Practical Method for First-Screening Assessment of New PV Connection Requests on Unbalanced Low Voltage Distribution Systems

Abstract

The massive growth of photovoltaic (PV) generators connected to low voltage (LV) systems is making it impractical for utilities to conduct a detailed technical analysis to approve every connection request. In response, this paper proposes simple equations to quickly estimate the PV hosting capacity on any circuit location without the need to run power flow simulations. By representing all loads and generators as constant current consumption/injection, the superposition theorem can be used to calculate the impact of each new PV on voltage magnitude and current flows. This approach can be used on a first screening assessment to immediately filter out cases that present no risk of technical violations to the circuit. Only connection requests flagged with risk of violation in this initial screening must be analyzed in detail by specialized engineers. Any type of PV connection (single-phase, two-phase, three-phase) in unbalanced multiphase LV systems can be analyzed. Extensive validation studies reveal that this approach is conservative, which makes it safe and reliable for quick first screening analyses. Its estimation errors are between 5% and 18%. Recommendations on how to employ the proposed approach in practice are also presented.