作者：薛家祥¹, 张祥颖¹, 周钢²

作者单位：1. 华南理工大学机械与汽车工程学院, 广东 广州 510640;
2. 东莞市钜大电子有限公司, 广东 东莞 523070

关键词：微网下垂;虚拟阻抗;SOGI;电压补偿;频率调节

摘要：

为降低传统微电网下垂控制中无功环流对系统稳定性的影响，提出一种基于虚拟阻抗的微电网自适应下垂策略。对闭环传递函数特征根进行分析，选取合适的虚拟阻抗参数。针对虚拟阻抗中微分环节存在高次谐波干扰的问题，提出SOGI模块，实验验证其具有良好的滤波能力以及产生正交信号的特性。提出电压自适应补偿环节，以解决虚拟阻抗导致压降增大的问题，仿真验证其对不同负载产生压降具有补偿作用。针对由功率扰动引起的频率波动问题，提出频率自适应调节环节。将频率变化值与频率变化率划分为五种情况，对幅值调节参数进行自适应调整，使频率扰动减小1.4 Hz波动峰值，减小0.045 s恢复时间。通过多机并联实验，各机输出无功功率差值为39.096 var，150.258 var，均分效果良好。文章不仅研究了微网功率分配问题，还为虚拟阻抗的应用提供了新的解决思路。

An adaptive droop strategy for microgrid based on virtual impedance
XUE Jiaxiang, ZHANG Xiangying, ZHOU Gang
1. School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou 510640, China;
2. Dongguan Juda Electronics Co., Ltd., Dongguan 523070, China
Abstract: In order to reduce the influence of reactive power circulation on system stability in traditional microgrid droop control, an adaptive droop strategy based on virtual impedance was proposed. The characteristic roots of the closed-loop transfer function are analyzed and the appropriate virtual impedance parameters are selected. To solve the problem of high order harmonic interference in the differential part of virtual impedance, the SOGI module is proposed, and the experiment proves that it has good filtering ability and the characteristics of generating orthogonal signals. A voltage adaptive compensation link is proposed to solve the problem of voltage drop increase caused by virtual impedance, and the simulation shows that the voltage drop can be compensated for different loads. Aiming at the problem of frequency fluctuation caused by power disturbance, a frequency adaptive adjustment link is proposed. The frequency change value and frequency change rate were divided into five cases, and the amplitude adjustment parameters were adjusted adaptively to reduce the frequency disturbance peak value of 1.4 Hz and the recovery time of 0.045 s. Through the multi-machine parallel experiment, the output reactive power difference of each machine is 39.096 var and 150.258 var, and the equalization effect is good. This paper not only studies the power distribution of microgrid, but also provides a new solution for the application of virtual impedance.
Keywords: microgrid droop;virtual impedance;SOGI;voltage compensation;frequency regulation
2023, 49(9):97-103,110  收稿日期: 2022-3-25;收到修改稿日期: 2022-6-4
基金项目: 国家自然科学基金资助（51875213）；2015 东莞市引进第三批创新科研团队项目（2017360004004）；东莞市科技装备动员项目（KZ2019-6，KZ2020-01）
作者简介: 薛家祥（1963-），男，江苏徐州市人，教授，博导，主要从事光伏离网，并网逆变器及其分布式发电系统，数字化开关 电源及智能控制的研究。
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