【摘要】 对电力系统的时变谐波分析 ,提出了用局部余弦变换进行滤波处理的方法。该方法的本质是利用了局部余弦变换时频窗良好的局部性和可调性 ,来分离各次谐波 ,同时跟踪它们随时间的变化。通过采用局部余弦最佳基搜索方法 ,对信息实现不同的时间分割 ,可非常容易地调整时频窗。不需要在分析窗内对信号作平稳假定 ,所得结果与原信号完全同步。理论分析和实际应用结果表明 ,该方法可有效地检测出时变谐波 ,同DFT和STFT相比 ,提取精度更高 ,有很好的应用前景更多还原

【Abstract】 The paper puts forward a new method based on Local Cosine Transform (LCT) for measuring the time varying harmonics in power system. Since the time frequency window of LCT is localized well and adjustable, the method can quantify the frequency, amplitude and phase of time varying harmonics more accurately than DFT and STFT.The time frequency window is adjusted conveniently by using optimum base searching method,moreover,it’s not necessary to have stable wave assumption in the window.The simulations and field tests show that LCT is a powerful tool and suitable for practical use.更多还原