Analysis and Enhancement of the Artificial Bus Method for Successful Low-Voltage Ride-Through and Resynchronization

Designing an optimal approach for effectively and efficiently connecting voltage-source converters (VSCs) to very weak grids has been gaining increased attention in the research. Recently, the artificial bus control method has been proposed as a successful solution to improve the stability of grid-connected VSCs and inject the maximum nominal power during very weak grid conditions. However, like other solutions available in the literature, its performance under grid faults has not yet been thoroughly investigated. This paper is devoted to analyzing and improving the performance of the artificial bus method under faults. Analyses are used not only to show that the loss of synchronization threatens the successful low-voltage ride-through of the converter but also to find a solution to improve the converter performance with a minimum change in the control structure and parameters while satisfying required standards. When a fault is sustained, disconnection is allowed, but a smooth reconnection is desired. This paper derives the internal admittance of a VSC with the artificial bus method to show how this control approach improves resynchronization in both weak and strong grids. Using a detailed model, participation factor analyses are employed to explain the impact of the artificial bus method in different situations, and time-domain simulations are used to verify the analytical results.