直流分布式系统源荷对等型阻抗比判据研究

传统直流系统的稳定性判据建立在明确区分源荷变换器的基础上。在储能单元加入后储能变换器将在源荷的角色间来回切换，这一特点对系统的稳定性判据提出了新的挑战。首先，建立多源系统稳定性模型，分别以传统阻抗比判据中右极点存在的数目与源荷变换器不对等的地位对多源系统中潜藏的不稳定区域进行了溯源。然后，构造出能解决该问题的源荷对等型阻抗比判据，并阐述了其特点与案例。最后，参照所提出的新判据及特征值法，描绘出了直流分布式系统中传统判据判断失准的区域。通过实验和建模，从时域、奈奎斯特曲线和零极点分布3个角度验证了所提判据的优势。由此表明，所提出的判据对直流分布式系统稳定性的研究具有重要的理论与实际意义。

Research on Source and Load Peer-to-peer Impedance-based Stability Criterion for DC Distributed System

The traditional stability criterion for DC system is based on clearly distinguishing source and load converters. After the addition of energy storage units, the role of an energy storage converter will change between those of the source and load converters, which is a new challenge to the stability criterion for the system. In this paper, based on the establishment of a stability model of multi-source system, the potential instability region in the multi-source system is traced from aspects of the number of right poles in the traditional impedance-based stability criterion and the unbalance between source and load converters, respectively. Then, a source and load peer-to-peer impedance-based stability criterion is constructed to solve this problem, and its characteristics and cases are described. Finally, by referring to the novel criterion and the eigenvalue method proposed in this paper, the region in the DC distributed system where the traditional criterion is inaccurate is depicted. The advantages of the novel criterion are verified by experimental and simulation results from three aspects, i.e., time domain, Nyquist curve and zero-pole distribution, showing that the study on the stability of DC distributed system conducted in this paper is of significance both in theory and in practice.