noisy environment.

Viscosity Reduction of Palm Oil via Ultrasonic Radiation

Insulation is one of the most important parts in the power transformer. Palm oil impregnated paper is investigated to replace the mineral oil impregnated paper due to the high viscosity of palm oil compared to the viscosity of the mineral oil. This paper discussed on ultrasonic radiation technique that was used to reduce the viscosity of the vegetable oil (palm oil) for transformer insulation application. The ultrasonic equipment produces 500W heating power, 240W ultrasonic power at a fixed frequency of 40 kHz. Ultrasonic radiation was applied on oil samples at 30 °C, 50 °C and 75 °C by using the sonicator water bath for several periods of time. The results show up to 42.6 % reduction from the original viscosity of palm oil and proved to have a long term effect on the viscosity of palm oil. The cavitation bubbles that occur in the sample during radiation is one of the mechanism in viscosity reduction.

Study on Palm Oil and Treated Waste Vegetable Oil Impregnated Paper

Oil impregnated insulation paper plays an important role in a transformer as it insulates the windings from high voltage and current. Other than the type of paper used, the properties of oil such as viscosity, relative permittivity and dielectric loss play a major factor that contributes to the quality of the insulation paper. This paper discussed the sonication and esterification process on palm oil and treated waste vegetable oil and its’ effects on the performance of oil impregnated paper. Basically through these processes, viscosity of oils will reduce. However, the resultant permittivity and dielectric loss as well as its’ breakdown strength are rarely reported. Experiments were set to process (sonicates and esterify) the natural oils prior to the paper impregnation process. Results show that esterification is more effective than sonication process in reducing insulation oil viscosity, relative permittivity and dissipation factors as well as increasing the breakdown voltage of the oil impregnated paper. Palm oil methyl ester (POME) could serve as an excellent insulation oil which is very suitable as transformer oil as well as the impregnation medium for paper insulation.

Regularized sphere decoding techniques for data transmission systems

Recently, the idea of regularization received a lot of interest in signal processing with ill-conditioned problems. In this paper, instead of using the traditional sphere decoding (LSD) technique, regularized LSD detection techniques have been used for block data transmission systems (BDTS). The first regularization scheme that has been used is Tikhonov regularization (L2-regularization) which is a summation of consistent norms while the other is L1-regularization which is a summation of mixed norms. Regularization shows a significant impact on the condition number. In performance analysis, simulation results clearly indicate the advantage of the regularized LSD techniques for BDTS over others. LSD technique using L2-regularization performance is very near to optimum performance. On the other hand, it has been shown that L2-regularization provides better performance than L1-regularization.

Evaluation of Rogowski coil sensor performance using EMTP-ATP software

Detection and measurement of partial discharge (PD) are important to monitor the insulation life in high voltage (HV) power equipment. This paper presents an electrical detection method which is Rogowski coil (RC) has been chosen as a measuring sensor to detect and measure the PD signal. Series of investigations on sensitivity and bandwidth for four types of RC using electromagnetic transient program-alternative transient program (EMTP-ATP) software was demonstrated. A single-end measuring method is used to locate the PD signal on three-phase MV underground cross-link polyethylene (XLPE) cable with 240 mm2 nominal area of copper conductor cable. An experiment was conducted in order to verify the simulation results. The precise selection of RC sensor based on the simulation and experimental results was compared with the previous design of researchers in term of sensitivity and bandwidth. In this case, result indicated that the new design of RC sensor performed better plays a vital role in detecting PD signal.