混合双极高压直流输电系统的特性研究

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(voltagesource converter based HVDC,VSC-HVDC)的优势,针对一种新型的混合双极高压直流输电系统(hybrid bipolar basedhigh voltage direct current,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。

Investigation of Hybrid Bipolar HVDC System Performances

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.