The control coefficient, often represented as a droop coefficient or gain parameter in frequency regulation systems, significantly affects the power system’s frequency behavior during severe disturbances by influencing the speed and magnitude of the system’s frequency response.
Effect of Control Coefficient on Frequency Regulation During Severe Disturbances
- Magnitude of Frequency Deviation:
A smaller control coefficient (droop or gain) results in a larger maximum frequency deviation when the system faces a power imbalance, meaning the system frequency can deviate more severely from its nominal value after a disturbance. Conversely, a larger control coefficient tends to reduce the maximum frequency deviation by enabling a more aggressive response to frequency changes. - Frequency Stability and Fluctuations:
Reducing the control coefficient degrades frequency stability, leading to bigger frequency fluctuations and a delayed frequency nadir (the lowest frequency point during disturbance). This means the system’s ability to stabilize frequency quickly is impacted adversely when the control coefficient is too low. - Quasi-Steady-State Frequency Deviation:
The control coefficient directly affects the steady-state frequency deviation after a disturbance. Increasing the control coefficient can increase the quasi-steady-state frequency deviation, while decreasing it can reduce steady-state deviation but potentially worsen transient behaviors. Therefore, there is a trade-off in tuning the coefficient. - Interaction with Other Parameters:
The control coefficient K works together with the droop setting R and system damping D. For instance, when K decreases due to reduced participation of renewable energy units like wind turbines, adjusting R can help maintain the desired frequency deviation setpoint. Proper tuning of these parameters is crucial for maintaining frequency regulation performance under severe disturbances. - Primary Frequency Control Contribution:
In interconnected grids, the power system frequency characteristic (represented by a coefficient similar to control coefficient) determines how much each control area contributes to primary frequency control following a disturbance. This coefficient influences how the system balances generation and load dynamically to stop frequency from drifting too far. - Enhanced Control with Energy Storage and Renewables:
Incorporating energy storage and wind power with appropriate control coefficients can provide additional frequency regulation capacity and inertia, improving frequency stability during disturbances. Optimizing these coefficients ensures coordinated response and reduces severe frequency deviations.
Summary Table of Control Coefficient Effects
| Aspect | Effect of Increasing Control Coefficient | Effect of Decreasing Control Coefficient |
|---|---|---|
| Maximum frequency deviation | Decreases | Increases |
| Frequency stability | Improves | Worsens |
| Frequency nadir delay | Decreases | Increases |
| Steady-state frequency deviation | Tends to increase | Tends to decrease |
| System frequency response speed | Faster | Slower |
| Coordination with droop R | Requires adjustment for optimal control | Requires adjustment for optimal control |
In summary, the control coefficient plays a critical role in frequency regulation during severe disturbances by determining the dynamic response and steady-state behavior of system frequency. Properly tuning this coefficient, often in coordination with droop settings and considering contributions from renewable energy and storage systems, is essential to maintain system stability and minimize frequency deviations under severe power imbalances.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/how-does-the-control-coefficient-affect-the-frequency-regulation-during-severe-disturbances/
