A rough summary of frequency stability and control in Power Systems

1. Frequency
Control of Power
Systems
EN 304 Course Project
Group-09
16D170022
16D170026

2. Types of Frequency Regulation
● Flat frequency regulation
○ Individual generating sources cater to increase/ decrease in demands of their respective
loads
● Parallel frequency Regulation
○ Any Change in overall loading is distributed through a control algorithm to multiple
sources so as to maintain frequency and reduce fatigue
● Flat-tie line loading
○ Individual generators supply to local loads while ensuring that power flow between two
generation-load systems is constant

3. Generation Control loops
-Control of turbine input (steam, gas, water)
● Load Frequency Control (LFC)
○ Speed governing system
■ Flyball speed governor
○ Rotating components (Turbine and
Generator)
○ Load and Power system
● Automatic Generation Control (AGC)
Flyball speed governor

4. Load Frequency Control (Primary control)

5. Load Frequency Control (Block Diagram)

6. Power system Control: Governor Response

7. Automatic generation control (AGC)
Three major objectives:
1. To hold system frequency at or very close
to a specified nominal value (e.g.,50 or 60 Hz).
2. To maintain the correct value of interchange power between control areas.
3. To maintain each unit’s generation at the
most economic value.

8. Primary and Secondary control in Power Systems
• Consider a turbine in a grid controlled by droop control.
• Primary control:
• Secondary control (voltage deviation compensation)

9. IEEE 9 bus
● 12 buses
● 6 transformers
● 6 transmission lines
● 3 synchronous machines
● 3 constant impedance loads
● Total load demand is 315 MW and 115 MVAr

10. Phase Locked Loop (PLL)
● If phase difference is constant, frequencies are the same.
● Building Blocks:

11. References
1. http://nptel.iitm.ac.in
2. Allen J. Wood, Bruce F. Wollenberg, Gerald B. Sheblé - Power Generation, Operation and
Control-Wiley-Interscience (2013)
3. [3] Power system balancing with large scale wind power Integration: A. Suwannarat , B. Bak-Jensen and Z. Chen
4. [4] Allen J. Wood, Bruce F. Wollenberg, Gerald B. Sheblé - Power Generation, Operation and Control-Wiley-Interscience (2013)