Modern Electric Power Systems 2010

Keynote Speakers


Dr. Bogdan Kasztenny Dr. Bogdan Kasztenny
Schweitzer Engineering Laboratories, Canada

General session speech:
Advancements in Line Current Differential Protection, PDF file (730kB)

Line current differential protection creates challenges for relay design and application. From the design perspective, the distributed nature of the line current differential system imposes limits on the amount of data that can be exchanged between the system terminals and calls for data alignment schemes between the relays at all line terminals to enable the differential protection principle.

Typically, channels available for line differential protection are limited to 64 kbps. This creates challenges for achieving fast speed of operation, proper restraint in applications with dual-breaker terminals, immunity to CT saturation conditions, or proper inrush and overexcitation inhibit in applications with in-line transformers.

The communications channel can be used to align the data reliably, but only if the channel is symmetrical with equal transmit and receive delays. Under asymmetrical channels, synchronization of data becomes inaccurate and protection needs to be less sensitive or the scheme must be compensated with the common timing signal, typically from satellite clocks (GPS). A line protection system requires security and may need fallback strategies should the GPS signal not be available.

From the application perspective, line current differential schemes are concerned with CT saturation, particularly in dual-breaker applications, in-zone reactors and line-charging current, in-line and tapped transformers, sensitivity to high-resistive faults, single-pole tripping, evolving faults, security on channel impairments, stub bus protection, application to lines with more than three terminals, and so on.

This keynote presentation reviews challenges and available solutions to the line current differential design and application. The paper educates in this new challenging area where protection and power system principles and applications mix with communications and signal processing.

Technical co-sponsor




The MEPS'10 symposium meetings took place in the Congress Centre of Wroclaw University of Technology.

Wroclaw, Poland

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