Modelling and experimental validation of a laboratory-scaled HVDC cable emulator tested in an MMC-based platform

Typical Modular Multilevel Converter (MMC)-based HVDC systems don't include capacitors directly connected to the DC-side in parallel with the HVDC lines. The dynamics of the HVDC line voltage depend on the equivalent capacitance of the HVDC system, which in turn depends on the length of the lines. Recent work in the literature has shown that this can become problematic for HVDC line voltage control in the case of short links. This paper describes the operation of a laboratory-scaled MMC-based HVDC short link platform devised to study this phenomenon. Special emphasis is put on the design and the scaling of a frequency-dependent cable emulator. Experimental results are compared with a benchmark high-voltage simulated model.