电网故障下直驱风电系统网侧变流器的电网同步化技术

为了能够在电网故障下对直驱风电系统传递给电网的功率进行持续控制,避免变流器保护跌落和提高瞬态故障穿越能力,对故障电压基波正负序分量进行快速而准确的检测是必要的。提出了一种不平衡和畸变电压运行条件下风电系统网侧变流器的新型电网同步化技术,即双二阶通用积分器-锁频环(DSOGI-FLL)。这个新的检测器包括正交信号发生器、正负序分量计算器和锁频环3个基本函数模块。对DSOGI-FLL进行的仿真和试验结果表明这种新型软件锁相环便于数字实现,能对不对称和畸变电网电压进行快速、准确检测和稳定跟踪;DSOGI-FLL是直驱风电系统网侧变流器在电网电压不平衡和畸变条件下的一个合适的电网同步化方法。

Grid Synchronization of Grid-side Converter in Direct Drive Wind Power Generation System Under Grid Faults

It is essential for accurate and fast detection of fundamental frequency positive-and negative-sequence component of the utility voltage under grid fault to keep the control over the power exchange with the grid to avoid trip of the converter protections and to allow the ride-through of the transient fault.We proposed a new technique for grid synchronization of grid-side converter in direct drive wind power generation system under unbalanced and distorted conditions,i.e.,the dual second order generalized integrator frequency-locked loop(DSOGI-FLL).The proposed detector includes three fundamental function blocks,namely,the quadrature-signals generator(QSG),positive-and negative-sequence calculator(PNSC) and frequency-locked loop(FLL).Moreover,the DSOGI-FLL was studied by simulation and experiment.The obtained simulation and experiment results demonstrate that this new software phase-locked loop is easy to implement by digital and can detect and track asymmetrical and distorted grid voltage rapidly and accurately,and the results indicate that the DSOGI-FLL is a very suitable solution for grid synchronization of grid-side converter in direct drive wind power generation system under unbalanced and distorted conditions.