schneider electric – global pq – june 2013 22 · pdf fileschneider electric...

Immediate Energy Efficiency with Power Factor Correction

Power Quality Clean power, Efficient business

Schneider Electric – Global PQ – June 2013 2 2

Outline

Power Factor:

●Definition & Examples

●Cost Savings

●Power Factor Correction Equipment

Harmonics:

●Introduction

●Harmonics and Power Factor Correction Capacitors

●IEEE 519 Standard

●Traditional Harmonic Mitigation Methods

●Active Filter Technology & Applications


Definitions: ●kW = Active Power: It does the "work" for the system - providing the

motion, heat, or whatever else is required.

●kVAR = Reactive Power: It doesn't do useful "work." It simply sustains the electromagnetic field.

●kVA = Apparent Power: It is the vector addition of Working Power and Reactive Power.

●Power Factor : The ratio of Active Power (output) to Total Power (input). It is a measure of efficiency.

What is Power Factor?

Total Power (kVA)

θ

Active Power (kW)

Power Factor = Active (Real) Power Total Power = kW kVA = Cosine (θ)

Reactive Power (kVAR)


Power Factor:The Beer Analogy

Mug Capacity = Apparent Power (kVA)

Foam = Reactive Power (kVAR)

Beer = Real Power (kW)

Power Factor = Beer (kW)

Mug Capacity (kVA)

Capacitors provide the Foam (kVAR), freeing up Mug Capacity so you don’t have to buy a bigger mug and/or so you can pay less for your beer !

kVAR Reactive Power

kW Active Power

kVA Apparent Power


Why is Power Factor Important? ●Low power factor results in:

●Poor electrical efficiency ●Lower system capacity ●Higher utility bills

●Most utilities have power factor penalties to encourage power factor correction. Otherwise the utility may have to:

– Build more power plants – Purchase new transformers – Use larger cables

●Power factor correction ●Reduces power cost ●Releases system capacity ●Reduces power losses ● Improves voltage


● The easiest solution to improve power factor is to add power factor correction capacitors to your electrical distribution system.

A2

Power Factor Correction

M

The Capacitor Supplies Reactive Current

Current that is drawn from the voltage source is then only used to do real work (kW) and not to create a magnetic field (kVAR). The source current is then minimized

» The customer only pays for the capacitor » Since the utility doesn’t supply the kVAR, the customer doesn’t

pay for it » In short, capacitors save money


In this example, demand is reduced from 100 kVA to 80 kVA by installing a 60 kVAR capacitor.

Before: PF = kW/kVA = 80%

After: PF = kW/kVA = 100%

Transformer loading is reduced



● Reduced Power Costs: lower utility bills since utility no longer supplies the reactive current.

● Released System Capacity

●Capacitors off-load transformers and cables

● Improved Voltage

● Reduced losses

kW 100

kVAR 100

kW 100

kVAR 75

kW 100

kVA = 141 PF = 70%

kVA = 125 PF = 80%

kVA = 100 PF = 100%

Benefits of Power Factor Correction


How do utilities charge for Power Factor?

Billing Actual Actual Possible Required Required % ReductionService Demand Power Demand Demand Cost Capacitor kVAR Capacitor kVAR of Transformer

Month kW Factor kVA kW Savings for 0.92 pf for 1.0 pf kVA Load05/14/11 900.0 0.8000 1,000.0 800.0 $550.00 259 600 20% 06/14/11 800.0 0.7950 888.9 706.7 $513.33 238 539 21% 07/16/11 850.0 0.7625 944.4 720.1 $714.24 304 611 24% 08/15/11 875.0 0.7511 972.2 730.2 $796.20 331 642 25% 09/16/11 910.0 0.7574 1,011.1 765.8 $793.01 334 660 24% 10/16/11 780.0 0.7722 866.7 669.2 $609.18 266 551 23% 11/16/11 890.0 0.7950 988.9 786.2 $571.08 265 600 21% 12/16/11 870.0 0.7950 966.7 768.5 $558.25 259 586 21% 01/16/12 760.0 0.7625 844.4 643.9 $638.61 272 546 24% 02/16/12 750.0 0.7511 833.3 625.9 $682.46 284 550 25% 03/16/12 690.0 0.7574 766.7 580.7 $601.30 253 501 24% 04/16/12 870.0 0.7722 966.7 746.5 $679.47 296 614 23%

0.0 0.0 Savings 2012 $7,707.13

Approximate cost of standard power factor correction equipment $12 to $15K === Payback about 2 years.

Approximate cost of filtered power factor correction equipment $18 to $21K === Payback about 3 years.

●Example with $5.50 per demand kW



●Capacitors: ● Low Voltage Power Factor Correction Capacitor Banks

●Fixed

●Standard Automatic

●Detuned

●Transient Free

●Medium Voltage Power Factor Correction Capacitor Banks

●Fixed

●Standard Automatic

●Detuned

●Active Filters ● LV and MV Hybrid VAR Compensation Products


Outline

Power Factor:

●Definition & Examples

●Cost Savings

●Power Factor Correction Equipment

Harmonics:

●Introduction

●Harmonics and Power Factor Correction Capacitors

●IEEE 519 Standard

●Traditional Harmonic Mitigation Methods

●Active Filter Technology & Applications


Harmonic Basics ● What are harmonics?

●A harmonic is a component of a periodic wave with a frequency that is an integer multiple of the fundamental frequency

●Created by power semiconductor devices ●Converts power (AC to DC)

●Characteristic harmonics are the predominate harmonics seen by the power distribution system

●Predicted by the following equation:

– HC = characteristic harmonics to be expected

– n = an integer from 1,2,3,4,5, etc.

– p = number of pulses or rectifiers in circuit

Harmonic Frequency Sequence 1 60Hz + 2 120Hz - 3 180Hz 0 4 240Hz + 5 300Hz - 6 360Hz 0 7 420Hz + : : 19 1140Hz +

Fundamental

3 rd Harmonic

5 t1h Harmonic

7 th Harmonic

Waveform seen with oscilloscope

1±= npHc


Harmonic Filtering


Multi-pulse Converters

Harmonic Orders Present

Hn1 phase 4-pulse

2 phase 4-pulse

3 phase 6-pulse

3 phase 12-pulse

3 phase 18-pulse

3 x x5 x x x7 x x x9 x x11 x x x x13 x x x x15 x x17 x x x x19 x x x x21 x x23 x x x x25 x x x x27 x x29 x x x31 x x x33 x x35 x x x x x37 x x x x x39 x x41 x x x43 x x x45 x x47 x x x x49 x x x x

Harmonics present by rectifier designType of rectifier

Hn = np +/- 1

Hn = characteristic harmonic order present

n = an integer

p = number of pulses

Elimination of lower orders removes largest amplitude harmonics

AccuSine SWP

AccuSine PCS


Harmonic Basics ●Nonlinear loads draw harmonic current from source

● Does no work

Inverter Converter

DC bus

M

A B C

Current: high TDD between 90-120%

Voltage: flat topping of waveform

Basic PWM VFD


Harmonic Basics

●Why the concern? ●Current distortion

●Added heating = reduced capacity

●Equipment failures

– Transformers

– Conductors and cables

– Nuisance tripping of electronic circuit breakers (thermal overloads)

●Heating proportional to harmonic order in cables & bus bars ●Squared effect on transformers & AC

motors

Loads

Ih

hhh ZIV ×=


Harmonic Basics

Voltage distortion

●Created as current harmonics flow

through the system

● Interference with other electronic loads ●Malfunctions to failure

● Induces harmonic currents in linear loads ●AC motor winding over heating & bearing failures

Loads

Ih

hhh ZIV ×=


M M M

Utility

VFD

Harmonics and Standard Capacitors

●Capacitors absorb harmonics ●Overheating of PFC capacitors

●Tripping of PF protection devices

●Reduced life expectancy

●Magnification of harmonics by resonance ●Amplification of current between

capacitor and transformer

●Current distortion rises

●Voltage distortion rises

●Main transformer &/or capacitor fuses blow

●Equipment damage


Capacitor Resonance


Detuned Capacitors


Conventional Switch Structure

HRC Fuses

Contactors

Optional De-tuned Inductor

L1 L2 L3 Electro- mechanical switching elements (contactors) are used to connect a capacitor group.


IEEE 519-1992

●Defines current distortion as TDD (Total Demand Distortion) ● Largest amplitude of harmonic current occurs at maximum load of

nonlinear device – if electrical system can handle this it can handle all lower levels of amplitudes

● Always referenced to full load current ● Effective meaning for current distortion

●Defines voltage distortion as THD ● Total harmonic voltage distortion

●Does not use THD(I) ● Total harmonic current distortion ● Instrument measurement (instantaneous values) ● Uses measured load current to calculate THD(I)

fII

THDi h∑=2

)(

2

FLAfII

TDD h∑=fVV

THDv h∑=2


IEEE 519-1992 ● Issues addressed:

● THD(V) delivered by utility to user (Chapter 11)

●THD(V) must be < 5% [< 69 KV systems]

●Defines the amount of TDD a user can cause (Chapter 10)

●Based upon size of user in relation to power source

●Table 10.3 for systems < 69 kV

●Defines limits for voltage notches caused by SCR rectifiers – Table 10.2

●Defines PCC (point of common coupling)


IEEE 519-1992

Total I, rms

Fund I, rms

Harm I, rms THD(I) TDD

Full load 936.68 936.00 35.57 3.8% 3.8%836.70 836.00 34.28 4.1% 3.7%767.68 767.00 32.21 4.2% 3.4%592.63 592.00 27.23 4.6% 2.9%424.53 424.00 21.20 5.0% 2.3%246.58 246.00 16.97 6.9% 1.8%111.80 111.00 13.32 12.0% 1.4%

Measured

• TDD and THD(I) are not the same except at 100% load

• As load decreases, TDD decreases while THD(I) increases.

• Example:


IEEE 519-1992 Table 10.3 Current Distortion Limits for General Distribution Systems (<69 kV)

Isc/Iload <11 11<=h<17 17<=h<23 23<=h<35 h>=35 TDD<20 4.0% 2.0% 1.5% 0.6% 0.3% 5.0%

20<50 7.0% 3.5% 2.5% 1.0% 0.5% 8.0%50<100 10.0% 4.5% 4.0% 1.5% 0.7% 12.0%

100<1000 12.0% 5.5% 5.0% 0.2% 1.0% 15.0%>1000 15.0% 7.0% 6.0% 2.5% 1.4% 20.0%

Isc = short circuit current capacity of sourceIload = demand load current (fundamental)

(TDD = Total harmonic current distortion measured against fundamental current at demand load.)

TDD = Total Demand Distortion


•Designed to protect utility •Most harmonic problems are not at PCC with utility

•Occur inside the plant •Occur where nonlinear loads are concentrated •Occur with generators & UPS (high probability of problems) •Need to protect the user from self by moving the PCC to where harmonic loads are located.

•Apply principals of IEEE 519-1992 Table 10.3 inside the plant

•Assures trouble free operations •Assures compliance to standard

•We have the products to meet 5% TDD inside the plant

Harmonic Standards

Harmonic mitigation methods - (Applied per VFD)

Solution Advantage Disadvantage Typical %

TDD Typical Price

Multiplier* Increase short circuit capacity Reduces THD(V)

●Increases TDD ●Not likely to occur**

Dependent upon SCR***

Cost of transformer and installation change out

C-Less Technology

●Lower TDD ●Simplified design ●Less cost

●Compliance is limited ●Application limited ●Size limited 30 - 50% TDD 0.90 - 0.95

Impedance (3% LR or 3% DC choke)

●Low cost adder ●Simple ●Compliance difficult 30 - 40% TDD 1.05 - 1.15

5th Harmonic filter

Reduces 5th & total TDD

●Does not meet harmonic levels at higher orders^ 18 - 22% TDD 1.20 - 1.45

Broadband filter Reduces TDD (thru 13th)

●Large heat losses ●Application limited 8 - 15% TDD 1.25 - 1.50

12-pulse rectifiers ●Reduces TDD ●Reliable

●Large footprint/heavy ●Good for >100 HP 8 - 15 % TDD 1.65 - 1.85

18-pulse rectifiers ●Reduces TDD ●Reliable

●Large footprint/heavy ●Good for >100 HP 5 - 8% TDD 1.65 - 1.85

Active front end converter

●Very good TDD ●Regeneration possible

●Large footprint/heavy ●Very high cost per unit ●High heat losses < 5% TDD 2.0 - 2.5

* Price compared to a standard 6-pulse VFD. ** Utilities and users are not likely to change their distribution systems. *** Increasing short circuit capacity (lower impedance source or larger KVA capacity) raises TDD but lowers THD(V). ^ Can be said for all methods listed.


Active Filter Concept

Source XFMR

Load(s)

Is

Ia

Il

Optional CT location

•Parallel connected

• includes 2nd to 50th harmonic current

• <5% TDD

las III

=+aI

sI

LOAD Sense

SOURCE Sense


●Price (first cost) ●Footprint required ●Heat losses ●Cost to operate

●Site cooling required ●Net Present Value (NPV)

System solution Comparison of 18-P VFD to AccuSine PCS + standard VFD

Harmonic Mitigation Solutions


Solutions by AccuSine Model


Schneider Electric Offer

●AccuSine SWP ●20-120 Amps

●400 VAC

●Neutral correction

●AccuSine PCS ●50-300 Amps

●208-480 VAC/600 VAC/690 VAC

●AccuSine PFV ●50-300 Amps

●208-480 VAC/600 VAC/690 VAC

●No harmonics

●Use customized transformers for higher voltages (to 15 kV for harmonics & 35 kV for non-harmonic modes)


AccuSine SWP

●The Schneider Electric solution for harmonic filtering in buildings.


AccuSine PCS

●The Schneider Electric solution for active harmonic filtering in industrial installations.

● Most common – VFD sites ●Centrifugal pumps and fans

●Pumping Stations

– Potable

– Wastewater

●Wastewater Plants

●Water Purification (potable)


AccuSine® PCS/PFV Power Diagram

+ C

E

C

E

C

E

C

E

C

E

C

E

C

Line Inductor

Filter Board

Pre-charge Contactor

Inductor

Fuse

Fuse

Fuse

AC Lines

S4

S5

S6

S1

S2

S3 DC Bus Capacitors

IGBT Module


AccuSine® PCS Performance Summary - Harmonics ●Discrete Spectrum Logic (DSL)

●TDD <= 5%, if loads have =>3% Z installed ● 2nd to 50th orders, discrete ● <2 cycle response ●Resonance avoidance logic ●Adjustable trip limits per harmonic order ●On-board commissioning program

●Phase rotation (clockwise required) ●Automatic CT orientation (phase rotation/polarity/calibration) ●Run lockout if not possible to re-orient

●Oscilloscope feature built into HMI ● Load/source bar graphs

●Load balancing ●Can parallel up to 99 units of each size and mix sizes


System Solution

AccuSine® PCS Sizing Example ●A 125 HP variable torque 6-pulse VFD with 3% LR

● Required AHF filtering capability = 47.5 amperes ●Two 125 HP VT 6-pulse VFD w/3% LR

● Required AHF size = 84.4 amps ●Three 125 HP VT 6-pulse VFD w/3% LR

● Required AHF size = 113.5 amps ●Six 125 HP VT VFD w/3% LR

● Required AHF size = 157.6 amps ● (not 6 x 47.5 = 285 amps)


Product Package ●Standard (UL/CSA, ABS) ● Three current ratings ●Enclosed – NEMA 1/IP20

● 50 amp – 52”(1321mm) x 21”(533mm) x 19”(483mm)

●Weight – 250#(114 K\kg) ● 100 amp – 69”(1753mm) x 21”(533mm) x

19”(483mm) ●Weight – 350#(159 kg)

● 300 amp – 75”(1905mm) x 32”(813mm) x 20”(508mm)

●Weight – 775#(352 kg) ●Wall mount – 50 & 100 amp ● Free standing – 300 amp with disconnect

AccuSine® PCS/PFV


Product Package

●Other enclosures (380 - 480VAC) ●NEMA 12, IP30, IP54

●50 amp – 75”(1905mm) x 31.5”(800mm) x 23.62”(600mm)

– Weight – 661Ib(300 kg) ●100 amp – 75”(1905mm) x 31.5”(800mm) x 23.62”(600mm)

– Weight – 771Ib(350 kg) ●300 amp – 75”(1905mm) x 39.37”(1000mm) x 31.5”(800mm)

– Weight – 1012Ib(460 kg) ●Free standing with door interlocked

disconnect ●CE Certified, C-Tick, ABS, UL, CUL

AccuSine® PCS/PFV


AccuSine PCS 600/690 VAC

● Includes autotransformer & input fused disconnect

●Simple installation ● 600 VAC: UL/cUL/CE ● 690 VAC: CE ●Ratings: PCS 600V 690V 50 A 39 A 33 A 100 A 78 A 67 A 300 A 235 A 200 A

300A

50/100A

Height

Height

1000 mm

800 mm

800 mm

600 mm

1900 mm

1972 mm

Depth 800 mm

600 mm


AS off AS on Order % I fund % I fund Fund 100.000%100.000% 3 0.038% 0.478% 5 31.660% 0.674% 7 11.480% 0.679% 9 0.435% 0.297% 11 7.068% 0.710% 13 4.267% 0.521% 15 0.367% 0.052% 17 3.438% 0.464% 19 2.904% 0.639% 21 0.284% 0.263% 23 2.042% 0.409% 25 2.177% 0.489% 27 0.293% 0.170% 29 1.238% 0.397% 31 1.740% 0.243% 33 0.261% 0.325% 35 0.800% 0.279% 37 1.420% 0.815% 39 0.282% 0.240% 41 0.588% 0.120% 43 1.281% 0.337% 45 0.259% 0.347% 47 0.427% 0.769% 49 1.348% 0.590% TDD 35.28% 2.67%

AccuSine Performance

AccuSine injection

Source current

At VFD Terminals


700 HP Drive – AccuSine ON – OFF


Ias = rms output current of AccuSine PCS

Ih = rms harmonic current

If = rms fundamental current

Ias Ih If100.0 10.0 99.5100.0 20.0 98.0100.0 30.0 95.4100.0 40.0 91.7100.0 50.0 86.6100.0 60.0 80.0100.0 70.0 71.4100.0 80.0 60.0100.0 90.0 43.6100.0 95.0 31.2

Examples

AccuSine® PCS Dual Mode Operation 22

fhas III +=

● Assignment of capacity ● Assign priority to Harmonic or PF/LB

(fundamental) modes ● Use % of harmonic mode to set split

●100% means capacity utilized for harmonic correction, then left over can be used for PF/LB ●0% assigns fundamental (PF correction/LB) current as primary mode, left over used for harmonic correction ●Can split to limit harmonic mode capacity, left over to PF correction/LB


Power Factor & VAR Compensation

●HVC (AccuSine PFV + PF caps) ●Larger systems approach

●HVC is Hybrid VAR Control

– Combines AccuSine PFV with PF caps – Caps on line all the time

●AccuSine adjusts fundamental current to attain unity DPF ●Cycle-by-cycle response ●Voltages to 33 kV (6.6 kV shredder in France, 12.47 kV in US

automotive, 13.8 kV steel mill in Colombia) ●Fundamental current balancing (optional since 1 Nov 10))

●Sometimes critical – i.e. two phase loads

AccuSine® PFV


Thank You

Questions?

schneider electric – global pq – june 2013 22 · pdf fileschneider electric...

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