Starter/Helper System

Variable speed drive system for LNG process optimization

GE Power Conversion offers variable speed drive systems specifically developed for LNG applications.

In starter/helper configuration, the motor can operate under 3 different modes:

  • Starter: allows a smooth starting of the compressor
  • Helper: provides additional power to the gas turbine if required, for example when the turbine output power is limited during summer, then maximizing the operating efficiency of the compressor
  • Generator: regenerates the excess of power during winter and sends it back to the grid

The use of electric motors to start or help the main turbine power supply allows the gas turbine to always perform at its optimal operating point. This in turn allows for optimal energy balance, continuous operation and stability of the whole system in possibly any situation.

Starter/Helper system


● Direct drive (2 poles, synchronous or induction)

● 3,000 rpm or 3,600 rpm depending on turbine speed

● Suitable for double shaft end in VSI + induction motor configuration


● Up to 47 MW with a single VSI drive panel

● Up to and 13,8 kV output motor voltage

● N+1 power cells redundancy


● Diode Front End except for generators mode

● Active Front End with reactive power generation & power factor control up to unit

● Transformer-less up to 13,8 kV for footprint, reliability and efficiency optimization and improved grid quality

We propose the complete system engineering including grid harmonics study and mechanical shaft analysis


  • High efficiency: 95%+
  • Full flexibility available in terms of power demand
  • Very high starting and operating reliability and availability: starting time <1 min
  • Emission-free solutions/Fit with environmental restrictions
  • Minimum maintenance period over life cycle
  • Low operation maintenance cost
  • Suitable for most areas, incl. with limited power availability
  • Real-time simulation for efficient commissioning