Abstract:
Solar power from solar photovoltaics (PV) is one of the fastest growing renewable energy sources in
the world. Recent government policy initiatives in Sri Lanka have significantly increased the number
of rooftop solar PV systems connected to the low voltage (LV) distribution network. As a result,
increased solar PV penetration to LV distribution network can nominally disrupt network operating
conditions and leading to power quality issues. Voltage rise has been reported as the most prominent
power quality issue with high solar PV penetration levels. This will significantly exceed the load
requirement. In order to reduce the voltage rise, excess power from the solar PV units must be
reduced. Therefore, battery energy storage systems (BESS) are recommended to store the excess
energy. This project presents real feeder and real data of the Rajagiriya area in Sri Lanka to prove
voltage violation issues and find optimal solution through research. All simulations are made using
the DIgSILENT powerfactory platform, mainly to detect the location of the voltage violation at the
selected feeder. Based on that, it has been identified which customers’ solar PV system is causing the
voltage violation for the particular time in the feeder. Subsequently time required to store energy
which is supplied from the particular solar PV system has been calculated for a day. Based on that,
the battery capacity was calculated and it is recommended to the particular solar PV customer. For
this study lithium-ion batteries were selected according to the Depth of discharge (DOD), efficiency,
and calendar life cycle. The amount of power that can be delivered to the grid for night peak demand
is calculated by the DOD rating of the lithium-ion battery. And it is decided that the hybrid inverter
was optimal for this system. Total cost is calculated considering the capital cost of solar PV,
batteries, and inverter. The income and the capital cost were compared and the payback period was
observed. Finally, it is verified that the cost of capital can be recovered by the customer within the
specified year.
Keywords: Solar Photovoltaic; Voltage Violation; Low Voltage Distribution Network; Battery
Energy Storage System
