1 Scope
This Standard specifies the allowable limit and measuring method of the interharmonic voltage in public supply network.
This Standard is applicable to public supply network with rated AC frequency of 50Hz and nominal voltage of 220kV or below.
2 Normative References
The following documents contain provisions which, through reference in this text, constitute provisions of this Standard. For dated reference, subsequent amendments to (excluding amending error), or revisions of, any of these publications do not apply. However, all parties coming to an agreement according to this Standard are encouraged to study whether the latest editions of these documents are applicable. For any undated references, the latest edition of the normative document referred to applies.
GB/T 14549-1993 Quality of Electric Energy Supply-Harmonics in Public Supply Network
3 Terms and Definitions
3.1
Point of common coupling (PCC)
It refers to the joint through which the user is connected with public supply network.
[GB/T 14549-1993, definition 3.1]
3.2
Interharmonic measurement points
It refers to the place where the interharmonics of supply network and users are measured.
Note: it is changed from GB/T 14549-1993, definition 3.2.
3.3
Fundamental (component)
It refers to the component with same frequency and power frequency and obtained by decomposing the Fourier series of periodic alternating current component.
[GB/T 14549-1993, definition 3.3]
3.4
Harmonic (component)
It refers to the component with a frequency one integral multiple greater than the fundamental frequency and obtained by decomposing the Fourier series of periodic alternating current component.
[GB/T 14549-1993, definition 3.4]
3.5
Harmonic order
h
It refers to the integer ratio of the harmonic frequency to fundamental frequency.
[GB/T 14549—1993, definition 3.5]
3.6
Interharmonic component
It refers to the component with a frequency other than the integral multiple of the fundamental frequency and obtained by decomposing the Fourier series of periodic alternating current component.
3.7
Interharmonic order
ih
It refers to the ratio of interharmonic frequency to fundamental frequency.
3.8
Interharmonic ratio (IHR)
It refers to the ratio of the root-mean-square value (r.m.s.) of the No. ih interharmonic component included in periodic alternating current component to that of the fundamental component (expressed in percent).
The content rate of No. ih interharmonic voltage is expressed in IHRUih.
3.9
Beat frequency
It refers to the absolute value of frequency difference (such as interharmonic frequency and fundamental frequency in public supply network) during the integration of two sine wave voltages at different frequencies.
4 Limit
4.1 The content rate of each interharmonic voltage at PCC of 220kV power system or below shall not be greater than the limit specified in Table 1.
1 Scope
2 Normative References
3 Terms and Definitions
4 Limit
5 Measuring Values and Conditions
6 Accuracy of Measuring Instrument
Appendix A (Normative) Relation Curve of Interharmonic Voltage Content Rate and Beat Frequency
Appendix B (Informative) Interharmonics, Its Hazard and Group Concept Introduction
Bibliography
