The new standard for single-phase voltage regulation

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Sin­gle-phase dis­tri­b­u­tion net­works have sev­er­al advan­tages, includ­ing straight­for­ward instal­la­tion and com­par­a­tive­ly low­er invest­ment costs. How­ev­er, with the increas­ing num­ber of pro­sumers and new loads such as EVs, those grids are quick­ly reach­ing their capac­i­ty lim­its. Sin­gle-phase volt­age reg­u­lat­ing dis­tri­b­u­tion trans­form­ers (VRDTs) have emerged as a high­ly effec­tive alter­na­tive to sec­ondary upgrades and recon­duc­tor­ing, pro­vid­ing numer­ous oper­a­tional ben­e­fits:

• Sim­pli­fied net­work plan­ning
• More effi­cient net­work topolo­gies
• Increased host­ing capac­i­ty for dis­trib­uted gen­er­a­tion
• Reduc­tion of deployed assets or enhanced usage of cur­rent assets
• Opti­mal oper­a­tion of ener­gy effi­cien­cy pro­grams (VVO/CVR)
• Sta­ble volt­age sup­ply for com­mer­cial and indus­tri­al cus­tomers
• Future-proof invest­ments for new loads (EV charg­ing, heat pumps)
• CAPEX defer­ral and Non-Wires Alter­na­tive

PHI’s pro-active approach

In the US, an increas­ing num­ber of house­holds are installing rooftop solar pan­els. In neigh­bor­hoods with high solar adop­tion rates, capac­i­ty from both load and over­volt­age can be reached quick­ly. This is evi­dent on a street in south­ern New Jer­sey, with­in the ser­vice ter­ri­to­ry of Atlantic City Elec­tric (ACE). ACE is a sub­sidiary of PHI (as part of the Exelon Oper­at­ing Com­pa­nies). For this project, PHI man­ages the plan­ning and imple­men­ta­tion.

John Budd, a Prin­ci­pal Engi­neer of PHI, is tasked with iden­ti­fy­ing solu­tions for the fol­low­ing sce­nario: “A cus­tomer sought to con­nect their PV array. As they’re in the inter­con­nec­tion queue, ACE was unable to approve their inter­con­nec­tion per­mit as there were already five arrays con­nect­ed to this 25 kVA trans­former, reach­ing the trans­former load lim­it.” In search of a solu­tion to accom­mo­date res­i­den­tial cus­tomers with their solar inter­con­nec­tion, and con­sid­er­ing con­struct­ing new lines would have been pro­hib­i­tive­ly expen­sive, PHI opt­ed to install a 50 kVA sin­gle-phase VRDT to the line and tie four of the hous­es with solar PV to this new trans­former.

“The instal­la­tion was as straight­for­ward as that of a stan­dard trans­former. Imme­di­ate­ly after the load was con­nect­ed, the VRDT adjust­ed the volt­age autonomous­ly with­in the spec­i­fied range through a tap-change oper­a­tion,” explains Budd. Ini­tial data analy­sis indi­cat­ed that with­out the VRDT, the volt­age would have increased beyond the accept­able tol­er­ance band. “With this set­up, we can now sup­port addi­tion­al neigh­bors in installing and con­nect­ing their PV arrays,” Budd adds.

This ini­tia­tive marks just the begin­ning. In the ser­vice ter­ri­to­ries of PHI and Atlantic City Elec­tric, which col­lec­tive­ly serve approx­i­mate­ly 1.5 mil­lion cus­tomers, the use of the VRDT would be high­ly ben­e­fi­cial at hun­dreds of net­work nodes cur­rent­ly being eval­u­at­ed. Addi­tion­al instal­la­tions are to fol­low in the near term.