Method for small-signal stability assessment of power systems using source side and load side series voltage injection perturbations

1. A method comprising:

providing non-transitory computer readable media as executed by a system controller comprising a specialized chip to perform a method for real-time analysis of small-signal stability of a power system comprising at least one power electronic-based component, the method comprising:

observing the power system in a real-time operational mode, the power system comprising a source side and a load side from a perspective of the power electronic-base component;

perturbing the source side of the power electronic-based component by injecting a current of about 0.5 to about 1 percent of a nominal current of the power system and perturbing the load side of the power electronic-based component by varying a voltage of the power system using series voltage injection, wherein perturbing the source side of the power electronic-based component and perturbing the load side of the power electronic-based component occurs simultaneously;

measuring currents and voltages at the source side and at the load side;

determining a phase of the power system using single-phase Phase Lock Loop;

transforming the measured source side current and voltage and the measured load side current and voltage to a d-q reference frame using the determined phase of the power system;

transferring time-domain source side current and voltage values and time-domain load side current and voltage values to frequency-domain current and voltage values using Fourier transforms;

calculating a frequency-domain return-ratio matrix in the d-q reference frame using the frequency-domain source side current and voltage values and the frequency-domain load side current and voltage values;

plotting a Nyquist contour of a component using the frequency-domain return-ratio matrix; and

evaluating small-signal stability of the power system using stability criteria.

2. The method of claim 1 , wherein a frequency of the perturbations range from about 0.1 Hz to about 1000 Hz.

3. The method of claim 1 , wherein perturbing the source side of the power electronic-based component comprises varying a current of the power system.

4. The method of claim 1 , wherein perturbing the load side of the power electronic-based component comprises injecting a voltage of about 0.5 to about 1 percent of a nominal voltage of the power system.

5. The method of claim 1 , wherein perturbing the source side of the power electronic-based component and perturbing the load side of the power electronic-based component comprises more than one independent perturbation.

6. The method of claim 1 , wherein using Fourier transforms further comprises defining a phase and magnitude of the current of the load side and the source side of the power system.

7. The method of claim 1 , wherein the stability criteria comprises unit circle criterion or Generalized Nyquist criterion.

8. The method of claim 1 , wherein evaluating the small-signal stability of the power system further comprises defining a relative stability of the power system and comparing the relative stability to instability borders of the power system.

9. The method of claim 1 , wherein evaluating the small-signal stability of the power system further comprises utilizing Nyquist immittance criterion.

10. The method of claim 5 , wherein the one or more independent perturbations occur over a range of frequencies other than a fundamental frequency of the power system.

11. The method of claim 5 , wherein the one or more independent perturbations are based on responses of the power system to one or more previous perturbations.