Frequency Control of Power Systems

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