US 11,656,297 B2
Power electronic instrument for continuously monitoring stability and stabilizing a DC microgrid
Rohail Hassan, Logan, UT (US); Hongjie Wang, North Logan, UT (US); and Regan A. Zane, Hyde Park, UT (US)
Assigned to Utah State University, Logan, UT (US)
Filed by Rohail Hassan, Logan, UT (US); Hongjie Wang, North Logan, UT (US); and Regan A. Zane, Hyde Park, UT (US)
Filed on Mar. 17, 2021, as Appl. No. 17/204,791.
Claims priority of provisional application 62/990,770, filed on Mar. 17, 2020.
Prior Publication US 2021/0293893 A1, Sep. 23, 2021
Int. Cl. G01R 31/40 (2020.01); G05B 19/042 (2006.01); H02J 1/00 (2006.01)
CPC G01R 31/40 (2013.01) [G05B 19/0428 (2013.01); H02J 1/00 (2013.01); G05B 2219/2639 (2013.01)] 20 Claims
OG exemplary drawing
 
1. An apparatus comprising:
a switching power converter comprising a control loop, the switching power converter connected to a direct current (“DC”) bus of a DC power system; and
a monitoring loop injected into the control loop, the monitoring loop comprising:
a sensor circuit configured to monitor voltage of the DC bus and current to the DC bus;
a small signal injector configured to produce a periodic signal comprising a variable amplitude and a variable frequency and to inject the periodic signal on a reference signal of the control loop;
a stability measurement circuit configured to vary a frequency input to the small signal injector until a fundamental component of the periodic signal has a frequency equal to a system minor loop gain crossover frequency of an impedance ratio of a converter closed loop output impedance and an impedance of the DC power system, the impedance ratio based on the monitored voltage and current; and
a measurement output circuit configured to output a DC power system stability margin at the system minor loop gain crossover frequency.