基于直流电压同步的构网型变流器低频振荡分析与阻尼控制  

Low-frequency Oscillation Analysis and Damping Control for Grid-forming Converters Based on DC Voltage Synchronization

作　　者：姜鑫 易皓[1] 卓放[1] 李雨果 王振雄[1] JIANG Xin;YI Hao;ZHUO Fang;LI Yuguo;WANG Zhenxiong(State Key Laboratory of Electrical Insulation and Power Equipment(Xi’an Jiaotong University),Xi’an 710049,China)

机构地区：[1]电工材料电气绝缘全国重点实验室(西安交通大学),陕西省西安市710049

出　　处：《电力系统自动化》2024年第16期30-39,共10页Automation of Electric Power Systems

基　　金：国家自然科学基金资助项目(51977172)。

摘　　要：基于直流电压同步的构网型变流器能够在稳定直流侧电压的同时实现变流器自同步,然而直流电压动态与控制环相互作用可能会引起系统低频振荡。为了研究低频振荡产生的机理,建立了计及直流电压同步控制环与交流电压环的构网型变流器“功率-功角”稳定性分析模型,分析发现直流电压同步相比于功率同步会引入更多的相位滞后,同时交流电压环也会在环路中引入相位滞后,导致系统环路增益在具有高幅值的低频范围内存在-180°相位穿越,进而引发低频振荡问题。基于低频振荡机理分析,提出两种对直流电压同步控制进行相位补偿的方法,通过重塑系统环路低频高增益区的相位,实现对低频段的阻尼控制和振荡抑制。最后,通过仿真和实验验证了理论分析的正确性和所提方法的有效性。The grid-forming converters based on DC voltage synchronization cannot only stabilize DC voltage but also realize the self-synchronization of converters.However,the interaction between DC voltage dynamics and control loops may cause lowfrequency oscillation of the system.To study the mechanism of low-frequency oscillation,the“active power-power angle”model for stability analysis is built with consideration of the DC voltage synchronization control loop and AC voltage loop.It is found that DC voltage synchronization introduces more phase lag compared with active power synchronization,while the AC voltage loop also introduces phase lag in the loop.As a result,the system loop gain has the-180°phase crossing in the low frequency range with a high magnitude,thereby triggering the low-frequency oscillation issues.Based on the analysis of the low-frequency oscillation mechanism,two phase compensation methods for DC voltage synchronization control are proposed.Through reshaping the system loop phase in the high-gain-amplitude area of the low-frequency range,the damping control and oscillation suppression in the low-frequency range can be realized.Finally,the simulation and the experiment verify the correctness of the theoretical analysis and the effectiveness of the proposed methods.

关 键 词：新能源 并网 构网型变流器 直流电压同步 低频振荡 小信号稳定性 相位补偿 

分 类 号：TM712[电气工程—电力系统及自动化] TM46