Provision of Synthetic Inertia Support for Converter-Dominated Weak Grids

Insufficient inertia is the paramount challenge in power system transition toward $ 100\%$ converter-based generation. A promising solution to this issue is utilizing distributed virtual inertia (DVI) concept, i.e., releasing energy stored in the dc-link capacitors of power converters employed in the grid following a frequency disturbance. Nevertheless, this method has two drawbacks: $ 1$) the dc-link voltage is not reverted to its reference value after the power mismatch between generation and demand, and $ 2$) it yields instability of a local mode associated with the control system when the converter operates in weak grids. To overcome the aforesaid problems, the conventional DVI loop is modified so as not to affect the outer loop voltage regulator after transient. Moreover, an efficient compensator is presented in this article which eliminates the adverse impact of DVI technique on the converter stability in weak grid connections. The efficacy of proposed control scheme is depicted by simulations in MATLAB. The results illustrate that an improvement of $ 23\%$ is evident in the grid frequency rate of change following a frequency contingency collated with the case in which the DVI loop staying nullified.