中文摘要：

为了充分发挥电网换相换流器高压直流输电系统 （line commutated converter based high voltage direct current,LCC—HVDC）和电压源换流器高压直流输电系统（voltagesourceconverterbasedHVDC，VSC．HVDC）的优势，针对～种新型的混合双极高压直流输电系统（hybridbipolarbasedhighvoltagedirectcurrent，HB—HVDC）进行了研究，该系统的正极是传统的12脉动LCC．HVDC系统，而负极是VSC—HVDC系统。建立了由LCC正极和VSC负极组成的混合双极高压直流输电系统的模型，推导了其在稳态时的数学模型，并设计了正负极之间的协调控制策略。在PSCAD／EMTDC环境下对HB—HVDC系统的稳态和暂态运行特性进行了研究分析。最后对HB—HVDC系统和闭锁负极VSC—HVDC后LCC—HVDC系统的运行特性进行了对比研究。结果表明：HB-HVDC系统可以更好地调节交流母线电压，减少LCC极换相失败的可能性，并且具有快速的故障恢复能力；同时也证明所设计的协调控制策略可以有效地改善HB—HVDC系统的稳态和动态特性。

英文摘要：

A new hybrid bipolar high voltage direct current system （HB-HVDC） was investigated to synthetically utilize the advantages of line commutated converter based HVDC （LCC-HVDC） and voltage source converter based HVDC （VSC-HVDC）. The positive pole was a conventional 12-pulse LCC-HVDC system and the negative pole was a VSC-HVDC system. The model of HB-HVDC was developed, and its steady-state mathematical model was deduced. Then the coordinated control strategy between positive pole LCC-HVDC and negative pole VSC-HVDC was designed. The operation performances of HB-HVDC system in steady and transient state were studied. Finally, the performances of the HB-HVDC system were compared with an identical LCC- HVDC with VSC-HVDC blocked. The results show that HB- HVDC system has a better regulation for AC busbar voltage, makes the LCC-HVDC less susceptible to commutation failure and has a faster fault recovery ability. Moreover, the proposed coordinated control strategy has the ability to improve the steady state and dynamic performances of HB-HVDC systems.