Piotr Pierz

Centralized substation level protection for determination of faulty feeder in distribution network

This paper presents a novel approach to design of a centralized substation level protection aimed at determining the faulty feeder in a distribution network. In opposite to phase-to-ground faults in the transmission networks (HV), impedance of phase-to-ground fault-loops in MV distribution networks is usually high. From all of these reasons, detection of ground-fault and determination of a faulty feeder at a bus-bar with many outgoing feeders arises as serious problem. However, during the ground-fault the transient component which provides important information about the disturbance in the system appears. Such signals consist of different frequency components, which result from charging or discharging of the network capacitances. In this paper new approach which is based on checking a phase displacement between a fundamental frequency component of zero sequence current and a voltage directly after the fault inception is presented. Provided simulation experiments in ATP/EMTP software package confirm the effectiveness of the proposed technique for selection of a faulty feeder during phase-to-ground fault in different and under different fault scenarios-different fault inception angles, including random mechanism and high resistance faults.

Optimization of distance protection algorithm for series-compensated transmission line

This paper is focused on optimizing the distance protection algorithm for series-compensated line. This algorithm requires estimation of three-phase voltage drops across capacitors bank. For this purpose a nonlinear differential equation is solved on-line, applying comparatively low sampling frequency. In order to assure high fidelity of the waveforms reconstruction using the up resampling procedure has been introduced. The other interest of this paper is in impedance calculation based on optimal solution of the fault loop model. Two methods for fault loop resistance and reactance calculation are taken for comparison. The developed algorithms have been tested and evaluated using signals taken from ATP-EMTP versatile simulations of faults on a series-compensated transmission line. The sample results of the evaluation are presented and discussed.

A method for internal and external fault discrimination for protection of series compensated double-circuit line

This paper presents a new method designated for determination whether detected fault is placed on a protected double-circuit line or outside the line. It suits for protection of parallel uncompensated or series-compensated lines and uses one-end phase currents measurements only. The developed algorithm has been tested and evaluated using signals taken from ATP-EMTP versatile simulations. A detailed model of considered transmission line including the SCs&MOVs banks as well as the measurement channels has been developed. Using this model, the reliable fault data on a double-circuit uncompensated/series-compensated transmission line as well as for faults outside the line have been generated under variety of fault conditions. The sample results of this evaluation are presented and discussed.

Location of inter-circuit faults on double-circuit transmission line

This paper deals with location of inter-circuit faults on a double-circuit transmission line with use of complete measurements from one line end. The fault location algorithm is derived with use of the generalized fault loop model. As a result, the algorithm is of compact form what allows for its easy implementation. The presented fault location algorithm has been evaluated with use of the fault data obtained from versatile simulation of transmission line inter-circuit faults. Sample results of the evaluation are presented and discussed.

Location of open conductor failure combined with phase-to-earth fault on power line

One-end algorithm for locating an open conductor failure combined with an earth fault on power lines has been presented. Two cases: an open conductor failure occurring in front of and behind a earth fault, respectively, have been considered. The sample case with the fault data obtained from ATP-EMTP simulation is included and discussed.

Optimization of distance protection algorithm for double-circuit series-compensated transmission line

Distance protection still faces problems in application to parallel lines with series compensation (SC). Present practice relies on using traditional distance relays but with modified settings. As a result of that the firs zone reach is shortened to 30–40% of the line length instead of 75–80%.

High voltage series-compensated transmission line - evaluation of new distance protection

This paper investigates a new distance protection principle for a transmission line compensated with 3-phase capacitor banks installed in the middle of the line. Series Capacitors (SCs) equipped with Metal-Oxide Varistors (MOVs), when set on a transmission line, create certain problems for its protective devices. Direct application of the classic distance protection (designed for traditional lines) to series-compensated lines results in considerable shortening of the first zone reach and also in poor transient behaviour. In order to overcome these difficulties the new distance protection principle for the first zone has been developed. The detailed model of considered transmission lines including the SCs&MOVs banks as well as the measurement channels has been developed. Using this model, the reliable fault data has been generated for evaluation of the new distance protection principle under variety of fault conditions. The study has shown considerable improvement of series-compensated line protection as a result of applying the developed new principle.

Measurement of fault-loop impedance in three-terminal line using signals of current differential relays

Issues related to fault-loop impedance measurement in a three-terminal power line for a fault locator associated with current differential relays are presented. The measurement is carried out for three hypothetical faults located at particular line sections and then the result consistent with the real fault is selected. In this way an influence of fault path resistance on the measurement is compensated. A sample fault location and measurement with use of signals from computer simulation is presented and discussed.

Design of ferroresonance suppression circuit for capacitive voltage transformer - analytical approach supported by simulation

Design of ferroresonance suppression circuit for capacitive voltage transformer is presented. For this purpose an analytical approach to ferroresonance is firstly introduced. With use of the harmonic balance method the condition for avoiding stable subharmonic oscillations of the 3rd mode is stated. In the next step the ATP-EMTP simulation based investigations are carried out to find the suppression circuit parameter (or parameters) which assure damping of the nonlinear oscillations in accordance to the requirements of the standards. Two kinds of suppression circuits designed for the considered capacitive voltage transformer construction are investigated. The obtained results are presented and discussed.