Stability analysis for weak meshed networks with power electronics-based distributed generation

An increased deployment of distributed generation in recent years has contributed to creation of meshed power networks usually seen as a way to improve power flow management capability. Also, power electronics converters have been commonly used to interface distributed resources to the grid, yet their impact on the network stability has not been sufficiently explored. In this paper the stability of meshed weak power networks with high penetration of power electronics converters is studied. For that purpose a small-signal state-space model of the complete power network has been developed by introducing linearized state-space models for each system component including power converters and their control systems, lines, loads and the grid connection. Both eigenvalue and maximum singular value analyses have been then used for the stability assessment. The variation of three typical parameters was studied and their impact on the stability evaluated: 1) PLLs bandwidth, 2) radial grid line inductance value and 3) cross-feeder line inductance value. The principal findings include a positive impact on the stability from the increase of the PLLs bandwidth and a potential compromise of the system safe operation from the increase of the grid inductances.