特高压双12脉波直流换流站系统可靠性评估

Ultra HVDC Converter System Reliability Evaluation

全国电网互联的趋势加快了对特高压直流输电技术的研究。特高压换流站系统输送容量大,电压等级高,考虑运行及设备制造原因,通常采用的都是双12脉波接线。由于特高压相对超高压而言,具有更多的元件设备数和运行状态模式,针对特高压双12脉波直流换流站系统的可靠性评估将变得更加困难。基于Markov过程基本原理和累积状态之间转移频率的性质,建立了特高压双12脉波直流换流站系统的数学模型。通过将特高压换流站系统划分为若干个子系统,建立各子系统的状态空间图和等效容量模型,并加以层层组合,最终建立起能表征整个特高压换流站系统运行状态及其转移关系的等效容量模型。建立了完整的针对双12脉波接线方式行之有效的可靠性评估方法,通过对特高压双12脉波和超高压单12脉波换流站系统可靠性评估的计算分析比较,证明了该方法的可行性,分析了双12脉波换流站特定结构对系统可靠性产生的影响。

With the development of nation-wide power system integration, the study on ultra high-voltage direct current （UHVDC） transmission has been speeded up, which generally use the scheme of two converters per pole to acquire a greater transmission capacity. The UHVDC converter system has more components and more operating modes compared to the conventional HVDC structure, it becomes even tougher to build an appropriate model for system reliability evaluation. In this paper, based on the theory of Markov process and properties of transition frequencies among cumulative states, a multi-state capacity model for a UHVDC converter system with two converters per pole is presented. The equivalent models and state space diagram for individual components, sub-systems and the whole UHVDC converter system are established step by step, and equivalent failure and repair rates are used to obtain probability, frequency and duration indices at each capacity state of the UHVDC converter system. An test system is used as an example to demonstrate feasibility of the UHVDC modeling method, and the detailed comparison with HVDC are presented in this paper.