Transient recovery voltage on the 13.8 kV subsea cable feeding a Saudi Aramco offshore platform

One of Saudi Aramco´s gas exploration expansion plans consists of powering an offshore platform via a 13.8 kV, 56 km subsea cable. Under various loading conditions on the offshore platform, voltage fluctuation and control becomes problematic. The installation of a 13.8 kV shunt capacitor bank (SCB) and shunt reactor bank (SRB), was initially introduced to remedy voltage control. During transient analysis, under faulty conditions adjacent to the SCB, the 13.8 kV circuit breaker (CB) will be exposed to an excessive transient recovery voltage (TRV) exceeding the limit of the 13.8 kV CB. The harmonic analysis also indicated high values on the 5^th, 7^th and 11^th harmonic voltage distortion. A comprehensive power system analysis was undertaken to investigate mitigation measures. The installation of a Static Synchronous Shunt Compensator (STATCOM) was retained as it will eliminate the need of a SCB and SRB with the high TRVs and resolve the harmonic problems.