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

A method for real-time analysis of small-signal stability of a power system, the method comprising:

• providing non-transitory computer readable media having computer-executable instructions for performing a method of running a software program on a computing device, the computing device operating under an operating system, the method including issuing instructions from the software program 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 at the source side using shunt current injection 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 using shunt current injection and perturbing the load side of the power electronic-based component using series voltage injection 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 d−d component of the frequency-domain return-ratio matrix;
• and
• evaluating small-signal stability of the power system using stability criteria.