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Generator start system - constant frequency converter system

Generator Start up System

Static Frequency Converter (SFC) has long been integrated into MECO products. MECO has recently developed its domestically-produced system called MAPLCI.

SFC Advantages

  1. Reducing equipment and system complexity
  2. Allowing unlimited generation of varying frequencies
  3. Significantly reducing maintenance costs
  4. Increasing accuracy in supplying varying frequencies

General system description:


In gas-fired power plants, once the engine starts, the compressor does not accelerate fast enough to provide sufficient air to support combustion. To this end, a starter assists gas unit turbines to initially start. The starter system is an advanced frequency converter that converts the synchronous generator into a synchronous motor during the first minutes when the turbine and generator are gathering speed, and provides the initial starting power for the gas generator. This system is designed and manufactured by MECO to run the V94.2 gas turbine using an advanced SFC control system under the Siemens license. Thus, at first, after receiving electrical energy from the grid, the generator is used as an electric motor and the gas turbine is started. The SFC converts the AC input to DC power and converts it back into AC power within the frequency range required by the turbine speed in the start-up phase in order to adapt the input power provided to the generator as a starter. In fact, SFC is an AC/DC/AC converter with input frequency of50HZ and output frequency of zero to 35HZ. The start-up operation starts with SFC from zero speed or turning gear and continues to spin at 600 rpm with fuel injection, flame ignition and acceleration concurrent with mechanical energy production in the turbine until it spins at 2100 rpm and then shuts off. After the turbine reaches the rated speed, the generator, assumes its main task, which is electrical energy production.



  • Installation of driver system components such as thyristor racks, inductive reactor to eliminate output distortion and control equipment in separate panels to optimize system performance in terms of safety and noise immunity
  • Using optical fibers for better isolation and separation of the control field from the power field
  • Using control equipment such as AC motor drive, and SINAMICS GL150 to produce well-suited fire pulses for thyristor bridges using CU320 processor
  • Smooth operation of the starter system control and protection loops to reduce current fluctuations during start-up on the line side and preventing adverse effects on the feeder short circuit surface
  • Establishing signal communication between the start-upsystem and excitation via the Profibus protocol
  • Offering considerable efficiency savings for starting and switching between multiple generators through a single SFC via connecting to the cross-board system
  • Not requiring mechanical accessories on the rotor monitor and applying open and closed loop controllers on the SFC to increase its reparability
  • Enabling the turbine and generator acceleration in lower speeds using DC-link pulsing method
SFC start-up system specifications
DC-link output power 2.9MW
Rated power 3.7MVA
DC-link start-up current 1850A
Input voltage 1400V
DC-link voltage 1560V
Line thrystor type
Machine thrystor type
T1551 N52
T1551 N52
Rated loss 36kW
Circulating cooling air flow 7.200M3/h
Noise pollution intensity
Feeder frequency 50Hz
Feeder frequency 60HZ

Weight 2,400kg
DC-link single-line reactor
Rated current
Insulation voltage

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