中文摘要：

为了更加快速、精确地检测出三相电力系统中的谐波和无功电流，基于瞬时无功功率理论，文章在传统d-q检测算法基础上进行了改进，针对锁相环容易受到电网波动影响的缺陷，采用一种无锁相环谐波和无功电流检测方法；针对低通滤波器滤波效果与响应速度无法兼顾的缺陷，采用一种变步长最小均方自适应滤波器；结合以上两种方法的优点，得到一种无锁相环无低通滤波器的检测方法。理论分析和仿真结果验证了该方法的可行性和准确性。

英文摘要：

To improve detection speed and accuracy of harmonics and reactive currents in three-phase power system, the paper adopts a detection method without phase-locked loop（ PLL）. The method is based on the instantaneous re-active power theory,and makes improvement for traditional d-q detection algorithm. Considering the problem of PLL that is prone to the influence of grid fluctuation,the method does not use PLL for detection. Considering the problem of low-pass filters（ LPF）that cannot obtain both the filter effect and the response speed,the method uses a variable step-size least mean square（ LMS ）adaptive filter. With the advantages of these two methods,a detection method without PLL and LPF is achieved. Theoretical analysis and simulation results verify the feasibility and accuracy of the method.