TY - JOUR
T1 - Stability-Oriented Minimum Switching/Sampling Frequency for Cyber-Physical Systems
T2 - Grid-Connected Inverters Under Weak Grid
AU - Wang, Rui
AU - Sun, Qiuye
AU - Zhang, Huaguang
AU - Liu, Lei
AU - Gui, Yonghao
AU - Wang, Peng
PY - 2022/2
Y1 - 2022/2
N2 - Although the cyber-physical system stability is widely studied, scholars focus more on system stability with communication time delay. Therein, grid-connected inverters with the digital control system are regarded as one simplest and typical cyber-physical system. Meanwhile, the switching/sampling frequency of the inverter is always selected as low as possible from an efficiency viewpoint, resulting in unavoidable delay time. This delay time is apt to cause the system instability, which is more prone to severity under weak grid. To this end, this paper provides a minimum switching/sampling frequency for grid-connected inverters. Firstly, the system impedance model with equivalent delay time is constructed, which is based on padé approximate approach. This equivalent delay time consists of three parts, i.e., sampling delay time in cyber/physical level, calculation delay time in cyber level and pulsewidth modulation delay time in physical level, which reflects the cyber-physical interaction impact. Furthermore, the stability forbidden criterion is applied to make the switching/sampling frequency solving process become Hurwitz matrix identification problem through space mappings. Based on these space mappings, an adaptive step search approach is adopted to obtain the minimum switching/sampling frequency. Finally, the proposed approach can well evaluate the system stability under different frequencies through simulation and experiment.
AB - Although the cyber-physical system stability is widely studied, scholars focus more on system stability with communication time delay. Therein, grid-connected inverters with the digital control system are regarded as one simplest and typical cyber-physical system. Meanwhile, the switching/sampling frequency of the inverter is always selected as low as possible from an efficiency viewpoint, resulting in unavoidable delay time. This delay time is apt to cause the system instability, which is more prone to severity under weak grid. To this end, this paper provides a minimum switching/sampling frequency for grid-connected inverters. Firstly, the system impedance model with equivalent delay time is constructed, which is based on padé approximate approach. This equivalent delay time consists of three parts, i.e., sampling delay time in cyber/physical level, calculation delay time in cyber level and pulsewidth modulation delay time in physical level, which reflects the cyber-physical interaction impact. Furthermore, the stability forbidden criterion is applied to make the switching/sampling frequency solving process become Hurwitz matrix identification problem through space mappings. Based on these space mappings, an adaptive step search approach is adopted to obtain the minimum switching/sampling frequency. Finally, the proposed approach can well evaluate the system stability under different frequencies through simulation and experiment.
KW - adaptive step search approach.
KW - Circuit stability
KW - Cyber-physical system
KW - Cyber-physical systems
KW - Delays
KW - grid-connected inverter
KW - Inverters
KW - minimum switching/sampling frequency
KW - Power system stability
KW - Stability criteria
KW - Switches
UR - http://www.scopus.com/inward/record.url?scp=85119620412&partnerID=8YFLogxK
U2 - 10.1109/TCSI.2021.3113772
DO - 10.1109/TCSI.2021.3113772
M3 - Journal article
SN - 1549-8328
VL - 69
SP - 946
EP - 955
JO - I E E E Transactions on Circuits and Systems Part 1: Regular Papers
JF - I E E E Transactions on Circuits and Systems Part 1: Regular Papers
IS - 2
ER -