STEG tenders 300 MW battery storage project to mitigate Tunisian grid shedding

Société Tunisienne de l'Électricité et du Gaz has initiated an international procurement process for large-scale energy storage assets to stabilize its national transmission network. The project targets an aggregate operational output of 300 MW across ten strategically selected locations. Designed to deliver a combined energy capacity of 600 MWh, the utility-scale battery storage deployments aim to address critical power shortages and prevent unplanned load shedding during periods of severe demand stress.

Grid integration and substation demands

Deploying battery systems at this scale presents specific technical requirements for existing transmission and distribution infrastructure. Integrating storage units across ten locations demands substantial modifications to local substation layouts. Step-up transformers at each site must withstand high cycling frequency and rapid bidirectional power flows, which can accelerate thermal ageing and increase mechanical stress on winding structures.

Furthermore, integrating 300 MW of storage across multiple nodes requires comprehensive grid connection studies to evaluate short-circuit levels and harmonic distortion. Circuit breakers and protection relays at target substations must handle high fault currents associated with inverter-based resources, while tap changers on inter-tier transformers must manage rapid voltage swings caused by sudden charging or discharging cycles.

Operational impact on network reliability

For the national grid, adding 600 MWh of rapid-discharge capacity provides crucial operational flexibility. Storage assets can act as virtual synchronous generators when equipped with grid-forming inverters, supplying synthetic inertia to stabilize system frequency. This capability is vital during sudden generator outages or extreme weather events, reducing reliance on emergency load shedding to maintain grid equilibrium.

What this means for asset owners in Africa: Engineers and asset managers in Tunisia must prepare regional substations for dynamic operational profiles associated with large storage facilities. Integrating 300 MW of fast-acting storage requires thorough diagnostic monitoring of step-up transformers, thermal analysis of switchgear, and recalibration of protection relays. Substation operators should schedule comprehensive transformer oil and insulation assessments before connecting large battery units to avoid unexpected outages caused by high thermal cycling.