The Honolulu rail authority has agreed to install special equipment to prevent any sudden swings in the electric voltage as the electric trains depart from the stations in neighborhoods around the rail line, according to a new report from a federal consultant.

The Honolulu Authority for Rapid Transportation will install seven units known as “STATCOMs” along the western end of the rail line by 2025, a step that moves the city closer to resolving an issue that was raised by the Hawaiian Electric Co. years ago.

The rail system’s four-car trains will need brief bursts of electrical power as they leave the 21 stations along the line, and HECO officials were concerned because the utility’s circuits are not designed for that kind of abrupt change in load.

Pedestrians walk along Dillingham Boulevard with rail guideway supports being built towards metropolitan Honolulu.
Pedestrians walk along Dillingham Boulevard with the rail guideway supports in the background. The rail authority will install new equipment to prevent voltage swings as the electric trains leave the stations. Cory Lum/Civil Beat/2021

If the trains use too much power as they accelerate, HECO was worried they might affect other customers served by the same lines, or possibly even damage electrical equipment in homes or businesses.

HART had hoped to prevent severe voltage swings by staggering train departures to ensure the system did not consume too much energy all at once.

In fact, HART’s train operations’ testing to this point has been limited “because of potential power quality issues affecting other customers on the same circuit,” according to Jim Kelly, HECO’s vice president for government, community relations and corporate communications.

Testing by HART and HECO found that power quality issues worsen when HART tries to ramp up to full operations, Kelly said in an emailed response to questions.

The two sides apparently have reached an agreement on that issue that involves installing equipment called STATCOMs, formally known as static synchronous compensators. Those are units used to provide voltage stability on electricity transmission networks.

Rail officials including HART Director of Government Relations and Public Involvement Joey Manahan and Interim Executive Director Lori Kahikina did not reply Tuesday to emailed questions about the issue, including how much the additional equipment will cost.

It is also unclear whether the cost of the STATCOM units was included in the most recent rail cost estimates provided to the Honolulu City Council last month.

HART estimated in March the budget shortfall for the rail project was about $3.5 billion, but Kahikina told the Honolulu City Council last month the shortfall is actually about $2 billion. HART now expects the total cost of the project will be nearly $11.4 billion.

Kevin Whitton, vice president of the public relations firm Pang Communications, said Tuesday in an email that his firm will reply on Wednesday to questions posed to HART executives about the STATCOM units.

Whatever the final cost turns out to be, HART will have to pay it.

Kelly said HECO customers won’t share the cost of the equipment “because it’s HART’s responsibility – their operations are having an impact on the electrical grid. That requirement is in line with that of any large industrial customer whose operations affect the system.”

The report by consultant Hill International Inc. said HART initially will install one unit at a location of HECO’s choosing to evaluate how well the STATCOMs function. Hill International is an outside consultant hired by the Federal Transit Administration to monitor the city rail project.

HART and HECO are working on a study to properly size the equipment, and the seven STATCOMs will be placed on the seven-mile segment of rail line that extends from East Kapolei to Aloha Stadium, according to the report.

The trains will draw most of their electricity from existing HECO circuits that feed 13 traction stations along the rail line.

The 20-mile system will require nearly 15 megawatts of power once it is fully operational, and the utility expects the train line will be among HECO’s top 10 power consumers.

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