Technical considerations

What drives the need for transmission system expansion?


We evaluate the impact of transmission congestion on wholesale power prices and study projects to determine economic savings to offset most or all of the congestion and loss costs. An example is evaluating increased access to markets outside our footprint.

Plans and actions: Two  projects are planned, four are proposed, and another two provisional projects are being studied.

Renewables/public policy

All of the states in which we operate and most other Midwestern states have adopted renewable portfolio standards. At the national level, discussions are underway to expand the use of renewableenergy and streamline federal permitting processes for transmission expansion.

Plans and actions: We are participating in several regional transmission studies to identify the transmission needed to integrate renewable generation, including wind, much of which could be located in areas remote from large load centers.

Generator retirements

Similar to new generator requests, when a large generator is retired due to age or other reasons, we will determine how system requirements will be affected. Recently issued EPA rules will impact retirements across the U.S. in the next 5 to 10 years.

Plans and actions: The closure of the Kewaunee Power Station earlier this year resulted in a major change to our proposed Barnhart-Branch River Project. Generation uncertainties are growing due to proposed Environmental Protection Agency regulations. We are working closely with generation owners and MISO to anticipate reliability impacts to our transmission system.

Distribution interconnections

The transmission system is dynamic; changes in the marketplace, as well as changes in generation – new plants coming on line, older units being retired – drive the need for additional transmissionto‑distribution interconnections.

Plans and actions: 143  are planned in the next 10 years. More than 333  new or improved T-D interconnections have been made since 2001.

New generation

When a new generating facility is proposed, we conduct a system impact study and, if requested, a facilities study. If the existing transmission system is inadequate to ensure generator stability or reliable transmission service, we will determine what system expansion will be needed.

Plans and actions: Eight  generators are active in our generation queue, and many reflect the growing development of wind energy; 24 generators added since 2001 required construction of transmission facilities.

Asset renewal

Keeping transmission lines, substations and related equipment in good operating condition extends the life of the facilities, improves system performance and safety and minimizes the potential for outages. Part of the $3 to 3.6 billion investment ATC will make over the next 10 years is dedicated to asset renewal. Major projects at substations include replacing circuit breakers, protective relays, lightning protection and transformers. Major work on transmission lines involves rebuilding or upgrading aging power lines, including the replacement of structures, conductors, insulators and other equipment.

Plans and actions: More than 110  projects to address asset renewal needs are planned in the next 10 years.

Transmission service requests

Virtually all entities that own power plants or provide electric service to customers, or both, seek to buy and sell electricity with other entities. We evaluate those requests to determine whether the transmission system will operate reliably if the request is granted. If the request can’t immediately be granted, we will identify transmission system reinforcements needed to grant the request.

Plans and actions: More than 35  projects to meet transmission service requests have been completed since 2001. 

Load growth

Demand for electricity during peak usage periods is projected to grow at a rate of approximately 0.9 percent across our service territory from 2012 through 2021.

Plans and actions: Load growth has slowed in recent years and we have adjusted our project planning accordingly. About 110 projects are planned, at least in part, due to load growth.

Regulatory environment

Physical and cyber security and reliability standards continue to increase, which affect planning criteria.

Plans and actions: We are participating in the NERC standards process to help anticipate the future impacts of these changes on our planning processes and systems.

Integration of new technologies

Demand-side management, variable generation, distributed resources and smart grid technologies all require changes in how the grid is planned and operated to maintain reliability.

Plans and actions: The type of flow-control device between Upper and Lower Michigan will be one of few utilized in the U.S.