Power system damping controls are essential for maintaining the stability and reliability of electric grids. They help to reduce the oscillations and fluctuations in the voltage, frequency, and power flow that can result from disturbances or faults. In this article, you will learn how to design effective power system damping controls using some basic principles and techniques.
The first step in designing power system damping controls is to identify the modes of oscillation that affect the system. These are the natural frequencies and shapes of the dynamic response of the system to disturbances. You can use various methods to find the modes of oscillation, such as eigenvalue analysis, modal analysis, or frequency domain analysis. The modes of oscillation can be classified into local, inter-area, or global modes, depending on the spatial distribution of the generators and loads involved.
Devices such as Flexible AC Transmission Systems (FACTS), and Battery Energy Storage Systems (BESS) could be used for injecting active power into the power system network to cancel/reduce the effect of damping. The location where these control systems are installed in the power system network is crucial and would require an adequate power system study to get an optimum solution. As a rule of thumb, the active power injectors are usually installed closer to the generator bus in the power system
The next step is to select the appropriate control devices and signals that can provide damping to the modes of oscillation. The most common control devices are power system stabilizers (PSS), which are installed in the excitation systems of synchronous generators, and flexible alternating current transmission systems (FACTS), which are power electronic devices that can control the voltage, impedance, or phase angle of transmission lines. The control signals are the inputs to the control devices that reflect the oscillatory behavior of the system. The most common control signals are speed deviation, power deviation, or voltage deviation.
The final step is to design the control parameters and settings that can optimize the performance and robustness of the power system damping controls. The control parameters include the gain, time constants, phase compensation, and filters of the control devices. The control settings include the selection of the control mode, the coordination of multiple control devices, and the tuning of the control parameters. You can use various methods to design the control parameters and settings, such as root locus, Nyquist, or Bode plots, optimization algorithms, or simulation tools.
Before implementing the power system damping controls, you should test and validate their effectiveness and stability. You can use different types of tests, such as open-loop, closed-loop, or small-signal tests, to evaluate the performance of the control devices and signals. You can also use different types of validation methods, such as transient stability analysis, modal analysis, or frequency response analysis, to verify the impact of the control parameters and settings on the system dynamics and stability.
After implementing the power system damping controls, you should monitor and maintain them regularly. You should check the status and operation of the control devices and signals, and update the control parameters and settings if necessary. You should also monitor the system conditions and performance, and detect any changes or anomalies that may affect the damping of the modes of oscillation. You should also perform periodic tests and validations to ensure the reliability and security of the power system damping controls.
To learn more about power system damping controls, consider exploring resources such as Power System Stability and Control by P. Kundur, Power System Dynamics: Stability and Control by K. R. Padiyar, Power System Oscillations by G. Rogers and Q. Wang, Power System Damping Controller Design by E. Larsen and D. Swann, or Power System Stabilizer and FACTS Controller Design by N. Martins and J. Pecas Lopes. Each of these texts offers an in-depth understanding of the topic with detailed explanations and insights.