Stability Enhancement of Power Synchronisation Control Based Inverter Using Power Decoupling Strategies

Power synchronisation control (PSC) was introduced initially for the HVDC applications as an alternative to the vector current control where it has demonstrated improved performance under weak grid conditions. However, the application of the PSC as a grid-forming inverter (GFMI) and its performance under different network impedance conditions have not been thoroughly investigated in the literature. This paper has evaluated the PSC based inverter performance under different network conditions, and showed that the stability performance of the PSC-based inverter deteriorates when the network is predominantly resistive. To address this issue, modified PSC-based controller, with virtual impedance and virtual power-based decoupling strategies, are proposed to improve the controller performance and stability for networks with low X/R ratios. It has been shown that the controller performance has been improved with the proposed decoupling strategies. This will enable the deployment of PSC-based GFMIs under weak grid conditions and improve the ability to provide system support services under predominantly resistive conditions without losing stability.