Abstract :
Currently network security is treated within a deterministic and preventive control framework where network constraints and balancing costs are not fully optimised by applying a range of advanced, technically effective and economically efficient corrective (or post-fault) actions from flexible network technologies such as phase shifter transformers, reactive compensation and HVDC links. This may be inefficient and lead to increased levels of congestion in the short term and over-investment in network capacity in the long term, potentially increasing cost of integration associated with low-carbon generation. In this context, this paper assesses the effects of coordinating flexible AC and HVDC transmission systems under both deterministic and probabilistic security frameworks and assuming an array of available preventive and corrective control actions. To do so, we use an Optimal Power Flow (OPF) based deterministic/probabilistic cost-benefit model that has been developed for assessing the economic and reliability performance of alternative control strategies enabled by coordination of AC and HVDC technology. This involves co-optimisation of a number of control variables associated with generating units, HVDC links, phase shifters and reactive compensation. We quantify the benefits of alternative control and security strategies applied to the GB transmission system, considering future development scenario with increased penetration of wind generation, demonstrating that probabilistic security with corrective control for AC/DC coordination is significantly more beneficial since it can lead to lower operating costs, increased utilisation of the network infrastructure and improved reserve allocation across transmission network.
