Modern power systems face power quality issues such as voltage fluctuations and flicker due to high penetration of renewable energy. Conventional IEC flicker meters, which perform well for stable single-frequency amplitude-modulated waves, may introduce errors when analyzing time-varying or multi-component flicker signals and are constrained by fixed sampling rates. To overcome these drawbacks, this paper proposed an algorithm based on autoregressive-chirp Z-transform-analytical mode decomposition (AR-CZT-AMD). The method enables accurate flicker parameter detection without being constrained by fixed sampling rates.
The procedure included five steps. First, data were acquired and a preliminary spectrum was estimated using FFT or CZT. Second, whether the data length met the AMD requirement was checked. Third, if data were insufficient, AR modeling was applied for forward and backward prediction to extend the sequence. Model order was carefully selected to avoid noise-induced drift. Fourth, when data were sufficient, CZT refined the frequency band of interest. Bisection points between adjacent frequencies were used as refinement centers to avoid errors from averaging. This step did not require prior knowledge of exact frequencies. Finally, Hilbert transform resolved instantaneous parameters. Median values were used for ideal signals, while sliding-window filtering was applied in noisy cases.
The algorithm was validated through simulations tests. Tests showed that at a resolution of $\Delta f$ conditions($\Delta f$ representing dense frequency intervals), both WFFT and AMD perform similarly, while the proposed method maintains high accuracy. Under the three specified resolution scenarios—$2 \Delta f$, in noise-free conditions, $\Delta f$ in low-noise conditions, and $\Delta f / 2$ for high-resolution requirements—the method consistently achieved high-precision parameter extraction. In all these cases, the relative root-mean-square error remained below 4%. Furthermore, simulations and practical measurements on multi-component dense flicker signals confirmed that the algorithm effectively detects parameters of multi-frequency amplitude-modulated waves. The short-term flicker error was less than 5%, meeting IEC standards.
The following conclusions are drawn: (1) The proposed algorithm requires fewer data points (in a shorter period of time) than other methods, reducing error accumulation from prolonged AR prediction. (2) AR-based data extension outperforms non-predictive approaches such as WFFT, AMD, and CZT. (3) CZT accurately locates bisection frequencies, avoiding mainlobe interference and enabling robust AMD decomposition. (4) The method is also applicable to multi-component harmonic and flicker signal analysis.
徐奥傲, 李开成, 罗溢, 袁文涛, 陆梓浩. 基于AR-CZT-AMD的多密频闪变信号参数提取[J]. 电工技术学报, 2026, 41(18): 6287-6303.
Xu Aoao, Li Kaicheng, Luo Yi, Yuan Wentao, Lu Zihao. A Method for Extracting Multi-Density Frequency Flicker Signal Parameters Based on AR-CZT-AMD. Transactions of China Electrotechnical Society, 2026, 41(18): 6287-6303.
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