10kV统一电能质量控制器配电网应用研究

给出了10 kV配电网基于模块化多电平变换器技术的统一电能质量控制器(modular multilevel converter based unified power quality conditioner,MMC-UPQC)装置提高实用性的五种方法。第一种方法采用变比可变的变压器代替传统MMC-UPQC的串联变压器,提高了MMC-UPQC电压暂降补偿深度;第二种方法采用双串联变换器串联代替传统MMC-UPQC的单串联变换器,减小了公共直流侧电压,降低了阀组柜绝缘要求;第三种方法在电压暂降期间控制并联变换器吸收适量的有功功率,减少了MMC-UPQC子模块直流电容的释放能量,减小了直流电容的容量;第四种方法 MMC-UPQC子模块采用混频控制,根据子模块需治理的电能质量问题设定控制脉冲的频率,减少了子模块内开关器件损耗,降低了散热措施要求;第五种方法在控制策略中引入环流抑制控制,减小了MMC-UPQC变换器内部的环流电流及桥臂电抗器感抗。与传统MMC-UPQC装置相比,采用所提五种方法的MMC-UPQC装置能提高电压暂降补偿能力,减小占地面积和成本。

Research on Application of 10 kV UPQC in Distribution Network

Five methods are proposed in this paper to improve practicability of the modular multilevel converter based unified power quality conditioner （MMC-UPQC）equipment in 1 0 kV distribution network.In the first method,variable turn ratio transformers are used to replace series transformer of the traditional MMC-UPQC,which increases the voltage sag compen-sation depth.In the second method,two series converters in series are used to replace single series converter in the traditional MMC-UPQC,which reduces the common DC link voltage level and decreases the insulation requirement of the valve set cab-inet.In the third method,shunt converter absorbs appropriate quantity active power during the voltage sag,which reduces releasing energy of the DC capacitors in sub-modules and decreases capability of the DC capacitors.In the fourth method, hybrid frequency control sub-modules are used in MMC-UPQC and the frequencies of sub-modules are set by power quality problems they handled,which reduces the switching power loss in sub-modules and decreases cooling requirement.In the fifth method,circulating current suppressing control is introduced in control strategy,which reduces the circulating current in MMC-UPQC’s converters and decreases inductance of the arm inductors.Compared with the traditional MMC-UPQC, MMC-UPQC with the proposed five methods can increase the voltage sag compensation capability and decrease the area and cost.