基于戴维宁等值的电压暂降模拟方法

Voltage sag simulation method based on Thevenin equivalent model

针对传统的电压暂降模拟方法,在正常和各种故障条件下仅模拟电网的电压特性,不考虑电网的阻抗特性,使得借助于传统电压暂降模拟方法作用于负载上的电压响应与实际电网不相同。因此,文章提出基于戴维宁等值的电压暂降模拟方法。文章提出采用基于阻抗切换方式辨识电网电压暂降时的戴维宁等值参数,该方法可对暂降前后的电压进行精确辨识。文章亦提出采用H桥级联型-逆变器作为电压暂降模拟装置,为使其能灵活可靠模拟实际电网电压暂降外特性,文中提出适用于H桥级联型逆变器的虚拟阻抗控制策略,其能通过参考电压、虚拟阻抗的设置实现所需的电压暂降戴维宁等值外特性的模拟。最后,通过仿真验证了所提电压暂降戴维宁等值参数辨识方法、电压暂降模拟装置控制策略的有效性及可行性。

The current voltage sag simulation method only considers normal and various fault situations of the infinite power grid so that the voltage drop on the load does not match the actual power grid.In this paper,voltage sag simulation method based on Thevenin equivalent model is proposed.Thevenin equivalent parameters on voltage sag based on impedance switching method is proposed to identify voltage value before and after sag.H-bridge cascaded inverter is chosen as voltage sag simulation device in this paper.In order to simulate external characteristics of actual grid voltage sag,the virtual impedance control strategy which is feasible to H-bridge cascaded inverter is proposed.Setting of voltage reference and virtual impedance can realize simulation of voltage sag Thevenin equivalent external characteristics.Finally,effectiveness and feasibility of proposed voltage sag Thevenin equivalent parameters identification method and voltage sag simulation device control strategy are testified.