适用于弱电网中大功率整流器次同步振荡抑制的新型控制策略研究

Research on New Control Strategy for Sub-synchronous Oscillation Suppression of High Power Rectifier in Weak Current Network

在弱电网中,由于电网的阻抗特性较大,线路中阻抗参数改变了整流器控制的关键参数,影响了整流器的整体性能,可能会导致整流器输出不稳定,使输出呈现次同步振荡特性。为此,在不增加硬件补偿系统的基础上,提出了一种能够有效抑制次同步振荡的控制策略,该抑制策略从数学模型角度出发,通过低频滤波器提取出次同步振荡交流电流分量,进行d/q变换后,将该次同步振荡的d/q电流分量进行PI闭环控制,次同步振荡分量的PI调节器输出值进行解耦补偿后乘以补偿系数得到电压的d/q补偿分量,对原电流内环的输出进行补偿。仿真和试验结果表明,该抑制策略有效、可行,能够有效抑制次同步分量。

In the weak current network,due to the large impedance characteristics of the power grid,the impedance parameters in the line change the key parameters of the rectifier control,affecting the overall performance of the rectifier,which may lead to the unstable output of the rectifier,and the output presents the characteristics of sub-synchronous oscillation.On the basis of not increasing the hardware compensation system,this paper proposes a control strategy that can effectively suppress the sub-synchronous oscillation.Based on the mathematical model,the AC current component of the sub-synchronous oscillation is extracted through the low-frequency filter.After d/q transformation,the d/q current component of the sub-synchronous oscillation is PI closed-loop controlled.The output value of the PI regulator of the subsynchronous oscillation component is decoupled and compensated,and then multiplied by the compensation coefficient to obtain the d/q compensation component of the voltage.The output of the original current inner loop is compensated.A simulation and test results show that the control strategy is effective and feasible,which can suppress sub-synchronous components.