GE LPS-D, Инструкция по эксплуатации

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20
LPS-D Line Protection System GE Power Management
2.3 PROTECTION SETTINGS 2 CALCULATION OF SETTINGS
2
• Step Distance and POTT1 Schemes
If the Zone 4 phase distance functions are to be used to provide time-delayed backup protection, then set
Z4PHASE = YES; otherwise, set Z4PHASE = NO.
402: Z4PHREACH - Zone 4 Phase Distance Reach
• Blocking, Hybrid and POTT2 Schemes
In a blocking scheme, the Zone 4 functions key the transmitter to send a blocking signal to the remote ter-
minal of the line to block tripping for an external fault (F1, for example) within reach of the Zone 2 functions
located at the remote terminal.
In a hybrid scheme, the Zone 4 functions prevent keying of the transmitter to block echoing of the trip sig-
nal that was received as a result of the operation of the remote Zone 2 functions for an external fault (at F1
for example) within their reach.
In a POTT2 scheme the Zone 4 functions establish transient blocking circuitry to prevent tripping during
fault clearing and fault current reversals.
In all of these schemes, it is therefore imperative that blocking functions be set with a reach that will allow
them to see all faults that the remote Zone 2 functions will see. The following guidelines are proposed:
1. If the reach of the Zone 2 phase distance function (Z2PHREACH
R
) at the remote end of the line is less
than twice the positive-sequence impedance of the line, then the proposed setting is:
Z4PHREACH = 0.85 x Z2PHREACH
R
2. If the reach of the Zone 2 functions at the remote end is greater than twice the positive-sequence
impedance of the line, then the proposed settings are:
Z4PHREACH = 1.7 x (Z2PHREACH
R
- Z
1 L
)
where:
Z2PHREACH
R
= reach of phase Zone 2 functions at remote line terminal
Z
1 L
= positive sequence impedance of protected line
With these proposed settings, proper coordination will be obtained between the tripping and blocking func-
tions at the remote terminal of the line. It may be possible to use a shorter setting or a longer setting than
proposed, but,
1. If a longer setting is used, the reach should be checked per the maximum allowable reach procedure
given under Section 2.3.2: ZONE 2, 3, AND 4 DISTANCE FUNCTIONS on page 2–13. See Figure 2–
4: MAXIMUM ALLOWABLE REACH on page 2–13.
2. If a shorter reach setting is used, then the reach should be checked to assure that the function will
operate for all faults that the remote Zone 2 function can operate for.
When series capacitors are used on the protected line or in lines adjacent to the protected line, set the
Zone 4 phase distance functions with a reach that is equal to or greater than the reach of the phase dis-
tance pilot tripping functions (normally Zone 2) at the remote end of the transmission line. For example:
Z4PHREACH
≥
Z2PHREACH
R
where Z2PHREACH
R
is the reach of the pilot tripping functions (Zone 2 in this example) at the remote end
of the line.
• Step Distance and POTT2 Schemes
In all other schemes, the Zone 4 phase distance functions can provide an additional zone of time-delayed
backup protection. They can be used to provide a fourth zone of protection in a straight Step Distance
scheme, or they can be reversed in direction to provide the so-called “reversed third zone” of protection.