三相变流器并网系统的广义阻抗及稳定判据

发布时间：2018-05-28 06:08

本文选题：三相变流器 + 并网变流器　；参考：《中国电机工程学报》2017年05期

【摘要】：三相变流器的输出阻抗矩阵特性对系统的稳定性有重要影响。无论在静止坐标系还是dq坐标系下,由于锁相环或电网等原因,变流器和电网的阻抗矩阵难以同时对角化解耦。耦合项的存在导致基于阻抗的变流器并网系统小干扰稳定性分析方法十分复杂或存在较大误差。为此,该文基于特征方程降阶的思路,在一定假设条件下提出可分析变流器系统小干扰稳定性的广义阻抗判据。首先,在极坐标下建立变流器端口和电网端口的小信号阻抗模型,并在此基础上定义了变流器及电网的广义阻抗。其次,利用严格的数学变换得到了反映变流器与电网交互影响的降阶特征方程。研究表明,系统振荡可以看作变流器与电网广义阻抗间的串并联谐振,广义阻抗判据是传统阻抗判据的扩展,在控制器外环和锁相环动态都可以忽略的前提下广义阻抗判据和正负序阻抗判据等价。最后,数字仿真和基于RT-LAB的硬件在环仿真验证了广义阻抗判据的有效性。
[Abstract]:The output impedance matrix characteristics of the three-phase converter have an important effect on the stability of the system. It is difficult to decouple the impedance matrix of converter and power network simultaneously because of phase-locked loop or power grid in static or dq coordinates. The existence of coupling term leads to the complexity or error of small disturbance stability analysis method for grid-connected converter system based on impedance. Therefore, based on the idea of reducing the order of the characteristic equation, a generalized impedance criterion for analyzing the small disturbance stability of the converter system is proposed under certain assumptions. Firstly, the small signal impedance models of converter port and power network port are established in polar coordinates, and then the generalized impedance of converter and power network is defined. Secondly, the reduced order characteristic equation which reflects the interaction between converter and power network is obtained by strict mathematical transformation. It is shown that the oscillation of the system can be regarded as a series and parallel resonance between the converter and the generalized impedance of the power network, and the generalized impedance criterion is an extension of the traditional impedance criterion. The generalized impedance criterion is equivalent to the positive and negative sequence impedance criterion under the condition that the dynamics of the controller outer loop and the phase-locked loop can be ignored. Finally, digital simulation and hardware in loop simulation based on RT-LAB verify the validity of generalized impedance criterion.
【作者单位】：浙江大学电气工程学院;云南电网有限责任公司调度中心;国网陕西省电力公司调控中心;
【基金】：国家重点研发计划项目(2016YFB0900104) 国家自然科学基金项目(51577168) 云南电网科技项目(yndw(2016)000303DD00124)~~
【分类号】：TM46

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