Voltage unbalance mitigation in LV networks using three-phase PV systems

Abstract

In this paper a new method is proposed to mitigate voltage unbalance caused by single-phase solar inverters in low voltage (LV) networks. The method is based on uneven reactive power absorption and injection by three-phase solar inverters. Independent control of each phase is performed to achieve this uneven injection. The average values of phase voltages at the connection points of the photovoltaic (PV) inverters are used as the references for the balancing algorithm. Voltage unbalance mitigation is achieved by use of this method in different scenarios with variable three-phase and single-phase inverters penetration in a realistic LV grid. In addition, the overvoltage is reduced by using this method.

Methods and strategies for overvoltage prevention in low voltage distribution systems with PV

“…However, a higher PV penetration may cause difficulties in the control and operation of LV grids. Among the challenges associated with high PV penetration are: overloading of the grid components such as LV transformers and cables [7,8]; active and reactive power flow fluctuations [9][10][11][12][13]; the network protection malfunction [14]; and voltage unbalance [15][16][17][18][19]. However, overvoltage is the main challenge in many LV grids with PV, and is one of the main limiting factors in increasing PV penetration in LV grids.…”

Review of Distribution Network Phase Unbalance: Scale, Causes, Consequences, Solutions, and Future Research Direction

“…K. H. Chua et al developed a control strategy for energy storage as part of the single-phase photovoltaic system to perform phase rebalancing [63]. C. C. Bajo et al developed an individual-phase control strategy for three-phase PV systems to perform phase rebalancing [64]. F. Shahnia et al developed a control method for single-phase PV converters to provide reactive power support, thus reducing voltage unbalance [65].…”

“…Space limit in MV/LV distribution substations Use small-sized phase balancers 3. Control energy storage, EVs, DG, and micro-grids [60], [61], [62], [22], [63], [64], [65], [66] Adaptive; no new phase balancer required Costs of implementation, operation, and maintenance; scalability issue when applied to millions of LV networks Use mature and low-cost technologies for control and communication. Perform automatic control phase unbalance degree for years into the future.…”

Review of Distribution Network Phase Imbalance: Scale, Consequences, Solutions, and Future Research Direction

“…K. H. Chua et al developed a control strategy for energy storage as part of the single-phase photovoltaic system to perform phase rebalancing [59]. C. C. Bajo et al developed an individual-phase control strategy for three-phase PV systems to perform phase rebalancing [60]. F. Shahnia et al developed a control method for single-phase PV converters to provide reactive power support, thus reducing voltage imbalance [61].…”

“…Space limit in MV/LV distribution substations Use small-sized phase balancers 3. Control energy storage, EVs, DG, and micro-grids [56], [57], [58], [22], [59], [60], [61], [62] Adaptive; no new phase balancer required Costs of implementation, operation, and maintenance; scalability issue when applied to millions of LV networks Use mature and low-cost technologies for control and communication. Perform automatic control paper suggests the following directions that will address the scalability, data-scarcity, and adaptability challenges arising from phase rebalancing: 1) use retrofit-able, maintenance-free, automatic solutions to overcome the scalability challenge; 2) use data analytics to overcome the data-scarcity challenge by extrapolating knowledge to data-scarce networks; and 3) use phase balancers or other online phase rebalancing solutions to overcome the adaptability challenge.…”