MW级风电变流器独立母线并联系统稳定性分析及控制器设计  

Stability Analysis and Controller Design of Paralleled MW Level Converters With Separate DC Links for Wind Power Generation

作　　者：李典 杨淑英[1] 王旭 谢震[1] 张兴[1] LI Dian;YANG Shuying;WANG Xu;XIE Zhen;ZHANG Xing(School of Electrical Engineering and Automation,Hefei University of Technology,Hefei 230009,China)

机构地区：[1]合肥工业大学电气与自动化工程学院,合肥230009

出　　处：《高电压技术》2023年第9期4022-4031,共10页High Voltage Engineering

基　　金：安徽省科技重大专项(202003a05020029)。

摘　　要：独立直流母线背靠背变流器并联运行不仅存在环流问题,而且相比单机控制而言,机侧变流器的容许带宽受到限制,稳定性降低,导致基于电机定子电压方程的设计方案出现不稳定现象。将并联变流器和电机看作级联系统,建立频域阻抗模型,并借助级联系统稳定性理论对系统稳定性进行了深入分析,从理论上揭示了不稳定现象。传统控制方案将并联驱动系统作为整体进行控制系统设计,影响了并联系统的灵活性。为实现各并联变流器的独立控制,提出了基于变流器输出电感的电流环设计方案。相比传统基于电机定子电压模型的电流控制器设计方案能够较为准确地计算电流环容许带宽边界,提升系统运行稳定性。仿真与实验证明了论文理论分析的正确性和控制系统设计的有效性。For paralleled converters with separate DC links,not only the problem of zero-sequence circulating current exists,but also the allowed control bandwidth of the machine-side converters is limited,and thus lowers the stability compared with the single converter drive.As a result,instability may even occur when the current regulators are designed based on the stator voltage equations.In this paper,the paralleled converters and the machine are regarded as series-connected system,and their impedance model is built in the frequency domain.By the stability theory for the series-connected system,stability of the drive with paralleled converters is analyzed deeply,and the instability phenomenon is explained clearly in theory.The parallel drive system is taken as a whole to perform control design,which will influence the flexibility of the system.To control each converter independently,a current controller design strategy based on the inductance in the AC output of each converter is proposed in this paper.Compared with the design based on the stator voltage equations,this strategy can decide the allowed bandwidth more accurately.Consequently,the stability is improved.The theory analysis and the design effectiveness are validated through simulation and experiments.

关 键 词：独立直流母线 并联变流器 级联系统 阻抗模型 稳定性 独立控制 

分 类 号：TM614[电气工程—电力系统及自动化] TM46