Harmonics in Offshore Electrical Power System
- Balesh Kumar (Kvaerner E&C) | Vinod K. Sethi (Kvaerner E&C Singapore Pte Ltd) | Saibal Bhattacharjee (Kvaerner E&C)
- Document ID
- Society of Petroleum Engineers
- SPE Projects, Facilities & Construction
- Publication Date
- March 2006
- Document Type
- Journal Paper
- 1 - 6
- 2006. Society of Petroleum Engineers
- 4.1.2 Separation and Treating, 4.2.3 Materials and Corrosion, 1.6 Drilling Operations, 4.5 Offshore Facilities and Subsea Systems, 3.1.2 Electric Submersible Pumps, 3.1 Artificial Lift Systems, 1.6.9 Coring, Fishing, 5.4.6 Thermal Methods, 1.10 Drilling Equipment
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Recently, electrical submersible pumps (ESPs) have become widely used in depleting oil fields with low pressure (dead crude) and in deep wells with marginal pressure to achieve oil production. These types of ESPs are variable-speed drives (VSDs) and operated at variable voltages and frequencies to optimize production. The introduction of a large amount of ESPs driven by VSDs into an electrical power system of an offshore oil field that is electrically weak leads to distortion of voltage and current profile beyond acceptable limits, thereby producing harmonics. The more distortion there is in the waveforms, the higher the harmonics.
The concept of harmonics, along with their impact and mitigation measures to be exercised in an offshore power system, is discussed in this paper. Furthermore, a method statement is provided for sizing the active harmonic filter (AHF). An attempt is made to arrive at an empirical relationship for an AHF rating in kVAR for offshore electrical power systems, but it is not yet well documented. A case study of harmonic analysis for an integrated offshore field in the South China Sea has been discussed.
The information contained in this paper is useful for design engineers as well as operators handling electrical power systems for offshore oil fields with significant amounts of nonlinear loads or VSD loads. This enables them to predict the requirement of harmonic treatment in offshore electrical power systems. It also helps them to take early action at the planning/design stage to avoid probable damage to equipment or loss of power resulting from harmonics and to conduct detailed harmonic analysis.
A highly reliable, high-quality power supply is of paramount importance in offshore oil and gas installations. Power outages and poor power quality have resulted in considerable cost in these installations. Power quality is defined in terms of voltage variation, voltage transients, and voltage waveform. One of the power-quality characteristics lies in its waveform. It is preferred to have a power-supply waveform as close as possible to that of a pure sine wave. In reality, the power-supply waveform is never purely sinusoidal. The power-supply waveform gets distorted because of nonlinear loads, rectifiers, VSDs, arc furnaces, fluorescent tubes, discharge lamps, fan regulators, and other power-distribution equipment. The waveform distortion is identified as a combination of fundamental sinusoidal waveforms and harmonics.
Harmonics are pollutants and impact the quality of power and the life of the electrical equipment. They need to be contained and can be contained by adopting the mitigation measures discussed in this paper. It has long been recognized that harmonic currents and voltages are highly detrimental to electrical power equipment and systems. Their presence can damage equipment and disrupt the production process, thereby costing the offshore oil and gas operators tremendously.
|File Size||752 KB||Number of Pages||6|
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