Inverter Station Connection Modes and Control Strategies of LCC-MMC Hybrid HVDC Systems

doi:10.3969/j.issn.1000-7229.2018.07.014

Abstract

Abstract: In this paper, the inverter connection modes and control strategies of LCC-MMC hybrid HVDC systems are analyzed, on the basis of a planned HVDC project. The considered factors include the form of access to the receiving-end AC system （concentrated access or distributed access）, the control mode of parallel-connected MMCs （fixed DC voltage or fixed active power） and the form of converter construction under the condition of multi-terminal access （joint station construction or separate station construction）. The analysis results show that the distributed access to AC system helps reduce the DC-side interaction of LCC and MMC under AC faults. Fixed DC voltage control on parallel MMCs contributes to system fast recovery after MMC AC-side faults, and the DC current balance control is able to eliminate the potential unbalance of DC current caused by possible parameter deviation. The joint station construction helps reduce the risk of DC faults and decrease investment cost as well as improve system reliability.

Key words: hybrid HVDC system, connection mode, control mode, joint/separate construction, concentrated/distributed access to AC system

CLC Number:

TM 722

XU Zheng，WANG Shijia，ZHANG Zheren，XU Yuzhe，XIAO Huangqing. Inverter Station Connection Modes and Control Strategies of LCC-MMC Hybrid HVDC Systems[J]. Electric Power Construction, 2018, 39(7): 115-122.

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