MMC柔直换流站稳态无功能力研究
摘要：模块化多电平换流器(modular multilevel converter，MMC)能够实现无功功率的独立控制和快速调节，MMC柔直换流站可以作为一种厂站级调节资源，提升电力系统无功区域优化水平。为此，针对MMC柔直换流站无功调节能力展开研究。首先，基于典型单端MMC柔直换流站拓扑建立数学模型；其次，分析影响柔直换流站无功能力的设备能力限制和系统运行状态2大类影响因素，提出联结变压器额定容量、联结变压器阀侧耐过电流水平和电压调制比3个约束条件，并推导了无功能力的计算步骤；最后，以张北±500 kV四端柔直电网工程为例，阐述了其在不同有功负荷、直流电压、并网点电压等稳态运行工况下的无功能力和对应的主要约束条件，为柔直工程无功电压控制策略设计和无功安全裕度控制提供了依据。
Abstract:By use of modular multilevel converter(MMC), the independent control and rapid regulation of reactive power can be implemented, flexible MMC-HVDC converter station can be used as a plant-level (or station-level) adjustment resource to promote the optimization level of regional power system reactive power. Therefore, a research on reactive power regulation capability of flexible MMC-HVDC converter station was performed. Firstly, according to the topology of typical single-terminal flexible MMC-HVDC converter station a mathematical model was proposed. Secondly, two major categories of influence factors, i.e., the equipment capability constraint influencing the reactive power regulation capability and the operating state of the system, were analyzed, and three constraint conditions, i.e., the rated capacity of converter transformer, the overcurrent withstand level at the valve side of converter transformer and the voltage modulation ratio, were put out, besides, the calculation steps of reactive power regulation capability was derived. Finally, taking Zhangbei ±500 kV four-terminal flexible HVDC project for example, its reactive power regulation capability under such steady state operating conditions as different active loads, DC voltage and voltage at grid-connected point and corresponding main constraint conditions were expounded, thereby, the obtained results provide the basis for the design of reactive voltage control strategy of flexible MMC-HVDC converter station as well as for the reactive power security margin control.
标题：MMC柔直换流站稳态无功能力研究
英文标题：Research on Steady-state Reactive Power Capacity of Flexible MMC-HVDC Converter Station
作者：王炳辉, 黄天啸, 吴涛, 谢欢, 李长宇, 陈瑞,
关键词：柔性高压直流输电, 模块化多电平换流器(MMC), 换流站, 自动电压控制(AVC), 稳态, 无功调节能力,
发表日期：2021-04-10
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