Multi-Terminal HVDC System With Offshore Wind Farms Under Anomalous Conditions: Stability Assessment

Droop control is widely adopted to control Multi-Terminal high-voltage Direct Current (MTDC) systems with offshore wind farms. During permanent faults, the faulty line should be isolated promptly to preserve a high reliability of the MTDC system. This paper examines the MTDC system performance following a faulty line outage. This study aims to identify the outage types that may lead to a complete loss of system voltage stability and the outages that may have a secondary effect on the system. Moreover, strategies for dealing with outages that may lead to a complete shutdown of the system are also presented. Furthermore, the ranges of droop gains' values that can be employed following fault occurrence to preserve system transient stability are studied. Different scenarios are explored during faulty conditions such as surplus and sparsity of wind power, line overcurrent, outage of lines connected to wind farms, and outage of lines connected to AC grids to validate this study. MATLAB/Simulink platform has been employed to elucidate the presented concept.