Path Rating Catalog 2013 - Western Electricity Coordinating Council

simultaneous analysis, only heavy summer conditions were studied. For the
Path 3 simultaneous analysis, both heavy summer and light spring
conditions were studied. For the Path 8 simultaneous analysis, only light
spring conditions were studied.
Study Criteria:
Remedial
Actions
Required:
Formal
Operating
Procedure:
For the 2012 wind addition sensitivity, Path 1 and Path 3 were studied
using both heavy summer and light spring system conditions. Path 8 was
not re-studied because the 2007 studies found no credible interactions.
NERC Reliability Standards (TPL-001-0.1, TPL-002-0b, TPL-003-0a, and
TPL-004-0), the WECC System Performance Criteria (TPL-001-WECC-
CRT-2, effective December 01, 2011), and local AESO and NWE system
criteria.
A distributed remedial action scheme (RAS) is proposed for MATL. The
primary objective of the RAS is to respond to a number of possible
contingency events by separating Montana and Alberta, in order to prevent
the development of instability. This purpose is accomplished as soon as
either end of MATL is opened. However, when one end of MATL is
opened, the other end should be opened as well. There are a number of
reasons to do this, among which are operational restrictions imposed by the
interconnected systems and equipment protection.
MATL RAS is designed to operate for the specific contingencies listed
below:
1. Langdon-Cranbrook (Path 1)
2. Cranbrook-Selkirk
3. Ingledow-Custer (double circuit)
4. 5L91 Ashton Creek-Selkirk & 5L96 Vaseux Lake-Selkirk (category C)
5. 5L91 Ashton Creek-Selkirk & 5L98 Nicola-Vaseux Lake
6. Custer-Monroe (double circuit)
When either RAS unit at either location makes the decision to trip, it will
open the circuit breaker at its location, disconnecting MATL at that end,
and initiate the orderly shutdown sequence logic to trip each segment of the
MATL system. An orderly shutdown sequence was developed as part of
MATL's normal protection scheme for the purpose of ensuring that both
ends open whenever one end does.
There will be installations for the RAS at both the Great Falls and MATL
120S substations. Each RAS installation shall be comprised of two
independent intelligent electronic devices (IED) providing full redundancy
and each RAS IED will be programmed to have the following two
detection functions:
• an under-voltage/over-power detection
• an out-of-step detection
The under-voltage/overpower detection will monitor the voltage and the
apparent power at its installed location. When the voltage is below the
setting threshold AND the apparent power is above the setting threshold for
the specified length of time, a trip output will be issued by the RAS. The
apparent power setting will be non-directional.
The following operating procedures will be developed and shared with
AESO, NWE and AltaLink prior to project energization:
• MATL RAS/SPS Operating Procedure
PART VI Item 1-217