柔性直流配电网混合拓扑变流器的自治控制  

Grid Forming Control of Hybrid Topology Converter for Flexible DC Distribution System

作　　者：吴杰[1] 李传江[1] 周鸣[1] 茅红伟[1] Wu Jie;Li Chuanjiang;Zhou Ming;Mao Hongwei(The College of Information Mechanical and Engineering Shanghai Normal University,Shanghai 200234 China)

机构地区：[1]上海师范大学信息与机电工程学院,上海200234

出　　处：《电工技术学报》2020年第24期5175-5186,共12页Transactions of China Electrotechnical Society

摘　　要：针对柔性直流配电网中混合拓扑模块化多电平换流器(MMC),提出一种适用于其并网和孤岛运行的自治控制策略,以提高直流配电网的可靠性。首先,提出混合MMC功率模块等效电容储能与变流器侧交流电压矢量角频率增量间的比例控制结构,作为变流器自治控制外环,实现利用变流器自身子模块电容缓冲功率波动的目的,与传统虚拟同步机外环所采用的惯性环节相比,动态响应速度有所提升。其次,设计总体控制结构包括自治控制外环和电流内环,其中,外环提供系统惯性,内环实现电流跟踪控制和对暂态电流较强的抑制。进一步地,建立混合MMC自治控制小信号模型,分析惯性等主要控制参数对系统特征根分布和稳定性的影响。最后,搭建直流配电网混合MMC仿真模型,分别对孤岛和并网运行方式以及暂态故障进行仿真,验证所提自治控制策略的正确性和有效性。A grid-forming control strategy for hybrid topology modular multilevel converter(MMC)in dc distribution network is proposed to improve the reliability of dc distribution network.Firstly,the proportional control structure between the equivalent capacitor energy storage of the hybrid MMC power module and the angular frequency increment of the AC voltage vector on the converter side is proposed,which is as an autonomous control outer loop of the converter.It can use the sub-module capacitance of the converter to buffer power fluctuations.Compared with the first-order inertial link used in the outer control loop of the traditional virtual synchronous machine,the dynamic response speed is improved.Secondly,the overall control structure is designed including the grid forming control outer loop and the inner current loop.The outer loop provides system inertia,and the inner one achieves current tracking control and suppresses transient fault current effectively.Further,the small signal model of the hybrid MMC grid forming control is established.The influence of main control parameters such as inertia on the distribution of eigenvalues and stability of the system is analyzed.Finally,a hybrid MMC simulation model for DC distribution grid is built to simulate the isolated island operation,grid-connected operation mode and transient fault respectively,which verifies the proposed grid forming control strategy.

关 键 词：柔性直流配电网 模块化多电平变流器 全桥-半桥混合 自治控制 虚拟惯性 

分 类 号：TM761[电气工程—电力系统及自动化]