2.. compensación reactiva

CARGAS INDUSTRIALES - COMPENSACION REACTIVA ING. HUBER MURILLO MANRIQUE

Expositor : Huber Murillo M.

TIPOS DE CARGAS

Three categories of loads

RESISTIVES

INDUCTIVES

CAPACITIVES

Ohms

Henry Hy

Farad F

R

L

C


RESISTIVE Furnaces Electrical

heaters Electrical irons Light bulbs ....

INDUCTIVE Transformers Induction motors Fluorescent lighting Induction furnaces Welding machines Drivers ........

CAPACITIVE Capacitors


TIPOS DE CARGAS

OHMIC LOAD.

RESISTIVE

VAC R

-400

-300

-200

-100

0

100

200

300

400

0 45 90 135

180

225

270

315

360

405

450

495

540

VAC


Corriente IR = U/R Amper

Potencia P = RI² = U²/R Watts

OHMIC LOAD.

RESISTIVE

IR

VAC R

-400

-300

-200

-100

0

100

200

300

400

0 45 90 135

180

225

270

315

360

405

450

495

540

VAC

IR


VACIR

INDUCTIVE LOAD.

INDUCTIVE

VAC L

-400

-300

-200

-100

0

100

200

300

400

0 45

90

135

180

225

270

315

360

405

450

495

540

VAC


Corriente IL = U / L Amper.

Potencia P = U² / L var or kvar

INDUCTIVE LOAD.

INDUCTIVE

IL

VAC L

-400

-300

-200

-100

0

100

200

300

400

0 45 90 135

180

225

270

315

360

405

450

495

540

VAC

IL


VAC

IL

90°

CAPACITIVE LOAD. CAPACITIVE

VAC C

-400

-300

-200

-100

0

100

200

300

400

0 45

90

135

180

225

270

315

360

405

450

495

540

VAC


Corriente Ic = C U Amper.

Potencia P = C U² var or kvar

CAPACITIVE LOAD. CAPACITIVE

IC

VAC C

-400

-300

-200

-100

0

100

200

300

400

0 45 90 135

180

225

270

315

360

405

450

495

540

VAC

IC


VAC

IC

90°

MIXED LOADS. Main industrial loads

I

V LVR

VL

RThe majority of industrial

loadscan be regarded as comprising resistor and inductor in series.

V : supply voltageVR: resistance voltage dropVL: inductance voltage dropI : total supply current


Main industrial loads

I

V LVR

VL

R

VR

VL

90°

I

V

"I" lags "V" by some angle


MIXED LOADS.

Main industrial loads


MIXED LOADS.

CAPACITOR CONNECTION

I

L

R

V

IRL IRL : current through the load

IC : current through the capacitor

I : total current drawn from supply

CIC


MIXED LOADS.

CAPACITOR CONNECTION

I

V L

RIC

V

IRL

C

IRL

IC

I

12

cos I


MIXED LOADS.

kW

- Active power (kW) performs the work (useful power)

kVA

- Apparent power (kVA) total power consumed

kvar

- Reactive power (kvar) sustains electromagnetic field (non useful power)


REACTIVE POWER COMPENSATION.

BASIC CONCEPTS.

kVA

Apparent power

Active or useful powerkW

Reactive power kvar

kvar

Power factorcos = kW / kVA


HOW CAN WE IMPROVE THE PF CORRECTION AND THUS REDUCE THE

CONSUMED POWER?

kW

Kvar2

The capacitor connected in parallel will draw kvar in the same way than the load but in phase opposition (leading)

kVAkvar1


BASIC CONCEPTS.


BASIC CONCEPTS.

kW

kvar

kVA1

kVA2

kvar2

kvar1

)2tan1kW(tankvarckWkvar

tan

kvar²kW²kW

cos

kvar²kW²kVA

kVAkvar

sin

kVAkW

cos

kW

kvar

kVA


BASIC CONCEPTS.

Power factor correction chartKvar = k * kW

Desired PF

Init

ial

PF


0.46

Nomogram

Kvar = k * kW


kW=410

kVA1=586

kvar1=419


Ejemplo

kW=410

kVA1=586

kvar1=419

284


Carga compensada

kW=410

kVA1=586

kvar1

=4

19

kvar2=135

284


Carga compensada

kW=410

kVA1=586

kvar1

=4

19

kVA2=432

kvar2=135

284


Carga compensada

Advantages of a good power factor


Transformers and distribution cables lightened ( I )

0.70.95

27%


Reduced Joule losses ( RI² )

46

cos final values

cos initial values

% reduction in losses


CABLES


1150

6000


TRANSFORMER

kVA output reduced

cos initial

% kVA recovered0.75


Voltage drop in transformer

5.1

Voltage drop

cos 0.6

Low losses


Normal lossesVOLTGE DROP

Cos ? = 0.6 * 5.1%

Cos ? = 0.6306

Cos = 0.6306

= 50.906

Typical PF encountered in industry


Energy saving calculation.

400 kVA400 V

P=80 kWcos = 0.75

P=170 kWcos = 0.75

1 cable70 mm²20 m

2 cables70 mm²100 m

A B



Consumer's electricity bill: Monthly kWh consumed = 70125 Monthly kvarh consumed = 63081 Assuming an activity of :

340 days/year 15 hours/day

Average kW = 70125/425 = 165 (66% of the full load) Average kvar = 63081/425 = 148 Average kVA = 165² + 148² = 222 Average P.F. = kW/ kW² + kvar² = 0.744



Min P.F. value to avoid penalty : 0.93 capacitor required = kW (tg1 - tg2)

=165 (0.898 - 0.395) = 83kvar(in practice cap. size is increased by 5 to 10% to ensure aP.F.> 0.93)

New situation

kW = 165 (unchanged)kvar = 148 - 83 = 65 ()kVA = 165² + 65² = 177 () (222 previously)Monthly demand (kVA) is reduced by 20%


Cable losses

Cos = 0.75

Workshop A :I = P*0.66/ 3 V cos

= 80000 * 0.66/ 3 400 0.75 = 102ACable losses : P = 3 RI²L (R= 1/S)

= 3 * 246.10-6 /m * (102)² * 20 =154W5100 h/year P = 785kWh

Workshop B :I = 170000 * 0.66/3 400 0.75 = 216ACable losses : P = 2 (3RI²L)

= 2 * 3 * 246.10-6* (216/2)² * 100 = 1722W5100h/year P = 8782 kWh


Cable losses

Cos : 0.93

Workshop A:- I = 102 (0.75/0.93) = 82A- Cable losses = 154 (82/102)² = 100W- Cable losses/year = 150kWh

Workshop B:- I = 216 (0.75/0.93) = 174A- Cable losses = 1722 (174/216)² = 1117W- Cables losses/year = 5697kWh


Transformer losses

Before correction:

Total losses = 1000 + 5000 [(80+170) 0.66]² / (0.75 * 400)= 2513WTotal losses/year = 2513X5100 = 12814kWhTotal kWh = 785 + 8782 + 12814 = 22381

After correction:

Total losses = 1000 + 5000 [(80+170) 0.66]²/ (0.93 * 400) = 1984WTotal losses/year = 10118kWhTotal kWh/year = 510+5697+10118 = 16325kWh reduction/year = 22381 - 16325 = 6056kWh

27% reduction


POWER FACTOR CORRECTION

The main reason for installing power capacitors is toreduce reactive power costs and avoid the penalties.

Typical pay back period is less than 1-2 years.Sometimes as little as a few months.


TYPICAL INSTALLATION

Individual compensation of large motors (>50kW 70hp)

Fixed compensation of transformers (+/-10 % of transformer rating)

Automatic capacitor bank to compensate varying load

Locating capacitors on your system

Capacitors may be installed at various locations on yourelectrical system.

1 : Capacitors on the incoming plant service2 : Capacitors on the main bus3 : Capacitors on the bus for various feeders4 : Capacitors a the individual load point

Capacitor location1 2 &3 4

Technical approach BestFlexibility Least Less Best

Savings Least less Max.Cost per kvar Least Lower Highest


TRANSFORMER COMPENSATION

- Increased useful capacity

- Reduced losses

- Reduced voltage drop

Degree of compensation :

1. "Rule of thumb" : +/- 10 % of transformer's nominal rating.

2. Calculation based on the individual transformer and its load pattern.

Note : check for resonance between transformer and capacitor.


Individual transformer compensation

T he resonant frequency can be calcu la ted from the fo llow ingform ula :

f f pP s c

P c

f = resonant frequencyfp = pow er frequencyP sc = short c ircu it pow er of the transform er ( kV A )P c = pow er of the capacito r (kV A R )

If the frequency ob tained is too c lose to that o f a harm onic , thevalue of the capacitor ra ting should be m odified .

M ost com m on harm onic frequencies, 3rd , 5th , 7 th , etc ...


MOTOR COMPENSATION


Methods for determining capacitor rating for motor

compensation1.- Rule of thumb Qc = 40% of motor KW . rating.

2.- Use of table the speed and motor power . into acount

3.- Calculation based on exact individual . motor charasteristics.

AUTOMATIC BANK COMPENSATION

Advantages of automatic capacitor banks :

- Regulation of cos

- Better utilisation of the capacitor compared to individual compensation.

- Eliminates the possibility of overcompensation.


AUTOMATIC BANK COMPENSATION

Points to consider for automatic banks

Choice of regulator characteristics (c/k and tolerance) and step size toavoid hunting.

Correlation between minimum interval between switching and dischargedevice of capacitor to avoid energising a charged capacitor.

Disconnecting of all steps in case of a mains outage. Insensitivity to harmonics.Possibility to extend existing banks without changes in the control

equipment.


LVCP

THE NEW CHOICE FOR POWER FACTOR

CORRECTION

BANCO DE CONDENSADORES ING. HUBER MURILLO M

Compact

Modular

Safe

Reliable

Compact Small dimensions

210 mm

200 mm78 mm

Compact High power density

20 kvar

@ 400/415 V


Modular

Terminals sized for common cable shoes

Built-in safety discharge resistors (<75V in 3 min.)

Enclosure with double casing insulation


Modular

Interconnection bars

Fixation holes

Clips system for group assembly


Modular

Easy and quick assembly of capacitor modules


DIN rail fixation

Examples of LVCP module assembly

30 kvar = 15 kvar + 15 kvar



400V/50Hz


Examples of LVCP module assembly

400V/50Hz

45kvar =

15kvar + 15kvar + 15kvar

50kvar =

16.7kvar + 16.7kvar + 16.7kvar

60kvar =

20kvar + 20kvar + 20kvar


Modular

External discharge deviceSafe discharge < 50V in 1 minute


Protective cover IP20

Safe

Built in safety discharge resistors

FusePressure sensitive disconnector

Thermo-setting resin

Dry type self healing capacitor winding

Insulating enclosure


Unique double action safety system

Self-healing +

Internal fuse +

Pressure sensitive disconnector


Reliable

In-house metallized film

Voltage withstand capability Peak current Capacitance stability Life Self-healing

Losses


Reliable

Automatized manufacturing process

Controlled performance Repeatable quality


IEC 60831 1&2

ISO 9001

ISO 14001

ReliableComprehensive testing

• Ageing• Temperature• Humidity• Dielectric• Self-healing• Current• Voltage


Range (50Hz)

0

2.5

5

7.5

10

12.5

15

17.5

20

230

400

415

450

465

KVAR


Range (60Hz)

0

2.5

5

7.5

10

12.5

15

17.5

20

220

240

380

440

450


THEN YOU ABB


YOUR choice for Power Factor Correction

2.. compensación reactiva

Education

Transcript of 2.. compensación reactiva