MMC HVDC Controller Hardware-in-the-Loop Testbench

With the increasing penetration of renewable energy sources in our energy mix, the modern power grids are in rapid transition into complex systems where the controller performances of power converters play a pivotal role in maintaining stable, reliable and economical operations of the power grids. Especially in converter-dominated and purely converter-based grids, such as offshore collector grids evacuating wind energy via HVDC systems, dynamic interactions over a wide frequency range may cause resonances and subsequent system outages.

In order to develop future-proof converter-dominated grids, it is prudent to analyse the system stability over a wide frequency range based on validated simulation models. Within the frame of the PROMOTioN project, DNV GL has developed a Control Hardware-in-the-Loop (CHiL) testbench in its Flex Power Grid Lab (FPGL) where, for the first time in the world, vendor provided controller replicas of an MMC HVDC interconnector and a wind turbine generator were connected to the real time digital simulation environment in an independent laboratory. Using the CHiL testbench, digital tests were successfully conducted to demonstrate the advanced control functionalities of the 1200 MW @ ±320 kV MMC HVDC system from NR Electric (Nanjing, China), including fault-ride-through, frequency responses and subsynchronous oscillation suppression. Furthermore, the harmonic characteristics of MMC HVDC converters are demonstrated to the participants.

The MMC CHiL testbench has been demonstrated to a broad audience of stakeholders on 21st November 2019 in Arnhem.