Fast harmonic phasor measurements are very useful in power system protection applications, e.g., high-impedance fault location and intelligent method-based islanding detection. To address this problem, a novel harmonic phasor estimator is proposed in this paper, especially for P-class phasor measurement units (PMUs). The exponential functions are used to model the decaying dc (ddc) component, and the optimal time constant (TC) set for the ddc model is searched based on an enumeration method. In addition, the dynamic harmonic phasors are modeled based on the Shannon sampling theorem. As a result, a filter bank is designed for harmonic phasor and frequency estimations. The rate of change of frequency (ROCOF) of the harmonic is estimated based on a second-order fitting method. The response time of the proposed method for harmonic phasor estimation is always no longer than 40 ms. Simulation test results indicate that the proposed method is more accurate than the Taylor–Fourier transform (TFT) under ddc offset and frequency deviation conditions. In particular, the proposed method is more robust to ddc’s TC variations. An experimental test is implemented to demonstrate the advantages of the proposed method.

中文翻译：

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用于 P 类相量测量单元的谐波相量估计器

快速谐波相量测量在电力系统保护应用中非常有用，例如高阻抗故障定位和基于智能方法的孤岛检测。为了解决这个问题，本文提出了一种新颖的谐波相量估计器，特别是对于 P 类相量测量单元 (PMU)。指数函数用于对衰减的直流 (ddc) 分量进行建模，并基于枚举方法搜索为 ddc 模型设置的最佳时间常数 (TC)。此外，动态谐波相量是基于香农采样定理建模的。因此，滤波器组被设计用于谐波相量和频率估计。基于二阶拟合方法估计谐波的频率变化率（ROCOF）。所提出的谐波相量估计方法的响应时间始终不超过 40 ms。仿真测试结果表明，在ddc偏移和频偏条件下，所提出的方法比泰勒-傅立叶变换（TFT）更准确。特别是，所提出的方法对 ddc 的 TC 变化更加鲁棒。进行了实验测试以证明所提出方法的优点。