KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/123456789/1

Browse

Search Results

Now showing 1 - 10 of 12

Some of the metrics are blocked by your
consent settings
Identify Direct Lightning Strike Location Based on Discrete Wavelet Transform for 115-kV Transmission System
(2022-01-01)
Chiradeja, Pathomthat
;
Ngaopitakkul, Atthapol
This paper proposes three techniques for locating lightning strikes in a 115 kV transmission system over 88.5 km, based on the arrival time of a transient wave obtained from a discrete wavelet transform (DWT). The first technique calculates the location based on the 'type D' travelling wave method. The second technique analyses the first arrival time and same reflected-back wave arrival time between two substations. In the third technique, two sensors are installed to record arrival times at each sensor. Case studies of direct lightning strikes to phase conductors (shielding failure) are simulated using the 'Alternative Transients Program/Electromagnetic Transients Program' (ATP/EMTP). The influences of three parameters are considered: inception angles, the phase of the conductor, and the position at which the lightning struck the transmission system. By performing an operation scheme for all techniques, a positive sequence current is calculated, using a three-phase current from the ATP/EMTP program which is converted using Clark's transform. A positive sequence current is extracted to several scales using the DWT, and the orders of arrival times for both substations are determined. After the arrival times are obtained, each technique uses a different order of arrival time for calculating the lightning location. By comparing the average error among the three techniques, it is shown that the arrival time of the two sensors' technique is less than that of the other techniques.
Some of the metrics are blocked by your
consent settings
Analyzing the Characteristics of Faults in a Transmission Line and High Voltage Capacitor Banks in a 115-kV-Power System Using Discrete Wavelet Transform
(2022-01-01)
Chiradeja, Pathomthat
;
Ngaopitakkul, Atthapol
The protection of conventional high voltage capacitor banks relies on an unbalance relay. However, investigating the faults requires time and human resources. To address this issue, the characteristics of system parameters were analysed in this study by performing simulations using the power systems computer-aided design software. The simulations were modelled based on a 115-kV-system of the Electricity Generating Authority of Thailand. The case studies involved faults in the transmission line, a single capacitor bank, and a back-to-back connected capacitor bank. Additionally, the influence of other factors on the system parameters was investigated, including the varying fault phase, location, and inception angles. Moreover, the discrete wavelet transform (DWT) was applied to analyse the system parameters comprehensively. The results indicate that the characteristics of system parameters in the case of faults occurring in a transmission line are unique when compared to those in the case of faults occurring in a capacitor bank. Furthermore, the discrepancy between the system parameters in the case of faults occurring in a single capacitor bank and two capacitor banks connected in a back-to-back topology was solved by applying DWT. Therefore, the study findings can aid in improving the efficiency of power systems and ensure their protection.
Some of the metrics are blocked by your
consent settings
Lightning location on 115-kV transmission line using travelling waves
(2018-11-01)
Bunjongjit, Sulee
;
Ngaopitakkul, Atthapol
;
Leelajindakrairerk, Monthon
A lightning strike can be very severe to the transmission system with high impulse current that can damage equipment and cause the operation of the system to be halted. However, currently used lightning location methodology that does not provide the desired accuracy. So, this paper proposed the lightning location methodology on the transmission line based on discrete wavelet transform (DWT) and travelling wave theory. The Alternative Transients Program/Electromagnetic Transients Program (ATP/EMTP) software has been used to simulate the transmission system using in this research. The comparative study between proposed and currently used has been done in order to evaluate the performance in term of accuracy to detect the lightning location on the transmission line. The result has shown that the proposed methodology can be achieved desire accuracy and can be further implemented in actual transmission line protection system in the future.
Some of the metrics are blocked by your
consent settings
A discrete wavelet transform approach to discriminating among inrush current, external fault, and internal fault in power transformer using low-frequency components differential current only
(2014-01-01)
Ngaopitakkul, Atthapol
;
Jettanasen, Chaiyan
This paper proposes an algorithm based on discrete wavelet transform (DWT) for discriminating among inrush current, internal fault, and external fault in power transformers. Fault conditions are simulated using the Alternative Transients Program/Electromagnetic Transients Program (ATP/EMTP). Daubechies4 (db4) is employed as the mother wavelet to decompose low-frequency components from fault signals. The ratio between per unit (p.u.) differential current and p.u. time is suggested as an index. The numerator of the ratio is the difference between the maximum differential current and the minimum differential current in terms of p.u. with a base value selected at the transformer-rated current. The ratio is calculated for all three phases, and from a trial and error process the indices for the separation among the internal fault condition, the external fault condition, and inrush condition are defined. The results obtained from the proposed technique show good accuracy for discriminating faults in the considered system. In addition, the proposed algorithm uses data of the differential current with a time of quarter cycle under the analysis. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Some of the metrics are blocked by your
consent settings
Algorithm improvement to predict fault location of simultaneous fault in underground cable
(2013-11-11)
Apisit, Chaowat
;
Ngaopitakkul, Atthapol
In the literature for fault location, most of research works have never been mentioned about effects of simultaneous faults. This paper presents a new decision algorithm that will be developed in order to predict precisely fault location, during simultaneous fault, in an underground distribution system using discrete wavelet transform (DWT). The advantage of the DWT is that the band of analysis can be fine adjusted so that high frequency components and low frequency components are detected precisely, consequently DWT is considered herein. The fault signal is simulated using ATP/EMTP. The DWT is used to detect the high frequency components. Coefficients of positive sequence current signals are calculated. The positive sequence current as extracted to several scales with the DWT, and the coefficients of the first scale from the DWT are investigated. The time that the fault signal uses to reach the ends of the distribution line is considered, then, applied so that the distance of fault can be calculated. Various case studies have been carried out including the single fault and simultaneous fault. The result is found that the proposed algorithm gives satisfactory both in case of single fault and simultaneous fault. © 2013 The Institute of Electrical Engineers of Japan.
Some of the metrics are blocked by your
consent settings
A novel probabilistic neural network-based algorithm for classifying internal fault in transformer windings
(2013-01-01)
Jettanasen, Chaiyan
;
Ngaopitakkul, Atthapol
The major function of protective devices in a power system is to detect the occurrence of faults and to isolate the faulty sections from the rest of the system. Much progress has been made in the development algorithms for detecting faults in power transformers, which depend on transients-based techniques. This paper presents an algorithm based on a combination of discrete wavelet transforms and probabilistic neural networks (PNNs) for classifying internal faults in a two-winding three-phase transformer. Fault conditions of the transformer are simulated using alternative transients program/electromagnetic transients program (ATP/EMTP) in order to obtain current signals. The mother wavelet Daubechies4 is employed to decompose the high-frequency components from these signals. All three phases of the differential current signals are used in the fault detection decision algorithm. The variations of first-scale high-frequency component that detects fault are used as an input for the training pattern. The training process for the neural network and fault diagnosis decision is implemented using toolboxes on MATLAB/Simulink. Various cases and fault types based on the Thailand electricity transmission and distribution systems are studied to verify the validity of the algorithm. Backpropagation neural network is also compared with the PNN in this paper. It is found that the proposed method gives satisfactory accuracy with less training time, and will be particularly useful in the development of a modern differential relay for a transformer protection scheme. © 2013 Institute of Electrical Engineers of Japan.
Some of the metrics are blocked by your
consent settings
A novel discrete wavelet transform based on traveling wave technique for identifying the fault location for transmission network systems
(2013-01-01)
Patcharoen, Theerasak
;
Ngaopitakkul, Atthapol
This paper proposes a technique to identify fault location on transmission systems using discrete wavelet transforms (DWTs). Fault conditions are simulated using alternative transients program/electromagnetic transients program (ATP/EMTP) in order to obtain the current signals. Various cases based on Thailand electricity transmission systems are studied to verify the validity of the proposed technique. The comparisons among the maximum coefficients in first scale of all buses that can detect fault are performed to detect the faulty bus. The first peak time of positive sequence current obtained from the faulty bus is used as input data for the traveling wave equation. It is shown that the proposed technique gives satisfactory accuracy and is suitable for all types of fault occurring in different sections of transmission lines. © 2013 Institute of Electrical Engineers of Japan.
Some of the metrics are blocked by your
consent settings
Discriminating among inrush current, external fault and internalwinding fault using coefficient of DWT
(2012-06-12)
Jettanasen, Chaiyan
;
Klomjit, Jittiphong
;
Yodkhuang, Apichart
;
Ngaopitakkul, Atthapol
;
Pothisarn, Chaichan
This paper proposes a technique for discriminating among inrush current, external fault and internal winding fault of three-phase two-winding transformer which variations of coefficients of high frequency component obtained from DWT of differential current are analyzed. The maximum coefficient details of DWT are performed as comparison indicator. Various cases based on Thailand electricity transmission and distribution systems are studied to verify the validity of the proposed algorithm. Results show that the proposed technique has good accuracy in the considered system.
Some of the metrics are blocked by your
consent settings
Behaviour of internal fault and external fault in power transformer using discrete wavelet transform
(2012-06-12)
Ngaopitakkul, Atthapol
;
Pothisarn, Chaichan
The differential protection is aimed at detecting internal faults in transformer windings. Therefore, it is necessary to understand fault behaviour before doing performing decision algorithm. This paper presents behaviour of internal winding fault and external short circuit in a three-phase two-winding transformer. The advantage of the discrete wavelet transform (DWT) is considered herein. The fault is simulated using ATP/EMTP and the behaviour analysis of signals is performed using DWT. The variation of high frequency components of differential current signals is presented in this paper. The results obtained from the analysis will be useful in the development of a fault detecting scheme for power transformer in the future.
Some of the metrics are blocked by your
consent settings
Behavior of interturn fault in transformer windings using discrete wavelet transform
(2010-12-01)
Jettanasen, Chaiyan
;
Ngaopitakkul, Atthapol
;
Apisit, Chaowat
In the literature for fault detection, most of research works have never been mentioned about the transformer models with the high frequency model including capacitances of the transformer. This paper presents behaviour of winding to ground fault signals in a three-phase two-winding transformer. The advantage of the discrete wavelet transform (DWT) is that the band of analysis can be fine adjusted so that high frequency components and low frequency components are detected precisely; that is why discrete wavelet transform is herein considered. The fault is simulated using ATP/EMTP and the behaviour analysis of signals is performed using DWT. The variation of high frequency components of differential current signals is proposed in this paper. The results obtained from the analysis will be useful in the development of a detect fault scheme for power transformer in the future.

KMITL

Browse

Filters

Settings

Sort By

Results per page

Search Results