POWER QUALITY REPORT

Transcription

1 Power Quality Research Lab., I-7, Wyb. Wyspiaoskiego 27, Wrocław, Poland phone , fax , Facility: XXX POWER QUALITY REPORT Start Monitoring: XX Stop Monitoring: XX Received Data: XX Report Generated: XX Survey Type: Equipment Installed and Operating Project Manager: Zbigniew Leonowicz, PhD Eng. Collaborators: XXX SUMMARY OF REPORT: Power quality assessment showed no significant issues. Voltages over upper limit were detected mainly in L2 of the 110 kv distribution network.

2 Acceptable Needs Follow-Up Problem Not Applicable Power Quality Report Category Summary Analysis GENERATOR (10,5 kv) Harmonic current factor Values within the limits Symmetrical components of currents Ratio of the negativesequence component of current to the rated current Voltage and frequency limits during operation Voltage dependence of the generator frequency Values within the limits Values within the limits Values within the limits Values within the limits Events No events recorded Power frequency assessment Long-term flicker severity DISTRIBUTION NETWORK (110 kv) Values within the limits Values within the limits Unbalance Values within the limits Harmonics Values within the limits THD Values within the limits Voltage Values within the limits Events Overvoltages, Voltage over RMS upper limit mainly in L2, see page 25. Page 2

3 CONTENT 1. MEASUREMENTS RELATED TO AC GENERATOR MEASURING EQUIPMENT AC GENERATOR PARAMETERS HARMONIC CURRENT FACTOR (HCF) SYMMETRICAL COMPONENTS OF CURRENTS RATIO OF THE NEGATIVE-SEQUENCE COMPONENT OF CURRENT TO THE RATED CURRENT (I 2 /I N ) VOLTAGE AND FREQUENCY VARIATIONS DURING OPERATION VOLTAGE DEPENDENCE OF THE GENERATOR FREQUENCY SUMMARY OF THE REPORT MEASUREMENTS RELATED TO 110 KV DISTRIBUTION NETWORK MEASURING EQUIPMENT POWER FREQUENCY ASSESSMENT LONG TERM FLICKER SEVERITY VOLTAGE UNBALANCE ASSESSMENT HARMONICS ASSESSMENT SUPPLY VOLTAGE VARIATION EVENTS SUMMARY OF THE REPORT LITERATURE Page 3

4 1. Measurements related to AC generator In this chapter, the power quality (PQ) report contains assessment of set of PQ parameters recorded indirectly at the AC generator (10,5 kv). Recorded values were compared with recommended values. Power quality report includes assessment of : harmonic current factor (HCF) [4] system of currents symmetrical components [4] ratio of the negative-sequence component of current to the rated current [4] voltage and frequency variations during operation [4] voltage dependence of the generator frequency [5] recorded power quality events and transients Measurements were done on the voltage and current transformers terminals in the XXX Localization of the power quality recorder in the generator circuitry presents XX 1.1. Measuring equipment Fluke 1760, Three-Phase Power Quality Recorder Topas, Serial No. Y760588, GPS time synchronization, Class-A compliance AC Generator Parameters Manufacturer: XXX Type: XXX Air cooled turbo generator, apparent power 76 MVA, rated voltage 10,5 kv, current 4205 A, power factor 0,85, speed 3000 rpm. The generator parameters during 1 week assessment time are shown in Table 1-1: Page 4

5 Table 1-1. Generator parameters during the assessment period Parameter min Values Percentile 95% max Active power P [MW] 24,515 62,975 64,291 Reactive power Q [MVAr] 2,604 18,361 22,961 Apparent Power S [MVA] 24,752 64,802 66,782 cosφ 0,934 0,994 0,999 tanφ 0,045 0,110 0,382 Power factor PF 0,964 0,993 0,998 PF is defined as: PF=(P/ S ) (Q h / Q h ) Fig Visualization of the generator s active power in 1 week. (yellow line sum of three phase quantities) Page 5

6 Fig Visualization of the generator s reactive power in 1 week. Fig Visualization of the generator s apparent power in 1 week. Page 6

7 Fig Visualization of the generator s power factor (cosφ) in 1 week. Fig Visualization of the generator s power factor (PF=(P/ S )*(Q h / Q h )) in 1 week. Page 7

8 Fig Localization of the power quality measurements in the generator circuitry Harmonic current factor (HCF) Three-phase a.c. generators shall be suitable for supplying circuits which, when supplied by a system of balanced and sinusoidal voltages result in currents not exceeding a harmonic current factor (HCF) of 5% [4]. The HCF shall be computed by using the following formula: where i n is the ratio of the harmonic current I n to the rated current I N ; n is the order of harmonic; k = 13. Harmonic components are shown in Fig Table 1-2. Assessment of the HCF HCF HCF assessment [%] min 1,01 Percentile 95% 1,69 max 1,83 During 100% of the assessment period the maximum HCF values are within the range of 1,01% 1,83%, all below the limit of 5%. Page 8

9 Fig Visualization of the currents harmonics averaged over 1 week. (in all figures the plots of L1 are blue, L2-red, L3-green) 1.4. Symmetrical components of currents Three-phase a.c. generators shall be suitable for supplying circuits which, when supplied by a system of balanced and sinusoidal voltages result in a system of currents where neither the negative-sequence component nor the zero-sequence component exceed 5% of the positive-sequence component [4]. Currents symmetrical components are shown in Fig. 1.8 and 1.9. Page 9

10 Fig Visualization of currents Zero to Positive sequence ratio. Fig Visualization of currents Negative to Positive sequence ratio. Page 10

11 Table 1-3. Assessment of the negative and zero-sequence components Components ratio assessment min Components ratio [%] Percentile 95% max Zero/Pos 0,43 0,50 0,50 Neg/Pos 0,55 1,11 2,35 During 100% of the assessment period measured values hold in range from 0,43% to 0,50% for zero sequence component and from 0,55% to 2,35% for negative sequence component, all below the limit of 5% Ratio of the negative-sequence component of current to the rated current (I2/IN) Three-phase synchronous machines shall be capable of operating continuously on an unbalanced system in such a way that, with none of the phase currents exceeding the rated current, the ratio of the negative-sequence component of maximum current for continuous operation (I 2 ) to the rated current (I N ) does not exceed the value of 8% for a.c. generators with direct cooled (inner cooled) rotor windings [4]. Table 1-4. Assessment of the I 2 /I N I 2 /I N assessment I 2 /I N [%] I 2 /I N min 0,008 I 2 /I N Percentile 95% 0,152 I 2 /I N max 0,356 Page 11

12 Fig Visualization of currents I 2 /I N ratio. Figure 1.10 and Table 1-4 contains statistical parameters which confirmed that in the investigated case requirements for I 2 /I N are fulfilled. The recorded r.m.s. values hold in range from 0,008% to 0,356% Voltage and frequency variations during operation For a.c. machines rated for use on a power supply of fixed frequency supplied from an a.c. generator (whether local or via a supply network), combinations of voltage variation and frequency variation are classified as being either zone A or zone B, in accordance with Figure 1.11 for generators and synchronous condensers. A machine shall be capable of performing its primary function, continuously within zone A, but need not comply fully with its performance at rated voltage and frequency [4]. Page 12

13 Fig Voltage and frequency limits for generators with plotted limit range of recorded values (red rectangle). Table 1-5. Assessment of voltage and frequency limits Voltage and frequency limits U, f U [p.u.] f [p.u.] min 0,9997 0,9981 Percentile 95% 1,0255 1,0010 max 1,0257 1,0016 Page 13

14 Fig Visualization of voltage variation in 1 week. Fig Visualization of frequency variation in 1 week. Page 14

15 Visualization of the recorded data in Figures 1.12 and and Table 1-5 contain statistical parameters which confirmed that in the investigated case requirements for voltage and frequency limits are fulfilled Voltage dependence of the generator frequency The generating unit should maintain the following relationship between the frequency of the generator and voltage [5] for where f is the change of frequency in p.u. and U g is the change of generator voltage corresponding to the change of frequency, in p.u. Table 1-6. Assessment of voltage dependence on generator frequency U g / f [p.u.] U g / f 10min f 8, U g -5 1, max 0,0196 For measured data, the maximum of numerical approximate gradient showed the point where the change of frequency was the highest ( :00:00), see Table 1-6. Corresponding change of voltage was determined and the ratio U g / f computed at this time point [2]. The requirements are fulfilled Summary of the report Presented in previous section assessment of crucial power quality parameters indicates that: in case of harmonic current factor (HCF), requirements are fulfilled in case of system of currents symmetrical components, requirements are fulfilled in case of the ratio of the negative-sequence component of current to the rated current, requirements are fulfilled in case of voltage and frequency variations during operation, requirements are fulfilled in case of voltage dependence of the generator frequency, requirements are fulfilled Page 15

16 During the assessment period no events were detected (with exception to one generator disconnection from the grid due to causes not relevant to power quality assessment). Page 16

17 2. Measurements related to 110 kv distribution network In this chapter, the power quality (PQ) report contains assessment of set of PQ parameters recorded indirectly at power line of the distribution network (110 kv). Recorded values were compared with recommended values. Power quality report includes assessment of : power frequency long term flicker severity voltage unbalance harmonics recorded power quality events and transients 2.1. Measuring equipment Fluke 1760, Three-Phase Power Quality Recorder Topas, Serial No. UO13379, GPS time synchronization, Class-A compliance. Measurements were done on the voltage and current transformers terminals of transmission line 1 in XXX. Localization of the power quality recorder in the distribution network of the 110 kv line No. 1 presents XX Fig Localization of the power quality measurements in 110 kv distribution network Power frequency assessment The standards [3] and [4] indicate that the nominal frequency of the supply voltage shall be 50 Hz. Under normal operating conditions the mean value of the fundamental frequency measured over 10 s shall be within a range of: for systems with synchronous connection to an interconnected system with the voltage below 220 kv: Page 17

18 50 Hz ± 1 % (i.e. 49,5 Hz... 50,5 Hz) during 99,5 % of a week; 50 Hz + 4 % / - 6 % (i.e. 47 Hz Hz) during 100 % of the week; Fig Visualization of power frequency variation. Table 2-1. Assessment of power frequency variation f Frequency assessment [Hz] f 10s min 49,905 f 10s Percentile 99,5% 50,009 f 10s max 50,109 Visualization of the recorded set of frequency values is shown in Fig Figure 2.2 and Table 1-2 contains the statistical parameters which confirmed that in the investigated case requirements for frequency standards are fulfilled. During 100% of the assessment period frequency values hold in range from 49,905 to 50,109 Hz. Page 18

19 2.3. Long term flicker severity Fig Visualization of long-term flicker severity Table 2-2. Assessment of long-term flicker severity Flicker assessment L1 L2 L3 [-] [-] [-] Plt 2h Percentile 95% 0,73 0,65 0,63 min 0,15 0,16 0,15 max 0,75 0,66 0,64 Visualization of the recorded set of long-term flicker coefficient values is shown in Fig 2.3. The standards indicate that under normal operating conditions, in any period of one week the long term flicker severity caused by voltage fluctuation should be Plt 0,8 for 95 % of the time [5]. Table 2-2 contains the statistical parameters which confirmed that in the investigated case requirements for flicker severity are fulfilled. 95% of the recorded long-term flicker values hold in range from 0,15 to 0,75. Moreover 100% of the recorded values follows by the standard expectation. Page 19

20 2.4. Voltage unbalance assessment Fig Visualization of the voltage unbalance variation Table 2-3. Assessment of unbalance variation Unbalance assessment Neg/Pos [%] Neg/Pos 10min Percentile 95% 0,26 min 0,15 max 0,29 Visualization of the recorded set of unbalance values is shown in Fig The standard [4] indicates that under normal operating conditions, during each period of one week, 95 % of the 10 min mean r.m.s. values of the negative phase sequence component (fundamental) of the supply voltage shall be within the range 0 % to 1 % of the positive phase sequence component (fundamental). Table 2-3 contains statistical parameters which confirm that in the investigated case requirements for unbalance standards are fulfilled. The recorded unbalance coefficient hold in range from 0,15% to 0,29%.(with 95% values not greater than 0,26%). Page 20

21 2.5. Harmonics assessment Table 2-4. Assessment of harmonic variations Harmonic assessment Percentile95% Max Order Limits L1 L2 L3 L1 L2 L3 Nr. [ % ] [ % ] [ % ] [ % ] [ % ] [ % ] [ % ] 2 1,50 0,06 0,06 0,06 0,09 0,09 0,08 3 2,00 0,26 0,30 0,15 0,28 0,33 0,19 4 1,00 0,03 0,02 0,02 0,04 0,03 0,04 5 2,00 0,74 0,66 0,71 0,90 0,89 0,95 6 0,50 0,02 0,02 0,02 0,04 0,03 0,03 7 2,00 0,41 0,39 0,39 0,53 0,48 0,50 8 0,50 0,03 0,02 0,03 0,05 0,05 0,05 9 1,00 0,04 0,04 0,04 0,07 0,07 0, ,50 0,03 0,03 0,03 0,07 0,06 0, ,50 0,14 0,16 0,15 0,18 0,19 0, ,50 0,02 0,02 0,02 0,02 0,02 0, ,50 0,19 0,19 0,19 0,27 0,28 0, ,50 0,02 0,02 0,02 0,03 0,03 0, ,50 0,02 0,02 0,02 0,03 0,03 0, ,50 0,01 0,01 0,01 0,02 0,02 0, ,00 0,10 0,10 0,12 0,13 0,12 0, ,50 0,01 0,01 0,02 0,02 0,03 0, ,00 0,07 0,06 0,06 0,09 0,10 0, ,50 0,01 0,01 0,01 0,02 0,03 0, ,50 0,01 0,01 0,01 0,03 0,03 0, ,50 0,01 0,01 0,01 0,02 0,02 0, ,70 0,07 0,08 0,08 0,11 0,14 0, ,50 0,01 0,01 0,01 0,02 0,03 0, ,70 0,07 0,06 0,07 0,13 0,11 0,13 26* 0,68 27* 0,66 28* 0,65 29* 0,63 0,02 0,02 0,02 0,02 0,02 0,02 30* 0,62 31* 0,60 0,02 0,02 0,02 0,02 0,02 0,02 Page 21

22 32* 0,59 33* 0,58 34* 0,57 35* 0,56 0,02 0,02 0,02 0,02 0,02 0,02 36* 0,55 37* 0,54 0,02 0,02 0,02 0,02 0,02 0,02 38* 0,53 39* 0,52 40* 0,51 41* 0,50 0,02 0,02 0,03 0,02 0,02 0,03 42* 0,50 43* 0,49 0,02 0,03 0,03 0,02 0,03 0,03 44* 0,48 45* 0,48 0,01 0,01 0,02 0,01 0,01 0,02 46* 0,47 47* 0,47 0,02 0,02 0,02 0,02 0,02 0,02 48* 0,46 49* 0,46 0,02 0,01 0,01 0,02 0,01 0,01 50* 0,45 *For harmonics higher than 25 th the formula for the harmonic limit is 0,2+0,5 (25/h) [%] [5]. Fig, 2.5. Visualization of the voltages harmonic spectrum averaged in 1 week. Page 22

23 Table 2-4 contains limits for particular harmonics defined in [5] and statistical parameters of recorded data. Distribution of the harmonics is also visible in Fig, 2.5. Performed measurements has detected no values over the limit. Fig, 2.6. Visualization of THDV variation Table 2-5. Assessment of THDV variation THDVL1 THDVL2 THDVL3 THDV assessment [%] [%] [%] min 0,37 0,38 0,29 THDV Percentile 95% 0,88 0,81 0,83 10min max 0,99 0,99 1,02 Visualization of the recorded set of total harmonics distortion in voltage is shown in Fig. 2-6, [5] indicates THD of the supply voltage (including all harmonics up to the order 40) shall be less than or equal to 3 %. Table 2-5 contains the statistical parameters of THDV which confirmed that in the investigated case requirements are fulfilled, 95% of the recorded THDV coefficient hold in Page 23

24 range from 0,83% to 0,88%, Moreover 100% of the recorded values follow by the standard expectation Supply voltage variation Fig Visualization of supply voltage variation. Table 2-6. Assessment of supply voltage variation U 10min Voltage assesment min Percentile 95% max VL1 VL2 VL3 [V] [V] [V] 67609, , , , , , , , ,00 Visualization of the recorded set of supply voltage values is shown in Fig, 2.7. The [5] indicates that under normal operating conditions: - during each period of one week 95 % of the 10 min mean r.m.s. values of the supply voltage shall be within the range of Un ± 10 %, i.e. in the range 57157, ,38 V. Table 2-6 contains statistical parameters which confirmed that in the investigated case requirements for r.m.s. supply voltage standards are fulfilled, 95% of the recorded r.m.s., Page 24

25 values hold in range from 69407,25 V to 69648,00 V Moreover 100% of the recorded values follows by standard expectation, i.e. are within the range of 50806,82 V 76210,23 V Events During the assessment period the following events were detected: Overvoltages Designation L1 L2 L3 L123-N Number Maximum value [V] Maximum duration 4h 56m 26s 8h 51m 14s 6h 9m 33s 8h 51m 14s Details of recorded events Event Location Detection Date & Time Voltage Swells V L :45:43,71 Voltage Swells V L :45:43,71 Voltage Swells V L :51:22,33 Voltage Swells V L :05:31,08 Voltage Swells V L :18:47,43 Voltage Swells V L :00:50,17 Voltage Swells 3-ph V L123-N :47:40,70 Voltage Swells 3-ph V L123-N :47:40,70 Voltage Swells 3-ph V L123-N :53:02,94 Voltage Swells 3-ph V L123-N :33:09,62 RMS Upper Limit V L :33:09,62 RMS Upper Limit V L :20:18,80 RMS Upper Limit V L :55:21,73 RMS Upper Limit V L :43:38,14 RMS Upper Limit V L :43:38,14 h06 Harmonics V L :15:00,91 h06 Harmonics V L :27:37,11 h06 Harmonics V L :38:24,90 h06 Harmonics V L :05:16,99 Duration 6h 9m 33s 4h 56m 26s 8h 51m 14s 5h 16m 0s 4h 8m 3s 4h 5m 8s 8h 51m 14s 5h 16m 0s 4h 8m 3s 4h 5m 8s 4h 44m 5s 10h 19m 45s 6h 11m 40s 4h 33m 42s 4h 23m 59s Value 6,99e+04 [V] 6,988e+04 [V] 7,014e+04 [V] 7,003e+04 [V] 6,999e+04 [V] 6,991e+04 [V] 7,014e+04 [V] 7,003e+04 [V] 6,999e+04 [V] 6,991e+04 [V] 6,987e+04 [V] 7,012e+04 [V] 7,001e+04 [V] 6,996e+04 [V] 6,989e+04 [V] 200,06ms 0,5343 [%] 200,05ms 0,5235 [%] 199,88ms 0,501 [%] 999,77ms 0,5519 [%] Page 25

26 h06 Harmonics V L :05:16,99 h06 Harmonics V L :05:19,01 h06 Harmonics V L :29:01,27 h06 Harmonics V L :55:14,98 h12 Harmonics V L :44:23,45 199,99ms 0,5788 [%] 1,0002s 0,5491 [%] 200,05ms 0,5054 [%] 200,11ms 0,5294 [%] 199,96ms 0,7392 [%] 2.8. Summary of the report Presented in previous section assessment of crucial power quality parameters indicates that: in case of power frequency, requirements are fulfilled in case of voltage supply, requirements are fulfilled in case of flicker severity, requirements are fulfilled in case of voltage unbalance, requirements are fulfilled in case of THD of the supply voltage, requirements are fulfilled in case of harmonics, requirements are fulfilled Multiple events were detected during the recording time. Closer follow-up require the overvoltages. 3. Literature [1] IEC :2008, Electromagnetic compatibility (EMC): Testing and measurement techniques -Power quality measurement method [2] Bollen M,H,J, Irene Yu-Hua Gu, Signal Processing of Power Quality Disturbances, 2006 The Institute of Electronics and Electrical Engineers, Inc [3] EN 50160: Voltage characteristics of electricity supplied by public distribution networks [4] IEC : Rotating electrical machines: 7 Electrical operating conditions [5] Regulations of the operation and exploitation of the distribution network Page 26