Protection Challenges of PV Integration in the Cameroon Southern Interconnected Power Network

Abstract

Integrating photovoltaic energy into existing electricity grids has become a common practice in the recent decades. However, this interconnection must be carefully planned in order to avoid their adverse impacts on the network operations. The aim of this study was to investigate the impacts photovoltaic (PV) integration may have on the protection of the Southern Interconnected Network (SIN) of Cameroon. In first time generalized fault study simulations were conducted for both three and single-phase faults. Battery energy storage systems (BESS) were added to each of three PV plants connected to the network, and then monitors were used to identify contribution of each component to the network fault currents. Impacts of PV on fuse, relay, and recloser operations were also assessed. Simulation results showed both decreases and increases in fault currents at different buses during generalized faults studies, but the differences were more severe with the single line to ground faults. The above findings are useful when calculating protective devices ratings in case of PV integration. Contributions of 683.694 A and 259.498 A from both the PV plant and the BESS at B15NGOUS1 bus respectively were recorded. There were also contributions of 42.274 A and 23.428 A to the fault currents from PV plants at B15BASS21 and B10ALU buses respectively while their corresponding BESSs rather take 10.289 A and 6.448 A in that order. The simulations result also showed that PV integration increases the fault critical clearing time by 0.444 seconds and 13.728 seconds for fuse and relay respectively, while there was no impact on fault clearing time in the case of recloser. From the findings it is obvious that PV integration into the SIN may affect the network protection arrangements by changing both fault currents and clearing time. Therefore, it is highly recommended to consider protection upgrades especially fuses and relays when planning PV integration into existing grids in general and into the SIN particularly.