Transcript Adaptive Relaying - Smart Grid Center

Jeffy Mathew
ECEN 679
Spring 2014
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Adaptive Relaying permits and seeks to make
adjustments automatically in various
protections in order to make them attuned to
prevailing power system conditions. [3]
Important features
◦ Functions defined through software
◦ Have communication capability
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Current relay settings are calculated off-line
Desirable to change settings based on the
dynamic variations in the system
◦ Frequency variation
◦ Fault resistance in SLG faults
◦ Power swings
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Using local data, or local data exchange
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High SIR (Source Impedance Ratio) causes low
fault voltage.
Cold Load Pickup
◦ Traditionally relays trip instantaneously followed by
time delayed operation to override the inrush
current.
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Adaptive Distance Protection Control System
Adaptive Distance Protection Control System
Adaptive loop consists of identification,
decision, and changes.
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Fault Detection and Measuring
◦ Fault Detection
◦ Fault Type Classification
◦ Fault Measurement
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Adaptive Method for Change in Frequency
Adaptive Method for Single Line to Ground
Fault Resistance
Adaptive Method for Power Swings in System
◦ Out-of-step relaying
◦ As power swing develops, relays can switch from
tripping to blocking function
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Adaptive relaying helps to discriminate
between 3-phase faults and power swings.
◦ It is possible to differentiate between a 3Φ fault and
a power swing by looking for the presence of prefilter group delay.
◦ Pre-filtering of signals allows for:
 Removal of travelling wave noise
 Removal of DC offsets
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Adaptive relay is capable of very high speed
operation, maintaining a good reach point
accuracy in the presence of travelling wave
noise and is immune to the presence of
harmonics or variation in power system
frequency.
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Faster computation of settings
Automatic Reclosing settings can be adjusted
◦ Type and Severity of Fault
◦ Hard or Soft Circuit Breaker Operation
◦ Optimizing Circuit Breaker Wear
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Faster protection, slower tripping time
Minimizes compromises between
dependability and security
◦ Achieve increased dependability and security
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If relays change their settings themselves,
there is a chance that the relays will not
coordinate with each other properly.
Risk of Liability
Expensive to design
Chance that communication systems may fail
◦ Have to develop fallback position and safety checks
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Lecture Notes
Zhang Zhizhe and Chen Deshu, “An adaptive
approach in digital distance protection”, IEEE
Transactions on Power Delivery, Vol. 6, No. 1,
January 1991.
Stanley H. Horowtiz and Arun G. Phadke,
“Power System Relaying”. pg 273-275
Y.Q. Xia, K.K. Li, and A.K. David, “Adaptive
Relay Setting for Stand-alone Digital Distance
Protection”, IEEE Transactions on Power
Delivery, Vol. 9, No. 1, January 1994
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Moore, P. J.; Johns, A.T., "Adaptive digital distance
protection," Developments in Power Protection,
1989., Fourth International Conference on , vol., no.,
pp.187,191, 11-13 Apr 1989
keywords: {digital simulation;microcomputer
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converter;16 bit microprocessor;digital distance
protection;digital distance relay;high-resistance earth
faults;microprocessors;power swings;power
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URL: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=
&arnumber=20639&isnumber=822