Open AccessOptimised design of DC‐side smoothing reactors in meshed multi‐terminal HVDC systems based on symmetrical bipolar modular multilevel converter
Author(s) -
Li Chengzhu,
Lin Lei,
He Zhen,
Xu Chen
Publication year - 2017
Publication title -
the journal of engineering
Language(s) - English
Resource type - Journals
ISSN - 2051-3305
DOI - 10.1049/joe.2017.0524
Subject(s) - smoothing , fault (geology) , modular design , transient (computer programming) , correctness , computer science , control theory (sociology) , power (physics) , fault current limiter , electric power system , engineering , electronic engineering , algorithm , physics , control (management) , computer vision , operating system , quantum mechanics , artificial intelligence , seismology , geology
Compared with the radial modular multilevel converter multi‐terminal direct current (MMC‐MTDC) system, the meshed system is with higher power supply reliability and flexibility. However, its vulnerability against DC fault is a significant issue. When a DC fault occurs, the DC‐side smoothing reactor will limit rising rate of the fast‐developing fault current, and then DC current breakers can isolate the fault. This paper proposes a method to optimise the design of smoothing reactors in meshed MTDC system. Firstly, fault characteristics of fault currents and the whole system based on different smoothing reactors are proposed through theoretical analysis. Then, the simplified calculation steps of fault currents at each point in the meshed system are introduced. Thus, the range of the optimal smoothing reactor can be deduced through comparing the rising rates of each current based on the expected post‐fault system states. Finally, the simulation model based on PSCAD/EMTDC is carried out to prove the correctness of the proposed method, and visually shows the distinct operating states of the system with different smoothing reactor at fault time.