Investigation of the impacts of the adoption of energy storage systems on voltage rise resulting from PV systems integrations on low voltage networks

Leveraging sunlight for electricity, which is a sort of renewable energy, has been increasing for the last decades, in turn, the adoption of rooftop Photovoltaic (PV) systems has been becoming widespread. Whilst the number of householders who want to sell the energy they produce rises, it is highly likely that reverse power flow (i.e., conventionally from end-users to the secondary transformers) on the LV network increases. One of the leading problems posed by reverse power flows is voltage rise. In other words, when increased energy generation due to high solar radiation coincides with low energy demand, voltage rise will occur on the network/householder level, as a significant volume of energy will be delivered back into the LV networks. In other words, the actual reason why voltage rise occurs on LV networks resulting from reverse power flow (i.e., from PV systems) and line resistors. Therefore, in this thesis, as to how benefits from Battery Energy Storage Systems (BES) will be offered to lower voltage rise on the network is tested. The effectiveness of BES is tested through 12 different scenarios (by changing the battery capacity or battery power in each scenario) and two different storage control methods (local and central control) so as to observe how far BES could be in effect. The test is carried out by using OpenDSS, a power flow analysis program that regards real data. Furthermore, for BES, the features of Tesla Powerwall 2, which is used in real life and is of Lithium-Ion technology, are considered. The results show that BES successfully prevents voltage rise. It is observed that voltage rise can be significantly prevented by increasing the battery capacity (kWh) (instead of using 2 Tesla Powerwall 2 versus using 1 unit). However, the limitation of storage power (kW) results in more energy being delivered back into the LV network during high energy generation time periods. On the other hand, high storage power brings about the battery to charge rapidly and become passive early. Moreover, considering the load and PV model used in this thesis, it is observed that voltage rise can be largely prevented by using 1 Tesla Powerwall 2 by altering the control method (i.e., using the central control approach). Unlike other studies, this study highlights the need for reviewing the upper limit power determined for rooftop unlicensed energy production allowed in the legislation in order to prevent voltage problems that may occur in the future and some grievances that customers may be exposed to (such as PV restrictions may make the investor suffer). Furthermore, it suggests that the power value of the BES in place should not exceed the corresponding PV system capacity. This indicates that the BES capacity should be chosen appropriately together with the BES charge/discharge power. Consequently, the conditions of grid connection the rooftop PV systems and BES behind the meter should be considered.