Cezary Dzienis

Novel impedance determination method for phase-to-phase loops

In this paper a novel impedance determination method for the phase-to-phase loops is described. This approach promises a better accuracy of the reactance calculation of the faulty loops. Thus, better selectivity and security in operation of the distance element applied for the protection of transmission and distribution lines is guaranteed. Moreover, with this new method the separation of the fault resistance from load condition is achieved. Due to this fact, special measures for load encroachment are not necessary. It contributes to simplification of distance protection settings.

Current transformer model with hysteresis for improving the protection response in electrical transmission systems

In this paper, a generic enhanced protection current transformer (CT) model with saturation effects and transient behavior is presented. The model is used for the purpose of analysis and design of power system protection algorithms. Three major classes of protection CT have been modeled which all take into account the nonlinear inductance with remanence effects. The transient short-circuit currents in power systems are simulated under CT saturation condition. The response of a common power system protection algorithm with respect to robustness to nominal parameter variations and sensitivity against maloperation is demonstrated by simulation studies.

Analysis of High-Speed-Distance protection

The modern power system often operates at its performance limit. Therefore, uncontrolled events, e.g. short circuits, can quite rapidly cause thermal stress of system components as well as instability of the entire power system with the risk of longer energy interruption. In order to maintain the reliability and security of the power system at good level, the reaction to such undesirable events must be very quick. This task is undertaken by protection equipment. One such fast protection function is the High-Speed-Distance (HSD) line protection, which provides selective tripping of the line within half of the fundamental cycle after short circuit beginning. In this paper, the High-Speed-Distance protection function is systematic analyzed.

Travelling wave fault location based on pattern recognition

Travelling Wave Fault Locators (TWFL) allow a higher precision in most cases than typical impedance based fault location methods. One of the major problems with it, is the measurement of the arrival times of Travelling Waves (TWs). In this paper, a new method to compute the difference of arrival times of the first wavefront is presented. The method is based on the telegraphers equations. The paper illustrates the algorithm approach, tested on simulation models. In addition, practical experience on the Belgian transmission network is discussed. The different sources of error of the algorithm and the practical difficulties to apply it are discussed in the paper.

Accurate impedance based fault location algorithm using communication between protective relays

The reactance method with fault resistance separation has been developed in order to determine the impedance of a fault loop as precisely as possible in a transmission or distribution power system line. This method has commonly been used for impedance calculation in the case of a single phase-to-earth fault in diverse power system protection applications. New developments in this area have shown that the extension of the method to multi-phase faults is not only possible, but also of practical relevance. This research consists of an improvement in the calculation method using data from both the own and the remote end of the line. This approach uses a communication link between two measurement units, e.g. protection relays, which have the advantage of not requiring a precise synchronization with each other. The additional time invariant parameters of the power system, acquired by each device and transferred to the remote end, allow for an exact computation of the fault reactance and fault resistance. In this paper, the derivation of this novel approach, as well as the experimental results in a fault location application are presented.

Precise impedance based fault location algorithm with fault resistance separation

The reactance method with fault resistance separation has been developed in order to determine as precisely as possible the impedance of a fault loop in a transmission or distribution power system line. This method has commonly been used for impedance calculation in case of a single phase-to-earth fault in diverse power system protection applications. New developments in this area have shown that the extension of the method to multi-phase faults is not only possible but also of practical relevance. However, all previous investigations focused on impedance calculation using data from one single side of the power system line. Due to missing data from the remote end, the determined impedance value can deviate from its real value. This research consists in an improvement of this calculation method using data from both the own and the remote line end. This approach uses communication between two measurement units e.g. protection relays, which have the advantage of not requiring a precise synchronization with each other. The additional time invariant parameters of the power system, acquired by each device and transferred to the remote end, allow an exact computation of the fault reactance and fault resistance. In this paper, the derivation of this novel approach as well as experimental results in a fault location application are presented.

Parameter Estimation in Electrical Power Systems Using Prony's Method

This paper presents the basic principle of Pronys method, which is used for determining electrical power system parameters such as phasors, angular speeds as well as damping factors in a large frequency range. For fixed sampling frequencies, the approach to finding an optimal model order and to extracting transient parameters for further identification of different system effects is shown. Furthermore, it is shown that the method can be applied to the diverse plausibility checks for a confirmation of the result obtained using a conventional Fourier based approach. It will be presented that the significant advantage of the Prony algorithm in comparison to Fourier based methods is the possibility of computing an accurate frequency and in determining a damping factor.