full paper madtharad chakphed

8/13/2019 Full Paper Madtharad Chakphed

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Abstract-- This paper illustrates a procedure to

design harmonic filters for industrial applications,

induction furnace load (22 kV, 27 MW, 0.84 PF, and

voltage distortion 16.15% from harmonics and

interharmonics). This is essential for eliminating and

reducing the effects of harmonics in a power system to

comply with limit of the Kingdom of Thailand (4.0%THDv for 22 kV distribution systems). Off-line steady

state simulation program, DIgSILENT, is used to

model loads, to study variation of the harmonics, to

study the impedance versus frequency, and to evaluate

the effect of harmonic filter in the system using actual

recorded data. After the designed harmonic filters are

placed, the voltage distortion are dramatically reduced

to be 2.7%.

Index Terms-- Harmonics, Harmonic Filter Design,

Induction Furnace

I. INTRODUCTION

The increase of harmonics in the power system

threatens the quality of the electricity supplied to the

customers. Fundamentally, one needs to control

harmonics only when they become a problem. When a

problem occurs, the basic options for controlling

harmonics are in [1].

This paper illustrates a procedure to design

harmonic filters for 27 MW induction furnace with

voltage distortion from harmonics and interharmonics

(3.713.4% of THDv and 7.89.0% of Total

Interharmonic Distortion in voltage (TIDv)). Section

II presents basic characteristic of harmonic filter. The

induction furnace load characteristic is presented in

section III. Section IV shows the criteria to select

parameter of harmonic filter, section V shows the

implementation results and conclusion is presented in

section VI.

This work was supported by the Provincial Electricity Authority (PEA),

Thailand.

II. HARMONIC FILTER

The harmonic shunt filter works by short-circuiting

harmonic currents as close to the source of distortion

as practical. This keeps the currents out of the supply

system and is the most common type of filtering

applied because of economics and because it also

tends to correct the load power factor as well asremove the harmonic current.

The first step to design filter is computer simulation,

then hypothetical harmonic filters are placed in the

model and the response of the power system to the

filter is examined. If unacceptable results are obtained,

the location and values of the filter parameters are

changed until the results are satisfactory.

III. INDUCTION FURNACE LOAD

The basic characteristic of the induction furnace load

is described in [3]. Fig. 1 shows the network

configuration of this load in PEA transmission and

distribution system. An induction furnace immediately

generated customer complaints to 115 kV customer of

PEA when connected in the same transmission system.

Complaints included noisy capacitors, capacitor

failures, flickering lights, UPS alarms, drive trips, and

other problems. Transformer noise would rise and fall

several times per second. It affected nearby industrial

customers and the PEA system.

IV. FILTER PARAMETER SELECTION CRITERIA

The major criteria to design harmonic filter is to

select a suitable capacitor size that results in a

reasonable PF at fundamental frequency. [4]

1)Load ParameterLoad:27 MW (max), 22 kV, 0.84 PF (17.44

MVAr), 13.4% THDv and 9.0 TIDv

Constrained:THDv less than 4.0% to comply with

limit of the Kingdom of Thailand, and

PF higher than 0.95

Harmonic Filter Design for

Induction Furnace Load in 22 kV Distribution SystemChakphed Madtharad Mark McGranaghanPEA, Bangkok, Thailand EPRI, Knoxville, TN, USA

[email protected] [email protected]


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Fig. 1 Single line diagram

2)Monitoring Device and LocationDranetz-BMI PowerXplorer PX5 Signature System

has been used, 256 samples/cycle. It is located at

22 kV bus inside PEAs substation.

3)Fundamental Frequency Reactive PowerCompensation

The reactive power, compQ , to improve the PF of 27

MW load from 0.84 to be 0.96 can be given by

( ) ( )1 127 tan cos 0.84 tan cos 0.96 9.57compQ MVAr = = (1)

The number of filter branches can be selected basedon the percentage of the harmonic components of

voltage and current. It may also, be necessary to place

filters elsewhere in the system to reduce resonance

problems (series or parallel), if any.

At the tuning frequency rh , the capacitive and

inductive components of the filter become equal. That

is

C Cr L r

r L

X Xh X Then h

h X= = (2)

To design harmonic filter, LX was normally defined interm of percentage of CX . That is

r L 2

L r

100 100h Then %X

% X h= = (3)

The parameters CX and LX are the fundamental

frequency capacitive and inductive components of a

single tuned filter, respectively. Ifcomp

Qis the total

reactive power generated by the filter, the critical or

rated reactive power ( crQ ) at fundamental frequency

can be given by

Event #286at 12/05/2007 07:55:19.800

Pre-trigger

Event Details/Waveforms

07:55:19.805

12/05/2007

Wednesday

07 :5 5: 19. 810 07:5 5: 19. 815 07 :5 5: 19. 820

-1000

-500

0

500

1000

Amps

A I BI CI

(a)Harmonic current waveform

Event #286at 12/05/200707:55:19.800

Pre-trigger


07:55:19.805

12/05/2007

Wednesday

07 :5 5: 19 .8 10 07 :5 5: 19 .8 15 07 :5 5: 19 .8 20

-20000

-10000

0

10000

20000

Vo

lts

AV BV CV

(b) Harmonic voltage waveform

Fig. 2 Monitoring result for designing harmonic filter.

2

crLcr comp

s

V100 %X Q Q

100 V

=

(4)

where sV is bus voltage of filter, and

crV is critical or rated voltage of capacitor.

The next step is to decide if how many harmonic

filter banks should be used. In this step the impedance

versus frequency analysis (frequency scan) and

harmonic load pattern have to be considered.

The three-phase power converter of induction

furnace in this case is a 12-pulse current-source. The

monitoring results and harmonic spectrum in Fig. 2

shows that the characteristic harmonics in the ac-sideline currents are the 11th

, 13th

, 23th

, 25th

, etc with some

non characteristic 2nd

, 5th

and 7th

and also

interharmonic.

Since the magnitude of harmonic and interharmonic

currents decreases as the harmonic order increases, a

damped or high pass filter is recommended to screen

out a broad range of higher order harmonics. The

parameters of these filters can be obtained similar to

the single tuned filter except the value of the

resistance which can be obtained as where quality

factor ( QF) has a low value. [4]


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30.2020.2010.200.20 [-]

80.00

60.00

40.00

20.00

0.00

-20.00

CSI 22 kV: Network Impedance, Line-Ground A in Ohm



With Filter 11 and 13

Without Filter

4.98459.180 Ohm

5.04810.298 Ohm

5.04829.460 Ohm

With Filter 5,11 and 13

DIgSILENT

Fig. 3 Frequency scans at 22 kV bus in customer side.

Fig. 3 shows frequency scans at 22 kV bus in

customer side, the black line shows frequency scan inexisting case (without harmonic filter). While the blue

line represents frequency scan in case of using

harmonic high pass filter just only in significant

characteristic harmonic orders (11th

and 13th

).The blue line in Fig. 3 show parallel resonance at

harmonic order 5th, harmonic order at parallel

resonance frequency would be magnified about 6

times of normal value. As a result, harmonic high pass

filter order 5 has to be added to shift the resonance

frequency and/or lower the impedance at resonance

frequency (red dotted line).

4)Capacitor, Inductor, and Resistor of each banksTo decide if how much reactive power in each banks

should be used, harmonic pattern have to be taken into

account. The harmonic orders 11th

and 13th

are

dominant harmonic components and filter order 5th

is

mainly used to shift the resonance frequency. Then

reactive power for harmonic high pass filter order 11th

and 13th

are 4.0 MVAr, and 2.0 MVAr for order 5th

.

The design of the filter bank may result in an iterative

process to optimize the capacitor bank size and filterthe unwanted harmonics [5].

For any banks of harmonic high pass filter, crQ can

be calculated using equation (4). For filter bank order

5th

, if sV is 22 kV, crV is 32.32 kV, and

compQ is 2.0 then

crQ would be 4.317 MVAr. In the same manner, if the

tuning frequencyr

h is 10.9 and crV is 38.80 kV then

crQ would be 12.435 MVAr.

If the value of reactive power to be supplied by the

filter ( crQ ) is known, the capacitive component of

wye-connection can be given by

2

50

6

50

( )

10( )

2

crC Hz

cr

C Hz

VX

Q

C FfX

=

=

(5)

The value of inductive reactance can then becalculated using equation (6).

50

3

50

( ) ( )

10( ) ( ) 2

2

C Hz

L Tuned C Tuned

r

L Tuned

L Hz

XX X

h

XL mH Then X fL

f

= =

= =

(6)

The value of parallel resistance can then be calculated

using equation (7).

50( )

r L HzR h X QF = (7)

where QFis the quality factor of the filter.

5)Evaluate filter duty requirementsEvaluation of filter duty requirements typically

involves capacitor bank and also inductor/resistor

duties. These duties include peak voltage, current,

kVAr produced, and rms voltage.Ref. [6-7] is used as

the limiting standard to evaluate these duties.

Table 1 summarizes the parameter of each harmonic

high pass filter banks.

Table 1Summarize the parameter of harmonic filter.

ItemsHarmonic filter order

5th 11th 13th

rh 4.5 10.9 12.8

QF 4.0 4.0 4.0

L%X 4.94 0.84 0.61

compQ 2.0 4.0 4.0

sV 22.0 22.0 22.0

crV 32.32 38.80 32.49

crQ 4.317 12.435 8.723

50 ( )C HzX 254.5289 122.0827 121.7518( )C F 12.5058 26.0733 26.1442

( )L TunedX 56.5620 11.2003 9.5119

( )L mH 40.0094 3.2708 2.3654

50 ( )L HzX 12.5693 1.0275 0.7431( )R 226.2480 44.8010 38.0474

V. IMPLEMENTATION RESULTS

Table 2 shows monitoring result comparing with

simulation result which the values are not far away

from each others.


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Table 2Monitoring & simulation results at 22 kV bus

Items

Monitoring results

(before/after)

Simulation results

(before/after)

A B C A B C

TIDi

5.25/

1.51

5.33/

1.48

5.28/

1.33

THDi

7.47/

4.77

8.17/

6.56

7.50/

4.61

Current

Distortion

9.37/

5.00

9.87/

6.73

9.21/

4.80

9.44/

6.90

9.94/

6.54

9.27/

6.27

TIDv

8.91/

0.60

9.03/

0.61

8.73/

0.62

THDv

11.81

/2.49

13.39

/2.68

12.20

/2.25

Voltage

Distortion

14.79

/2.57

16.15

/2.75

15.00

/2.33

14.52/

2.45

15.06/

2.49

13.90/

2.36

1.0 3.0 5.0 7.0 9.0 11. 13. 15. 17. 19. 21. 23. 25. [-][-]

30.00

20.00

10.00

0.00

Induction Furnace: Phase Current A in A

115/22 kV: Phase Current A/LV-Side in A

11.00026.052 A

11.0003.363 A

13.00026.497 A

13.000

2.557 A

4.0006.977 A

4.00019.639 A

DIgSILENT

Fig. 4 Harmonic current spectrum of before (red line)

and after (green line) the filters are placed.

Event #1 at 06/14/2008 09:35:39.800

Snapshot


09:35:39.800

06/14/2008

Saturday

0 9:3 5: 39. 805 0 9:3 5: 39 .8 10 09 :3 5: 39 .8 15 0 9:3 5: 39. 820

-750

-500

-250

0

250

500

750

Amps

A I B I C I

(a)Harmonic current waveform

Event #1 at 06/14/2008 09:35:39.800

Snapshot


09:35:39.800

06/14/2008

Saturday

0 9:3 5: 39 .8 05 0 9: 35 :3 9. 81 0 0 9:3 5: 39 .8 15 09 :3 5: 39 .8 20

-15000

-10000

-5000

0

5000

10000

15000

Volts

A V B V C V

(b)Harmonic voltage waveform

Fig. 5 Monitoring result after the filter are placed.

Total RMS: 462.54 A

DC Level: -1.60 A

F un damen ta l(H1 ) R MS : 4 98 .7 6 A

Total Harmonic Distortion THD: 23.84 A (Even: 10.54 A, Odd: 21.39 A)

THD H10 H20 H30 H40 H50

0

5

10

15

20

25

Amps

A IHarm

(c) Harmonic current spectrum (Fig.5 cont.)

From simulation (Fig. 4) and monitoring (Fig. 5)

results we have found that, designed harmonic filtercan dramatically improve voltage distortion.

VI. CONCLUSION

The procedure to design harmonic filters for

induction furnace load using actual recorded data has

been presented. The results of harmonic high pass

filters are dramatically reduced voltage distortion on

the 22 kV bus; 3.713.4% to be 1.02.7% of THDv

and 7.89.0% to be 0.22.0% of TIDv. In addition the

filters also reduced flickering (1.8 to be 0.6 of Pst) and

improved plant PF (0.84 lagging to be 0.99).

VII. REFERENCES

[1] R.C. Dugan, M. McGranaghan, S. Santoso, and H.W. Beaty,"Electrical Power System Quality, Second Edition,"

McGraw-Hill

[2] J. C. Das, "Passive FiltersPotentialities and Limitations,"IEEE Trans. Industry Applications, VOL. 40, pp.232-241,

Jan/Feb 2004. 126821

[3] R.C. Dugan, Sr. Conrad, and L.E., Sr., "Impact of InductionFurnace Interharmonics on Distribution Systems," The IEEE

Transmission and Distribution Conference, New Orleans,

LA, USA, Apr. 1999. 756150

[4] Elham B. Makram,E. V. Subramaniam,, Adly A. Girgis, andRay Catoe, "Harmonic Filter Design Using Actual Recorded

Data,"IEEE Trans. Industrial Application, vol. 29, pp. 1176-

1183, Nov. 1993. 259730

[5] D. Andrews, M.T. Bishop, and J.F. Witte, "HarmonicMeasurements, Analysis, and Power Factor Correction in a

Modern Steel Manufacturing Facility," IEEE Trans.

Industrial Application, vol. 32, pp. 617-624, May/June 1996.

502174

[6] IEEE Standard 18-1992,IEEE Standard for Shunt PowerCapacitors.

[7] IEEE Standard 1531TM-2003,IEEE Guide for Applicationand Specification of Harmonic Filters.

full paper madtharad chakphed

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