一种新型直流串联风机并网拓扑结构及其控制策略

摘要

为了解决风速不均衡时海上风机串联中风速高的风机出现电压过高的问题,提出一种新型直流串联风机并网系统及其控制策略.该结构只需在陆上的直流母线末端设置Cuk电路,控制直流输电电流保持恒定,并对每台风机进行最大功率追踪;其控制方法包括最大功率点追踪控制、电流控制和并网控制.详细论述了该系统的结构及其控制策略,并在Simulink中搭建系统模型.该系统具有硬件相对投入少、风能利用率高等优势,还能防止在风速不均衡时风机的过压问题,保证了系统的可靠运行;同时Cuk的降压功能还能使逆变器节省一台降压变压器.仿真实验结果验证了该系统及其控制策略的可行性.%In order to solve the problem of overvoltage caused by the unbalanced wind speeds,this paper presents a nov?el topology of series-connected DC offshore wind turbines system and its control strategy. The proposed structure only need a Cuk circuit at the end of the DC bus onshore to keep the DC current steady and track the maximum power of ev?ery fan. Its control methods include maximum power point tracking control,current control and grid-connected control. The structure of the system and its control strategy are discussed in detail,and a simulation model is established in Simulink. This system has the advantages of relatively less hardware and high utilization rate of wind energy ,and it can avoid overvoltage under unbalanced wind speeds,which can guarantee its reliable operation. Meanwhile,the step-down function of Cuk circuit can save a buck converter for the inverter. The simulation results verify the feasibility of the sys?tem and its control strategy.