US 9,316,701 B1Granted

Real-time small-signal stability assessment of power electronic-based components in contemporary power systems

AssigneeThe Florida State University Research Foundation, Inc.

InventorsMohamadamin Salmani, Chris S. Edrington

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Abstract

A novel method for real-time small-signal stability analysis for power electronic-based components in a power system. The method is based on impedance measurement techniques and Generalized Nyquist Criterion. The method is capable of real-time application. The method may be used to monitor a system in real-time by perturbing the system persistently and utilizing the system's responses to calculate source/load impedance in time-domain and based on d-q impedance measurement theory. Time-domain results may be transferred to frequency-domain results by taking advantage of a fast Fourier transform algorithm (or optionally discrete Fourier transformer for discrete systems) and monitoring the system's stability by obtaining a Nyquist contour and employing Generalized Nyquist Criterion or unit circle criterion.

Claims18

Dependent claims

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-based 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;
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 using the frequency-domain return-ratio matrix;
and
evaluating small-signal stability of the power system using stability criteria.

8 more elements

A method comprising:

providing non-transitory computer readable media as executed 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-based 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 using shunt current injection;
perturbing the load side of the power electronic-based component by varying a voltage of the power system using series voltage injection;
measuring voltages and currents due to perturbations 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 by Phase Lock Loop;
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 using the frequency-domain return-ratio matrix;
and
evaluating small-signal stability of the power system using stability criteria.

9 more elements

Dependencies are inferred from the claim text.

Facts

Application: 14/702,063Filed 1 May 2015 · us provisional application
Priority: 6 May 2014
Granted: 19 Apr 2016
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

G01R 31/40
Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by…
G01R 19/2506
Using digital measurement techniques: arrangements for conditioning or analysing measured signals, e.g. for indicating peak values ; Details…
G01R 19/2513
Using digital measurement techniques: arrangements for monitoring electric power systems, e.g. power lines or loads; Logging
G01R 27/00
Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom