风电变流器系统线路阻抗模拟策略研究

Research on Line Impedance Simulation Strategy of Wind Power Converter System

随着分布式新能源发电技术渗透率的不断增加,实际电网具有不可忽略的线路阻抗并呈现出弱电网特性。同时,由于谐波线路阻抗的不同导致功率分配不均在并网系统中也是亟待解决的问题。为满足分布式发电系统在可变线路阻抗下的测试需求,提出一种风电变流器系统线路阻抗模拟策略。首先建立了风电变流器系统等效阻抗模型,分析并推导出线路阻抗模拟控制方程,以此为基础,在线路阻抗模拟控制中引入短路比(SCR)的概念,使得系统具备模拟特定SCR下线路阻抗的能力,并从风电变流器系统输出阻抗角度对线路阻抗模拟策略进行分析论证。最后,通过搭建2 MW全功率风电变流器系统实验平台,验证了风电变流器系统线路阻抗模拟策略的有效性。

With the increasing permeability of distributed new energy generation technology,the actual power grid has line impedance that can not be ignored and presents the characteristics of weak power grid.At the same time,due to the different impedance of harmonic lines,the uneven distribution of power in grid-connected system is also an urgent problem to be solved.In order to meet the test requirements of distributed generation system under variable line impedance,a line impedance simulation strategy for wind power converter system is proposed.Firstly,the equivalent impedance model of wind power converter system is established,and the simulation control equation of line impedance is analyzed and deduced.On this basis,the concept of short circuit ratio(SCR)is introduced into the simulation control of line impedance,which makes the system have the ability to simulate line impedance under specific SCR,and the impedance model of line from the angle of output impedance of wind power converter system is presented.The proposed strategy is analyzed and demonstrated.Finally,an experimental platform of 2 MW full power wind power converter system is built to verify the effectiveness of line impedance simulation strategy for wind power converter system.