Milenko B. Djurić

Voltage phasor and local system frequency estimation using Newton type algorithm

A new approach to the design of a digital algorithm for voltage phasor and local system frequency estimation is presented. The estimation problem is considered as an unconstrained optimization problem. The algorithm is derived using Newtons iterative method, very commonly used in load-flow studies. The algorithm showed a very high level of robustness as well as high measurement accuracy over a wide range of frequency changes. The algorithm convergence of order two provided fast response and adaptability. To demonstrate the performance of the algorithm developed, computer simulated, experimentally obtained and real-life data records are processed. The presented work is a part of a project concerning the application of microprocessors in frequency relaying. >

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

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. >

Distance protection and fault location utilizing only phase current phasors

Two numerical algorithms for fault location and distance protection which use data from one end of a transmission line are presented. Both algorithms require only current signals as input data. Voltage signals are unnecessary for determining the unknown distance to the fault. The solution for the most frequent phase to ground fault is presented. The algorithms are relatively simple and easy to be implemented in the on-line application. The algorithms allow for accurate calculation of the fault location irrespective of the fault resistance and load. To illustrate the features of the new algorithms, steady-state and dynamic tests are presented.

A new self-tuning algorithm for the frequency estimation of distorted signals

This paper introduces a new self-tuning digital signal processing algorithm for local power system frequency deviation measurement. The algorithm is derived using the nonrecursive least error square technique accompanied with an updating procedure, which generally improves the algorithm properties: the measurement range; the immunity to a random noise; and the accuracy. The algorithm developed takes into account the components of the fundamental frequency, the second through the M-th harmonics and a decaying DC component, so it could be used for the real-time distorted signals frequency estimation as well as for the harmonics measurement. To demonstrate the efficiency of the algorithm proposed, the results of the computer simulated, experimentally obtained and real-life data records tests are presented. >

Time domain solution of fault distance estimation and arcing faults detection on overhead lines

In this paper a new numerical algorithm for arcing faults detection and fault distance estimation is presented. The solution is given in the time domain. It is based on the line terminal voltages and currents processing. A simple new mathematical model of arc voltage is introduced in the estimation. Thereby, the more accurate approach to fault location is derived, particularly for the close-in faults. The new algorithm can be utilized for blocking the automatic reclosing. The unknown model parameters, including the line resistance and inductance, fault resistance and arc voltage amplitude, are estimated by using the least error squares method. The new algorithm is successfully tested through computer simulation and laboratory tests.

Arcing faults detection on overhead lines from the voltage signals

This paper presents a simple algorithm for arcing faults detection on overhead lines. The algorithm is based on the harmonic analysis of the bus voltage signals. It uses only the sine components of the odd higher harmonics of the bus voltage. Such an approach provides the algorithm with insensitivity to the cosine components of the bus voltage odd higher harmonics which can be generated by current odd cosine higher harmonics. The algorithm can be used for blocking the automatic reclosing of lines with permanent faults. A very simple arc model has been adopted. The algorithm was successfully tested with signals recorded on a real power system and signals obtained through computer simulated and laboratory tests.

Spectral domain arcing fault recognition and fault distance calculation in transmission systems

A new numerical algorithm for recognizing arcing faults for the purpose of automatic reclosing is presented. The fault distance can also be calculated using this algorithm. The solution for both symmetrical and unsymmetrical faults is given. A simple empirical arc voltage model is obtained through a table of numerical values. By means of computer simulation and laboratory testing it is shown that the algorithm can be used as an effective tool in transmission and distribution system protection.

Digital signal processing algorithm for arcing faults detection and fault distance calculation on transmission lines

In this paper a new digital signal processing algorithm for arcing fault detection and fault distance calculation is presented. It was derived by processing the line terminal voltages and currents. A simple square wave arc voltage model was assumed to represent the long arc in free air. The unknown model parameters (the line resistance and inductance, and arc voltage amplitude) were estimated by using the least squares error technique. The new algorithm was successfully tested by computer simulated and laboratory tests.

A numerical Algorithm for Direct Real-Time Estimation of Voltage Phasor, Frequency and its Rate of Change

ABSTRACT A new algorithm for direct estimation of voltage phasor, frequency and its rate of change, of a voltage signal distorted by a DC component and contaminated by random noise is presented. The method is based on the non-recursive Least Error Squares Technique (LS Technique). Using digitized samples of voltage at the relay location, the estimation of the voltage signal unknown parameters is improved by means of an update procedure. The algorithm is adapted to the actually estimated frequency iteratively, which improved the measurement accuracy, increased the measurement range and reduced sensitivity to the noise. To demonstrate the performance of the algorithm developed, computer simulated data record tests are presented. The proposed method seems to be particularly useful in the field of frequency relaying.

A recursive Newton type algorithm for digital frequency relaying

This paper presents a new recursive Newton type algorithm devoted to frequency relaying. The algorithm is designed from the nonrecursive Newton type algorithm and recursive least error squares algorithm. The frequency is estimated from the uniformly sampled voltage signal. The algorithm testing based on computer simulated and experimentally obtained data record processing confirmed the good features of the algorithm developed. Due to its computational efficiency, the algorithm is suitable for various real-time power system measurement applications.