BSI PD IEC TR 61000-4-40:2020
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Electromagnetic compatibility (EMC) – Testing and measurement techniques. Digital methods for the measurement of power quantities of modulated or distorted signals
Published By | Publication Date | Number of Pages |
BSI | 2020 | 38 |
This part of IEC 61000, which is a Technical Report, deals with the assessment of electrical power quantities (RMS voltage, RMS current and active power). It explains and compares two digital algorithms suitable for power quantity measurements in fluctuating or non-periodic loads. The examples are from 50 Hz or 60 Hz power systems.
This document does not attempt to cover all possible digital implementations of the algorithms used for power quantity assessment in fluctuating loads, for example in the context of the EMC assessment described in several IEC documents. Rather, it compares averaging with one of the filtering algorithms. This document aims to highlight some examples of applications that illustrate how the presented algorithms work. Further, guidance is given for quantifying the accuracy of each approach.
PDF Catalog
PDF Pages | PDF Title |
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2 | undefined |
5 | CONTENTS |
7 | FOREWORD |
9 | INTRODUCTION |
10 | 1 Scope 2 Normative references 3 Terms and definitions 4 General |
12 | 5 Modulated sine waveforms used in this document to compare measurement algorithms 5.1 General |
13 | 5.2 Half-wave rectification 5.3 Full-wave rectification Figures Figure 1 – Typical resistive load current and supply voltage waveform of half-wave rectification |
14 | 5.4 Multi-cycle symmetrical control Figure 2 – Typical full-bridge rectifier current and supply voltage waveforms Figure 3 – Current and voltage patterns in an MCSC circuit, (left) 1/3 MCSC and (right) 2/3 MCSC |
15 | 5.5 Random on-off control 6 Measurement algorithms 6.1 General 6.2 Averaging algorithms 6.2.1 General Figure 4 – Amplitude of 50 Hz current with on and off periods varying within a 1 min to 2 min range |
16 | 6.2.2 Performance of the averaging algorithm |
17 | Figure 5 – Step response of an algorithm in Formula (6) with a half-cycle, 1-cycle and 10-cycle measurement interval |
18 | Figure 6 – RMS current and active power for half-wave rectification Figure 7 – Sliding average RMS current and active power of a device controlled with a 1/3 MCSC circuit |
19 | Figure 8 – Worst case 1/3 MCSC circuit active power calculation variation Table 1 – Calculated power of 2/3 MCSC for different measurement windows |
20 | Figure 9 – Example of a 10 min sliding average power calculation for a load having a 92 s period |
21 | 6.2.3 Instrumental errors of the averaging algorithm Figure 10 – Active power of randomly fluctuating load averaged over a sliding 10 min interval |
22 | 6.3 Smoothing filter algorithm 6.3.1 Frequency and step response Figure 11 – Sensitivity of the full-bridge rectifier RMS current and active power measurement to time interval error of single-cycle sliding average calculation |
23 | Figure 12 – Comparison of the first and the 10th order filters used to estimate RMS current of a step signal Figure 13 – Filter frequency responses Figure 14 – Filter step responses |
24 | 6.3.2 Verification of the smoothing filter algorithm Figure 15 – Output of the 10th order smoothing filter used to calculate the active power of a signal with a step change |
25 | Figure 16 – Delay and response time of a 10th order filter used to assess the sinusoidal current of a sinusoidal waveform Figure 17 – Measurement of the current and power of a half-wave rectified signal using a smoothing filter with a 10 Hz cut-off frequency |
26 | Figure 18 – Power quantities in full wave rectification assessed using a smoothing filter with 16,667 Hz cut-off frequency Figure 19 – MCSC 1/3 pattern power quantities filtered with approximately 5,556 Hz cut-off frequency |
27 | Figure 20 – Active power of a load having a 92 s period measured with different algorithms |
28 | 6.3.3 Instrumental errors of the filtering algorithm 7 Conclusions Figure 21 – Active power of randomly fluctuating load measured using different algorithms |
30 | Annex A (informative)Smoothing filter studied in this document A.1 Algorithm |
34 | A.2 General C++ class program code |
37 | Bibliography |