Balancing Act

Power load balance is essential to the health of a grid. “Power Load” is the amount of electricity demand by customers at any given time. Demand fluctuates constantly, requiring a delicate balance between equipment in the field and software used to ensure energy is distributed properly, even during peak times.

PUD line worker removes a pole cutout to de-energize a down line.
PUD line crew are now working to replace single-phase power along 49th Street (shown here during a January cold spell outage), with 3-Phase power. Replacement extending to customers along Cook Ave is planned for completion by mid-summer.

Peak demand highlights areas where usage pushes equipment up to or beyond working capacity, guiding PUD staff to regions in need of additional infrastructure. Often, these areas go unseen until Mother Nature comes calling as we experienced in Port Townsend during near-record cold. High demand caused the single-phase line feeding Cook Ave. to overload, knocking out power multiple times.

To address this demand, PUD electrical engineers turn to upgrading infrastructure by extending three-phase power.

Three-phase power balances the energy load for an area from a single line to 3 lines. Each line has its own phase making for a smoother flow of power. Line crews segment areas by estimated load, placing homes onto each phase as evenly as possible. Balancing of the power load goes all the way back to the substation level to feeders that manage the power for the region. 

Three-phase power is more efficient, as each line provides distribution voltage (typically 7,200V), but with reduced amps. Excessive amps caused by high demand can cause wire to heat up and result in power outages.

Line crew in two bucket trucks work to mount hardware to a new pole installed in Port Townsend.
Line crew complete a lateral tap to a residence off of 49th Street in Port Townsend as they replace poles and upgrade the system from single-phase to 3-phase power for improved load balancing during peak demand.

Extension of 3-phase power is underway from the Fairgrounds in PT down 49th St., with replacement of 15 poles during the first section of work. A second section extending to Cook Ave. is planned for summer. 

The big question: Why not have 3-phase everywhere? Not every location needs 3-phase power. For most regions, power usage and equipment are sized for the peak load. Three-phase is also expensive, with the 49th St. and Cook Ave. line extension expected to cost an estimated $100k.

The PUD continually works to identify areas where power load issues exist and work to extend capacity and balance load for better service reliability. 



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