Power Quality Assessment of Grid-Connected Photovoltaic Systems in Buildings with Distributed Renewable Energy

Abstract

The increasing penetration of distributed renewable energy sources, particularly grid-connected photovoltaic (PV) systems, has introduced new challenges related to the quality and stability of electrical power in low-voltage distribution networks. Buildings equipped with distributed generation units often integrate both single-phase and three-phase PV inverters, which may influence voltage stability, harmonic distortion, phase balance, and overall power quality in the electrical installation. As photovoltaic capacity continues to expand in urban and institutional buildings, systematic assessment of power quality parameters becomes essential to ensure compliance with international standards and reliable operation of electrical infrastructure. This paper presents an experimental investigation of power quality characteristics in a building equipped with distributed photovoltaic generation connected to a three-phase low-voltage electrical system. The analyzed installation includes both single-phase and three-phase PV systems with a nominal capacity of 10 kW each. Measurements were carried out using a Class-A power quality analyzer compliant with IEC 61000-4-30 measurement standards. The monitoring campaign was conducted over an extended period under different operating conditions, including periods without photovoltaic generation, partial generation, and peak solar production. The study focuses on the evaluation of key power quality indicators such as voltage magnitude variations, frequency stability, harmonic distortion, voltage unbalance, and power factor. Particular attention is given to the impact of single-phase photovoltaic inverters on phase voltage asymmetry within the three-phase building supply network. The obtained results are compared against the limits specified in international standards such as EN 50160 and IEEE 519. The measurement results reveal that photovoltaic generation can lead to noticeable variations in phase voltage levels, particularly in cases where single-phase PV systems inject power asymmetrically into the distribution network. Under high solar generation conditions, localized voltage rise and increased phase voltage imbalance were observed. Furthermore, harmonic distortion associated with inverter operation was analyzed through spectral decomposition and total harmonic distortion (THD) evaluation.