Stability analysis of multi-terminal HVDC with diode rectifier connected offshore wind power plants

摘要

This paper addresses the detailed modeling and small-signal stability analysis of a multi-terminal high voltage direct current (HVDC) system including a large diode rectifier-connected off-shore wind power plant (WPP). The study covers both islanded and connected WPP operation with different control scenarios. Islanded WPP stands for non-conducting HVDC diode rectifier (DR) whereas in connected WPP operation the DR is conducting. The study of both modes is important as the WPP would be in one of these modes during normal operation.Variable off-shore ac-grid frequency and a dynamic diode rectifier model have been considered for adequate dynamic modeling. The proposed models have been validated against detailed PSCAD EMT simulations and have been used to carry out the small-signal stability analysis of the islanded and connected WPP with different scenarios. Moreover, the dynamic model is used to assess the system robustness against parametric uncertainties, communication delay and power level, ensuring the integration of the off-shore WPP into the on-shore electrical power system. This study also points out that adequate droop control of the HVDC grid has a larger impact on overall stability than the diode rectifier connected off-shore WPP controllers.