Balancing Mechanisms: Keeping the Grid in Harmony
Exploring the automatic systems and manual controls that maintain grid frequency and stability
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Section 3 of 5The Balancing Control Hierarchy
Grid balancing operates on multiple timescales with different mechanisms for each level. Primary control responds within seconds to maintain frequency. Secondary control (AGC) corrects deviations over minutes. Tertiary control involves manual adjustments and market-based corrections over hours.
Automatic Generation Control (AGC) is the workhorse of grid balancing. It continuously monitors frequency and adjusts generation to keep the grid at exactly 60 Hz. AGC uses proportional-integral (PI) control algorithms to provide stable, responsive balancing without human intervention.
Control Hierarchy
Primary (0-30 seconds): Automatic governor response on generators
Secondary (30 seconds - 15 minutes): AGC adjusts participating generators
Tertiary (15+ minutes): Manual dispatch and economic optimization
Interactive AGC Control Simulator
Automatic Generation Control (AGC)
Current Frequency
60.000 Hz
Target Frequency
60.000 Hz
Control Error
0.0 mHz
Generation Adjustment
0.0 MW
Real-Time Frequency Monitoring
Apply System Disturbances
How AGC Works
Proportional Control: Responds immediately to frequency deviations
Integral Control: Eliminates steady-state errors over time
Deadband: Prevents unnecessary adjustments for minor fluctuations
AGC maintains grid frequency within ±0.01 Hz of target