Engineering of Power Flow Control across the Zambia - Zimbabwe Interconnector with Phase-Shifting Transformers

The paper reports the engineering performance evaluation and simulation studies of the phase-shifting transformers (PSTs) applied to the planned interconnector between the national electric grids of Zambia and Zimbabwe, in Africa. This solution was proposed to the Zambezi River Authority, the implementing agent for the Batoka Gorge Hydroelectric Scheme (BGHES), on the Zambezi River, for addressing the issue of controlling power flows across the newly conceived interconnector in a reliable, safe and resilient manner. For the engineering purpose, the feasibility studies have proved and confirmed the expected performances and effectiveness on the controlled interconnector operation. The authors describe the assessment of the viability of this solution from a system operation perspective, having carried out a screening of possible alternatives other than PST-based, and checked the expected PST's capabilities in both static (load flow) and dynamic behaviour through a comprehensive network study campaign.