Leveraging Model Identification for Voltage Improvement in Renewable-Powered LV Microgrids (LIVABLE-LV)

Prime concerns that exist with renewable energy systems (RES) based medium/low
voltage (LV) distribution networks (DNs) are; a) intermittent nature of renewable energies like 
solar PV power, and b) consequent reverse power flow. These LV networks being dominantly 
resistive tend to have voltage rise occurrences and ultimate reverse power flow. Intermittency 
associated with RESs, is countered by well knitted voltage regulation regime, which swiftly 
responds to these changing dynamics. Modern DNs with battery energy storage systems 
(BESSs) as key attribute, facilitates storage of surplus power and strategically discharge in 
absence of RESs to meet the load demand.All the RESs may interchangeably be thus called 
inverter-based sources (IBRs). These smart inverters are capable of operating in both the 
quadrants of 𝑃-𝑄 plane as per the reactive power (𝑄) and active power (𝑃) adjustments needed 
at the time of operation. IBRs of different sizes and capabilities operate through grid-following 
voltage source converters (VSCs), for smooth operation of weak grid configurations, so that 
distant PV/battery operations do not violate grid codes and in fact furnish voltage strength to 
the grid. 
In order to develop an equivalent dynamic model (EDM) of an active distribution net
work, the modelling was deliberated, based on experimental measurements obtained from 
point of common coupling (PCC) and local nodes of IBRs. This modeling is inspired to perform 
stability analysis, such that modeling is targeted as multiple point operation, with realization of 
linear/non-linear characteristics for various zones of IBR operations. 
The experiment set up consisted of 40kW, 66 kWh Li-ion battery and programmable load 
connected at PCC, which in turn connected at 400V to utility grid. The observations are taken 
for different set points applied at the PV inverter under varying solar radiation profile. The PV 
inverter is perturbed with different set points and data is collected at PCC.