摘要
逆变型分布式电源通过并网换流器接入电网,故障电流特性与常规设备存在显著差异,为配电网的故障保护带来挑战。基于T/4延时的正、负序分离算法被广泛用于并网换流器控制系统,然而,延时环节对暂态故障电流特性的影响尚未被充分研究。为此,首先在梳理换流器故障瞬态响应链路的基础上,分别建立换流器拓扑以及含正、负序分离环节控制系统的数学模型,并通过Pade近似实现延时环节线性化;进而,建立并网换流器暂态故障电流的闭环模型,并分析延时环节对暂态故障电流特性的影响;最后,利用MATLAB/Simulink仿真验证所提计算方法和分析结果的正确性,所提暂态电流计算方法的计算误差在1%以下。研究表明,暂态电流的含量可达到额定电流的2倍以上,延时环节将使测量值与实际值之间存在测量误差,该测量误差输入到电流闭环中会带来正、负序dq轴电流振荡,低次谐波含量暂时性上升等新特征。
The inverter interfaced distributed generation(IIDG)is connected to the power grid through grid-connected inverters,and the fault current characteristics are significantly different from traditional equipment,posing challenges for fault protection in the distribution network.The positive and negative sequence separation algorithm based on T/4 delay is widely used in the grid-connected converter control system.However,the effect of delay link on the transient fault current characteristics has not been fully studied.Therefore,on the basis of sorting out the transient response link of the converter fault,the mathematical models of the converter topology and the control system with positive and negative sequence separation links were respectively established firstly,and the delay link was linearized by Pade approximation.Furthermore,a closed-loop model for the transient fault current of grid-connected inverters was established,and the impact of delay link on the transient fault current characteristics was analyzed.Finally,the correctness of the proposed calculation method and analysis results were verified by the MATLAB/Simulink simulation.The calculation error of the transient current calculation method proposed in this paper was below 1%.The research shows that the content of transient current can reach more than 2 times the rated current.The delay link will result in measurement errors between the measured value and the actual value,and the input of this measurement error into the current closed-loop will cause new features such as positive and negative sequence dq axis current oscillation,and temporary increase in low harmonic content.
作者
黎承新
刘沈全
李杰
王钢
LI Chengxin;LIU Shenquan;LI Jie;WANG Gang(School of Electric Power,South China University of Technology,Guangzhou,Guangdong 510641,China)
出处
《广东电力》
2023年第7期1-12,共12页
Guangdong Electric Power
基金
国家自然科学基金项目(51477057)
广东省基础与应用基础研究基金面上项目(2023A1515010343)。
关键词
逆变型分布式电源
暂态电流计算
T/4延时法
故障分析
故障电流特性
低电压穿越
inverter interfaced distributed generation(IIDG)
transient current calculation
T/4 time delay method
fault analysis
fault current characteristic
low voltage ride through
