船舶微电网源-荷级联系统母线电压振荡有源阻尼抑制策略

Active Damping Suppression Strategy for Bus Voltage Oscillation in Ship Microgrid Source-Load Cascade System

为解决船舶微电网源-荷级联系统中LC输入滤波器与恒功率负载CPL(constant power load)引起的母线电压振荡问题,提出一种基于非线性扰动观测器NDO(nonlinear disturbance observer)的虚拟负电感有源阻尼稳定控制策略。首先分析了恒功率负载的负阻抗特性及其能量反馈作用,深入研究了源-荷级联系统低阻尼振荡的机理;详细推导了级联系统的稳定约束条件,进而提出适用于源侧变换器的有源阻尼稳定策略,建立了级联系统小信号阻抗模型,利用奈奎斯特判据进行了稳定性分析。利用非线性扰动观测器摆脱了控制算法对输出电流传感器较强的依赖性,抵消了负阻抗特性对系统稳定性造成的不利影响。最后,通过仿真验证所提控制算法的有效性,并对稳定性分析部分进行了实例论证。

To solve the problem of bus voltage oscillation caused by the LC input filter and constant power load(CPL)in a ship microgrid source-load cascade system,a virtual negative inductance active damping stability control strategy based on nonlinear disturbance observer(NDO)is proposed.First,the negative impedance characteristics of CPL and its energy feedback effect are analyzed,and the mechanism of low damping oscillation in the source-load cascade system is studied.Second,the stability constraints of the cascade system are derived in detail,and an active damping stabilization strategy suitable for the source-side converter is put forward to construct a small signal impedance model of the cascade system,and the stability analysis is performed according to the Nyquist criterion.At the same time,NDO is used to get rid of the strong dependence of the control algorithm on the output current sensor,thus counteracting the adverse influence of negative impedance characteristic on the system stability.Finally,the effectiveness of the proposed control algorithm is verified by simulations,and the corresponding stability analysis is demonstrated by examples.