Mitigation of operational risk in South African distribution networks with integrated renewable generation

Abstract

Under the Department of Energy's (DoE) renewable energy independent power producer procurement program (REIPPPP), utility scale renewable energy projects were connected to sub-transmission networks. To date 4138 MW of renewable energy has been commissioned. All renewable energy (RE) generation must comply with the RE grid code in South Africa. This ensures a predictable response of the RE facility under normal, weak and fault conditions. As the penetration level of RE generation increased, the requirements imposed on the RE generators also increased and become more advanced. However, even with fully grid code compliant RE facilities, there are operational risks. This study explores the operational risks to both the network service provider (NSP) and the RE generators, especially under weak grid conditions. The operational risks include voltage control under normal and weak grid conditions, RE generation stability connected on traction networks, the response of RE generation during faults and the prevalence of supraharmonics present in the sub-transmission network as a result of RE generation. The objective of this study is to determine the operational risks associated with RE generation operating on sub-transmission and distribution networks; provide mitigating solutions for operational plants and offer recommendations for future connections.