Communication-free Approach for Frequency Support in the MTDC grids - A Comparative Study

Frequency Support (FS) through the Multi-Terminal HVDC (MTDC) grids is become obligatory by most of the Transmission System Operators (TSOs). Providing this support without any communication between converter stations is challenging. In the literature, researchers try to obtain the FS from the dc grid in a communication-free manner to improve the stability and reliability of the AC surrounded MTDC (AC-MTDC) grids. Moreover, in most of the literature, based upon the test system considered, the researchers have adopted a suitable control scheme. However, a study of various communication-free based FS control schemes and comparison among them are unavailable in the literature, which is the subject matter of this paper. Further, to conclude the various frequency supporting control methodologies, simulation of two case studies have been carried out with three schemes in PSCAD/EMTDC software. The conclusion is drawn based upon the simulation results and comparative study.