The integration of distributed photovoltaic (PV) generation into distribution networks can degrade voltage quality by changing feeder power flows, increasing voltage deviations, and aggravating three-phase voltage unbalance. To address these operational challenges, this study develops a coordinated voltage quality regulation method for a low-voltage distribution station area using an improved particle swarm optimization (PSO) algorithm. Effective voltage regulation is increasingly important for maintaining reliable and efficient distribution network operation as the penetration of variable renewable generation continues to grow. The proposed approach first examines the effects of individual and multiple PV connections on nodal voltages and phase unbalance. It then evaluates the regulation mechanisms of reactive power compensation devices, including capacitor banks and the available reactive power resources of distributed PV systems. By modifying the inertia weight, dynamically adjusting learning factors, and incorporating a neighborhood reference into the PSO search process, the method seeks an improved solution to a multi-objective voltage regulation problem. A 380-V low-voltage distribution network in Jiangsu Province, China, is used to assess the proposed coordination strategy through simulation. Relative to independent reactive power regulation, the coordinated approach reduces the reported main-feeder voltage deviation by an average of 30.72% during the daytime evaluation period and improves the three-phase voltage unbalance at representative nodes. These results indicate that the coordinated use of existing compensation equipment and distributed PV reactive power can improve voltage profiles and phase balance without introducing additional compensation devices in the simulated system. The proposed multi-objective method therefore provides an applicable framework for jointly considering voltage deviation, unbalance, operating constraints, and control-resource coordination in PV-rich station areas.
