Patent ID: 9575138
Date: 2017-02-21
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 using a Hardware-in-the-Loop (HIL) simulation system, the power system comprising a source side and a load side from a perspective of the power electronic-based component, wherein the power electronic-based component is selected from a solid state transformer (SST), a machine drive and an inverter; 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 injecting a voltage of about 0.5 to about 1 percent of a nominal voltage of the power system at the load side, wherein perturbing the power system comprises perturbing the source side and the load side of the power electronic-based component simultaneously; measuring a current and a voltage at the source side to generate a measured source side current and a measured source side voltage and measuring a current and a voltage at the load side to generate a measured load side current and a measured load side voltage; determining a phase of the power system using single-phase Phase Lock Loop; transforming the measured source side current and the measured source side voltage and the measured load side current and the measured load side voltage to a d-q reference frame using the determined phase of the power system, to generate a transformed time-domain source side current value and a transformed time-domain source side voltage value and a transformed time domain load side current value and a transformed time-domain load side voltage value; transferring the transformed time-domain source side current value to a frequency-domain source side current value, transferring the transformed time-domain source side voltage value to a frequency-domain source side voltage value, transferring the transformed time-domain load side current value to a frequency-domain load side current value and transferring the transformed time-domain load side voltage value to a frequency-domain load side voltage value using Fourier transforms; calculating a frequency-domain return-ratio matrix in the d-q reference frame using the frequency-domain source side current value and the frequency-domain source side voltage value and the frequency-domain load side current value and the frequency-domain load side voltage value; plotting a Nyquist contour of a component using the frequency-domain return-ratio matrix; evaluating small-signal stability of the power system using stability criteria; and preventing instabilities of the power system based upon the evaluation of small-signal stability of the power system using stability criteria.