Download OTP TO Planning Criteria

Transmission Planning Criteria, Guidelines and
Study Procedures
Version 5.0
August 27, 2015
Document History
Revision
Number
---
Revision
Date
4/1999
Effective
Date
4/1999
Owner
Summary of Changes
OTP Criteria included in MAPP Operating
Studies Manual
3/05/10
MAPP Operating
Review
Subcommittee
Working Groups
MAPP Planning
Standards
Development
Working Group
Northern MAPP
Operating and
Review Working
Group
Jason Weiers
---
7/2003
7/2003
---
4/2009
4/2009
1
3/05/10
9/24/10
9/24/10
Jason Weiers
3
2/29/12
4/01/12
Michael Riewer
4
3/10/14
4/01/14
Michael Riewer
OTP Criteria copied into OTP specific
document called “Facility Loading and Voltage
Criteria”
Corrected emergency rating of terminal
equipment and MISO BPM revision date (to
reflect issue date)
Changed transient voltage criteria for
Jamestown 345 kV bus and added more detail
to summary table of ratings
Additional study procedure clarification added
2
5
8/27/15
8/27/15
Jesse Tomford
General Updates
MAPP Operating Studies Manual revised and
named MAPP Members Reliability Criteria and
Study Procedures Manual
MAPP Members Reliability Criteria and Study
Procedures Manual updated by NMORWG
Reference Documents
Reference Document Title
Revision
Number
BPM020-r12
8.0
Revision
Date
04/28/2015
Guidelines for Generation, Tie-Lines, and
Substation Interconnections
3.3
11/15/2013
Transmission System Planning Performance
Requirements
TPL-0014
MISO Transmission Planning Business Practices
Manual
Otter Tail Facility Ratings Methodology
Otter Tail Planning Criteria, Guidelines and Study Procedures
12/30/2014
Page 2
Contents
0)
1)
Introduction ............................................................................................................................ 4
0.1)
Purpose............................................................................................................................. 4
0.2)
General Use ...................................................................................................................... 4
Study Procedures .................................................................................................................... 5
1.1)
General Transmission Planning Criteria ........................................................................... 5
1.1.1)
NERC Reliability Standards ........................................................................................ 5
1.1.2)
Modeling ................................................................................................................... 5
1.1.3)
Special Protection Schemes (SPSs), Dynamic Line Ratings, and Operation Guides . 6
1.2)
Interconnection Guidelines .............................................................................................. 7
1.2.1) Generation Interconnection and Outlet Transmission................................................. 7
1.2.2) Load Interconnection and Power Factor ...................................................................... 8
1.2.3) Operation Studies ......................................................................................................... 9
2)
Facility Loading Criteria ......................................................................................................... 10
3)
Voltage Criteria ..................................................................................................................... 11
3.1)
Pre-contingent Voltage Criteria .................................................................................. 11
3.2)
Transient Period Voltage Criteria ............................................................................... 12
3.2.1)
Transient Period Damping Criteria ......................................................................... 12
3.2.2)
Transient Switching Criteria (Voltage Flicker)......................................................... 13
3.3)
4)
Post-Contingent Voltage Criteria ................................................................................ 14
Other Planning Guidelines .................................................................................................... 14
4.1)
Radial MW-Mile .......................................................................................................... 14
4.2)
Load Break Switches ................................................................................................... 14
4.3)
Motor Operator Switches ........................................................................................... 14
4.4)
Ring Bus and Breaker and a Half Treatment .............................................................. 15
Otter Tail Planning Criteria, Guidelines and Study Procedures
Page 3
0) Introduction
Otter Tail Power Company (“Otter Tail”) is a transmission-owning member of the Midcontinent
Independent System Operator (“MISO”); which serves as the Planning Authority for Otter Tail.
As a transmission-owning member of MISO, Otter Tail follows the transmission planning
practices of MISO pursuant to Attachment FF of the MISO Tariff and as outlined in its
Transmission Planning Business Practices Manual.
This document outlines the system planning procedures, guidelines and criteria that are to be
used for performing studies of the Otter Tail transmission system. The specific criteria outlined
in this document for Otter Tail are designed to meet the requirements included within the
North American Electric Reliability Corporation (“NERC”) Planning and Operating Standards.
These criteria assist in determining whether the transmission system meets acceptable
performance requirements as defined in the applicable NERC standards.
0.1) Purpose
This document outlines the planning criteria, guidelines and study procedures to be used when
assessing the Otter Tail transmission system and was developed for the following reasons:
1.
2.
3.
To provide a readily available reference covering Otter Tail study practices.
To provide a well-documented guide for engineers involved in studies of the Otter Tail
transmission system
To meet the annual filing requirements of FERC Form No. 715
0.2) General Use
While the criteria outlined in this document provide framework for performing studies of the
Otter Tail system, it must be recognized that each need, issue, or circumstance is different and
should be assessed according to each unique situation. The projects developed from this
document may be altered due to other considerations (e.g. engineering judgment, regulatory
requirements, management directives, contractual relations, and/or socio-environmental
considerations) or differences in the study system compared to the actual system. The criteria
within this document remain fluid and are revised as needed.
Otter Tail Planning Criteria, Guidelines and Study Procedures
Page 4
1) Study Procedures
The measure of successful transmission planning is attaining a transmission system that delivers
electricity as reliably, economically, and environmentally responsible as possible that can
accommodate a reasonable level of growth and development.
1.1) General Transmission Planning Criteria
Otter Tail will apply the planning criteria outlined in this general section to all interconnection
and reliability studies. This includes, but is not limited to, NERC TPL compliance studies,
transmission interconnection studies, generation interconnection and load interconnection
studies. More details regarding specific studies can be found in sections 1.2 through 1.4.
1.1.1) NERC Reliability Standards
Otter Tail is required to comply with all applicable NERC Reliability Standards. Otter Tail’s
transmission planning criteria outlined in this document are established to provide full
compliance with NERC Planning Standards. NERC Reliability Standard TPL-001-4 is foundational
for performing planning studies of the Otter Tail transmission system. Study procedures and
modeling assumptions deemed necessary by Otter Tail for TPL compliance are to be used in
other studies of the Otter Tail system including but not limited to interconnection studies.
1.1.2) Modeling
Any study performed is dependent on an accurate model. The study and resulting reliability
performance identified through a study are only as accurate as the models and associated
modeling assumptions. The following section outlines the general modeling assumptions used
in performing studies of the Otter Tail system. Some variations of these general assumptions
are necessary from time to time in order to more accurately assess system performance in
accordance with defined reliability criteria.
1.1.2.1) Loads
Otter Tail projects its future load in models on historic load levels and procedures outlined in
the Energy Information Administration’s Form EIA-411. Otter Tail’s future load growth is
estimated as a 50/50 estimate or a 1 in 2 years probability of occurring. Otter Tail generates
monthly peak load estimates on a system-wide basis, which are then reflected into the
applicable condition (peak, off-peak, summer, winter, summer off-peak, etc.) for the defined
model building processes of the Midcontinent Reliability Organization’s Model Building
Subcommittee Manual.
Otter Tail determines future load estimates on a bus-by-bus basis according to historical MW
demand and power factor. These historical numbers are scaled based on the future load
Otter Tail Planning Criteria, Guidelines and Study Procedures
Page 5
projections submitted by Otter Tail through Long-Term Reliability Assessment (LTRA) submittals
to MISO. Slight variations in modeled load and LTRA submittals may occur in certain situations.
Otter Tail is a winter peaking utility and because of this unique nature, studies should include
models that evaluate the system under a Winter Peak load condition in addition to other
required study scenarios.
1.1.2.2) Generation
Otter Tail follows the MRO Model Building Subcommittee Manual for determining generation
dispatch patterns within transmission models. However, generation dispatch assumptions
should be altered depending on the type of study being performed. Examples of these
variations are described in later sections. As a baseline, Otter Tail models wind at 20% in Peak
load models and 35% in off peak load models when performing reliability studies for purposes
of compliance with transmission planning standards. Peaking plant units are generally modeled
as offline in the off-peak models and online in the Peak load models. Further details on ratings
of different generation plants owned by Otter Tail can be found in the Otter Tail Facility Ratings
Methodology document.
1.1.2.3) Topology
Otter Tail follows the MRO’s Model Building Subcommittee Manual for determining the
appropriate transmission topology within the models. Otter Tail models all facilities which are
to be in service at the time of the study timeframe. Details on how ratings of Otter Tail facilities
are determined can be found in the Otter Tail Facility Ratings Methodology document.
1.1.3) Special Protection Schemes (SPSs), Dynamic Line Ratings, and Operation
Guides
Special Protection Schemes, Dynamic Line Ratings, and Operation Guides are generally not an
allowed long-term mitigation technique to building adequate transmission facilities. These
techniques may be used on the Otter Tail system only as an interim solution to alleviate
transmission constraints identified in near-term models pending completion of necessary
network upgrades. However, when used as an interim solution for generation interconnection
purposes, only energy resource (ER) status should be granted to an interconnected generator.
The use of Special Protection Schemes (SPSs) or Dynamic Line Ratings on the Otter Tail system
must be applied in compliance with the Otter Tail applicable guidelines. Any such measure on
the Otter Tail system must be approved by Otter Tail, as well as the applicable Regional
Reliability Organization and/or Reliability Coordinator, as necessary.
Otter Tail also uses Operation Guides to reliably operate the transmission system. However,
these operation guides are not to be applied or developed for conditions identified in the
Otter Tail Planning Criteria, Guidelines and Study Procedures
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planning horizon (greater than 1 year into the future). Operation guides on the Otter Tail
system shall only be used in the operation horizon.
1.2) Interconnection Guidelines
The general philosophy for transmission interconnections to, from and between the Otter Tail
transmission system is to provide sufficient transmission interconnection capability between
reliability regions, sub regions, neighboring utilities, as well as between areas within the Otter
Tail system to accommodate energy transfers under determined modeling conditions in a
reliable manner. Such energy transfers could be associated with normal market operations,
regional load diversity, regional transfer conditions, and abnormal operating conditions.
Interconnections to the Otter Tail system should follow the General Transmission Planning
Criteria in section 1.1 as well as the Guidelines for Generation, Tie-Lines, and Substation
Interconnections, which can be found at the following link:
https://www.otpco.com/media/328977/OTPtechGuideCASOT.pdf
New interconnections should be studied using models that represent conservative assumptions
so as to ensure that the system maintains reliability under all possible scenarios. Conservative
assumptions should be included in models as stressing the transmission system, such as
assuming certain load levels and/or regional transfer patterns, such as a Manitoba or North
Dakota import and export.
1.2.1) Generation Interconnection and Outlet Transmission
The general philosophy used in performing transmission studies of the Otter Tail system is to
provide adequate and sufficiently reliable generating plant transmission outlet capability to
ensure that it is not necessary to consider variations in the dispatch of existing generators to
compensate for single-contingency transmission deficiencies.
Studies of generation facilities fall under the requirements outlined in section 1.1, but also
require unique consideration of existing generation and load. For example, to ensure that
transmission outlet capability of existing generators is not compromised as a result of a new
generator interconnection, load levels may need to be reduced in a local area, as well as all
existing generation increased in the same local area (regardless of generation type) so that
adequate transmission outlet is identified for the new generator. Transmission for generator
outlet requirements is considered adequate when facility loadings following valid local single
contingencies do not result in the loading of any circuit in the local area above its emergency
rating when all local generation is dispatched at a maximum level. Likewise, the performance of
the transmission system must also maintain reliable voltage limits.
Otter Tail Planning Criteria, Guidelines and Study Procedures
Page 7
Variations in regional flow patterns and load levels should be considered as well. In areas of the
Otter Tail system, some facilities are more stressed in certain simultaneous or nonsimultaneous regional flow conditions, such as a Manitoba or North Dakota exports. Likewise,
different load levels, coupled with certain flow conditions, can also lead to more conservative
modeling assumptions commonly used in performing studies of the Otter Tail system. Though
these flow patterns and load levels may not occur often, these assumptions do represent
plausible scenarios given historic load levels and firm transmission rights on the existing
transmission system. Using conservative assumptions when performing studies of the Otter Tail
system ensures the reliability of the existing transmission system is not adversely affected.
Future generation interconnections should not adversely affect the stability performance of the
transmission system. Transmission outlet capacity for a new generation interconnection is
considered adequate when the plant remains stable under contingency conditions at a variety
of possible operating conditions. Stability studies should be performed for conditions which
represent the transmission system with the least amount of damping capability, such as a light
load scenario when there are fewer existing generators and load online to help dampen the
oscillations on the system following a disturbance.
The Guidelines for Generation, Tie-Lines, and Substation Interconnections also includes other
criteria for interconnecting generation to the Otter Tail system.
It should be noted that the administration of generation interconnections to the Otter Tail
transmission system are processed by MISO. The full procedures that MISO follows are fully
documented and found on the MISO website at the following address:
https://www.misoenergy.org/Planning/GeneratorInterconnection/Pages/GeneratorInterconne
ction.aspx
1.2.2) Load Interconnection and Power Factor
Load interconnections to an Otter Tail transmission line will be studied to ensure no adverse
reliability impacts are caused as a result of the new load interconnection. Otter Tail will
generally perform studies of the transmission system due to new load interconnections based
on applicable NERC reliability criteria. Otter Tail requires that new load interconnections must
be able to maintain a power factor of 90% or better at the point of interconnection. These
requirements as well as others are outlined in the Guidelines for Generation, Tie-Lines, and
Substation Interconnections.
Similar to unique study assumptions for new generation interconnections, load
interconnections need special consideration as well. Depending on the characteristics of the
new load and the existing system, multiple study models (i.e. winter peak, summer peak) may
Otter Tail Planning Criteria, Guidelines and Study Procedures
Page 8
be needed to ensure the worst case scenario is studied and reliability is maintained with the
new load interconnection.
The design of the new load interconnection to the Otter Tail system will be evaluated on a case
by case basis. Factors that will be considered in the design of a new load interconnection will
include factors such as (1) the number of existing taps along a line, (2) future expansion plans in
the local area, and (3) historical line performance. Section 4.4 in this document outlines the
substation guidelines of Otter Tail.
1.2.3) Operation Studies
Operational studies are required for all interconnections to the Otter Tail System. These
studies look for more localized issues in addition to regional issues identified in the planning
studies.
Dynamic simulations as well as steady state power flow simulations are required. These studies
look at impacts to the system under prior outage conditions to ensure there are no new
constraints being introduced that may not be captured in the planning process. It is the
responsibility of the interconnecting party to make sure these studies are completed and
reports submitted to Otter Tail.
In addition, Otter Tail reserves the right to review and the right to approve or reject the
following:




Scope of the study
Models used for the study
Dynamic simulations and faults
Update models
*Otter Tail will assist in deriving the faults required for dynamic simulations along with update
models and will be reimbursed by the interconnecting party.
The interconnecting party is responsible to ensure all comments are addressed and concerns
are mitigated prior to interconnection. Otter Tail may waive this requirement on a case by case
basis depending on interconnection type, size and location.
Otter Tail Planning Criteria, Guidelines and Study Procedures
Page 9
2) Facility Loading Criteria
Otter Tail publishes continuous (i.e. normal) and emergency ratings for its Facilities
within the study models created by the Midwest Reliability Organization (“MRO”)
and MISO. Facility loadings at or below the applicable rating fields within these
models shall be the basis for determining acceptable facility loadings on the Otter
Tail transmission system.
The threshold for determining significant loading impacts on the Otter Tail
transmission system is defined in the MISO’s Transmission Planning Business
Practices Manual.
The following table is a summary of the continuous and emergency ratings used by Otter Tail
for various pieces of equipment that may comprise a Facility on the Otter Tail transmission
system. These are based on the Otter Tail Facility Ratings Methodology (FRM).
Table 1 – Summary of Otter Tail Facility Ratings
Facility
Continuous
Rating1
Emergency
Rating2
Seasonal
Ratings
Apply4
Transmission Line &
Substation Conductors3
100%
110%
Yes
Protective Relay Devices
100%
100%
No
Transformers
100%
125%
No
Series and Shunt Devices
100%
110%
No
Terminal Equipment
100%
110%
No
1
Continuous Ratings are based on the manufacturer’s specifications.
Emergency Ratings are based on a percentage of the Continuous Rating.
3
Continuous and Emergency Ratings for Transmission Lines are based on a variety of factors,
including conductor type and required NESC clearances and may not always be as shown in the
table.
4
Seasonal Ratings may exist for certain pieces of equipment that comprise a facility. These
seasonal ratings shall be appropriately included in the applicable study models.
2
Otter Tail has developed guidelines that allow for the conditional use of dynamic ratings to
some of its transmission lines. These dynamic ratings are derived using real time ambient air
temperature and/or wind speed. Dynamic ratings are used for increasing the short-term
Otter Tail Planning Criteria, Guidelines and Study Procedures
Page 10
emergency ratings for transmission lines in the operating horizon to allow for safe operation of
the transmission lines when weather conditions allow a higher transmission line rating. These
dynamic transmission line ratings are not allowed to exceed the short-term emergency rating of
the most limiting transmission element.
Dynamic ratings are not included in study models, but rather applied on a real-time basis.
Applying dynamic transmission line ratings may result in different emergency ratings than those
included in the study models created by the Midwest Reliability Organization and MISO.
Otter Tail maintains separate documents relating to the application and use of dynamic line
ratings and special protection schemes. Additionally, Otter Tail publishes Guidelines for
Generation, Tie-Lines, and Substation Interconnections which can be found at the following link
- https://www.otpco.com/media/328977/OTPtechGuideCASOT.pdf.
3) Voltage Criteria
The voltage criteria for transmission studies of the Otter Tail system are defined in the following
section.
The threshold for determining a significant impact to bus voltages on the Otter Tail
transmission system is defined by MISO within the Transmission Planning Business Practice
Manual.
3.1) Pre-contingent Voltage Criteria
All voltages in the pre-contingent (i.e. system intact) cases of a study shall meet the following
criteria for the Otter Tail transmission system after all known and documented system
adjustments have been implemented.
Table 2 – Pre-contingent Voltage Criteria for Otter Tail Substations (Buses)
Rated
Voltage
Maximum
per unit
Minimum
per unit
345 kV
1.05
0.97
230 kV
1.05
0.97
115 kV
1.07
0.97
Otter Tail Planning Criteria, Guidelines and Study Procedures
Page 11
3.2) Transient Period Voltage Criteria
During dynamic simulations of transient events on the transmission system, transient voltages
on the Otter Tail transmission system (with a few exceptions noted below) shall meet the
following criteria during transient events immediately following the clearing of a system
disturbance.
Table 3 – Transient Voltage Criteria for Otter Tail Substations (Buses)
Rated
Voltage
Maximum
per unit
Minimum
per unit
345 kV
1.20
0.70
230 kV
1.20
0.70
115 kV
1.20
0.70
Given the nature of the Otter Tail system, there can be exceptions to the general transient
voltage criteria stated above. One exception is noted below:

The transient voltage at the Wahpeton 115 kV bus shall not decrease lower than
0.80 p.u. or increase higher than 1.18 p.u. following any system disturbances.
3.2.1) Transient Period Damping Criteria
The following criteria apply to generator angle oscillations when performing transient stability
studies.
The generator angles shall be positively damped and calculated from the “Successive Positive
Peak Ratio” (SPPR) of the peak to peak amplitude of the rotor oscillation. The SPPR is utilized to
calculate the damping factor with the following formulas and constraints:
o SPPR = Successive swing amplitude / Previous swing amplitude
 Fault disturbance maximum = 0.95
 Line trip maximum = 0.90
o Damping factor percentage = (1-SPPR)*100
 Fault disturbance minimum = 5%
 Line trip minimum = 10%
The damping calculation can be performed using the PSS/E use model “DAMPCHK” which
utilizes SPPR. “DAMPCK” cases may fail due to a constant rate of change in rotor angles caused
by a significant generation loss leading to an appreciable frequency variation.
Otter Tail Planning Criteria, Guidelines and Study Procedures
Page 12
A Prony analysis can be utilized for calculating damping ratios as an equivalent to the damping
factor. The damping ratio criteria are as follows:


Fault disturbance minimum = 0.0081633
Line trip minimum = 0.016766
3.2.2) Transient Switching Criteria (Voltage Flicker)
Voltage fluctuations may be noticeable as visual lighting variations (flicker) and can damage or
disrupt the operation of electronic equipment. Otter Tail’s single flicker limits are based on
engineering judgment and IEEE standard 141-1993. All Otter Tail buses should maintain the
following criteria:

Relative steady state voltage change is limited to 3 percent of the nominal
voltage for system intact conditions.
 Relative steady state voltage change is limited to 5 percent of the nominal
voltage for contingency conditions.
* The relative steady state voltage change is the difference in voltage before and after a
switching event, such as a capacitor bank switching or large motor starting.
When running simulations for determining the voltage change described above, Otter Tail
requires any nearby generation that could contribute fault current to be offline. Further, when
determining the contingency voltage change, the element that contributes the most fault
current should be considered offline.
Any element that will produce frequent flicker may be analyzed to more stringent criteria than
the single flicker criteria listed above. Otter Tail will reference IEEE standard 141-1993 for
guidance in special situations.
Otter Tail Planning Criteria, Guidelines and Study Procedures
Page 13
3.3) Post-Contingent Voltage Criteria
All voltages in the post-contingent cases of a study shall meet the following criteria for
the Otter Tail transmission system. These criteria shall be applicable to post-contingent
conditions prior to any operator intervention, special protection schemes, or any other
automatic scheme.
Table 4 – Post-contingent Voltage Criteria for Otter Tail Substations (Buses)
Rated
Voltage
Maximum
per unit
Minimum
per unit
345 kV
1.10
0.92
230 kV
1.10
0.92
115 kV
1.10
0.92
4) Other Planning Guidelines
4.1) Radial MW-Mile
Otter Tail will use the following “radial MW-Mile” guideline to assist in the decision on when it
is appropriate to consider looping radial facilities. Criteria for such examination are when the
summation of the peak flows across each radial line segment times the mileage of the
respective segment is greater than 100 MW-Mile. If the line exceeds the 100 MW-Mile value,
further investigation of other factors will be examined before a looped system is needed. (e.g.
reliability of loads, cost, system effects, future needs, distribution ties)
4.2) Load Break Switches
Otter Tail maintains extensive 41.6 kV and 69 kV systems that contain many non-load break
switches. As future projects are created on these systems and switches are replaced or
installed, load break switches shall be installed at strategic locations with input and guidance
provided from internal Otter Tail sources. Some factors that will be considered are personnel
location, operational needs/reliability, safety, and cost.
4.3) Motor Operator Switches
Future motor operator placements on Otter Tail’s system will use the guideline to install motor
operated switches at any place where three sources connect. Further, it is also desirable to
install motor operators at locations where there is a normally open point along the 41.6 kV or
69 kV systems. Like load break switch placement, other factors for motor operator placement
will be considered such as personnel location, operational needs/reliability, safety, and cost.
Otter Tail Planning Criteria, Guidelines and Study Procedures
Page 14
4.4) Ring Bus and Breaker and a Half Treatment
For future connections and substation development above 100 kV, Otter Tail will use the
following guidelines shown in Table A. This guideline is consistent with past planning philosophy
that provides the highest reliability configurations. In future substations, Otter Tail will be the
sole owner for all connection points for NERC CIP Standards. Further, a facility connected to a
ring bus or breaker and a half bus will be rated based on the lowest adjacent single breaker
amperage. In Figure A below, the facility would be rated to 600 amps even though one breaker
is capable of 1200 amps. This Facility could be re-rated during real time operations if breaker 1
was opened.
Type
Connections
Ownership
Breaker and a Half
5+
Solely Otter Tail
Ring Bus
3-6
Solely Otter Tail
Tap/Straight Bus
2-3
Solely Otter Tail
Table A – Substation Guideline




1 – 600 amps
2 – 1200 amps
Line – 1000 amps
Overall Rating – 600 amps
2
Line
1
Figure A – Ring Bus Example
Otter Tail Planning Criteria, Guidelines and Study Procedures
Page 15