Managing harmonics and resonance with active harmonic filters in an offshore ring main oil field

An international oil company acquired and modified the power supply for a number of offshore oil platforms in one field to conserve operating costs for fuel for the generators. This was accomplished by installation of a 33 kV undersea cabling system between the platforms. The resultant harmonic voltage distortion at the generators and on each platform created major safety concerns due to the explosion proof environments on the platforms and the large voltage resonance potential. The use of nonlinear devices has made the electrical world a lot more complex. AC and DC motor speed controls contribute to the harmonic current and voltage distortion directly and are widely used on off shore platforms for many uses. There are both medium and low voltage drives employed. Active harmonic filters bring a new perspective for solving the problems associated with harmonic distortion and displacement power factor correction. But not all active harmonic filters are created equal. This paper reviews the reasons for the excessive harmonic distortion and presents the first step to resolving the problem.