VSC-HVDC Protection and Control

Good knowledge of VSC-HVDC technology is presently held only by the manufacturers (who for competitive reasons do not want to share). Given the potentially large number of VSC-HVDC links into the UK, and the rapid planned rollout of the technology the utilities and government need to develop a better understanding of VSC-HVDC. A key weakness is that presently most public domain R&D on VSC-HVDC is based on simplified simulation models. This fails to capture key hardware complexities. The limitations real-time control places on system operation is a key element here. Nonlinearities in the hardware are a further problem. There is an urgent need for research to develop a low-power hardware model that particularly addressed the real-time control issues to develop better models of this component and allow the utility networks to develop a better understanding of the hardware. The PhD will construct a low-power reduced-scale hardware model of a modular multi- level VSC-HVDC converter. As far as possible the control dynamics will be preserved so that the controller for each sub-module will be partitioned from the master controller, to test multi-layer control concepts. Algorithms for such system control will be explored. The fidelity of power system models presently used for network modelling will be assessed in this context, and improvements suggested as appropriate. If time permits, interfacing the hardware model with Real-Time Digital Simulation (RTDS) will be examined of the type used in the UK utility MTTE project. The PhD will involve software programming (both FPGA and microcontroller), real-time control, sensing and measurement, electronics, power electronics, hardware-in-the-loop, as well as some power systems modelling and analysis.