Influence of Subsea Cables on Offshore Power Distribution Systems

Subsea cable applications for the offshore power distribution systems create technical challenges in the system design, operation, and maintenance. Harmonic parallel resonance introduced by subsea cables is one of the main concerns. In this paper, parallel resonance is investigated for an offshore distribution system with lengthy subsea cables on four interconnected platforms. Variable frequency drives (VFDs) are the dominant loads on the platforms, which make up to 98% of the total load demands. Subsea cables create a complicated parallel resonance condition in the system. Several resonant frequency bands could interact with harmonic currents injected by VFDs. The ways to attenuate resonance and mitigate harmonics are discussed and compared. An optimized solution for harmonic mitigation is proposed for the system.