Voltage Quality Improvement in Low Voltage Distribution Networks Using Reactive Power Capability of Single-Phase PV Inverters

The rapid growth of residential rooftop photovoltaic (PV) systems may cause significant power quality problems such as severe voltage fluctuation and unbalance which can restrict further PV integrations to the network. In this paper, the potential capability of residential PV inverters is investigated to develop a distributed reactive power compensation scheme for voltage regulation in three-phase four-wire unbalanced low voltage distribution networks (LVDNs). For this purpose, an effective method is proposed by means of single-phase PV inverters arbitrarily connected among different phases. The aims are improving voltage profile along the feeder and reducing the voltage unbalances. The PV inverters are connected in such a way that they form distributed delta and wye configurations to compensate the negative and zero sequence components of voltage, respectively and to regulate voltage within the allowed limits as well. The proposed consensus-based algorithm considers each PV system as a smart agent and updates its reactive power control setting based on only local measurements and data communications with neighboring agents. The effectiveness of the proposed strategy in terms of voltage regulation and unbalance and energy losses is shown through detailed simulations over 24-hours period on a three-phase four-wire unbalanced LVDN with realistic data.