Open AccessModelling and stability assessment of the MMC‐HVDC energy interconnected system with the cyber delay of communication network
Author(s) -
Cao Jingming,
Dong Chaoyu,
Yu Xiaodan,
Wang Rui,
Xiao Qian,
Jia Hongjie
Publication year - 2021
Publication title -
iet energy systems integration
Language(s) - English
Resource type - Journals
ISSN - 2516-8401
DOI - 10.1049/esi2.12006
Subject(s) - control theory (sociology) , harmonics , high voltage direct current , computer science , modular design , controller (irrigation) , stability (learning theory) , transcendental equation , telecommunications network , transmission delay , converters , transmission (telecommunications) , voltage , mathematics , control (management) , engineering , telecommunications , differential equation , direct current , electrical engineering , machine learning , mathematical analysis , agronomy , artificial intelligence , biology , operating system
Modular multilevel converters (MMCs) are favoured in high voltage direct current (HVDC) systems because of huge energy transmission capacity and few harmonics. However, the complicated control and the intricate communication network introduce cyber delay that affects the system dynamics. The communication structure is discussed and delay components are studied. The authors derive the MMC‐HVDC system model considering the cyber delay effect. Padé approximation is utilised to transform the transcendental characteristic equation of the delay model into an algebraic equation so that the dynamics can be observed through the eigenvalues. The comparison between the established model and the simulation in Simulink validates the proposed model's accuracy. The exact delay margin and the root cause of losing the stability are also discussed. The results show that the model is able to obtain the delay margin with a tiny error caused by the omitted high‐order harmonics and the cyber delay destabilises the system by lowering the controller performances.