Redy Mardiana

Ground Fault Location on a Transmission Line Using High-Frequency Transient Voltages

This letter presents a fault-location method using high-frequency transient voltages generated by ground faults on a transmission line. The method is based on the measurement from one end of the line. The fault location is determined solely from the arrival time of initial waves of modal voltages at the measuring bus. The method does not need to use the reflected waves. The method is tested using the Electromagnetic Transient Program and the statistical results are presented.

Partial discharge location in power cables using a phase difference method

This paper presents a new partial discharge (PD) location technique for power cables. Unlike commonly used time-domain reflectometry (TDR) methods, this technique is based on the analysis of phase difference between the direct and reflected waves of a PD pulse measured at the cable end. The phase difference at various frequencies can be obtained from the cross Fourier spectral density function. After implementing a phase unwrapping algorithm, the defect is located. This technique has been tested using the Electromagnetic Transient Program (EMTP) on the model of a 20 kV, 1-km underground cable. The simulation takes into account the frequency-dependent parameters of the cable and the measurement accuracy of the A/D converter (8-bit). The signal-to-noise ratio (SNR) varies from 10 dB to -5 dB for all computer simulations. The statistical results are given to demonstrate the performance of the proposed technique.

Effects of terminal connections on sweep frequency response analysis of transformers

Many problems can arise in power transformers, beginning from the moment they arrive at the sites where they are to be installed [1], [2]. Sweep frequency response analysis (SFRA) is used by many industries and manufacturers to assess the mechanical integrity of the core, winding, and clamping structure of power transformers. It usually involves the application of low-voltage (LV) signal (2 to 15 V) at one terminal of the transformer, over the frequency range 20 Hz to 2 MHz, and measurement of the response at another terminal, as shown in Figure 1 [1]. The amplitude and phase transfer function are then determined.

Phase Difference Method for Two-end Partial Discharge Locating System of Power Cables

Abstract A method to locate partial discharges in power cables is presented in this article. The method is based on the phase difference between the first arriving waves of a partial discharge pulse at the cable terminals. The phase difference as a function of frequency is obtained using the cross-Fourier spectral density function. The partial discharge location can be determined from the slope of the unwrapped phase difference. The performance of the method is tested using the electromagnetic transient program on a 20 kV, 2-km underground cable, which takes into account the frequency-dependent parameters. The statistical results indicate high location accuracy.

Phase difference method for two-end partial discharge location in power cables

This paper presents a method to locate partial discharges (PD) in power cables based on the phase difference between the first arriving waves of a PD pulse at the cable terminals. The phase difference as a function of frequency is obtained using the cross Fourier spectral density function. The final PD location can be determined from the slope of the phase difference. The performance of the proposed method is tested using the Electromagnetic Transient Program (EMTP) on the model of a 20 kV, 2km underground cable. The simulation takes into account the frequency-dependent parameters of the cable. The statistical results are given and discussed.

Mitigation of magnetic fields near transmission lines using a passive loop conductor

This paper presents a concept to reduce the magnetic field generated from ac overhead transmission lines. The mitigation of magnetic field is performed by using a passive loop conductor. The method is applied to a flat transmission line configuration which is used frequently in extra high-voltage system. The effect of width and height of passive loop conductor on the reduction of magnetic field intensity is further investigated. Numerical results of magnetic field mitigation and further discussion are provided.

3D localization technique for broad band impulsive noise source

This paper presents a three-dimensional (3D) localization system for locating partial discharge (PD) on high-voltage apparatuses. An antenna array consisted of four sensors is employed to record the electromagnetic waves (EM) emitted from PD. The localization algorithm is based on the time difference of arrival (TDOA) of the signals. The TDOAs can be determined using the cross-correlation method, peak detection method, Akaike Information Criterion (AIC) method, Energy Criterion (EC) method, Gabor Centroid method, and/or threshold detection method. These system use two kind of antenna configurations. The first configuration is squared array with distance between antennas are 2 meter, and the second configuration is squared array with distance between antennas are 4 meter. In experimental setup, the implemented configuration is the first configuration, due to limitation of the experiment area. The effectiveness of the location method is tested through a computer simulation and the results are presented. From simulation result, the second configuration gives 11.12% better accuracy than the first configuration.

Effect of terminal connections on SFRA results of three-winding power transformers

This paper presents some case studies on the effects of terminal connections that affect Sweep Frequency Response Analysis (SFRA) results. Wrong or different terminal connections might lead to confusing SFRA results which could be misinterpreted in the assessment of transformer winding conditions. Effect of grounding the tertiary winding, opening the tertiary winding, and connecting the neutral point in the terminal connections are highlighted in this work.

Parameters affecting the ampacity of HVDC submarine power cables

This paper explains some parameters that affect the ampacity of HVDC submarine power cables. The parameters include ambient temperature, burial depth, and spacing distance between two cables. The analytical computation of cable ampacity is carried out in steady-state conditions. Internal, external, and mutual thermal resistances of power cables are taken into account in the calculation. The ampacity calculation is applied to a single conductor armored mass-impregnated polypropylene laminated paper (MI-PPLP) submarine cable. The HVDC system which has bipolar configuration with earth return is considered as a case study. The calculation results of cable ampacity are presented and discussed.

A frequency domain method for partial discharge location in underground power cables

A frequency domain method to determine the location of partial discharges (PD) from one-end of underground power cable is presented in this paper. This method is developed based on the phase difference between the direct and reflected waves of a PD pulse. The phase difference as a function of frequency is obtained using the cross Fourier spectral density function. The defect in the cable can be located after implementing a phase unwrapping algorithm. Laboratory experiments using a model of a 3.3 kV, 50m underground cable have been carried out and the statistical results are presented as well. The comparison results with the time domain methods are also given to demonstrate the effectiveness of the proposed method.