Role of quadrature boosters in boundary transfer capacity planning: case study of 2035 energy scenario

The Great Britain (GB) transmission network faces future stress due to geographical imbalances between expanding renewable generation in the North and increasing demand in the South. This imposes security challenges on the power transfer capabilities of the North-South network boundaries. Conventional reinforcements, such as adding new double-circuit 400kV lines, are effective but costly and slow to deliver. This study evaluates the role of Quadrature Boosters (QBs) as a possible low-cost alternative to effectively enhance boundary transfer capability in the network. A DIgSILENT PowerFactory model was built using data from the published 2024 Electricity Ten Year Statement (ETYS). The model incorporated DC power flow and sensitivity analysis and was used to identify critical circuits and influential QBs. In the specific scenario, seven boundary-double-circuit lines plus one strategically placed QB was assessed against an alternative with eight boundary-double-circuits, with the comparison focusing on the transfer capability of the associated boundary. Comparative simulations across three operating scenarios (N-0, N-1, N-D) show that the eight double-circuit baseline achieves greater incremental gains, but the seven boundary-double-circuit with the additional strategically placed QB can deliver comparable transfer capability. This demonstrating the suitability and effectiveness of QB reinforcement in enhancing the boundary transfer capability, with potential to defer or reduce the need for new transmission lines in future planning.