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Abstract:

A multi-terminal offshore HVDC grid can provide significant financial and technical benefits for the connection of offshore wind farms. The development of protection strategies for such systems has attracted a lot of attention. The aim of this work is to propose a method to perform a cost-benefit analysis (CBA) to compare such protection strategies. The method calculates the steady state limit violations in branch flow and node voltages in the connected AC grid as a result of DC grid protection. The cost of utilizing a particular strategy is determined in terms of cost of generator re-dispatch, which is obtained using an optimal power flow of hybrid AC/DC network. A comparison between selective and non-selective protection strategy is made based on the yearly operating costs. This comparison is essential as the non-selective protection strategy is expected to be cheaper to install (lower CAPEX) but yield higher reliability costs (higher OPEX).