一种直流微网双向并网变换器虚拟惯性控制策略  

A Virtual Inertia Control Strategy for Bidirectional Grid-connected Converters in DC Micro-grids

作　　者：伍文华[1] 陈燕东[1] 罗安[1] 周乐明[1] 周小平[1] 杨苓[1] 

机构地区：[1]国家电能变换与控制工程技术研究中心(湖南大学),湖南省长沙市410082

出　　处：《中国电机工程学报》2017年第2期360-371,共12页Proceedings of the CSEE

基　　金：国家自然科学基金重点项目(51237003);国家自然科学基金项目(51577056);中央高校基本科研业务费专项资金(2015-001)~~

摘　　要：针对直流微网中母线电压易受微网内部功率波动影响,通过类推交流微网中虚拟同步发电机的虚拟惯量,提出了一种直流微网双向并网变换器(bidirectional gridconnected converter,BGC)虚拟惯性控制策略,增强了直流微网的惯性,平抑了直流母线电压波动。建立BGC虚拟惯性控制小信号模型,推导出直流母线电压与BGC直流侧输出电流之间的小信号传递函数,深入分析直流微网功率突变下的系统动态特性,发现BGC直流侧输出电流相当于扰动量,会对直流母线电压的动态响应过程产生冲击性影响。对此,提出了BGC的直流侧输出电流前馈扰动抑制方法,平滑了直流母线电压的动态响应。分析了BGC系统的稳定性,选取了合适的BGC虚拟惯性控制参数。最后,仿真与实验验证了所提控制策略的有效性。In DC micro-grids, the DC bus voltage is vulnerable to power fluctuation. In this paper, a virtual inertia control strategy for bi-directional grid-connected converters（BGC） analogized with a virtual synchronous generator（VSG） was proposed to strengthen the inertia of the DC micro-grid, and to restrain the dc bus voltage fluctuation. Also, the small-signal model of the proposed strategy was built, and then the small-signal transfer function between the DC bus voltage of DC micro-grids and the output current of BGC was deduced. The system dynamic characteristic with the power suddenly changing in DC micro-grids is further analyzed. As a result, the dc-link output current of BGC is equivalent to a disturbance which leads to an impact on the dynamic response of the dc bus voltage. To solve this problem a DC-link output current feed-forward disturbance suppressing method for BGC is proposed to smooth the dynamic response of the DC bus voltage. The BGC control system stability was analyzed, and the appropriate virtual inertia control parameters were selected. Finally, simulations and experiments verified the validity of the proposed control methods.

关 键 词：虚拟同步发电机 直流微网 双向并网变换器 功率波动 虚拟惯性控制 小信号模型 输出电流前馈控制 

分 类 号：TM71[电气工程—电力系统及自动化]