摘要
虚拟同步发电机(virtual synchronous generator,VSG)可实现分布式电源友好并网。然而,传统的VSG控制不具备低电压穿越能力,在电网电压暂降时难以提供无功支撑,且容易发生输出电流幅值越限。为此,提出一种基于模式平滑切换的VSG低电压穿越控制方法。首先结合传统低电压穿越控制的数学模型,分析了其与VSG平衡电流控制之间的关联以及两者在切换时存在的问题;在此基础上,设计了VSG低电压穿越控制的整体方案,利用VSG平衡电流控制无差跟随的特点实现了控制模式的平滑切换,使得VSG在电压跌落过程中,其控制信号可很好地跟随电流指令参考值。该方法能够避免故障恢复时由于控制模式突变造成的暂态电流冲击,实现VSG在不同工况下的低电压穿越。仿真结果验证了所提方法的正确性和有效性。
Virtual Synchronous Generator（VSG） can make distributed generation friendly connect to power grid. However, traditional VSG control is not able to ride through low voltage faults. During voltage sag, VSG cannot provide reactive power support or restrict output current amplitude. To solve this problem, a VSG low voltage ride-through（LVRT） control method based on mode smooth switching is proposed. First, connection between traditional LVRT control and VSG balanced current control and smooth switching problem between the two modes are analyzed. Based on this, whole control scheme of VSG LVRT is established. The scheme utilizes no-error track feature of VSG balanced current control to design mode smooth switching strategy, making VSG control signal accurately follow current output reference during voltage sag. The proposed method can avoid transient current impact resulting from mode mutation and realize VSG LVRT under different conditions. Simulation results verify validity and effectiveness of the proposed method.
出处
《电网技术》
EI
CSCD
北大核心
2016年第7期2134-2140,共7页
Power System Technology
基金
国家自然科学基金创新研究群体项目(51321005)
国家自然科学基金资助项目(51567021)~~
关键词
虚拟同步发电机
低电压穿越
模式平滑切换
状态跟随
virtual synchronous generator
low voltage ride-through
mode smooth switching
state followed
