摘要
电压控制型逆变器VCI(voltage-controlled inverters)在弱电网下表现出更强的稳定性,有望在可再生能源发电中得到更广泛的应用。然而,VCI的有功功率控制带宽通常低于电流控制并网逆变器CCI(current-controlled inverter)。随着电网阻抗增大和电网强度进一步降低,其调节时间甚至将长达数秒,难以满足可再生能源发电最大功率点跟踪MPPT(maximum power point tracking)的要求。此外,现有的以功率环改造为特点的VCI有功功率快速控制方法,则可能导致弱电网下VCI稳定性损失。针对这一问题,建立了VCI并网系统的详细输入-输出模型,揭示了弱电网下VCI功率环改造法面临稳定性和快速性矛盾的根源,并提出了一种基于外环改造和功率指令前置滤波的VCI有功功率快速控制方法,能够有效提升VCI有功功率控制带宽,且不影响其弱电网下的稳定性,进一步实现了基于VCI的MPPT控制;针对短路容量比和电网阻抗大幅波动对所提控制的影响,又提出了一种基于电网阻抗在线辨识的VCI有功功率快速控制自适应方法。最后,实验结果验证了所提方法的有效性。
Since voltage-controlled inverters(VCIs) show a strong stability under weak grid conditions,they are expected to gain increasing applications in renewable energy power generations.However,the VCI active power control bandwidth is usually lower than that of the current-controlled inverter(CCI).In addition,as the grid impedance increases and the grid weakens,the settling time of VCI active power control can even be as long as a few seconds,which is difficult to meet the requirements of maximum power point tracking(MPPT) in renewable energy power generations.Moreover,the existing VCI rapid active power control methods characterized by power-loop modification may lead to stability loss under weak grid conditions.To address this problem,the main contributions of this paper are as follows.First,a detailed input-output model of the VCI grid-connected system is established,and the reasons for the contradiction between stability and rapidity of the VCI power-loop modification method under weak grid conditions are revealed.Second,a rapid active power control method based on external loop modification and power reference pre-filtering is proposed,which can effectively improve the VCI active power control bandwidth without affecting its stability under weak grid conditions and further realizes the VCI-based MPPT control.Third,aimed at the influence of fluctuations of short-circuit ratio and grid impedance on the proposed control,an adaptive method based on the grid impedance online identification is proposed.Finally,experimental results validated the effectiveness of the proposed method.
作者
郭梓暄
张兴
李明
付新鑫
韩峰
王继磊
GUO Zixuan;ZHANG Xing;LI Ming;FU Xinxin;HAN Feng;WANG Jilei(National and Local Joint Engineering Laboratory for Renewable Energy Access to Grid Technology(Hefei University of Technology),Hefei 230009,China)
出处
《电源学报》
CSCD
北大核心
2023年第4期56-66,共11页
Journal of Power Supply
基金
国家电网公司科学技术资助项目(5500-202055324A-0-0-00)。
关键词
电压控制型逆变器
有功功率快速控制
指令前置滤波自适应控制
弱电网
电网阻抗辨识
voltagecontrolled inverter(VCI)
rapid active power control
reference prefiltering adaptive control
weak grid
grid impedance identification Project Supported by Science and Technology Project of State Grid Corporation of China(5500202055324A0000)
