基于虚拟阻尼补偿的船舶并网变换器直流母线电压振荡抑制方法

Suppressing DC bus voltage oscillation method of marine grid-connected converter based on virtual damping compensation

为解决船舶直流微电网中恒功率负载与LC滤波器级联引起的母线电压高频振荡问题,提出一种基于虚拟阻尼补偿的并网变换器母线电压振荡抑制方法。首先,建立源侧并网变换器及恒功率负载的小信号模型,分析恒功率负载负阻抗特性减小LC滤波器阻尼引起电压振荡的机理,推导出LC滤波器与恒功率负载级联的稳定约束条件。在此基础上,引入基于非线性扰动观测器的虚拟负电感有源阻尼补偿方法,对并网变换器直流侧输出电流进行虚拟测量,并构建虚拟负电感补偿环节抵消LC滤波器较大电感值,从而抑制系统的低阻尼振荡。最后,采用奈奎斯特判据分析级联系统的稳定性,建立Simulink仿真模型验证了所提控制算法的有效性。

In order to solve the bus voltage high frequency oscillation problem caused by cascading constant power load and LC filter in marine DC microgrid, a suppression method for bus voltage oscillation based on virtual damping compensation of DC microgrid grid-connected converter was proposed. Firstly, the small signal model of source-side grid-connected converter and constant power load was established to analyze the mechanism of voltage oscillation caused by negative impedance characteristic of constant power load reducing LC filter damping, and the stable constraint conditions of cascade connection between LC filter and constant power load were derived. On this basis, a virtual negative inductance active damping compensate method based on nonlinear disturbance observer was introduced to estimate the output DC current of the grid-connected converter, and a virtual negative inductance compensation link was constructed to counteract the larger inductance value of the LC filter, thus suppressing the low damping oscillation of the system. Finally, the Nyquist criterion was used to analyze the stability of the cascade system, the effectiveness of the proposed control algorithm was verified by Simulink simulation model.