适用于中压配电网的无联结变压器柔性环网控制器

Flexible Ring Network Controller Without Interface Transformer for Medium Voltage Distribution Network

无联结变压器柔性环网控制器在交流侧出现故障时无法阻止零序电压分量传输,从而扩大了故障范围。文中采用经典电路分析方法和正负序分析算法,解释了零序电压分量的形成与传输的基本原理。提出了一种无联结变压器的柔性环网控制器拓扑,交流侧换流器都采用传统半桥子模块的模块化多电平换流器,而在正负极性母线上分别串联全桥子模块阀串。利用全桥子模块输出正负电压的能力,抑制了直流侧电压波动,同时也阻止了故障范围扩大。通过MATLAB/Simulink软件对故障时零序电压被抑制的特性进行了仿真分析,仿真结果验证了理论分析的正确性和所提拓扑的有效性。

For the flexible ring network controller without the interface transformer, the transmission of the zero-sequence voltage component cannot be prevented when the fault occurs at the AC side, thus increasing the fault range. Therefore, this paper uses the classical circuit analysis method and positive and negative sequence analysis algorithm to explain the basic principles of the formation and transmission of zero-sequence voltage components. A topology of the flexible ring network controller without the interface transformer is proposed. The AC side converters are all modular multilevel converters with traditional half-bridge submodules. And the full-bridge sub-module valve strings are connected in series on the positive and negative polarity busbars.Utilizing the ability of the full-bridge sub-module outputing positive and negative voltages, the DC-side voltage fluctuations are suppressed, and the fault range expanding is prevented. By using the MATLAB/Simulink software, the characteristics of zerosequence voltage suppressed during the fault are simulated and analyzed. The simulation results verify the correctness of the theoretical analysis and the effectiveness of the proposed topology.