Operation of meshed high voltage direct current (HVDC) overlay grids

Energy turnaround from conventional to renewable energy generation needs bulk power long distance transmission. This new transmission objective can be meet with an HVDC overlay grid spanning the existing AC transmission system. This thesis proposes an operation management strategy for future HVDC overlay grids subdivided in tertiary, secondary and primary control instances. The tertiary control ensures coordination among HVDC converters and with the AC system. It determines converter reference values on a regular basis. It is proposed for the case of having multiple as well as a single system operator responsible for the overlay HVDC grid. The secondary control instance locally adapts tertiary control’s converter references to the actual grid requirements (e. g. after disturbances). The primary control ensures DC energy balance. Therefore, a continuous p v characteristic is proposed as well as two appropriate parameterization methods. One emulates piecewise linear p v characteristics and the other performs an automatic parameterization according to available balancing power provision capabilities on related AC point of common coupling. All control methods are validated by numerical case studies.