The way of neutral point to earth via full compensation arc suppression coil can solve the problem of residual current compensation in coal mine power network effectively. Based on the analysis on the grounding curren...The way of neutral point to earth via full compensation arc suppression coil can solve the problem of residual current compensation in coal mine power network effectively. Based on the analysis on the grounding current detection results of Xieqiao coal mine, the conclusion that harmonic component of grounding current is dominated by higher harmonics with complex harmonic sources in coal mine power network system was obtained. The influences of harmonic source type and fault point position on harmonic voltage and harmonic current were analyzed theoretically. The influences of earthed fault feeder detection result and the estimation errors of parameters to earth on residual current compensation were analyzed. A new thought of residual current prediction and the selections of model method and control method were proposed on this basis. The simulation results prove that harmonic amplitudes of zero sequence voltage and zero sequence current are determined by harmonic source type as well as fault point position in coal mine power network, and also prove that zero sequence voltage detection can avoid the unstable problem of coal mine power network system caused by undercompensation of capacitive current. Finally, the experimental device of full compensation arc suppression coil is introduced.展开更多
文中以非隔离型柔性互联配电网为研究对象,针对交流系统发生单相接地故障时,因零序分量传递特性导致的典型接地故障检测方法适应性问题开展研究。首先,建立非隔离型智能软开关(soft open point, SOP)的零序等值拓扑网络,提出零序分量的...文中以非隔离型柔性互联配电网为研究对象,针对交流系统发生单相接地故障时,因零序分量传递特性导致的典型接地故障检测方法适应性问题开展研究。首先,建立非隔离型智能软开关(soft open point, SOP)的零序等值拓扑网络,提出零序分量的传递方程并定量分析零序分量传递至非故障侧的大小,分析不同场景下零序分量抑制效果;然后,分别对小电流互联系统、小电阻互联系统、小电流和小电阻互联系统的典型保护进行适应性分析,结果表明,在非隔离型柔性互联系统中,零序分量传递至系统健全侧后保护可能发生误动或误告警;最后,基于PSCAD建立典型非隔离型柔性互联配电网模型,对不同互联系统的保护适应性分析进行验证。文中研究结论可为非隔离型柔性互联配电网的保护配置提供理论支撑。展开更多
为抑制模块化多电平换流器(modular multilevel converter,MMC)内部的三相环流,在MMC内部数学模型的基础上,采用二倍频负序旋转坐标变换将换流器内部的三相环流分解为2个直流分量,并设计了相应的环流抑制控制器(circulating current sup...为抑制模块化多电平换流器(modular multilevel converter,MMC)内部的三相环流,在MMC内部数学模型的基础上,采用二倍频负序旋转坐标变换将换流器内部的三相环流分解为2个直流分量,并设计了相应的环流抑制控制器(circulating current suppressing controller,CCSC),从而消除了桥臂电流中的环流分量,大大减小了桥臂电流的畸变程度,使其更逼近正弦波。最后通过PSCAD/EMTDC搭建了包含该附加控制器的MMC仿真模型,结果证明所提出的控制方法可以在不用增大桥臂电抗值的情况下,有效地抑制换流器的内部环流,同时不会对MMC外部输出的交流电压和电流产生负面影响。展开更多
基金The financial support from the National Natural Science Foundation of China (No. 51107143)
文摘The way of neutral point to earth via full compensation arc suppression coil can solve the problem of residual current compensation in coal mine power network effectively. Based on the analysis on the grounding current detection results of Xieqiao coal mine, the conclusion that harmonic component of grounding current is dominated by higher harmonics with complex harmonic sources in coal mine power network system was obtained. The influences of harmonic source type and fault point position on harmonic voltage and harmonic current were analyzed theoretically. The influences of earthed fault feeder detection result and the estimation errors of parameters to earth on residual current compensation were analyzed. A new thought of residual current prediction and the selections of model method and control method were proposed on this basis. The simulation results prove that harmonic amplitudes of zero sequence voltage and zero sequence current are determined by harmonic source type as well as fault point position in coal mine power network, and also prove that zero sequence voltage detection can avoid the unstable problem of coal mine power network system caused by undercompensation of capacitive current. Finally, the experimental device of full compensation arc suppression coil is introduced.
文摘文中以非隔离型柔性互联配电网为研究对象,针对交流系统发生单相接地故障时,因零序分量传递特性导致的典型接地故障检测方法适应性问题开展研究。首先,建立非隔离型智能软开关(soft open point, SOP)的零序等值拓扑网络,提出零序分量的传递方程并定量分析零序分量传递至非故障侧的大小,分析不同场景下零序分量抑制效果;然后,分别对小电流互联系统、小电阻互联系统、小电流和小电阻互联系统的典型保护进行适应性分析,结果表明,在非隔离型柔性互联系统中,零序分量传递至系统健全侧后保护可能发生误动或误告警;最后,基于PSCAD建立典型非隔离型柔性互联配电网模型,对不同互联系统的保护适应性分析进行验证。文中研究结论可为非隔离型柔性互联配电网的保护配置提供理论支撑。
