Trail of FGMO in BD

Trail of FGMO in BD
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The Trail of FGMO in BD take off on April 8, 2016 to October 29, 2016, and kept the sparks flying for a whole month!

Timeline if FGMO trail in BD

  • 1st trail : 08 April 2016 for 02 hours.
  • 2nd trial : 06 August 2016 for 08 hours.
  • 3rd trail: 29 October 2016 and continued for 01 month.

Trail in BD

  1. Trial Capacity: In Bangladesh , FGMO trials were conducted with 7-10 plants to provide 300-400 MW of spinning reserve. Total capacity of plants in FGMO was 1400-1900 MW.
  2. Plant Diversity: Different types of plants – gas turbines, combined cycle, hydro – participated in the trials. Their individual responses to frequency changes were analyzed.
  3. Frequency Band: FGMO trials showed the system frequency could be maintained within 50±0.5 Hz band compared to 48.9 – 51.4 Hz on normal days.
  4. Energy Loss Reduction: Energy losses from high frequency operation reduced by 2200 MWh/day. Under frequency load shedding also declined by 81%.

Power plants in FGMO trail in Bangladesh

In FGMO, the governor is allowed to respond automatically to frequency changes based on its droop setting. Droop determines how much the plant output changes for a given frequency deviation. Typically droop is 4-6% for thermal plants and 2-3% for hydro units.

  • Most plants don’t participate in automatic frequency control.
  • No secondary/tertiary control like Load Frequency Control or AGC
  • Large load fluctuations from industrial loads
  • Old generators with governor system problems
  • Plants operating in wrong control mode.
  • Lack of fast load management

Responses from Different Power Plants in bd

Natural gas driven gas turbine (Sikalbaha Plant)

Capacity150 MW
FuelNatural gas
Ramp Rate11 MW/Min
Set Point at 50Hz100 MW
Regulating Range-33.3% to +33.3%
trail of fgmo in bd
Md. Adil Chawdhury. “An Endeavor of Frequency Regulation by Free Governor Mode of
Operation in Bangladesh Power System

During the test, the output of Sikalbaha GT varied from 73 MW to 123 MW with the variation of system frequency. The plant’s output exhibited a wide range of variation with frequency changes, bypassing the governor. When the system frequency increased to 50.46 Hz, the plant’s output reduced to 75 MW. Conversely, when the system frequency decreased to 49.58 Hz, the plant’s output increased to 123 MW.

Natural gas driven CCPP (RPCL plant)

Test Results for 210 MW Combined Cycle Power Plant (CCPP) Running on Natural Gas:

Power Output210 MW
Gas Turbine Capacity4 x 35 MW
Steam Turbine Capacity1 x 70 MW
GT-1/2 Unit Drop4.2%
GT-3/4 Unit Drop3.5%
Set Power during Tests150 MW at 50 Hz
Regulation Range-28.5% to +28.5%
Output Range during FGMO Test112 MW to 156 MW
Md. Adil Chawdhury. “An Endeavor of Frequency Regulation by Free Governor Mode of
Operation in Bangladesh Power System

HSD fried CCPP (Summit Meghnaghat)

Total Capacity305 MW
Generating Units2 x 110 MW GT, 1 x 85 MW ST
Droop (GT)10%
Droop (ST)4.5%
Plant Set Point280 MW @ 50 Hz
Spinning Reserve25 MW
Regulating Range-8.2% to +8.2%
FGMO Test Output Range260 MW to 295 MW
Md. Adil Chawdhury. “An Endeavor of Frequency Regulation by Free Governor Mode of
Operation in Bangladesh Power System

This table summarizes the key specifications and parameters of the independent power producer (IPP) with a liquid fuel (high-speed diesel) driven Combined Cycle Power Plant (CCPP).

Response of different type of plants

  • Gas turbines showed excellent fast response
  • Steam turbines had good initial but slower response
  • Combined cycle response depended on GT/ST combinations
  • Hydro units had slower initial but excellent long-term response

Results of the FGMO (Free Governor Mode of Operation) test

Stable system frequency:

  • During the FGMO tests with 7-10 power plants operating in FGMO mode, the system frequency remained stable within a narrow range compared to normal days.
  • On a normal day in August, the frequency varied from 48.90 to 51.4 Hz.
  • On 06 August 2016 (during the 8-hour test), the frequency remained within 49.58 to 50.54 Hz despite contingencies.
  • On 29 October 2016 (during the final trial), the frequency variation was reduced to 0.9 Hz (49.61 to 50.61 Hz), and the average frequency decreased from 50.61 Hz to 50.11 Hz, indicating better frequency discipline and energy saving.
trail of fgmo in bd

Reduction of energy loss for high system frequency:

  • On 06 August 2016 (8-hour test), approximately 800 MWh of energy was saved compared to a normal day due to reduced high-frequency energy loss.
  • On 29 October 2016 (full-day test), it was estimated that approximately 2200 MWh of energy could be saved for the whole day with 7-10 plants running in FGMO mode, translating to potential cost savings of USD 125,000 to 150,000 per day.
Trail of fgmo in bd
Md. Adil Chawdhury. “An Endeavor of Frequency Regulation by Free Governor Mode of
Operation in Bangladesh Power System

Quality power due to reduction of power interruption and SCADA operations:

  • During the one-month final trial, under-frequency operations were reduced by 81%, and SCADA operations on 33 kV feeders for load shedding were reduced by 90%.
  • Power interruptions to consumers were remarkably reduced, ensuring consumer satisfaction.

Increased system reliability under contingency conditions:

  • During the FGMO test hours, the system frequency remained within 1.0 Hz even when contingencies occurred, such as tripping of 50 MW generating units, forced shutdown of a 50 MW hydro unit, 128 MW load rejection, etc.
  • The impact of fluctuating loads (e.g., arc furnaces) was remarkably dampened when the system was running on FGMO.

October 2016 FGMO trial lessons

Important feedback from the NLDC and power plant includes:

  • Positive feedback from gas turbines in base load (temperature control) worsens frequency control issues.
    Steam turbine trips resulted from frequency-responsive gas turbines and fluctuations in steam temperature or pressure.
  • Sudden output variations produced fuel pressure fluctuations, gas pressure instability, and frequent safety valve operation.
  • Certain operation levels of inlet guide vanes led to excessive cycling.
    Among other major results, numerous generator governors did not operate, indicating improper settings.
  • Some generators lack the ability to enable FGMO mode on their control desks.
  • Governors who participated in the experiments had lower energy levels due to providing FGMO range.
  • Generators preferred constant frequency for streamlined plant operation.

Major Benefits Observed from FGMO Trials

  • Reduced frequency fluctuations within 50±0.5 Hz band
  • Lowered energy losses from over frequency
  • Cut under frequency load shedding events
  • Improved reliability under contingencies

FGMO proved highly effective for Bangladesh grid frequency control at minimal cost. It enables larger power plants and renewable energy integration for a clean, reliable electricity system.


Md. Adil Chawdhury. “An Endeavor of Frequency Regulation by Free Governor Mode of
Operation in Bangladesh Power System
.” IOSR Journal of Electrical and Electronics
Engineering (IOSR-JEEE) 12.4 (2017): 75-87

Bangladesh Power System Reliability and Efficiency Improvement Project final report 4 May 2017

Report of the Committee on Free Governor Mode Operation of Generating Units


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