This standard specifies the limit, test, calculation and evaluation method of voltage fluctuation and flicker.
This standard is applicable to the occasion of rapid change for voltage of point of common coupling caused by fluctuating load and thereby obvious sense to lighting flicker for human under normal operation mode of AC 50Hz power system.
2 Normative References
The following standards contain provisions which, through reference in this text, constitute provisions of this standard. For dated reference, subsequent modification to, 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 edition of these documents is applicable. For undated references, the latest edition of the normative document is applicable to this standard.
GB/T 156-2007 "Standard Voltage" (IEC 60038:2002, MOD)
GB 17625.2 "Electromagnetic Compatibility (EMC)-Limits-Limitation of Voltage Changes, Voltage Fluctuations and Flicker in Public Low-voltage Supply Systems for Equipment with Rated Current≤16A per Phase and Not Subject to Conditional Connection"(GB 17625.2-2007, IEC 61000-3-3:2005, IDT)
GB/Z 17625.3 "Electromagnetic Compatibility-Limits-Limitation of Voltage Fluctuations and Flicker in Low-voltage Power Supply Systems for Equipment with Rated Current Greater than 16A"(GB/Z 17625.3-2007, idt IEC 61000-3-5:1994)
IEC 61000-4-15:1996 "Electromagnetic Compatibility (EMC)-Testing and Measurement Techniques-Flickermeter-Functional and Design Specifications"
3 Terms and Definitions
For the purpose of this standard, the following terms and definitions apply.
3.1
Point of common coupling
PCC
It refers to the joint of more then one users in power system.
3.2
Fluctuating load
It refers to the load periodically or aperiodically adopting change power from power supply network during production (or operation) process. For example: electric-arc steel furnace, rolling mill and arc welding machine.
3.3
Voltage fluctuation
It refers to the change of a series of change or connection for voltage root mean square value (effective value).
3.4
R.M.S. voltage shape
U(t)
It refers to the time function of root mean square value (effective value) per half fundamental wave voltage cycle.
3.5
Relative voltage change
d
It refers to the difference of voltages of two adjacent extreme points on R.M.S. voltage shape, which is expressed with percentage of nominal voltage of system.
3.6
Rate of occurrence of voltage changes
r
It refers to the times of relative voltage change in unit time (respectively calculating one change of voltage from large to small or from small to large). Several times change of different directions shall be calculated as one change if the interval time is less than 30ms.
3.7
Flicker
It refers to the visual sense caused by instable lighting illumination.
3.8
Short term severity
Pst
It refers to one statistic value measuring strong or weak flicker within a short time (several minutes) (see Appendix A), and the basic record cycle of flicker within a short time is 10min.
3.9
Long term severity
Plt
It refers to the quantity value reflecting strong or weak flicker for a long time (several hours) and predicted by short term severity Pst (see Appendix A), and the basic record of flicker for a long time is 2h.
3.10
Cumulative probability function
CPF
The lateral coordinate expresses the measured value and the longitudinal coordinate expresses the percentage of time exceeding corresponding lateral coordinate value accounting for the whole measuring time (See Figure A.2).
