基于余弦平顶窗的谐波相量测量

Harmonic phasor measurement based on a cosine flat-top window

针对电力系统中带外干扰、频率偏移及其他动态情况下的谐波相量估计问题,提出了一种基于余弦平顶窗的谐波相量估计器。首先基于余弦窗频域表达式,利用理想幅值响应和最小二乘法获得平顶窗的窗系数。在此基础上,为使得滤波器频率响应在标称谐波频率下具有零增益,将所得窗函数与频域采样定理相结合,通过最小二乘法设计一组有限脉冲响应滤波器,用于估计谐波相量。然后,分析了余弦平顶窗和谐波相量测量滤波器的频率响应。最后,采用稳态和动态条件下的不同信号模型对提出的谐波相量估计器进行了性能验证。仿真结果表明,相对于基于Sinc插值函数和频域采样定理的两种谐波相量估计器,所提方法有较强的带外干扰抑制能力,在多种条件下能实现较高精度的谐波相量测量。

There is a problem of harmonic phasor estimation under out-of-band interference,frequency deviation and other dynamic situations in power systems.Thus a harmonic phasor estimator based on a cosine flat-top window is proposed.First,the window coefficients of the flat-top window are obtained by the ideal amplitude response and the least squares method based on the cosine window frequency domain expression.To obtain a frequency response with zero gain at the nominal harmonic frequency,the obtained window function is combined with the frequency domain sampling theorem.Based on this,a bank of finite impulse response filters is designed by the least squares method,and they are used to estimate the harmonic phasor.Then,the frequency response of the cosine flat-top window and the harmonic phasor measurement filter is analyzed.Finally,the performance of the proposed harmonic phasor estimator is verified by different signal models under steady-state and dynamic conditions.The simulation results show that,compared with the two harmonic phasor estimators based on the Sinc interpolation function and the frequency domain sampling theorem,the proposed method has a stronger ability to suppress out-of-band interference,and more accurate harmonic phasor estimation can be realized under the various conditions.