GB/T 123262008 (GB/T123262008, GBT 123262008, GBT123262008) & related versions
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Power quality  Voltage fluctuation and flicker

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Quality of electric energy supplyAdmissible voltage fluctuation and flicker

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Preview PDF: GB/T 123262008
GB/T 123262008: PDF in English (GBT 123262008) GB/T 123262008 GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA ICS 27.100 F 020 Replacing GB 123262000 Power quality  Voltage fluctuation and flicker ISSUED ON. JUNE 18, 2008 IMPLEMENTED ON. MAY 1, 2009 Issued by. General Administration of Quality Supervision, Inspection and Quarantine; Standardization Administration Committee. Table of Contents Foreword ... 3 1 Scope ... 5 2 Normative references ... 5 3 Terms and definitions ... 5 4 Limits of voltage fluctuation ... 7 5 Limits of flicker ... 7 6 Measurement and estimation of voltage fluctuation ... 9 7 Flicker measurement and calculation ... 11 8 Superposition and transfer of flicker ... 12 Annex A (Normative) Flicker measurement and calculation formulas ... 15 Annex B (Informative) Estimation method for total supply capacity StHV of high voltage (HV) ... 19 Annex C (Informative) Estimation method for flicker of electric arc ... 20 Annex D (Informative) Statistical method of flicker qualification rate ... 21 Bibliography ... 22 Foreword This Standard replaces GB 123262000 Power qualityVoltage fluctuation and flicker. Compared with GB 123262000, the main contents of this modification are as follows.  adjusted the limits of flicker, used the longterm flicker value Plt as the limit for flicker, a certain degree of relaxation than the original flicker limit. For flicker caused by a single fluctuating load, according to the actual situation, it was still divided into three levels, but there was a certain simplification, and put forward a clear management requirements for excessive user;  adjusted the criterion of the voltage fluctuation limit. For voltage fluctuation of low voltage fluctuation frequency or regular periodic voltage fluctuation, the current limit was still used as the criterion; for irregular voltage fluctuations, it specified the maximum value of the voltage fluctuation as criterion and adjusted the previous limit. This enhanced the voltage fluctuation measurement and judged whether the operability was qualified;  adjusted the flicker’s measurement duration, value method. The flicker of the common connection point of the power system used one week (168 h) to measure. The flicker caused by a single fluctuating load used one day (24 h) to measure. They all took the maximum value as criterion for qualification;  simplified flicker estimation method; deleted the sine wave which was not commonly used, triangular wave voltage fluctuation Pst = 1 curve analysis method, the simulation method which was difficult to implement and flicker time analysis in the previous standard;  simplified flicker analysis examples and evaluation methods involved in Annex C of the previous standard; used a more concise way to list various arc furnace flicker evaluation coefficients;  expanded the application scope of voltage fluctuations and flicker limits to extra high voltage (EHV) system, regardless of the flicker transmission of EHV to the next voltage level; unified the flicker transfer coefficient to 0.8, the recommended value;  added statistical method of flicker passing rate, so as to facilitate the assessment of flicker conditions. Power quality  Voltage fluctuation and flicker 1 Scope This Standard specifies the limits and test, calculation and evaluation methods of voltage fluctuation and flicker. This Standard is applicable to the rapid change of the voltage of the common connection point caused by the fluctuating load under the normal operation mode of the AC 50Hz power system and the occasion where people may obviously feel the light flicker. 2 Normative references The following standards contain the provisions which, through reference in this Standard, constitute the provisions of this Standard. For dated references, subsequent amendments (excluding corrections) or revisions do not apply to this Standard. However, the parties who enter into agreement based on this Standard are encouraged to investigate whether the latest versions of these documents are applicable. For undated reference documents, the latest versions apply to this Standard. GB/T 1562007 Standard voltage (IEC 60038.2002, MOD) GB 17625.2 Electromagnetic compatibility (EMC)  Limits  Limitation of voltage changes, voltage fluctuations and flicker in public lowvoltage supply systems, for equipment with rated current ≤ 16 A (GB 17625.22007, IEC 6100033.2005, IDT) GB/Z 17625.3 Electromagnetic compatibilityLimitsLimitation of voltage fluctuations and flicker in lowvoltage power supply systems for equipment with rated current greater than 16A (GB/Z 17625.32000, idt IEC 610003 5.1994) IEC 61000415.1996 Electromagnetic compatibility (EMC)  Testing and measurement techniques  Flicker meter  Functional and design specifications 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. Each user, according to the ratio between its agreed capacity Si (Si = Pi /cos φi) and the total capacity, shall determine the flicker limits of this user after considering the factors such as the effect of the last level on the next level flicker transfer (the transmission of next level to the last level is generally ignored). The flicker limits of single user can be calculated as follows. First, calculate the total flicker limits G generated by all loads connected to PCC point. where, LP  Long term severity Plt limit of PCC corresponding voltage level; LH  Long term severity Plt limit of last voltage level; T  The flicker transfer coefficient of the last voltage level to the next voltage level, 0.8 as recommended. The flicker transfer of EHV system to the next level voltage system shall not be considered. The flicker limits of each voltage levels are shown in Table 2. The flicker limit of single user Ei is. where, F  Simultaneous coefficient of fluctuating load of which the typical value F = 0.2 ~ 0.3 (but it must meets Si/F ≤ St); the determination method for PCC’s total capacity StHV of HV system is shown in Annex B. 5.2.4 The third level regulation. For the single fluctuating load user which does not comply with the regulations of the second level, if it still exceeds its flicker limits after treatment, it shall relax the limit appropriately, based on PCC point actual flicker conditions and development forecast of grid. However, the flicker value of PCC point must comply with the provisions of 5.1. 6 Measurement and estimation of voltage fluctuation The voltage fluctuation can be described by R.M.S. voltage shape U(t). The relative voltage change d and rate of occurrence of voltage changes r are indicators to measure the voltage fluctuation size and speed. where, ΔSi  Threephase load changes. For phase singlephase load. where, ΔSi  Phase singlephase load. NOTE In absence of shortcircuit capacity of normal smaller way, the system shortcircuit capacity designed to take can be calculated by the maximum short circuit capacity of the system during production multiplied by 0.7, the coefficient. 7 Flicker measurement and calculation Flicker is the cumulative effect of voltage fluctuations over a period of time. It reflects the light perception caused by the instability of the illumination. It is mainly measured by short term severity Pst and long term severity Plt. The calculation method of short term severity Pst is shown in Annex A. The long term severity Plt is obtained by the calculation of short term severity Pst contained in the measurement period. where, Pstj  The short term severity of No. j within 2 h. The flickers caused by various types of voltage fluctuations can be directly measured by flicker meter which complies with IEC 61000415.1996. This is the baseline method for determining the flicker value. For threephase equiprobable fluctuating load, it can select any phase to measure. When the load is a periodic, interval and rectangular wave (or step wave), the flicker can be estimated by its relative voltage change d and rate of occurrence of voltage changes r. When the relative voltage change d and the rate of occurrence of voltage changes r are known, it can use Figure 1 (or Table 4). Use Pst = 1 curve, check out the relative voltage change dLim when Pst = 1 that corresponds to r and calculate its short term severity. m  The value depends on the nature of the primary flicker source and the overlapping possibilities of its operating conditions; m=1  Used for a situation in which fluctuating load causes relative voltage change and a high overlap ratio; m=2  Used for a situation in which random fluctuating load causes relative voltage change simultaneously (for example, electric arc furnace of overlapped melting period); m=3  Used for a situation in which fluctuating load rarely causes relative voltage change simultaneou... ......
Standard ID  GB/T 123262008 (GB/T123262008)  Description (Translated English)  Power quality. Voltage fluctuation and flicker  Sector / Industry  National Standard (Recommended)  Classification of Chinese Standard  F020  Classification of International Standard  27.100  Word Count Estimation  16,158  Date of Issue  20080618  Date of Implementation  20090501  Older Standard (superseded by this standard)  GB 123262000  Quoted Standard  GB/T 1562007; GB 17625.2; GB/Z 17625.3; IEC 610004151996  Drafting Organization  China Electric Power Research Institute  Administrative Organization  Voltage and current rating and the National Standardization Technical Committee frequency  Regulation (derived from)  Announcement of Newly Approved National Standards No. 11 of 2008 (No. 124 overall)  Proposing organization  Voltage and current National Standardization Technical Committee level and frequency  Issuing agency(ies)  Administration of Quality Supervision, Inspection and Quarantine of People's Republic of China; Standardization Administration of China  Summary  This standard specifies the voltage fluctuation and flicker limits and testing, calculation and assessment methods. This standard applies to AC 50Hz power system normal operation mode, the load fluctuation caused by the voltage at the point of common coupling quick movements and thus may cause people obviously feel the flashing lights of the occasion. 
