Probabilistic assessment of the influence of transformer rating on power quality indices in future residential networks

This paper proposes a methodology to assess the influence of transformer rated power on the power quality
indices in future low voltage residential networks. Taking into account the stochastic nature of residential loads
and the possibility of photovoltaic generation, a Monte Carlo methodology is developed in order to account for
the probabilistic aspects of the problem. In this work, different transformer ratings are simulated and the effect
on power quality parameters, such as voltage unbalance and voltage total harmonic distortion, is assessed using
probabilistic approach. These power quality indices are compared to the compliance limits proposed in standard
EN50160. Several case studies are presented for two different networks, the IEEE European Low Voltage network
and a larger 471-buses residential network. These studies allow establishing general conclusions regarding
desirable transformer size in order not to exceed power quality limits and considering the influence of photovoltaic
generation on power quality parameters.