张津京 王兴贵 宋汶秦 杨维满

摘   要：针对微源逆变器串联微电网中，微源投切对微电网与电网交互稳定性影响机理复杂，传统方法建模困难且无法及时决策的问题，提出一种基于梯度提升决策树（gradient boosting decision tree，GBDT）模型的交互稳定性评估方法.首先提出微源投切特征函数的构造方法，所提方法能够有效提取采用载波移相SPWM调制的串联结构系统中特有的投切微源位置特征，同时具有降低特征维数、提高模型效率、通过简单拟合使模型具备迁移能力的优势;其次将交互稳定性评估视为多分类任务，且对其中较不稳定样本进行谐振频段预测，从而可针对不同投切工况采取不同应对策略.在验证集和新建测试集上的测试结果表明特征提取方法正确、有效，可为类似串联结构系统在电能质量分析、优化运行等方面提供方法参考;所建模型泛化能力强且具有实用性，可为并网运行系统稳定性在线分析及决策提供新思路.

关键词：微源投切;微源逆变器串联;交互稳定性;特征提取;机器学习

Abstract：Due to the complex mechanism of the effect of micro-source switching on interactive stability between the grid and the micro-grid with series micro-source inverters， traditional methods were difficult to model and can't make decision in time. In this study， therefore， an assessment method of interactive stability based on gradient boosting decision tree （GBDT） was proposed. Firstly， the feature functions of the micro-source switching were constructed to extract the position feature which existed typically in series structure system modulated by carrier phase shifted SPWM. The proposed functions can reduce the feature dimension， thus improving the efficiency of assessment model and making the model migration capable by feature fitting. Secondly， the assessment of interactive stability was treated as a multi-classification task and the resonant frequency bands of instable samples were predicted. Thus， the different strategy can be taken according to the classification and prediction. Finally， the tests on validation data sets and new test sets verified the correctness and effectiveness of the feature construction functions which can provide references for the similar series structure system in power quality analysis， optimal operation and other aspects. The results also verified the high generalization performance and practicality of the proposed assessment model， which can provide a new tool for on-line stability analysis and decision-making of grid-connected operation systems.

Key words：micro-source switching;series micro-source inverters;interactive stability;feature extraction;machine learning

微電网是分布式电源（distributed generation，DG）接入电网的一种有效手段.相比于DG和负荷在馈线上横向分布的并联结构微电网，本文讨论的微源逆变器串联微电网（micro-grid with series micro source inverters，SMSI-MG）输出的电压和电流具有更好的正弦度，同一输出电压等级下可有效降低各微源直流侧电压[1-3]. 类似的逆变器串联结构因其高输出电压、低dv/dt、高效率等优势而在光伏并网系统中获得广泛应用[4-5]. SMSI-MG系统则在此基础上将……