基于阻抗复数平面的自适应距离保护方案应用中的正则性问题研究

当双馈风电场送出线发生短路故障时,基于傅里叶算法的传统距离保护受双馈风机频偏特性以及过渡电阻的影响,保护动作性能较差。因此,通过分析保护安装处测量阻抗与故障点阻抗的关系,采用一种抗过渡电阻的新型自适应距离保护。针对该保护中出现的病态化问题,采用正则化处理病态表达式,在线修改自适应系数使保护的动作边界随自适应系数动态调整。最后,基于Matlab/Simulink平台搭建双馈风机电磁暂态仿真模型,考虑不同风电场规模和风速变化,对比分析传统距离保护和自适应距离保护的动作特性。结果表明自适应距离保护的动作性能较好,可靠性更高。

Research on regularity of adaptive distance protection scheme based on impedance complex plane

Traditional distance protection based on a Fourier algorithm is affected by the frequency offset characteristics and transition resistance of a Doubly Fed Induction Generator (DFIG) when the short-circuit fault occurs in the outgoing line of a doubly fed wind turbine. Protection action performance is poor. Therefore, by analyzing the relationship between the measured impedance and the fault point impedance, a new adaptive distance protection with resistance to transition resistance is adopted in this paper. Given that there is an ill-conditioned problem in the protection, regularization is used to deal with the ill-conditioned expression. The adaptive coefficient is modified online to make the action boundary of the protection adjust dynamically with the adaptive coefficient. Finally, based on the Matlab/Simulink platform, an electromagnetic transient simulation model of a DFIG is built. Considering different wind farm scale and wind speed changes, the operational characteristics of traditional and adaptive distance protection are compared and analyzed. The results show that the operational performance of adaptive distance protection is better and the reliability is higher. This work is supported by the National Natural Science Foundation of China (No. 52037003).