Crowbar电路在低电压穿越技术中的研究

电力系统风电并网中,风机需要具备低电压穿越性能,即电网电压波动时风机可以不脱离运行并向电网回馈能量,通过对三电平整流器的SVPWM的控制算法、二极管钳位型三电平变流器和电网跌落对风电变流器的影响三方面的研究,针对大功率直驱变流器提出一种基于耗能型的Crowbar电路,相比于传统保护电路和控制策略,所提出的方案增加了制动单元,并设计了其中开关管的控制方法,来实现低电压穿越的能力,并通过1.5MW的直驱风电机组及并网变流器构成并网系统验证设计的合理性.

Study on the Crowbar circuit used to improve the lower voltage ride-through capability of wind power system

When the wind generators are paralleled into the power grid, the lower voltage ride-through capability is needed to keep the wind generators to feed energy back into the grid when the grid voltage fluctuation happens. In this article, an energy dissipation model of Crowbar circuit specific to the high power direct drive converter is proposed as the conclusion of studies on the different effects to the drive converter with the three-level rectifier SVPWM control al- gorithm, diode clamping type three level converter and grid voltage drop. Compared with the traditional protection cir- cuit and the control strategy, the model is useful to improve the lower voltage ride-through capability with added bra- king unit and the specific control method of its switch tube. And the computer simulation with the grid-connected system constituted by a 1.5MW direct drive wind turbine and inverter verifies its rationality.