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Quality of electric energy supply
Harmonics in public supply network
1. A theme content and application
This standard stipulates allowable value of public network harmonics and testing methods.
This standard applies to the public network of the AC rated of 50 Hz, and the standard voltage 110 KV and below.
The standard voltage 220 KV network can refer to 220 KV standards to perform.
This standard does not apply to transient phenomenon and short-term Harmonic.
2. Use standard
GB 156 rated voltage
3. Term
3.1、Point of common coupling.
It is where users access to the Connection of public network.
3.2、harmonic measurement points
They are where test the harmonic of network and Users
3.3、fundamental (component)
Carried through Fourier series decomposition for cyclical exchange, getting frequency is the same as the work frequency.
3.4、harmonic (component)
Carried through Fourier series decomposition for the cyclical exchange volume, getting frequency is more than once the fundamental wave frequency.
3.5、harmonic order(h)
Integer of Harmonic frequency divides integer of fundamental wave frequency.
3.6、harmonic content (for voltage or current).
Harmonic content is volume which gets from the cyclical exchange volume subtracts fundamental wave component.
3.7、harmonic ratio(HR)
The root-mean-square-value of cyclical exchange volume containing the first h harmonics divides the root-mean-square-value of fundamental component (with percentage).
3.8、total harmonic distortion (THD).
The root-mean-square-value of cyclical exchange volume of the harmonic content divides the root-mean-square-value of fundamental component (with percentage).
The rate of total harmonic voltage distortion --THDu. The rate of current total harmonic distortion --- THDi.
3.9、harmonic source
It is that puts harmonic current to the public network or is electrical equipment that produces harmonic voltage in public network.
3.10、short duration harmonics
Duration of the impact is not more than 2 s, and the impact between the two intervals is not less than 30 s , it causes Electricity containing harmonics and the harmonic voltage.
Note : expression of harmonic terms sees Appendix A (Supplement)
4、Harmonic voltage limits
Public network harmonic voltage (phase voltage) limits are shown in Table
1.
5、 Harmonic current allowable value
5.1、The harmonic current component (root-mean-square-value) which all users of public access point put into this point should not exceed the permit value in table 2 . When the minimum short- circuit capacity of public access point is different from the benchmark short-circuit capacity, the conversion of the harmonic current allowable value in Table 2 sees Appendix B (Supplement)
5.2、The harmonic current allowable value which each user of public access point puts into network is distributed; according to agreement capacity of this user at this point divides the power supply equipment capacity of the public connection. Allocation method of calculation sees Appendix C (supplement).
6、 measurement
Measurement of harmonic method, data processing and measurement equipment requirements, see appendix D (Supplement) . Allowable value of the harmonic current which in Table 2 put into the public connection.
