Miroslaw Lukowicz

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

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.

Time Coordination of Distance Protections Using Probabilistic Fault Trees With Time Dependencies

Distance protection of the electrical power system is analyzed in the paper. Electrical power transmission lines are divided into sections equipped with protective relaying system. Numerical protection relays use specialized digital signal processors as the computational hardware, together with the associated software tools. The input analogue signals are converted into a digital representation and processed according to the appropriate mathematical algorithms. The distance protection is based on local and remote relays. Hazard is the event: remote circuit breaker tripping provided the local circuit breaker can be opened. Coordination of operation of protection relays in time domain is an important and difficult problem. Incorrect values of time delays of protective relays can cause the hazard. In the paper, the time settings are performed using probabilistic fault trees with time dependencies (PFTTD). PFTTD is built for the above mentioned hazard. PFTTD are used in selection of time delays of primary (local) and backup (remote) protections. Results of computations of hazard probabilities as a function of time delay are given.

Comparison of different approaches to arc fault location on power transmission lines

This paper presents a three different fault location approaches: one-end Takagi algorithm, two-end algorithm considering natural fault loops and neural network. It is assumed that three-phase voltages and currents from both ends of the line measured asynchronously are the input signals of the fault locator. In addition to natural fault loop signals also use of symmetrical components (positive and negative or incremental positive sequence components) to fault location were considered as well. Results of evaluation study have been included, analyzed and discussed. Influence of filtration have been also considered.

Selection of Tripping Times for Distance Protection Using Probabilistic Fault Trees with Time Dependencies

Distance protection of electrical power system is analyzed. This protection is based on local and remote relays. Hazard is the event: remote circuit breaker tripping provided the local circuit breaker can be opened. Coordination of operation of protection relays in time domain is important and difficult problem. Incorrect values of delay times of protection relays can cause the hazard. In the paper, the impact of delay time settings on performance of protective scheme is analyzed using Probabilistic Fault Trees with Time Dependencies (PFTTD). PFTTD are introduced in the paper and used for the above-mentioned hazard analyzes. The outcomes are hazard probabilities as a function of delay time values.

Verification of new protection algorithm for compensated MV distribution systems

In the paper authors propose the application of optimization techniques to developing filters dedicated for computation of criterion quantities suitable for distribution feeders protection. The fault detection algorithm has been investigated on the basis of data acquired from the physical model of the compensated MV distribution network and data from computer simulations in EMTP. The investigated algorithm is based on computational scheme with linear filtration that is used for analyzing fundamental component and high frequency components induced in compensated MV network during arcing faults in faulty and sound feeders. Since proposed structure realizes linear filtration and is composed of only five computational units, it is easy to interpret the final decision on the state of the feeder. The relaying scheme requires much less computational units when compared to approaches proposed so far. It is highly selective and secure.

Fault location under CT saturation for overhead transmission lines based on asynchronous measurements and ANNs

The paper is concerned with location of arcing faults on power transmission lines. Presented method makes use of artificial neural networks worked out for various fault types. The investigation is focused on the fault cases with accompanying saturation of current transformers, resulting in significant transformation errors. Fault location is based on asynchronous measurements of voltages and currents at two ends of the line under the knowledge of fault type. The method has been evaluated for versatile operating conditions of the 400 kV power transmission line modeled in EMTP.

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.

ANALYSIS OF TIMING PROPERTIES OF ELECTRICAL POWER SYSTEM PROTECTION

Abstract In electrical power systems, the coordination of protections in time domain is important and difficult problem. The time settings of protection relays have to be adapted to the time characteristics of electrical power system plants and the delay times of the other protections. In the paper, Fault Trees with Time Dependencies (FTTDs) are used in selection of values of the delay times of primary (local) and remote backup protections. In the FTTD, events and gates are characterized by time parameters. These time parameters are derived from the time characteristics of protection devices and the inherent delay times of protection equipment.