Reducing Overvoltage-Induced PV Curtailment Through Reactive Power Support of Battery and Smart PV Inverters

Abstract

Most rooftop solar photovoltaic systems in Australia export excess power to the grid after meeting local demand, leading to overvoltage issues in distribution feeders. Australian standard AS/NZS 4777.2.2020 mandates grid-connected PV inverters to utilise real and reactive power quality response modes to mitigate these issues. These response modes result in the injection or absorption of reactive power and curtailment of active power when voltage exceeds prespecified thresholds. If the voltage exceeds a maximum permissible limit, the PV inverter shutdown to ensure safe operation. This paper proposes a method to reduce active power curtailment and inverter shutdown by utilizing reactive power support from local battery inverters, if available. The battery inverter provides reactive power support to mitigate overvoltage without affecting its active power flow. If the reactive power of the battery inverter is insufficient, the PV inverter response modes are activated. This technique reduces reliance on PV inverters and thus minimizes active power curtailment. The proposed method is tested on an 11-kV distribution feeder in South Australia. Simulation results indicate that by combining the support of battery inverter and PV inverter, overvoltage, active power curtailment, and the associated financial loss can be eliminated for the studied feeder. The impact of selecting the feeder source bus voltage on overvoltage issues is also investigated, and it is found that selecting lower source bus voltages during high solar radiation periods can eliminate overvoltage problems.

Keywords

• Battery energy storage system
• distribution network
• overvoltage
• photovoltaic systems
• PV curtailment
• reactive power