How can you measure the effectiveness of power system stabilizers?

1 Frequency response

One way to measure the effectiveness of PSS is to analyze the frequency response of the power system. Frequency response is the ability of the system to maintain a constant frequency under disturbances, such as load changes or faults. A well-designed PSS should enhance the frequency response by reducing the frequency deviations and the settling time. To evaluate the frequency response, you can use tools such as Bode plots, Nyquist plots, or modal analysis, which show how the system responds to different inputs and frequencies.

2 Time-domain simulations

Another way to measure the effectiveness of PSS is to perform time-domain simulations of the power system. Time-domain simulations are numerical methods that solve the differential equations that describe the dynamic behavior of the system. They can capture the transient and steady-state responses of the system to various scenarios, such as small or large disturbances, normal or emergency conditions, or different operating points. By comparing the simulation results with and without PSS, you can assess the impact of PSS on the system stability and performance.

3 Damping ratio

A third way to measure the effectiveness of PSS is to calculate the damping ratio of the power system. Damping ratio is a dimensionless parameter that indicates how quickly the system returns to equilibrium after a disturbance. A higher damping ratio means that the system has more damping and less oscillations, while a lower damping ratio means that the system has less damping and more oscillations. A well-designed PSS should increase the damping ratio of the system by providing supplementary control signals to the generators. To calculate the damping ratio, you can use methods such as eigenvalue analysis, root locus, or Prony analysis, which estimate the damping characteristics of the system modes.

4 Field tests

A fourth way to measure the effectiveness of PSS is to conduct field tests on the power system. Field tests are real-world experiments that apply disturbances to the system and measure the responses of the system variables, such as frequency, voltage, or power. They can provide the most accurate and realistic evaluation of the PSS performance, as they account for all the uncertainties and nonlinearities of the system. However, field tests are also more complex and costly than other methods, and they may pose some risks to the system operation and security. Therefore, they should be carefully planned and executed, and complemented by other methods.

5 Performance indices

A fifth way to measure the effectiveness of PSS is to use performance indices that quantify the quality of the system response. Performance indices are numerical values that reflect how well the system meets certain criteria, such as stability, robustness, or efficiency. They can be used to compare the performance of different PSS designs or settings, or to optimize the PSS parameters. Some examples of performance indices are the integral of time-weighted absolute error (ITAE), the integral of squared error (ISE), the damping factor, or the damping torque coefficient.