Convex Model for Estimation of Single-Phase Photovoltaic Impact on Existing Voltage Unbalance in Distribution Networks

Abstract

Due to the increasing adoption of solar power generation, voltage unbalance estimation gets more attention in sparsely populated rural networks. This paper presents a Monte Carlo simulation augmented with convex mixed-integer quadratic programming to estimate voltage unbalance and maximum photovoltaic penetration. Additionally, voltage unbalance attenuation by proper phase allocation of photovoltaic plants is analysed. Single-phase plants are simulated in low-voltage distribution networks and voltage unbalance is evaluated as a contribution of measured background and photovoltaic-caused unbalance. Voltage unbalance is calculated in accordance with EN 50160 and takes into account 10-minute average values with 5% tolerance condition. Results of the optimization revealed substantial unbalance attenuation with optimal phase selection and increased potential of local generation hosting capacity in case of higher background unbalance.

Analysis of the Impact of a Photovoltaic Farm on Selected Parameters of Power Quality in a Medium-Voltage Power Grid

“…In the case of medium-voltage networks, additional unevenness of earth capacitances may occur, mainly in the overhead lines and incorrect tuning of the compensating choke, in networks operating with a neutral point grounded using a Petersen coil, leading to resonance [23,24]. Renewable energy sources may serve as sources of voltage asymmetry: photovoltaic power plants [22,25,26], wind farms [4], agricultural biogas plants [27,28], electric car charging stations [29][30][31], and energy storage facilities [32,33].…”

Electric Arc Furnaces as a Cause of Current and Voltage Asymmetry

“…They cause, among other things, an increase in voltage and voltage asymmetry. The assessment of the power quality of PV systems supplied from distribution grids was presented in the publications [3][4][5][6]. Also [7] presents an analysis of the impact of photovoltaic systems for power quality, including a voltage imbalance.…”