Harvesting the flexibility of energy communities from a DSO perspective

As non-controllable power sources, photovoltaics can create overvoltage and overloading in low voltage (LV) distribution feeders during periods of high generation and low demand. This is usually prevented passively by limiting the penetration level of PV to very conservative values, even if the critical periods rarely occur. Alternatively, one can use active power curtailment techniques, reducing the amount of active power injected by the PV inverters. In this way, it is possible to prevent overvoltage of the network buses and overloading of the network lines. This study investigates an approach for controlling the PV power generated in the town of Rolle, Switzerland, equipped with a large number of rooftop PV systems. Simulations of a one year period with typical solar irradiance and load profiles are conducted to assess the quantity of PV generation that needs to be curtailed to avoid violated constraints. A comparison between the economical loss of the curtailed power and the economical cost of the reinforcement of the grid to reach a safe operation of the network is proposed. This allows to give the distribution system operator an overview of which method is economically profitable. The study shows that the curtailment of the PV systems is less profitable than reinforcing the network.