Investigation into control accuracies and non-compliance  issues

TNEI investigated issues regarding control accuracies for two solar PV plants. Renewable power plants smaller than 20 MW are classified as Category B plants, according to the South African grid code. Category B plants are only required to inject or absorb reactive power within a power factor range of 0.975 leading to lagging. The plant is thus only required to inject or absorb reactive power 0.2779 times its maximum export capacity.

Whilst this requirement is less onerous than that of larger Category C plants, it also poses a limitation in that the allowable tolerances associated with the control modes are narrower. These constraints make it difficult for the power plants to adhere to the South African grid code requirements, especially at low set point values (e.g. 0 MVAr). TNEI can assist in identifying any possible solutions to mitigate non-compliances or unresolved issues.