Overload Rotation to Increase Capacity of Transmission Boundaries

Abstract

This thesis is a feasibility study aims to increase transmission boundary power flows in the GB electrical power systems. The objective is to reduce transmission network reinforcements and costs to customers, whilst increasing MVA capacity of boundary circuits with the aid of available controls. The main contribution is development of the Overload Rotation concept and the mathematical model. The project is centred around the idea of overloading the boundary circuits for a limited time period and then transferring overloads to other (non-overloaded) boundary circuits in such a way that neither circuit ‘health’ nor system security/stability is jeopardized. The boundary circuit overloading capabilities are found from circuit dynamic thermal ratings, and the “Overload Rotation” model is set as a MI(N)LP optimization model. The model gives the amounts of generation rescheduling and load curtailments (or, new generation connections) required to eliminate boundary circuit overloads and thus postpone the boundary reinforcements. The developed “Overload Rotation” model is tested on the IEEE RTS96 test system and a reduced GB network model in this feasibility study. The results on the IEEE RTS96 test system show that generation rescheduling and some load curtailments can be very efficient in the reduction of circuit overloads. On the other hand, overload rotation applied to the reduced GB network model showed that in the most of the N-1 boundary circuit contingencies quite significant load curtailments were required to bring the boundary interface power flows within permissible limits. This indicated that incorporation of additional controls into the Overload Rotation model was necessary. The main conclusions reached in this thesis are: • The full potential of the overload rotation can be obtained if additional control remedies are introduced in the Overload Rotation optimization model. • The future work needs to address the following aspects: • Modelling of existing and optimal connection of new phase-shifters. • Modelling of energy storage and optimal connection of new phaseshifters. • Modelling of bus/branch switching and installation of inter-tripping schemes. • Sensitivity studies related to different operating regimes, new connections, different network development strategies, etc. • Improved network modelling.

Date of Award	29 Jul 2025
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Jovica Milanovic (Co Supervisor) & Victor Levi (Main Supervisor)