Ring busbar differential protection scheme based on inverse-time principle for closed-loop offshore-platforms power systems

The closed-loop power system has the advantages of energy saving, emission reduction and improving efficiency of the entire offshore-platform. It has become the preferred alternative for dynamic positioning offshore-platform power systems which require high reliability in complex and harsh environment. However, due to the intercoupling between the distribution boards of the closed-loop power system, the fault will affect the adjacent segment which result in the challenges of diagnosing faulty distribution board. Regarding the difficulties in coordination between the upper and lower levels of protection, the concept of core layer and regional layer in the closed-loop offshore-platform power system is introduced. To prevent the blackout of whole offshore-platform, this paper proposes a ring busbar differential protection scheme that enables the adjacent distribution board to serve as the backup protection for the faulty distribution board. This busbar differential protection also introduces inverse-time principle which allows for adaptive adjustment of the operation time based on the severity of fault. The closed-loop offshore-platform power system is built in Matlab / Simulink and the results show that the protection scheme can quickly and accurately remove the faulty distribution board which can ensure the safety and reliability for the closed-loop power system of offshore-platforms.