Some Recent Results on Direct Delay-Dependent Stability Analysis: Review and Open Problems

2018 ◽  
pp. 25-34
Author(s):  
Libor Pekař ◽  
Pavel Navrátil ◽  
Radek Matušů
Keyword(s):  
Stability Analysis ◽  
Open Problems ◽  
Delay Dependent ◽  
Delay Dependent Stability

New results on delay-dependent stability analysis for neutral stochastic delay systems

2013 ◽  
Vol 350 (4) ◽  
pp. 840-852 ◽  
Author(s):  
Bo Song ◽  
Ju H. Park ◽  
Zheng-Guang Wu ◽  
Ya Zhang
Keyword(s):  
Stability Analysis ◽  
Delay Systems ◽  
Stochastic Delay ◽  
Delay Dependent ◽  
Delay Dependent Stability

Gain-phase margins-based delay-dependent stability analysis of pitch control system of large wind turbines

2019 ◽  
Vol 41 (13) ◽  
pp. 3626-3636 ◽  
Author(s):  
Omer Turksoy ◽  
Saffet Ayasun ◽  
Yakup Hames ◽  
Sahin Sonmez
Keyword(s):  
Control System ◽  
Stability Analysis ◽  
Wind Turbines ◽  
Time Domain ◽  
Dynamic Performance ◽  
Pitch Control ◽  
Wide Range ◽  
Delay Dependent ◽  
Delay Dependent Stability ◽  
Large Wind

This paper investigates the effect of gain and phase margins (GPMs) on the delay-dependent stability analysis of the pitch control system (PCS) of large wind turbines (LWTs) with time delays. A frequency-domain based exact method that takes into account both GPMs is utilized to determine stability delay margins in terms of system and controller parameters. A gain-phase margin tester (GPMT) is introduced to the PCS to take into GPMs in delay margin computation. For a wide range of proportional–integral controller gains, time delay values at which the PCS is both stable and have desired stability margin measured by GPMs are computed. The accuracy of stability delay margins is verified by an independent algorithm, Quasi-Polynomial Mapping Based Rootfinder (QPmR) and time-domain simulations. The time-domain simulation studies also indicate that delay margins must be determined considering GPMs to have a better dynamic performance in term of fast damping of oscillations, less overshoot and settling time.

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