TANG Jun,ZHANG Qingwu,ZHANG Jianfeng,et al.Fault Characteristics and Protection Scheme for Bipolar Zone of Site-division Cascaded UHVDC Transmission Systems[J].Automation of Electric Power Systems,2026,50(18):223-231.
TANG Jun,ZHANG Qingwu,ZHANG Jianfeng,et al.Fault Characteristics and Protection Scheme for Bipolar Zone of Site-division Cascaded UHVDC Transmission Systems[J].Automation of Electric Power Systems,2026,50(18):223-231.DOI: 10.7500/AEPS20250915001.
Fault Characteristics and Protection Scheme for Bipolar Zone of Site-division Cascaded UHVDC Transmission Systems
The site-division cascaded ultra-high-voltage direct current (UHVDC) transmission system exhibits unique operating characteristics and protection requirements. This paper introduces the topology of the proposed system and proposes the principle of configuring independent bipolar-zone protections for each of the two converter stations
along with corresponding protection criteria. Under the operating condition
in which both poles are in service and each pole is grounded via the electrode lines of different stations
the failure of protections—such as the bipolar neutral-bus differential protection and the station grounding overcurrent protection—to isolate faults after operation is investigated. A scheme is proposed that
depending on the hot-standby status of the electrode lines
selects either electrode‑line switchover or blocking one pole while restarting the other with phase shift (with bipolar blocking applied for the station grounding overcurrent protection). Moreover
for a single open-circuit fault
the issue that the sound electrode line may still be damaged even after pole balancing is activated by the overload protection is studied
and a power runback scheme for the faulty pole is presented. Finally
real-time digital simulation verifies the feasibility and effectiveness of the proposed schemes.
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