Assessing cyber attack vulnerabilities of distributed generation in grid-connected systems

Abstract

The widespread integration of solar PV, a type of distributed generation, is becoming more common in power grids, but this is raising concerns about their vulnerability to cyberattacks. The impact of widespread solar PV integration on the resilience of medium voltage power systems against cyberattacks remains largely unknown, particularly in the context of South Africa. This research aims to explore how solar PV integration affects the vulnerability of South Africa's power grid to cyber-attacks, during worst conditions, focusing on voltage stability, short circuits, and power losses. A static and dynamic power flow analysis was conducted on a model system consisting of two 132/11 kV transformers, four feeders, and 81 loads connected to the 11 kV busbar. The analysis of static power flow reveals that the majority of nodes have violations, particularly feeders 1 and 4. However, when solar PV penetration (PVP) reaches 100%, nodes with voltage violations are brought within the acceptable range. Moreover, the highest power loss is 412 kW, occurring at zero PVP during peak loads. The dynamic simulation results indicate that certain nodes still have violations even with 100% PVP. Feeder 1 is at the greatest risk of voltage collapse due to a cyber-attack, followed by feeder 4. In order to address issues with the network, multi-objective optimization was used to determine the optimal placement for tie-lines interconnections. This strategy shows that not only the power loss of the system significantly reduced by 50% but also the voltage profile of the system shifts to an acceptable level and is safe for any cyberattack. Further study may consider other mitigation techniques such as energy storage to mitigate the challenges beside the Tie line interconnection with minimum cost.