基于虚拟谐波阻抗的孤岛微电网谐波功率均分控制策略

摘要

Each distributed generation unit in an islanded micro-grid has the problem to achieve a good load sharing, especially for the nonlinear load. Aiming at the problem, a new control scheme for harmonic power sharing based on virtual harmonic impedance in an islanded micro-grid was proposed in this paper. The new control strategy used negative virtual harmonic impedance to compensate the effect of line impedance on harmonic power delivery. The controller changed the harmonic equivalent feeder line impedance to minimize the influence to nonlinear load sharing, which caused by mismatched line impedance between the nonlinear load and the different distributed generations. Furthermore, a new droop method, named as Zh-H droop, was proposed to estimate the virtual harmonic impedance value adaptively. The proposed control method can realize the sharing of nonlinear load without affecting the voltage quality at the load bus, and have no influence in linear load sharing. Finally, the validity of the proposed control scheme was verified by using a small power micro-grid experimental platform.%微电网孤岛运行存在各个发电单元均分负载(包括非线性负载)的问题.为此,提出一种孤岛微电网谐波功率均分控制策略,该新型控制策略采用负虚拟谐波阻抗来补偿馈线阻抗对谐波功率均分的影响,即改变在谐波频率处的等效馈线阻抗,使得不同发电单元至负载的不同馈线阻抗对非线性负载分配的影响最小化;在此基础上,提出一种新的Zh-H下垂控制方式,可以自适应地调整虚拟谐波阻抗值.新型控制方案的优势在于可以实现非线性负载均分的同时,不影响线性负载均分,对负载侧电压质量也没有不利影响.最后,利用小功率微网试验平台验证了该方案的有效性.