Voltage imbalance analysis in residential low voltage distribution networks with rooftop PVs

Abstract

Abstract-The installation of domestic rooftop photovoltaic cells (PVs) are on the rise due to feed-in tariff and changes driven by environmental concerns. Even though the increase in the PV installation is gradual, their locations and ratings are often random. Therefore, such single-phase bi-directional power flow can have adverse effect on the voltage imbalance of a threephase distribution network. In this paper, a voltage imbalance sensitivity analysis and stochastic evaluation based on the ratings and locations of single-phase grid-connected rooftop PVs in a residential low voltage distribution network are presented. The stochastic evaluation, based on Monte Carlo method, predicts a failure index of non-standard voltage imbalance in the network in presence of PVs. Some improvement methods are discussed and a new improvement method based on PV converter control is proposed.

Comparative analysis of domestic and feeder connected batteries for low voltage networks with high photovoltaic penetration

“…Domestic PV installations, by their nature, provide a very inconsistent power injection onto a single phase in the network and as such greatly contribute to voltage unbalance [14]. It is possible that, within a feeder system, 70-90% of the PV installations are on the same phase and in this situation a very large voltage unbalance would be expected to occur under conditions of domestic solar power export [11] and this effect is increased with distance from the substation. The definition of voltage unbalance is, however, not always consistent.…”

“…unbalance is one of the biggest problems facing LV networks [11]. It is stated in Engineering Recommendation P29 [12] that voltage unbalance be kept to within 2% for the entire network.…”

Voltage and current balancing in Low and Medium Voltage grid by means of Smart Transformer

“…The unbalanced voltage problem raised by the integration of small single-phase Photovoltaic (PV) power plants in the LV grid is e.g. presented in [4]. Depending on the installation distance of the PVs from the substation, the impact on the voltage unbalance can vary significantly.…”

Application of Distribution Static Compensator (D-STATCOM) to Voltage Sag Mitigation

“…Among different types of disturbances occurring in power system, voltage sag is known to produce the most devastating impact on the loads [2]. Studies show that 92% of all disturbances in the electrical power distribution systems are voltage sags, transients, and momentary interruptions [3,4]. Voltage sags are not tolerated by sensitive equipment used in modern industrial plants such as process controllers; programmable logic controllers (PLC), adjustable speed drive (ASD) and robotics [5].…”