An independent third-party audit of Consumers Energy Company and DTE Electric Company’s distribution systems found that both performed worse than average among utilities in the average time it takes to restore service.
The audit results come nearly two years after the Public Service Commission ordered the review. The review stemmed from concerns over what it had considered a lack of progress in reducing power outages after repeated major power outages in recent years following severe storms.
Conducted by Lebanon, Pennsylvania-based The Liberty Consulting Group, the group reviewed the infrastructure, programs and processes of the two utilities. The firm spent 50 days in the field conducting site reviews while also holding about 150 meetings and holding 50 interviews at each company with executives, managers and employees, a release from PSC said.
Results of the audits were outlined in a Part 1 and Part 2 for DTE and a Part 1 and Part 2 for Consumers filed with the PSC’s e-docket system.
Auditors found that for DTE Electric’s 2022 and 2023 Customer Average Interruption Duration Index metrics which measure the average time required to restore services the utility was in the fourth quartile when both including and excluding major event days. This was worse than average among utilities.
Major event days are when the distribution system experiences significant effects such as from extreme weather.
During 2022 and 2023, DTE Electric’s System Average Interruption Duration Index metrics were in the fourth quartile when including major event days and in the third quartile when excluding major event days. This metric measures the total number of minutes of interruption the average customer experiences.
For Consumers, the results in this area were similar. The utility’s 2022 and 2023 CAIDI metrics including and excluding major event days were also in the fourth quartile and worse than average among utilities. The utility’s SAIDI metrics had them in the fourth quartile when including major event days and in the third quartile when excluding them.
“This audit is the first of its kind in Michigan, exploring the equipment and operations of the two utilities that provide electricity to more than 80 percent of Michigan electric customers,” PSC Chair Dan Scripps said in a statement. “The audit underscores that now is the time for both companies to focus more on strategic investments to prevent outages rather than reacting to them.”
In its audits, the firm compared Consumers and DTE Electric’s performance and infrastructure to similar sized investor-owned utilities in Illinois, Commonwealth Edison and Ameren Illinois as well as the Lansing Board of Water and Light.
The group will present its findings at the commission’s Thursday meeting.
Consumers spokesperson Katie Carey in a statement said the audit has been a constructive process and they appreciate the expertise Liberty brought to bear in conducting its work. She said the company was proactive in providing data for the audit.
“Michiganders are facing more severe and frequent storms, which is why we announced our Reliability Roadmap in 2023, a blueprint for fewer and shorter outages including no customer going more than 24 hours without power,” Carey said. “Our investments are focused on the customers we serve by adding technology, burying power lines and clearing trees.”
DTE Electric President and CEO Matt Paul in a statement said the company remains focused on its goal of reducing power outages by 30 percent and lowering outage duration by half by 2029.
“We are always looking for ways to improve our processes and programs and thank the audit team for recognizing our progress, as well as providing recommendations on improvements we can make to better serve our customers,” Paul said. “We are currently reviewing the full report and will provide a formal response through the regulatory process.”
Auditors found that the number of DTE Electric customers experiencing four or more interruptions per year and those who have experienced more than eight hours of interruptions were higher than usually acceptable for utilities. More than 13 percent of DTE Electric customers experienced four or more interruptions during 2023 while nearly 45 percent experienced interruptions of eight hours or longer.
During 2023, the audit shows, more than 10 percent of Consumers customers experienced four or more interruptions and more than 25 percent of customers experienced interruptions of eight hours or longer.
The audits also detailed information about infrastructure.
For DTE Electric, about 45 percent of its customers are served by an underground 4.8 kilovolt system, the audit said. This, auditors said, requires more time to locate and fix problems compared to more modern 8.3 kilovolt and 13.2 kilovolt systems. Older systems also come with more risk to workers and the public from electric shock, auditors stated.
About 40 percent of its 4.8 kilovolt substation transformers were installed between 1924 and 1960 while some of its 13.2 kilovolt transformers are from the 1960s. These are older than comparable utilities’ transformers, it was stated.
It was found that about 40 percent of DTE Electric’s circuit breakers and reclosers were installed between 1930 and 1960 and that its legacy oil circuit breakers require more maintenance and achieve lesser performance than modern gas circuit breakers.
More than half of the utility’s overhead primary lateral lines are located in back lots. These are more costly to maintain the circuits and to trim trees due to difficulties in getting equipment to the locations, auditors said.
DTE Electric’s goal is to trim trees near its lines every five years, with the effective cycle currently being five to seven years.
In looking at Consumers’ infrastructure, it was found it has many different low-distribution voltages due to various mergers with legacy utilities. This situation requires Consumers to use isolating transformers to connect circuits with different voltages.
It was added that this variety of non-standard substation and circuit assets require Consumers to maintain mobile substations and additional inventory between what is needed for standard voltage substations and circuits.
About 62 percent of Consumers’ low-voltage distribution poles are classified as being of small diameter classes that are more likely to be damaged during severe storms.
Consumers’ goal for tree trimming is a cycle of five to nine years, depending on circuit voltages, for an average effective cycle of seven years. In practice, auditors found the current average effective cycle for the utility to be about 10 years due to a backlog of tree trimming.
“The results from this audit will inform our next steps and strategies to make the electric grid more resilient and reliable,” PSC Commissioner Katherine Peretick said in a statement. “It provides unprecedented transparency into the utilities’ infrastructure and operations and allows us to make better decisions to improve service and affordability for Michigan customers.”
PSC Commissioner Alessandra Carreon agreed in a statement.
“It will take time for both utilities to make the necessary investments to improve reliability,” Carreon said. “That data from this audit will help shape strategies to prioritize the deployment of the investment needed to reduce outages from severe weather, restore power faster when it goes out, and significantly lower the risk of the public coming in contact with downed power lines.”
–By Nick Smith
