基于虚拟电抗的主动支撑型新能源机组低电压穿越控制方法

Low Voltage Ride-through Control of Actively-supported New Energy Unit Based on Virtual Reactance

故障期间,新能源机组中电力电子设备容易出现过电流导致机组脱网运行,严重影响系统的安全稳定。针对上述问题,提出了一种基于虚拟电抗的主动支撑型新能源机组低电压穿越控制方法。首先,在传统电压源型换流器(voltage source converter,VSC)控制策略的基础上引入了一阶暂态电压方程,构建了dq坐标系下的主动支撑型新能源机组控制策略,有效提升了机组的无功电压支撑能力;然后,建立了主动支撑控制策略下的虚拟电抗控制模型,完成了虚拟电抗触发开关系数和虚拟电抗-并网点电压拟合曲线的参数设计,并利用所求参数确定了虚拟电抗的投切大小与时间,限制了短路电流,实现了机组的低电压穿越;最后,在仿真软件中搭建了两机系统,对比了不同电压跌落程度下不同控制策略的无功支撑能力,验证了所提方法的有效性和优越性。

During a fault, the power electronic equipment in the new energy unit is prone to overcurrent, resulting in the unit off grid operation, which seriously affects the safety and stability of the system. To solve the above problem, this paper proposes a low-voltage ride-through control method of actively-supported new energy units based on virtual reactance. Firstly, based on the traditional VSG control strategy, the first-order transient voltage equation is introduced, and the active support new energy unit control strategy in the dq coordinated system is constructed, which effectively improves the reactive power and voltage support capacity of the unit;Then, the virtual reactance control model under the active support control strategy is established: The parameter designing of the fitting curve of the virtual reactance trigger switching coefficient and Xfd-Ut is completed, and the switching size and time of the virtual reactance are determined by using the obtained parameters, which limits the short-circuit current and realizes the low-voltage ride-through of the unit;Finally, a two-machine system is built in the simulation software, and the reactive power support capabilities in different control strategies under different voltage dropping degrees are compared, verifying the effectiveness and superiority of the proposed method.