基于DDC的直流微电网接入技术研究

Research on DC micro-grid access technology based on DDC

以直流配电中心为核心构建的柔性互联配电网,有效解决了电磁环网问题,真正意义上实现了多回馈线闭环运行,文中基于直流配电中心重点研究了以直流电力电子变压器为核心的直流微网接入技术。首先对直流电力电子变压器的基本结构和工作原理进行了分析和介绍,并设计了相应的控制策略;然后对含有光伏、直流负载的简单直流微网及相关模型进行介绍;最后利用PSCAD/MTDC搭建了四端交直流柔性互联配电系统,并通过直流电力电子变压器接入了光伏和直流负载单元,验证通过直流电力电子变压器实现直流微网与直流配电中心互联的技术可行性。结果证明直流配电中心系统能够稳定运行,直流变压器能够满足直流微网接入的技术需求;在稳态及受到扰动时,系统能够维持稳定运行,直流负荷供电不受影响。

The flexible interconnected distribution network based on DC distribution center effectively solves the problem of electromagnetic loop network and realizes the closed-loop operation of multiple feedback line.Based on DC distribution center,this paper focuses on the DC micro-grid access technology with DC power electronic transformer as the core.Firstly,the basic structure and working principle of DC power electronic transformer are analyzed and introduced,and the corresponding control strategy is designed.Secondly,the simple DC micro-grid with photo-voltaic and DC loads and related models are introduced.Finally,a four-terminal AC/DC flexible interconnected distribution system is built by using PSCAD/MTDC,and the photo-voltaic and DC power electronic transformer is connected to the system through DC power electronic transformer.Load unit verifies the technical feasibility of interconnecting DC micro-grid with DC distribution center through DC power electronic transformer.The results show that the DC distribution center system can operate stably,the DC transformer can meet the technical requirements of DC micro-grid access,and the system can maintain stable operation under steady state and disturbance,and the DC load power supply is not affected.