Data centers are changing the seasonal pattern of electricity demand, according to an October 15 update from PJM Interconnection. PJM said approximately 11,000 MW of data center load is already connected to its system. Unlike demand that rises mainly during hot or cold weather, these facilities operate throughout the year.
Spring and fall have traditionally given grid operators time to schedule generator and transmission maintenance. PJM said growing round-the-clock demand, combined with equipment outages and unusual weather, can now put pressure on the grid during those periods as well.
PJM reported that it operated reliably through this week’s conditions. Although a federal order gave it authority to direct data centers and other large customers to use backup generation if necessary, PJM said it had not used that authority.
For facility operators, the practical question is whether the complete backup power chain is ready whenever it is needed. A UPS must support the protected load while a generator starts and stabilizes. Once generator power is available, the UPS must accept the input without interrupting the load. The battery bank, transfer equipment, generator and UPS should therefore be tested as one system.
Testing should include the actual protected load, battery condition, generator start time, input voltage and frequency, and the UPS response when it returns to normal operation. Operators should also check whether battery charging after transfer adds more demand than the generator can comfortably supply.
A low frequency online UPS with an external battery bank is one equipment option for appropriately sized three-phase loads. Its capacity and battery runtime still need to be selected from the site’s measured load and tested generator sequence.
As data center demand becomes less seasonal, backup power readiness becomes a year-round operating requirement rather than a check reserved for summer or winter.
