Hitachi Energy Switzerland Ag

Abb Schweiz Ag

Abb Power Grids Switzerland Ag

Hitachi Energy Ltd

YouYi Li

Jianping Wang

Kai Liu

Jiuping Pan

Reynaldo Nuqui

Zhanpeng Shi

Arkadiusz Burek

Aken-Kai Liu

Fabian Hohn

There is provided mechanisms for differential protection of a transmission line () of a transmission system (). A method comprises obtaining a restraining current and a differential current from the transmission line (S). The method comprises determining a compensation current for the differential current (S). The method comprises providing the differential current as compensated for by the compensation current and the restraining current to a differential protection arrangement for making a trip decision (S). The method comprises detecting an internal fault for the transmission system (S). The method comprises, as a result thereof, providing the differential current without being compensated for by the compensation current and the restraining current to the differential protection arrangement for making the trip decision (S).

Differential protection of a transmission line

A method for detecting fault in a power transmission line of a power transmission system and protection system using the same. The method includes: obtaining a system parameter of the power transmission system, adjusting protection reachability of a fault detecting element based on the obtained system parameter such that the adjusted protection reachability of the fault detecting element is applicable to a predetermined protection range, identifying whether there is an internal fault occurring on the transmission line using the adjusted fault detecting element, and generating a fault detection decision signal indicating the identified fault. If the predetermined protection range is desirable for the fault detecting element, its protection reachability may be adjusted in consideration of the influence imposed by the SIR such that the reach point of the adjusted fault detecting element can be extended to approach the end of the predetermined protection range. Consequently, the influence on its accuracy by various SIR values can be taken into account and accordingly the fault detecting solution can remove substantial errors as a result thereof.

Method for detecting fault in power transmission line and protection system using the same

An arrangement and method for zero sequence differential protection of a transmission line of a power system are disclosed. A zero sequence differential protection unit is configured to detect an internal fault of the transmission line using current measurements of each phase A, B, C of the transmission line. The zero sequence differential protection unit is configured to initiate a trip when an internal fault is detected. A phase selection unit is configured to determine whether or not any of the phases A, B, C of the transmission line is faulty using a comparison of differential values of the current measurements for each phase. The phase selection unit is configured to, based on the initiation of the trip, determine which of the phases A, B, C is faulty and to finalize the trip for any faulty phase.

Zero sequence current based line differential protection solution

A method can be used for fault detection of a transmission. The method includes obtaining instantaneous measurements of local voltages and local currents of the transmission line, obtaining filtered measurements of the local voltages and local currents by subjecting the measurements of the local voltages and local currents to low pass filtering, obtaining a compensated voltage calculated by subjecting the filtered measurements to a differential equation based algorithm, and performing fault detection by forming a ratio between the compensated voltage and the a reference voltage. An internal fault is determined when the ratio is below a threshold and an external fault is determined when ratio is larger than above the threshold.

Time domain distance protection based on polarity comparison for power transmission lines

A method can be used for phase selection using multi-terminal measurements of a transmission line of a power system. The method includes obtaining, using measurements from a plurality of terminals of the transmission line, delta differential current values &#x394;I(t), &#x394;I(t), &#x394;I(t), at time t, between pre-fault differential current measurements and post-fault differential current measurements from all three phases (A, B, C) of the transmission line. The method also includes determining at least one of the phases to be faulty when the absolute value of the corresponding delta differential current value is larger than k times the minimum of all the absolute values I&#x394;I(t)|, |&#x394;I(t)|, |&#x394;I(t)| of the delta differential current values, where k&#x3e;1 is a scale factor.

High sensitive phase selection method

A mechanism for travelling wave pilot protection of a transmission line and method for receiving indications of a travelling wave from two terminals of a transmission line, wherein two terminals are time synchronized. The method includes making a trip decision based on the indications using a short trip window. An arrangement is configured to perform the disclosed method.

Travelling wave pilot protection of a transmission line based on time synchronization

A method, control system and protective relay are provided for detecting faulted phases of transmission lines in an AC power system. The method includes sampling electric signals at one end of the transmission lines at a series of time points; computing instantaneous voltage values of electric signals at compensated points on the transmission lines from the values of the sampled electric signals based on a time domain lumped parameter differential equation for the transmission lines for the series of time points; recording the computed instantaneous voltage values of the electric signals; computing fault component or sudden-change of the instantaneous voltage values of the electrical signals; detecting the faulted phases or fault types by comparing the calculated fault component of the instantaneous voltage values at the preset compensated points; and generating signals indicating the faulted phases of fault types.

Method and control system for faulted phase detection

There is provided mechanisms for travelling wave protection of a transmission line. A method includes performing high-pass filtering of a current and/or voltage measurement of a transmission line so as to detect fault-caused high-frequency components of the current and/or voltage measurement. The method includes providing a result of the high-pass filtering as input to a trip decision maker performing travelling wave detection.

Travelling wave protection of a transmission line based on high-pass filtering

There is provided mechanisms for detecting a fault of a transmission line () in a power system () comprising at least one of an extreme weak system () and an extreme strong system (). A method comprises obtaining travelling wave polarities from two terminals () of the transmission line during occurrence of the fault, the travelling wave polarities being defined by two current polarities and two voltage polarities. The method comprises determining the obtained travelling wave polarities to be detectable and the obtained travelling wave polarities to be non-detectable. The method comprises detecting the fault to be internal based on the detectable travelling wave polarities and the non-detectable travelling wave polarities. There is also provided an arrangement configured to perform such a method.

Fault detection of a transmission line

A method and an apparatus for fault detection in a mixed configuration power transmission line including a plurality of sections arranged between one end of the transmission line and the other end of the transmission line and including at least one overhead line section and at least one cable section are disclosed. Based on a comparison travelling wave voltage or current time derivatives at the one end and the other end of the power transmission line with selected threshold values, it is determined if there is a fault occurring in at least one cable section of the power transmission line. Embodiments utilize amplification of travelling wave voltages and/or currents which may occur at junctions between a cable section and an adjacent overhead line section in determining if the fault occurs in a cable section of the power transmission line.

Method and apparatus for detecting fault in a mixed configuration power transmission line

A mechanism for travelling wave protection of a transmission line and a method for acquiring information of both voltage and current polarities from two ends of a transmission line. The method includes comparing the voltage and current polarities of both ends of the transmission line to each other. The method also includes making a trip decision based on the comparison.

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YouYi Li