Dynamic Line Ratings in the West: Recommendations for Adoption

WIEB Stanford Shultz Energy Fellowship ProjectBella Meyn and George Rosa

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2021 WIEB Fellows

Bella Meyn George Rosa

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Recommendations: Policy Options to

Accelerate DLR Integration

Presentation Flow:

Introduction: The Current Status of

Line Ratings

Dynamic Line Rating (DLR):

A Potential Solution to Existing Issues

Roadblocks: Barriers to Widespread

DLR Adoption

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IntroductionCurrent Transmission Line

Rating Practices

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Introduction: Fundamentals of Line Ratings

I. Transmission line ampacityII. Facility ratings & system operating

limits

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I. Transmission Line Ampacity

Cr. Electrical Transient Analyzer Program, Dupin and Michiorri (2017) 6

a. Impacts of changing conditions

7S. K. Aivaliotis, “Dynamic Line Ratings for Optimal and Reliable Power Flow [Slides],” FERC Technical Conference, 2010.

Compared to a static rating of 787

Amps

● Transmission Owners establish facility ratings○ Must follow NERC standards

● Owners provide facility ratings to Transmission Operator, ISO/RTO, and Reliability Coordinator.

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II. Facility ratings

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SOLs are based on normal and emergency facility ratings, voltage limits, transient and voltage stability limits, any of which can be the most restrictive limit.

● Reliability coordinators ensure the reliable operation of the system within all defined SOLs.

● The majority of SOLs are facility ratings, which comprises transmission line ratings.

● Facility ratings/SOLs are used for○ Reliability studies○ Day-ahead and real-time operations

II. System operating limits

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P66, the California-Oregon Intertie, was operated at ≥75% of its rated capacity for >30% of the time in 2016.

Introduction: Issues with Line Ratings

I. Differing line ratings

II. Non-Dynamic line ratings

III. Shortcomings of static ratings

IV. Transmission expansion challenges

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SEASONALBased on seasonal

averages of ambient conditions

DYNAMICBased on real-time

measures of transmission capacity factors

STATICBased on a conservative

point-estimate of ambient conditions

AMBIENTBased on forecasted air

temperatures and updated frequently

I. Differing Line Ratings

Least Dynamic Most Dynamic

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II. Non-Dynamic Line Ratings

Based on a conservative point-estimate of

ambient conditions.

STATIC SEASONALBased on seasonal

averages of ambient conditions.

AMBIENTBased on near-term or

real-time forecasts of air temperature.

a. Static (SLR)● Historically the norm in

calculating line ratings

● Assumes constant temperature,

wind speed & direction, and

solar

● Overcoming technological

limitations by minimizing

reliability concerns

● Cannot take advantage of

favorable conditions

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b. Seasonally-Adjusted (SAR)

● Typical transmission line rating

methodology today

● Reflects seasonal averages for

ambient conditions

● Better reflects seasonal variation in

electricity demand

● FERC NOPR recently mandated SARs

for longer-term transmission service

requests

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c. Ambient-Adjusted (AAR)

● Incorporates near-term and sometimes

rel-time air temperature forecasts

○ Updated more frequently (e.g., daily,

hourly, or every 15 minutes).

● Some use forecasts from online monitoring

services, then calculate rating

● Others use step functions, such as one

rating per 5 degree block

● Potential for automation

● NOPR mandated AAR for near-term

transmission service requests16

c.1. Precedent AAR use

ISO-NE, 2018 “Bomb Cyclone”

● “the scheduling limit on the NY ties was increased from 1,400 to 1,600 MW. The increased limit was made possible by the cold conditions which helped to improve thermal transfer capability.”

17V. Chadalavada, “Cold weather operations [Slides],” ISO New England, 2018

III. Shortcomings of static ratings

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Reliability

Flexibility

Situational Awareness

Congestion

a. Inflexibility can lead to higher consumer rates

Scenario: Transmission operator gets more

transmission requests than the line can handle,

according to its line rating.

Action: Operator dispatches higher-cost

generation to meet increased demand.

Result: Higher-cost generation used to relieve

congestion is reflected in higher electricity rates;

no direct effect to utility.

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$683.5MIncurred by CA ratepayers for congestion-related costs from 2009-2017.

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IV. Transmission expansion

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—Energy Construction Consultant

“In the West, you’re limited a lot by where you’re building as

opposed to what.”

The Problem

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1. Misrepresentation of the grid can result in reliability issues.

2. Congestion charges accrue in consumer rates.

3. Due to system inefficiencies, we are not maximizing the existing grid.

4. Building new transmission may not be feasible.

5. These problems are only getting worse.

Dynamic Line Rating (DLR)A Potential Solution to

Existing Issues

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DLR Basics● Different flavors of “dynamic line rating”

● How it works

○ Sensors installed on transmission lines

■ Often live installation

■ Targets “critical spans”

● Those likely to reach thermal or clearance limits

○ Provides real-time data on status of lines, accounting for

■ Wind speed

■ Ambient temperature

■ Conductor temperature

■ Line tension

● What it can do

○ Maximize load without compromising safety25

● Real-time data inputs > fed into DLR system > dynamic ratings sent to Energy

Management System used by Transmission Operators

● Types of new ratings possible

○ Real-time

■ Emergency ratings

○ Forecasts

■ Same day, hours ahead

■ Day-ahead

DLR Data Flows

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Lower● Reduce load on line● Increase reliability

Higher● Safely increase load● Minimize congestion● Reduce curtailment (involuntary

reduction in generation)

Data applications

If, compared to the static rating, the dynamic rating is:

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DLR StudiesEntities that have studied

implementation of DLR in their operations.

1. REE, Spain, 1998

2. Elia, Belgium, 2008 and 2019

3. Northern Ireland Electricity, 2009

4. Scottish & Southern Electricity Networks, 2009

5. RTE, France, 2011 and 2017

6. Kepco, South Korea, 2013

7. TERNA, Italy, 2013

8. NYPA, 2013

9. Oncor, Texas, 2013

10. Idaho Power, 2013-2018

11. AEP, PJM, 2017

12. AltaLink, Canada, 2015

13. World Bank, Vietnam, 2016

14. TWENTIES Project, 2017

15. Ampacimon, Germany, 2019

16. PPL Electric Utilities, 2021

PPL 30% avg. ratings gain in pilot, now integrating into ops

Idaho Power Company DLR value above static rating 95% of the time on short transmission lines

Oncor, Texas 30-70% over SLR, 6-14% over AAR

New York Power Administration 30-44% over SLR

AltaLink, Canada 22% avg. increase over SLR 76% of the time

Kepco, South Korea 35% over current values

Northern Ireland Electricity 10-20% in most remote locations, 26% in some cases

Elia, Belgium and RTE, France 30% over current values

Ampacimon, Germany 25% gain 50% of the time, 15% gain 90% of the time.

Estanqueiro et al. (2018), Germany 20-40% gain, 145-156% during high winds 31

Capacity Gains

Cost savings

Oncor, Texas, 2013

● 5% additional capacity would relieve congestion by 60% on target lines

● 10% would almost eliminate congestion

● Average daily congestion cost of $250,000 -> ~$150,000/day

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AltaLink, Canada, 2015

● DLR avoided need for system upgrades, saving $2 million.

U.S. Department of Energy, “Dynamic line rating Smart Grid Demonstration Program final report,” Oncor Electric Delivery Company, 2013.International Renewable Energy Agency, “Dynamic Line Rating: Innovation Landscape Brief,” ISBN 978–92-9260-182-9, 2020.Marmillo et al., “Simulating the Economic Impact of a Dynamic Line Rating Project in a Regional Transmission Operator (RTO) Environment”

Ampacimon, Germany, 2019

● 1,200 MWh avoided redispatch, would save EUR 27,000 ~ $32,000/day

Payback period

AEP transmission zone of PJM, 2017 DLR Study

● Three sections of 22-mile Cook-Olive 345 kV transmission line● Rapid simulated installation● DLR installation + implementation costs of $500K● Net congestion savings over 1Y: $4M+

○ Over 1mo: $333.3K

● Payback period: < 2 months.● Comparison: economic upgrade would have cost $22-$176 million

○ Based on one large utility cost-per-mile estimate

● Yearly ongoing O&M costs: estimated 10-25% of initial investment● Note: line length important factor for determining cost

33Marmillo et al., “Simulating the Economic Impact of a Dynamic Line Rating Project in a Regional Transmission Operator (RTO) Environment”

J. McCall and T. Goodwin, "Dynamic Line Rating as a Means to Enhance Transmission Grid Resilience," in CIGRE U.S. National Committee 2015 Grid of the Future Symposium, 2015.

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Study Operational Efficiency

Situational Awareness

Reduced Curtailment Reliability Load

Growth

TERNA, Italy ✓ ✓

Idaho Power ✓ ✓ ✓

Northern Ireland ✓ ✓

Vietnam ✓ ✓

Oncor (Texas) ✓ ✓ ✓

NYPA ✓ ✓

Other benefits individually highlighted

U.S. Department of Energy, “Dynamic line rating Smart Grid Demonstration Program final report,” Oncor Electric Delivery Company, 2013.International Renewable Energy Agency, “Dynamic Line Rating: Innovation Landscape Brief,” ISBN 978–92-9260-182-9, 2020.Marmillo et al., “Simulating the Economic Impact of a Dynamic Line Rating Project in a Regional Transmission Operator (RTO) Environment”

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—UTILITY COMPLIANCE CONSULTANT

“In the Texas February event, it was critical that every kilowatt available got onto the grid …

Generation owners exceed[ed] maximums to put as much energy on grid as possible. In a world of

extreme weather events, the ability to have flexibility in system operations is important.”

“NORE”: Network Optimization before Reinforcement and

Expansion (Georgios Papaefthymiou, Elia)

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Key takeaway: “NORE principle”

● Belgium

● France

● Italy

● Germany

● Uruguay

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RoadblocksBarriers to Widespread DLR

Adoption

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Expert interviews

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SAMPLE N=21

EXPERTS Utilities, academia/research, FERC/NERC, WECC, RTOs/ISOs, DLR developers, industry consultants

METHOD Anonymous, guiding questions and unstructured discussion

STAGE 1 Review and validate findings about barriers to DLR adoption identified in literature

STAGE 2 Exploratory stage, dive deeper into sample-identified barriers and potential solutions

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● 5 Major Categories of Roadblocks

○ Information

○ Economic

○ Industry

○ Operational

○ Transmission Planning

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Interview findings

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Roadblock Type Identified RoadblockHigh

ImportanceModerate

Importance

Information DLR technology is not widely known, and can refer to different things. ✓

Information Issues with older DLR systems have left a lingering bad reputation. ✓

Economic Utilities lack the motivation or incentive to invest in DLRs. ✓

Industry The structure of the West makes wide agreement on DLR implementation difficult. ✓

Operational Energy management systems and data protocols need adaptation to support DLR. ✓

Transmission Planning DLRs would add complexity to transmission planning due to inflexibility in study standards. ✓

Sample-identified roadblocks and our estimate of relative weights for each

Information roadblocks

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“Utilities don’t know the benefits, consumers don’t know the benefits.”

- Executive at a DLR Developer

Economic roadblocks

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“If utilities don’t have a compelling reason to move to DLR, they won’t. Putting in DLR would not give much return on

investment … [It] has to [be] compelled, otherwise utilities will only do it when it’s most financially beneficial for them.”

- Power System Services Consultant

Industry roadblocks

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● Individual transmission owners can themselves be a barrier to other entities installing DLR.

“There are just so many avenues for utilities to push back...but if you can get everyone in a room together, a few weeks is [how long

it takes to install].”

- Energy Construction Consultant

Transmission planning roadblocks

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● Without the ability to consider a range of ratings, planners may resort to using the most conservative rating available.

“You can only operate within studied conditions. Without looking at a range of line ratings, it would be

chaos if DLR were implemented.”

- Transmission Planning Consultant

● Industry and consumers: current DLR technology benefits unknown

● Agreement on DLR implementation difficult & individual transmission owners

can impede

● Operational adaptation needed

● Transmission planning: worry of increased complexity

Synthesis of biggest roadblocks

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RecommendationsPolicy Options to Accelerate

DLR Integration

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—System Planning Engineer

“We certainly look at DLR as a tool in our toolbox. Given a contingency, we may

want to pull that tool out and use it.”

Our suite of recommendations provides suggestions to the following

● Reliability Coordinators● Public Utilities Commissions● FERC● WECC● Utility Transmission Planners.

Ultimately, progress hinges on acknowledging Dynamic Line Rating as a Best Practice.

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Overview

Determine applicability of DLR for facilities in the RC area● Work with TOPs and BAs within respective RC footprint to

a. develop criteria for identifying facilities that would see a reliability benefit from DLR deployment, and

b. apply criteria to determine subset of facilities for which the RC will request dynamic line ratings to set up dynamic SOLs.

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02Enable the use of more dynamic ratings

Reliability Coordinators (RCs)

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● Establish the systems and data collection processes to enable use of dynamic line ratings, such as the ability to update ratings at least hourly.

● Affirm that consideration of DLRs is a part of utility and RC best practices as they are an important tool for supporting the reliable and efficient operation of the Western Interconnection.

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Public Utility Commissions (PUCs)

03Affirm consideration of DLR as a best practice

04Establish collaborative forum for metrics and reporting● Develop metrics and public reporting process with regulated utilities,

RCs and other stakeholders to advance implementation of DLR.

● Direct NERC to review standards to ensure language allows for dynamic ratings in transmission planning studies.

● Provide flexibility for Transmission Planners to determine the appropriate range of dynamic facility ratings to be used in transmission planning studies.

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05Reevaluate planning study standards

06Require RCs to enable DLR utilization● In areas not under the jurisdiction of an RTO/ISO, require RCs to

establish the systems and procedures necessary for Transmission Operators to electronically update line ratings at least hourly.

FERC & NERC

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07Create Western Interconnection DLR Roadmap

● Using stakeholder involvement, assess impact of DLR implementation across long-term planning, operations planning, and real-time operation horizons.

● Create a Western Interconnection roadmap/blueprint to DLR implementation that transmission owners & operators can use as a guide and reference.

WECC

Utility Transmission Planners

08 Assess DLR as a potential solution to SOL exceedances● Evaluate using DLR as a potential solution for SOL exceedances

identified in transmission planning studies.

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Recommendation Entity Targeted Suggested Next Step

#1 – Determine applicability of DLR for facilities in the RC area.

Western RCsBegin exploring possible criteria for identification of facilities alongside TOPs.

#2 – Establishing the systems and procedures necessary to enable the use of DLRs

Western RCsResearch what these systems and procedures would look like, using guidance from FERC.

#3 – Affirm that consideration of DLR is a part of RC and utility best practices

PUCsRelease communications or statements affirming the benefits of DLR technology.

#4 – Establish collaborative forum for metrics and reporting

PUCs Identify points of contact at utilities in West to participate in forum.

Recommendation Entity Targeted Suggested Next Step

#5 – Reevaluate planning study standards for rating methodology flexibility

FERC & NERCMeet with transmission planners and collect their feedback on constraints from current standards.

#6 –Require RCs to enable DLR utilization FERCEvaluate expanding the recommendation in the NOPR to include RCs for areas not under an RTO/ISO.

#7 – Identify DLR barriers and develop Western Interconnection roadmap for DLR implementation.

WECC

Create a brief on impacts of DLR technology for different time horizons. Identify what needs to be done before DLR transition.

#8 – Assess DLR as a potential solution to SOL exceedances

TPsWhen identifying SOL exceedances in studies, investigate whether DLR could be a solution.

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Concluding note

1. With the effects of climate change present, it is more important than ever to accurately reflect the status of the transmission system.

2. DLRs are a relatively inexpensive & successful tool that allows Transmission Operators to a. Maximize the existing grid without sacrificing reliability.b. Capture real-time grid conditionsc. Respond quickly to fluctuations

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—Federal Regulatory Commission Staff Member

“Renewable energy is coming either way and DLR has the potential to help

integrate that power.”

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Thank you.