Stability Assessment of Grid-Following and Grid-Forming Interlinking Converters in Hybrid AC/DC Networks

Interlinking converters (which connect AC and DC grids) are a key technology for future hybrid ACIDC networks. According to the network operation modes, synchronization methods to the AC grid and interlinking converter control strategies, grid following (GFL) and grid forming (GFM) interlinking converters have emerged. However, the control and stability of these interlinking converters have recently gained enormous interest. Based on the network full-order model, this paper investigates and compares the control performance of a small-scale GFL and GFM hybrid ACIDC network. Model validation is performed by comparing to a built-in simulated system in Matlab/Simulink to determine accuracy. In addition, eigenvalue stability assessment is done for different cases, which reveal that a weak AC grid (i.e., SCR < 2) and high SRFPLL bandwidth impact the GFL hybrid ACIDC network stability. Also, the stability of the GFL hybrid ACIDC setting improved when the reactive power control was activated.