Evaluation of Measures to Operate Urban Low Voltage Grids Considering Future PV Expansion

The Swiss federal government set forth its energy policy, titled ”Energiestrategie 2050,” in which photovoltaics (PV) production would reach 20% of the total yearly electrical energy production by the year 2050. Such a drastic expansion rate of PV and the resulting excess energy thereof, however, can lead to technical challenges for the infrastructure of the power system. In this paper, the impact of the future PV penetration on a real urban low voltage (LV) area is presented. To this end, two PV scenarios are devised and implemented, and quasi dynamic load flow simulations are conducted for every fifteen minutes interval of a whole year. To generate the input data, a load profile generator is developed based on smart meter measurement data. It is concluded that the examined urban area appears to be prepared for a certain amount of further PV integration as there were no violations detected for the medium PV production scenario (43% of the total consumption in the area). However, for the maximum PV penetration scenario to be implemented, violations such as over voltage and transformer overloading are detected. To resolve these issues, different mitigation measures such as battery energy storage system, active power curtailment and short-term overloading of the transformer are implemented and examined with the aid of appropriate mathematical models. As a result, at least 20% of the PV energy needs to be stored, curtailed or used by demand side management, in order to run the low voltage grid as it is. In a further work, an intelligent combination of different measures could be examined to fully utilize the excess energy.