Availability assessment of voltage source converter HVDC grids using optimal power flow‐based remedial actions

Abstract

This study proposes a methodology for assessing the availability of voltage source converter high-voltage direct current (HVDC) grids based on the enumeration methodology of contingency analysis with N − 2 criteria and makes contributions in the computation of remedial actions and the definition and computation of reliability indices applied for HVDC grids. Thus, this study proposes the computation of remedial actions based on an optimal power flow, looking to maintain power exchanges between HVDC and high-voltage alternating current grids, when a contingency occurs on the HVDC grid and converter stations or HVDC lines are out of their operating limits. On the other hand, an HVDC grid has the function of injecting and extracting power from AC interconnected zones, and then traditionally used nodal reliability indices must be modified to indices that reflect the performance of the HVDC network to fulfil its function of interconnection of systems. This study defines two sets of availability indices applicable to HVDC grids: (i) loss of power and energy extracted from the DC grid to the AC zones and (ii) loss of power and energy injected to AC zones from the DC grid. The proposed methodology is applied to perform the availability assessment of the CIGRE B4 DC grid test system and the results are presented.