Mitigating the stability issues pos

Mitigating the stability issues post-commissioning can be tedious or expensive, as it is significantly easier to avoid the stability issues instead of attempting to fix them. In general, the main contributor for stability issues in systems that consist of multiple parallel converters is a high grid impedance, that increases the interaction between the converters. In an ideal grid, an arbitrary number of converters can be connected in parallel, as all the current is directed to the zero-impedance grid and the bus voltages are rigid, and consequently, the converters cannot interact with each other. Consequently, the most straightforward method for resolving stability issues in such systems is to decrease the grid impedance by strengthening the grid through investments such as increasing the power rating of the grid-interfacing transformer or adding parallel cables from the transformer to the converters. However, these are often costly investments, and the viability should be carefully assessed by utilizing, for example, the presented measurement-based impedance analysis. In the presented data center, the PSUs were highly unsuited for multi-parallel operation due to the drastic resonant peak and present RHP zero pair. Very significant grid investments would have been required to decrease the grid impedance enough to stabilize the system, and thus, the most applicable solution was to completely replace the PSUs. Again, the replacement PSUs should be assessed beforehand to ensure the compatible operation.