M. Michalik

High-impedance fault detection in distribution networks with use of wavelet-based algorithm

A new simple and effective algorithm of arcing fault detection in distribution networks with the application of a wavelet transform technique is presented in this paper. The protection algorithm developed observes the phase displacement between wavelet coefficients calculated for zero-sequence voltage and current signals at a chosen high-level frequency. The final decision in regards to feeder switching off (or alarm issuing) is met either with a deterministic logic scheme or with the use of a neural net trained especially for that purpose. The developed wavelet-based high-impedance fault (HIF) detector has been tested with Electromagnetic Transients Program-Alternative Transients Program (ATP)-generated signals, exhibiting better performance than traditionally used algorithms and methods. The protection method proposed may be used for HIF detection independent of the network neutral-point grounding mode. The scheme proved to be robust against transients generated during normal events such as feeder energizing and de-energizing as well as capacitor bank switching

New ANN-Based Algorithms for Detecting HIFs in Multigrounded MV Networks

Application of two new ANN-based algorithms for arcing high impedance fault (HIF) detection in multigrounded medium-voltage (MV) distribution networks is presented in this paper. The paper provides an evaluation of two new structures of artificial neural networks (ANNs) that may be used for reliable HIF detection in multigrounded as well as isolated, compensated, and grounded via small resistance distribution grids. The results obtained by use of both neural nets are presented. The performance was tested using data obtained from staged HIFs in real MV network as well as from electromagnetic transients program-alternative transients program simulations. A small number of necessary neurons in developed ANNs, short measuring sliding data window, and easy interpretation of obtained output signals are the main advantages of the proposed approach. Satisfactory results of ANN performance were observed for all examined HIF cases in which the ground fault current was greater than 16 A. The selected ANNs of best performance show high reliability and immunity to transients resulting from switching operations in protected feeders and from capacitor bank switching.

Verification of the Wavelet-Based HIF Detecting Algorithm Performance in Solidly Grounded MV Networks

The application of the wavelet-based algorithm for arcing high-impedance fault detection medium-voltage (MV) distribution networks is presented in this paper. This paper describes continuation of research on HIF detection with particular reference to algorithm application in solidly grounded MV networks. The results obtained by use of the improved version of the algorithm are presented. The algorithm performance was tested using data obtained from staged HIGFET in a real MV network as well as from EMTP-ATP simulations. Satisfactory results of the algorithm performance were observed for all examined HIF cases in which the ground fault current was greater than 3 A root mean square. The improved algorithm also proved to be more immune to transients generated during switching operations in protected feeders and to capacitor bank switching.

Wavelet transform approach to high impedance fault detection in MV networks

Application of wavelet transform technique to high impedance arcing fault detection in distribution networks is presented. Phase displacement between discrete wavelet coefficients calculated for zero sequence voltage and current signals at natural network frequency is tracked. The developed wavelet based HIF detector has been tested with EMTP-ATP generated signals, proving better performance than traditionally used algorithms and methods. The protection method proposed is efficient, robust and may be used for HIF detection independently of the network neutral point grounding mode.

Application of the wavelet transform to backup protection of MV networks-wavelet phase comparison method

Application of the wavelet transform (WT) to design of a single phase-to-ground protection that could be applied as a backup to standard medium voltage relays in (MV) overhead transmission lines is presented. The concept is based on the phase comparison between wavelet decomposition coefficients of zero sequence voltage and current signals. The idea was tested for signals generated in ATP/EMTP model of MV network. The results obtained are presented and the advantages as well as the drawbacks of the method are discussed.

Adaptive measurement of power system currents, voltages and impedances in off-nominal frequency conditions

The problem of basic power system electric quantities (current, voltage magnitudes, power and impedance) measurement in off-nominal frequency conditions is considered under the assumption that the quantities are calculated from orthogonal components of input current and voltage phasors which are obtained by the use of nonrecursive digital filters. Adaptive algorithms which make the measurement insensitive to wide range frequency changes of the input signals are presented. The adaptive features of the algorithms are obtained by use of the frequency measuring algorithm and modification of orthogonal filter coefficients and data window length. Sample results of simulation studies which show the algorithm performance are presented and discussed.

Application of Kalman filter technique to stationary and nonstationary state observer design

The paper presents a method of power system current and voltage estimation using the state space signal model approach. Design of stationary and nonstationary state observers based on Kalman filter technique is described. The results of dynamic performance of the state observers are presented for simulated fault currents and voltages obtained from EMTP model of 400 kV transmission line. The advantages and drawbacks of both types of state observers are discussed.

New variable window adaptive distance protection for Tee'd feeders

The new enhanced protection method dedicated for HV three-ended transmission lines is presented. Estimation of the fault location based on orthogonal components of voltages and currents calculated by use of developing window filters is discussed. The core contribution lies in introduction of variable reach characteristics of distance protection that are coordinated with proposed expanding data window filters. The performance of the scheme was tested with use of data obtained from EMTP-ATP simulations of faults in an HV test power network.