ABB Relion REG670, Техническое руководство

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The ZMFPDIS function is a six zone full scheme protection with three fault loops for
phase-to-phase faults and three fault loops for phase-to-earth faults for each of the
independent zones, which makes the function suitable in applications with single-
phase autoreclosing.
The zones can operate independently of each other in directional (forward or reverse)
or non-directional mode. However, zone1 and zone2 is designed to measure in
forward direction only, while one zone (ZRV) is designed to measure in the reverse
direction. This makes them suitable, together with a communication scheme, for
protection of power lines and cables in complex network configurations, such as
parallel lines, multi-terminal lines, and so on.
A new built-in adaptive load compensation algorithm prevents overreaching of the
distance zones in the load exporting end during phase-to-earth faults on heavily
loaded power lines. It also reduces underreach in the importing end.
The ZMFPDIS function-block itself incorporates a phase-selection element and a
directional element, contrary to previous designs in the 670-series, where these
elements were represented with separate function-blocks.
The operation of the phase-selection element is primarily based on current change
criteria (i.e. delta quantities), with significantly increased dependability. There is also
a phase selection criterion operating in parallel which bases its operation only on
voltage and current phasors.
The directional element utilizes a set of well-established quantities to provide fast and
correct directional decision during various power system operating conditions,
including close-in three-phase faults, simultaneous faults and faults with only zero-
sequence in-feed.
Section 7
1MRK502052-UEN B
Impedance protection
204
Technical manual