Milan, Italy: PV Inverters Provide 500 kVAr Reactive Power Regulation to the Grid at Night
en.Wedoany.com Reported - September 17 news: Politecnico di Milano's PoliGrid completed a trial in which PV inverters participated in distribution network regulation at night. From 1:00 to 5:00 a.m. on the nights of September 8 and 9, the inverters of the campus PV system continuously provided 500 kVAr of inductive reactive power regulation service to the Milan distribution network for 4 hours, to verify the feasibility of PV equipment participating in voltage and reactive power control at night when it is not generating electricity. The trial is part of the MiNDFlex pilot project promoted by Unareti.
During the trial, PoliGrid did not fix the inverters at a single 500 kVAr setpoint. Instead, it used the reactive power exchange under normal campus operating conditions as the baseline, monitored and adjusted the setpoints of each inverter in real time, so that the grid connection point continuously provided 500 kVAr of reactive power regulation relative to the baseline. The baseline was calculated from the average operating data of the previous several days.
The PV system participating in the trial used Huawei SUN2000 inverters and was controlled via Huawei SmartLogger 3000. The LePo energy management system, jointly developed by the Department of Energy of Politecnico di Milano and the Piacenza Energy and Environment Laboratory, was responsible for forecasting and optimized scheduling, while the Optimo IoT architecture was responsible for issuing control commands to each PV control unit and inverter.
To support nighttime operation, the project team configured the inverter management system so that it remained online even when the PV modules were not outputting active power. Since the inverters do not need to handle solar active power conversion at night, their remaining capacity can be used for reactive power regulation, thereby participating in distribution network voltage control without affecting PV power generation.
Unareti procured this service through the MiNDFlex pilot market and compensated the available capacity on a euro/kVAr/hour basis. This contract window corresponds to Italy's F3 period, i.e., 23:00 to 7:00 the next day on weekdays. The Politecnico di Milano research team stated that this is the first reactive power flexibility service provided through a market mechanism in Italy that it is aware of.
This trial is also part of the SIMBIOsi project funded by Italy's Ministry of the Environment and Energy Security, with participants also including A2A, LEAP, Loccioni, and Terna. Follow-up research will focus on aggregation control, communication, and monitoring systems for larger-scale distributed inverters, as well as market-based procurement mechanisms for reactive power services.
