Patent ID: 9612293
Date: 2017-04-04
CPC Classifications: G01R

Claim:
1. 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, and perturbing the load side of the power electronic-based component by varying a voltage of the power system, wherein perturbing the source side of the power electronic-based component and perturbing the load side of the power electronic-based component occurs simultaneously and independently; 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 General Nyquist Criterion.