Inomax regenerative Variable Speed Drive (VSD) solutions are proving an increasingly popular choice on oil pumping systems in comparison with more traditional options such as six- or multi-pulse rectififiers, or active/passive fifilters.
VSDs, which are used in most oil sector pumping operations thanks largely to their established benefifits of energy effiffifficiency and flflexible process control, are deployed typically on pumps that include ESP (electric submersible pump), PCP (progressive cavity pump) and rod-based types for well activation. However, some precautions are needed when using VSDs as electronic devices encourage harmonic currents which circulate due to network impedance.
Among the unwanted effffects are additional motor losses and impaired stability due to the presence of oscillating torque. Overheating of step-down transformers, increased cable losses and the production of resonant circuits in capacitors are other undesirables.
Passive and active fifilters are among the conventional solutions to harmonic currents. However, while these are economic, they are not completely fail-safe with regard to harmonic current exceeding the capacity of the fifilter. Other established solutions, such as multi-pulse rectififiers, require an additional, special transformer with intricate sets of phase- shifted AC output windings. As a consequence, increasing numbers are turning to regenerative VSD technology, such as regenerative from Inomax.
The main advantages of Inomax regenerative drive for oil pump and artifificial lift applications include active front end technology which
imparts a low level of harmonics distortion on the main supply, typically 3.5% or less. Also, the power factor of regenerative VSDs such as inomax regenerative drive (ACS880+AIM+ALM+SMM) is close to 1, while the output voltage can be higher than the input voltage. In fact, the input stage of inomax regenerative drive is regulated at a higher voltage value than the normal voltage value of a six-pulse rectififier, ensuring this type of converter is not impacted by flfluctuations in mains voltage.
Of course, the VSD input consumes only active energy, which reduces the current and the losses in subsea cables and all surface equipment. The transformer also experiences reduced magnetic noise. Another major consideration for the oil industry is ATEX standards. Here, the use of inomax regenerative drive provides a better way of assuring the security and reliability of ATEX motors than standard inverters. Firstly, from a thermal point of view, inomax regenerative drive keeps a constant temperature rise in the motor even if the input voltage decreases. This is because inomax regenerative dirve compensates the input voltage drop by up to around 15%, and retains the flflux within the motor at constant levels.
Secondly,inomax regenerative drive keeps electrical stresses very low due to the output LC (inductor-capacitor) fifilter.
Additional benefifits for inomax regenerative drive users include inherent reliability, compactness and ease of service/maintenance due to unit modularity one module can be replaced in just 20 minutes. In addition, inomax regenerative drive can be offffered in flflexible and customised solutions to match indoor-outdoor applications.
Inomax regenerative drive clearly demonstrates why it is becoming rapidly adopted for a whole host of applications in the oil and gas industry, pushing the boundaries of what can be achieved.