This paper describes a novel fault detection technique of high impedance faults (HIFs) in high voltage transmission lines using the wavelet transform. Recently, the wavelet transform (WT) has been successfully applied in many fields. The technique is based on utilising the absolute sum value of coefficients in multiresolution signal decomposition (MSD) based on the discrete wavelet transform (DWT). A fault indicator and fault criteria are then used to detect the HIF in transmission line. In order to discriminate between HIF and non-fault transient phenomena such as capacitor and line switching and arc furnace loads, the concept of duration time, i.e. the transient time period, is presented. On the basis of extensive investigations, optimal mother wavelets for the detection of HIF are chosen. It is shown that the technique developed is robust to fault type, fault-inception angle, fault resistance and fault location. The paper demonstrates a new concept and methodology in HIT in transmission lines. The performance of the proposed technique is tested under a variety of fault conditions on a typical 154kV Korean transmission line system.

Discussion of "A novel fault detection technique of high impedance arcing faults in transmission lines using the wavelet transform"

To avoid automatic reclosing on permanent faults, a new numerical algorithm for power transmission network arcing faults detection has been developed. Some important features of a long arc in air are investigated and used as a basis in the algorithm design. The fact that the nonlinear arc behavior influences other voltages and currents distorting them, offered an opportunity to detect the arc by measuring and processing the transmission line terminal voltage and current. A series of simulation studies have shown that the algorithm can be used as an effective tool for arcing faults detection. >

A new approach to the arcing faults detection for fast autoreclosure in transmission systems

For maintaining security of distance relays, power swing blocking is necessary to prevent unintended operation under power swings. To be dependable, distance relays must operate whenever a fault occurs. Therefore, detecting faults during power swings is an important issue since the relay should be able to differentiate the fault condition and not be blocked during that time. This paper presents a new method for detecting a symmetrical fault during a power swing, based on extracting components of the current waveform using the Prony method. The merit of the method is demonstrated by simulating different faults during power swing conditions using the Alternate Transients Program version of the Electromagnetic Transients Program.

Detection of Symmetrical Faults by Distance Relays During Power Swings

This paper presents a new concept, based on variable dead time control, in adaptive single pole auto-reclosing (SPAR). The proposed scheme can give rise to a high rate of successful reclosing by adapting to variable dead times. The significance of this algorithm is that it uses the waveform patterns of the voltage transients following initial breaker opening. The performance of this proposed method is tested under a variety of fault locations on the Korean 765 kV system, and the outcome of the study clearly indicates that variable dead time auto-reclosing scheme can be used as an attractive and effective means of better management and operation of a high voltage transmission system.

An Alternative Approach to Adaptive Single-Pole Auto Reclosing in High-Voltage Transmission Systems Based on Variable Dead Time Control

Distributed generation is changing the way electricity distribution networks are designed and operated One of the key issues and prerequisites for having significant share of total production of distributed generation is that the operation of system protection is not jeopardized Automatic reclosing is very important for the reliability of overhead networks On the other hand, reclosing can be problematic when distributed generation (DG) units are connected to the network In order to find out the impact of distributed generation on protection, dynamic simulations have been carried out PSCAD/spl trade/ transient simulation software and advanced power system models have been applied The simulations verify the challenges distributed generation causes to protection, especially to high-speed reclosing

Analysis of the impact of distributed generation on automatic reclosing

A realistic simulation of fault arcs is extremely important in the successful design and development of alternative and improved transmission system equipment such as adaptive auto-reclosure and novel protection schemes It is also particularly important in relation to the design of single pole switched systems This paper discusses, in some detail, techniques that have been developed to model fault arcs more realistically than has been achieved hitherto A time dependent dynamic resistance representation of the primary arc is proposed with emphasis on an empirical approach which is used to determine the parameters concerned In particular, significant improvements have been made to the dynamic conducting characteristic of secondary arc models The paper concludes with a presentation of some interesting studies relating to typical 400 kV single circuit and double circuit systems when the new are models are incorporated into the electromagnetic transients program (EMTP)

R.K. Aggarwal

Papers

Improved techniques for modelling fault arcs an faulted EHV transmission systems