三电平中压变流器NPC与NPP拓扑结构对比分析

Comparison and Analysis on NPC and NPP Topology of Three-Level Middle-Voltage Converter

随着海上风电机组的功率等级的不断增加,越来越多的整机厂商采用中压等级的机组,而三电平因更低谐波和更好的控制性能得到越来越广泛的使用。分析了采用NPC和NPP拓扑的三电平变流器工作原理,并通过MATLAB进行了两种拓扑的SVPWM仿真验证,仿真结果显示两种拓扑结构输出的电流波形基本一致。针对两种电路的特点进行扩展分析,通过分析说明当电路的电压等级和容量进一步上升时,NPP拓扑结构具有明显的优势,扩容易于实现、控制简单且具有冗余功能,在更高电压等级和更大容量系统中具有一定的优势。

With the increasing of the power level on offshore wind power system, more and more machine manufacturers use the medium voltage wind power system, and the three level converter are used more and more widely because of lower harmonic and better control performance. This paper analyses the working principle of NPC and NPP topology, and carries on the SVPWM simulation of two kinds of topology by MATLAB, the simulation results show that the current waveform of two kinds of topology structure output are basic consistent. Aiming at the extended analysis according to the characteristics of two kinds of circuit, through the analysis of the circuit when the voltage grade and capacity to rise further, NPP topology has obvious advantages, the capacity expansion is easy realization, simple control and redundant function, has a certain advantage in the higher voltage and larger capacity system.