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A locating diagnosis of partial discharge on cross-bonding ground system
(2021-05-19)
Inwanna, W.
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Mongkolsatitpong, S.
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Chancharoensook, P.
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Pattanadech, N.
At the present, Thailand has turned the attention to Underground Cable (UC) systems and trends to use it more to safety, stability and reliability of electrical system. However, one problem that can affect to this electrical system is the Partial Discharge (PD) problem. Most of PD problems are caused by incomplete installation, maintenance reason and insulation degradation on the weakest part, especially cable joint. This paper proposes a method of analysis to locate the PD source in UC systems with Cross Bonding (CB) focus on cable joints. This work has carried out in laboratory on CB system model using 50ohm R58 coaxial cable instead of underground cable. The PD detection technique according to IEEE 400.3 standard with a RFCT sensor to refer the appropriate signal. This work uses a PD diagnostic device that can filter noise from the PD groups and separate groups of PD for greater analysis accuracy. To determine which cable joint is PD source and to be able to fix it on the spot. The PD signal analysis are performed by using time of arrival method considered together with the characteristics and the polarity of the PD pulse.
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Dielectric response analysis for cable joint problems in medium voltage underground cable system
(2020-01-01)
Klienhom, Sitthisak
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Boonsaner, Nutthaphan
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Nimsanong, Phethai
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Chancharoensook, Phop
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Kunakorn, Anantawat
This paper represents the investigation of dielectric response analysis of a cable system composed of a medium voltage XLPE underground cable, a heat-shrink cable joint and a heat-shrink cable termination. A 12/20(24) kV single core XLPE underground cable with the nominal cross-section area of 240 mm<sup>2</sup>, three pieces of 22 kV cable joints, and eight pieces of 22 kV cable termination were prepared for the experiment. Then, polarization and depolarization current (PDCs) measurement were performed. The experiments were divided into two parts. The first part was composed series of three tests, A — C, and the second part consisted series of two tests, D — E, as follows: Test A examined dielectric response of a 6 m healthy XLPE underground cable, Test B examined dielectric response of a 6 m healthy XLPE underground cable with two healthy cable terminations, Test C examined dielectric response of a two of 3 m healthy XLPE underground cable with healthy cable terminations connected by a healthy cable joint, Test D used the test object similarly as case C but the cable joint was contaminated with copper particles, and Test E used the test object similarly as case C but the cable joint was contaminated with tiny pieces of water blocking. From the experiment, the PDCs and the derived dielectric parameters such as geometrical capacitance, insulation resistance, polarization index, depolarization index, charge difference curve and charge ratio curve were analyzed. The PDCs and the derived parameters were found different for each case of study as details in this paper. Besides, the charge ratio proposed by authors is a valuable parameter for the diagnosis of insulation system of high voltage equipment.
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The study on wavelet coefficient behavior of simultaneous fault on the hybrid between overhead and underground distribution system
(2019-05-01)
Pothisarn, Chaichan
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Jettanasen, Chaiyan
This paper proposed the study on behaviour and characteristic of wavelet coefficient in case of simultaneous fault occurrence on hybrid transmission system. The ATP/EMTP software has been used to simulate 115-km hybrid transmission line that modelled after on part of PEA distribution system. The case study system is 40 km distribution line with overhead line on first 20 km section and underground cable on the second half. The Discrete Wavelet Transform (DWT) has been used to analyse fault signal. Various factor that can affect system characteristic such as inception angle, location, and type of fault has been taken into consideration. The result shown the significant change in coefficient of high frequency component when simultaneous fault occurs compared to single fault especially in hybrid distribution system when fault occur on both overhead and underground cable, thus result in problematic analysis of coefficient and complexity in design suitable algorithm. This change in system characteristic must be taken into consideration when develop protection system in order to achieve the satisfactory performance with even more complex power system in the future.
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Discrete wavelet transform and probabilistic neural network algorithm for classification of fault type in underground cable
(2012-01-01)
Ngaopitakkul, A.
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Suttisinthong, N.
This paper proposes an algorithm based on a combination of discrete wavelet transform (DWT) and probabilistic neural network (PNN) for classifying fault types on underground cable. Simulations and the training process for the PNN are performed using ATPIEMTP and MATLAB. The mother wavelet daubechies4 (db4) is employed to decompose high frequency component from these signals. The maximum coefficients of DWT of phase A, B, C and zero sequence for post-fault current waveforms are used as an input for the training pattern. Various cases studies based on Thailand electricity distribution underground systems have been investigated so that the algorithm can be implemented. The coefficients of DWT are also compared with those of PNN in this paper. The results show that the proposed algorithm is capable of performing the fault classification with satisfactory accuracy. © 2012 IEEE.
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DWT and RBF neural networks algorithm for identifying the fault types in underground cable
(2011-12-01)
Ngaopitakkul, A.
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Pothisarn, C.
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Bunjongjit, S.
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Suechoey, B.
A new technique for classifying fault type in underground distribution system has been proposed. Discrete wavelet transform (DWT) and Radial basis function (RBF) neural network are investigated. Simulations and the training process for the RBF neural network are performed using ATP/EMTP and MATLAB. The mother wavelet daubechies4 (db4) is employed to decompose high frequency component from these signals. Positive sequence current signals are used in fault detection decision algorithm. The output pattern of RBF is divided into two case studies training for comparison between classifying of the fault types and identifying the phase with fault appearance. The variations of first scale high frequency component that detect fault are used as an input for the training pattern. The comparison of the coefficients DWT is also compared with the RBF neural network in this paper. The result is shown that an average accuracy values obtained from RBF gives satisfactory results. © 2011 IEEE.
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Study of characteristics for simultaneous faults in distribution underground cable using DWT
(2011-12-01)
Ngaopitakkul, A.
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Pothisarn, C.
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Leelajindakrairerk, M.
In the literature for fault detection, most of research works have never been mentioned about effects of simultaneous faults. This paper presents behavior of characteristics for simultaneous fault signals in an electrical distribution underground cable using wavelet transform. The fault signal is simulated using ATP/EMTP, and the behavior analysis of signals is performed using discrete wavelet transform (DWT). The DWT is used to detect the high frequency components. The results obtained from the analysis will be useful in the development of a detect fault scheme for electrical distribution underground cable in the future due to an effect of the other fault that occurs at the other side of the system; this leads to the malfunction of the protective relays. © 2011 IEEE.
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Discrete wavelet transform and back-propagation neural networks algorithm for fault classification in underground cable
(2011-07-26)
Kaitwanidvilai, S.
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Pothisarn, C.
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Jettanasen, C.
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Chiradeja, P.
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Ngaopitakkul, A.
This paper proposes a new technique using discrete wavelet transform (DWT) and back-propagation neural network (BPNN) for fault classifications on underground cable. Simulations and the training process for the back-propagation neural network are performed using ATP/EMTP and MATLAB. The mother wavelet daubechies4 (db4) is employed to decompose high frequency component from these signals. Positive sequence current signals are used in fault detection decision algorithm. The variations of first scale high frequency component that detect fault are used as an input for the training pattern. Various cases studies based on Thailand electricity distribution underground systems have been investigated so that the algorithm can be implemented. The results are shown that an average accuracy values obtained from BPNN can indicate the fault classification with satisfactory accuracy, and will be very useful in the development of a power system protection scheme.
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Identification of fault locations in underground distribution system using Discrete Wavelet Transform
(2010-12-01)
Ngaopitakkul, A.
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Apisit, C.
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Pothisarn, C.
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Jettanasen, C.
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Jaikhan, S.
In this paper, a technique for detecting faults in underground distribution system is presented. Discrete Wavelet Transform (DWT) based on traveling wave is employed in order to detect the high frequency components and to identify fault locations in the underground distribution system. The first peak time obtained from the faulty bus is employed for calculating the distance of fault from sending end. The validity of the proposed technique is tested with various fault inception angles, fault locations and faulty phases. The result is found that the proposed technique provides satisfactory result and will be very useful in the development of power systems protection scheme.

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