Microsoft PowerPoint - 041_Power Quality.ppt

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1 Jame Huang 黃昭明 Front End Sales ABB Taiwan Power Quality 電力品質 May, 27 TWABB - 1 -

2 Power Quality: What is it? Power quality is 電力品質是電壓波形的改變程度 [ 包含頻率變動電壓變動諧波歧變不平衡程度...] Quality of the voltage waveform [ f, U, harmonic distortion, imbalance,...] + Reliability of the power supply 供電系統可靠度 => Governed by International Guidelines (IEEE 519, G5/4 etc..) TWABB - 2

3 Power Quality Overview Interruption Notches Sag / Dip Frequency changes Swell Spikes Harmonics Interferences TWABB - 3

4 Power Event Classification (IEEE 1159) RMS variations : Sags Swells Interruptions 電源壓突降現象, 通常指電壓降低於額定電壓 9%, 但高於額定電壓 1% 以前也稱為突波 (surge), 是㆒種電壓突昇的現象, 通常指電源電壓超過額定電壓 11% 以斷電時候也稱為停電, 斷電時電壓已經降低為 % Overvoltage 過電壓的發生原因㆒般來大型負載的變動或者是切換, 以長時間控電壓值, 而其電壓高於額定電壓 1% -2%, 且時間持續㆒分鐘以 TWABB - 4 Undervoltage 低電壓類似過電壓之情況, 只不過目標鎖定在負載變動所造成之壓降, 電壓低於額定電壓 1% -2%, 且時間持續㆒分鐘以

5 Power Event Classification (IEEE 1159 Classifications) Waveform Distortions : Harmonics Notching DC offset Interharmonics 正弦波電壓或電流, 而其頻率是電源頻率的整數倍. 諧波歧變的來源是非線性負載. 週期性的電壓干擾, 大容量電力電子元件運作時, 切口電壓發生於電流換相 (commutation) 之暫態現象. 交流供電系統出現直流電壓或電流. 電壓或電流產生波形歧變, 但分析為基本波頻率的非整數倍頻, 稱為互諧波. TWABB - 5 Noise 雜訊為供電系統不需要的電氣訊號, 其頻帶通常低於 2kHz, 並且疊加於系統各相導體, 或者出現在性相導體.

6 Definitions, Harmonic and Interharmonic Harmonic f = h * f1,where h is an integer > DC component f = Hz, f = h * f1,where h = Interharmonic Sub-harmonic f <> h * f1, f = h * f1,where h is an integer > f > Hz and f < f1,where f1 is the fundamental frequency TWABB - 6

7 Sources of Harmonics AC-DC converter power supplies (computers) Rectifiers VFDs(Inverter) DC motor speed controls(converter) Uninterruptible power supplies (UPS) Arc furnaces Solid state motor starters (soft starters) Electronic lighting ballasts TWABB - 7

8 Effects of loads on power quality Slow varying loads with Low Power Factor E.g. motors, lighting,... -Decreased power transmission efficiency -Increased losses in the system (transformers, lines, ) Solution: Power factor correction by automatic capacitor banks using state of the art power factor regulators TWABB - 8

9 Effects of loads on power quality Fast varying loads with Low Power Factor E.g. welders, cranes, lifts, presses, -Decreased power transmission efficiency -Voltage fluctuations and/or collapse -Flicker Visual impression of light unsteadiness due to time fluctuating luminance Solutions: Thyristor based capacitor banks IGBT-based compensator technology TWABB - 9

10 Effects of loads on power quality Non-linear loads with high harmonic pollution E.g. drives, UPS s, welders, PCs, fluorescent lighting systems, -Increased losses in system (# R. I 2 RMS = R. I R. Σ I h2 ) - Tripping of circuit breakers and other protective devices Increase of RMS Thermally Increase of peak Magnetically -Motor problems Additional losses in windings & iron (RMS increase & skin effect) Perturbing torques on shaft (negative phase sequence harmonics) TWABB - 1

11 Effects of loads on power quality -Excessive neutral current Mainly zero phase sequence harmonics (e.g. H3 phase-neutral) TWABB - 11

12 IEEE Voltage Distortion Limits PCC= Point of Common Coupling (typically utility-consumer interface) - 責任分界點 Bus Voltage at PCC Individual Voltage Distortion (%) Total Voltage Distortion (THD, in %) 69 kv and less 3.% 5.% kv 1.5% 2.5% 161 kv and above 1% 1.5% TWABB - 12

13 TWABB - 13 IEEE Current Distortion Limits

14 TWABB - 14 TPC Current Distortion Limits

15 PF correction by automatic capacitor banks POWER FACTOR REGULATOR RVC RVT TWABB - 15

16 PF correction by automatic capacitor banks -Advanced switching strategies Direct and progressive strategies Direct: switches the bigger steps first to reach the target cos j faster Progressive: switches the steps sequentially one by one Q (kvar) Target cos j Q (kvar) Target cos j TWABB C1 ON C2 ON C1 OFF C2 ON C1 ON C3 ON C1 OFF C2 OFF t (s) 5 switchings 1 switching C3 ON t (s)

17 Compensation of DV and harmonics Solutions The equipment measures the changes in (reactive) power demand and has fast compensation capability Thyristor switched capacitors (TSC) IGBT-based compensation technology Online monitoring of harmonics and filtering Active harmonic filters (IGBT-based technology) TWABB - 17

Thyristor switched capacitors: Dynacomp -Power factor

(e.g. hospitals) - Reduction of voltage drops (e.g. motor starts) - Reduction of flicker (e.

reaction possible -Harmonic filtering possible -Single

18 Thyristor switched capacitors: Dynacomp -Power factor correction - Transient free switching (e.g. hospitals) - Reduction of voltage drops (e.g. motor starts) - Reduction of flicker (e.g. welders) -Step size up to Mvar range -Instantaneous reaction possible -Harmonic filtering possible -Single phase and three phase versions TWABB - 18

-Three wire and four wire versions available + - PQC -Active compensation of flicker and

19 IGBT-based compensation systems: PQFx - PQC PQFx -Filter up to 15/2 individual harmonic components in a range up to the 5th harmonic -Reactive power compensation possible -Three wire and four wire versions available + - PQC -Active compensation of flicker and voltage drops -Balancing of unbalanced loads -Filter capacity up to the 13th harmonic TWABB - 19

20 Ex. 1: Transient free switching of capacitors Problem: Transient during capacitor switching Solution: Dynacomp replaces contactor switched bank Before: After: VOLTAGE CURRENT VOLTAGE CURRENT Voltage [V] Current [A] Voltage [V] Current [A] TWABB Time [ms] Time [ms] -4

21 Ex. 2: 375 kw motor start Problem: Excessive voltage drop during compressor start Solution: Dynacomp provides the required reactive power Before: V/V = 7.5% After: V/V = 1.5% LINE VOLTAGE LINE CURRENT LINE VOLTAGE LINE CURRENT Time (s) Time (s) TWABB - 21

22 Ex. 3: 26 kva welding application Problem: Flicker problem due to repetition rate of welder Solution: Dynacomp reduces the V/V and flicker Before: V/V = 13.7 % After: V/V = 1.7 % 5 LINE VOLTAGE WELDER CURRENT 5 5 LINE VOLTAGE WELDER CURRENT Time (s) Time (s) TWABB - 22

23 Ex. 4: Load variations in an offshore installation Problem: Generators collapse due to abrupt current demand Solution: Dynacomp provides the necessary reactive power Y3 V 4 1. Y8 PF Before: Y4 I 6 Y3 V 4 1. Y8 PF After: Y4 I TWABB Sec. LINE VOLTAGE(V) LINE CURRENT(I) DYNACOMP CURRENT(I) LINE POWERFACTOR(PF) Sec. LINE VOLTAGE(V) LINECURRENT(I) DYNACOMP CURRENT(I) LINEPOWERFACTOR(PF)

24 Ex. 5. Harmonic distortion problem in oilfield Problem: High THD v causes equipment to malfunction in pumping installation (35 VSD s, kw) Solution: Strategic application of active filters 75 Before:THD V = 12% / THD I = 25% After:THD V = 3% / THD I = 3% Volts Volts Amps Amps TWABB :25: :25: :25: :25: :25: :25: :25: :25: :25:44.761:41: :41: :41: :41: :41: :41: :41: :41: :41:56.76 CHA Volts CHB Volts CHC Volts CHA Amps CHB Amps CHC Amps CHA Volts CHB Volts CHC Volts CHA Amps CHB Amps CHC Amps

25 Ex. 6: Filtering unbalanced loads Problem: Reducing the THD I of biphase loads generating H3 (e.g. welders) Solution: Installation of an active filter Before: After: I [2A/div] L3 L2 L1 I [2A/div] L3 L2 L1 TWABB - 25 Time [5ms/div] Time [5ms/div]

26 TWABB Top 3 Priority In Taiwan, we Take Lead in Safety Take Pride in Ethics Take Heart in Quality 為工安帶頭以操守為榮對品質用心 TWABB - 26

27 TWABB - 27

Chroma 61500/ bit / RMS RMS VA ()61500 DSP THD /61508/61507/61609/61608/ (61500 ) Chroma STEP PULSE : LISTLIST 100 AC DC

Chroma 61500/ bit / RMS RMS VA ()61500 DSP THD /61508/61507/61609/61608/ (61500 ) Chroma STEP PULSE : LISTLIST 100 AC DC MODEL 61509/61508/61507/ 61609/61608/61607 PROGRAMMABLE AC POWER SOURCE MODEL 61509/61508/61507/ 61609/61608/61607 61509/61609: 6kVA 61508/61608: 4.5kVA 61507/61607: 3kVA : 0-175V/0-350V/Auto : DC, 15Hz-2kHz