Use of Butterworth Filters for Real Time RMS Value Measurement
Abstract
RMS (Root Mean Square) value is the most common value that is used quantitative evaluation of currents and voltages in electrical energy systems. The most commonly used method to obtain this value is based on numerical integration of the signal. Methods based on numerical integration have disadvantages such as high computational load, requiring precise determination of frequency and being sensitive to noise. As an alternative method, methods based on filtering for RMS calculation do not have the disadvantages mentioned. In this study, RMS value calculation using digital low-pass Butterworth filter is introduced and investigated. For investigation, Butterworth filters with various orders and cut-off frequencies are simulated and compared in MATLAB. The response of this filtering-based method to sudden changes in the amplitude and frequency of the input signal is also simulated and examined. The results clearly demonstrate that the method is suitable for real-time RMS value computation, with its low computational load and robustness to frequency changes.
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