Operational analysis of security constrained optimal reactive power flow solutions

Loss minimisation studies on the Great Britain (GB) transmission network indicate an average theoretical loss reduction of 2.3%. This energy is equivalent to annual emissions of around 74,000 tonnes of carbon dioxide. These studies are based on Security Constrained Optimal Reactive Power Flow (SC-ORPF) calculations, constrained by 800 credible contingencies and voltage limits consistent with the GB security and Quality of Supply Standards (SQSS). This work demonstrates the value of a multi-staged approach to the transmission loss minimisation problem, both in terms of reducing the overall objective function and removing constraint violations created by discretization. The work reveals additional key findings. Firstly, when starting from a secure GB network operating point, the loss minimisation process encounters few binding contingencies (contingency cases with binding constraints). Secondly, the loss minimisation solutions reduce leading and lagging reactive generation volumes by an average of 13.1%.