S06-SoundTutorial

(1)

AUDIBLE SOUND REGULATORY

REQUIREMENTS FROM A

UTILITY PERSPECTIVE

JANE ANN VERNER P.E.

MARCH 2006

(2)

(3)

Overview

 

F

Fa c

a ctt o r

o r s

s T

Th

h a t

a t D e

D ett e r m

e r m i n e

i n e

A c

A cc

ce p t

e p t a b l e S

a b l e So u

o u n

n d L e

d L ev

v e l s

e l s

 

B

Ba

a c

ck g r

k g r o u n d I

o u n d I n f o r m

n f o r m a

a t i o n

t i o n

 

Z

Zo n i n g

o n i n g R

Re

e q u i r

q u i r e

e m

m e

e n t

n t s

s

 

P

Prr o j

o j e c

e ct

t S

Sp

p e c

e ci f

i f i c F

i c Fa c

a ctt o r

o r s T

s To

o H e l p

H e l p

M e

M ee t Z

e t Zo n i n

o n i n g R

g Re q u i r

e q u i r e m

e m e

e n t

n t s

s

(4)

Factors That Determine Acceptable

Sound Levels

 

P

Pr o x

r o x i m

i m i t y

i t y o f s

o f su b s

u b s tt a

a tt i o

i o n o r

n o r

tt r a n s f o r m

r a n s f o r m e

e r

r tt o s l

o s l e

e e p i

e p i n g

n g f a c

f a ci l

i l i t i e s

i t i e s,,

e

e i t h

i t h e

e r c o m

r c o m m

m e

e rr c

ci a

i al o r r

l o r r e

e s

si d e

i d e n t

n t i a

i a ll

 

Z

Zo n

o n i n g o r

i n g o r u s e

u s e o f l a n d

o f l a n d

 

II n d

n d u s t r

u s t r i a

i a l

l h i g h

h i g h e

e r n

r n o i s

o i se

e l e

l ev e l

v e l s

s

p e r m i t t e d

 

T

Ti m

i m e

e o f d a

o f d a y o r

y o r n i g h t

n i g h t f o r s o

f o r s o u n

u n d

d

a c t i v i t y

 

D

D u r

u r a

a tt i o

i o n ,

n , v o l u m

v o l u m e

e a

a n d n

n d n a

a tt u r

u r e

e o f

o f

s

so u n

o u n d s u c

d s u c h

h a s

a s tt o n

o n e ,

e , f r

f r e q u e n c y

e q u e n c y

a

a n d

n d b r

b r o a

o a d b a n d

d b a n d

(5)

Background Theory



Pe r i o d - Ti m e t h a t i t t a k e s f o r o n e

v i b r a t i o n c y c l e ( T se c)



Fr e q u e n c y # o f v i b r a t i o n c y c l es

p e r se c ( f H z)



F = 1 / T



5 0 0 Hz = 1 / 0 .0 0 2 se c

(6)

(7)

Background Theory



Pu r e To n e s j u st o n e Fr e q u e n cy



N o ise – co n t a i n s m a n y

f r e q u e n c i e s



Tr a n sf o r m e r s So u n d s



Co r e , w i n d i n g s & co o l i n g



Co r e n o i s e 1 2 0 H z & e v e n

h a r m o n i c s



H u m a n A u d i b l e Ra n g e



2 0 H z t o 2 0 , 0 0 0 H z

2 0 H z t o 1 6 , 0 0 0 H z

(8)

(9)

(10)

Background Theory



A w e i g h t e d So u n d s – si m u l at e s

t h e f r e q u e n c y r e sp o n s e o f t h e

h u m a n e a r . A d j u s t e d p r i m a r i l y

f o r l o w f r e q u e n c i es.



Se e C5 7 .1 2 .9 0 Ta b l e s 9 & 1 0

(11)

(12)

Perception of Sound Intensity

Ch a n g e i n d B

H u m a n Pe r ce p t io n

1 d B

I m p e r ce p t i b l e

3 d B

Ju st N o t i ce a b l e

5 d B

Cl e a r l y N o t i ce a b l e

1 0 d B

Su b st a n t i a l Ch a n g e

(13)

Requirements



M o st Co m m o n



7 A M t o 7 PM 6 5 d b A



7 PM t o 7 A M 5 5 d b A



So m e ar e a s m o r e st r i n g e n t



Li m i t o f 1 0 d e ci b e l s o v e r

e x i s t i n g so u n d l e v e l s

(14)

Requirements PHI NJ (Con’t

)

Continuous sound level limited to 50 dbA

H z

d B

3 1 .5

9 6

6 3

8 2

1 2 5

7 4

2 5 0

6 7

5 0 0

6 3

1 0 0 0

6 0

2 0 0 0

5 7

4 0 0 0

5 5

8 0 0 0

5 3

(15)

Project Specific Factors

(16)

(17)

(18)

Project Specific Factors



Ba se l i n e so u n d m e a su r e m e n t s



Gr e e n f i e l d si t e - M ea su r e a t

si m i l a r s i t e



To u r f o r zo n i n g p e r s o n n e l



I n c l u d e so u n d l i m i t i n y o u r s p ec



Sp e ci f y l o w so u n d e m i t t i n g

e q u i p m e n t



Se t b a c k s I EEE C5 7 .1 3 6 A n n e x B

(19)

Calculating Transformer Noise Level

with Setback from Property Line

Step 1: Determine Transformer Sound Power Level

(Lw)

Lw = LpIEEE + 10 log10 (Surface Area)

(B1)

Where:

Lw

= Transformer Sound Power Level (dBA)

LpIEEE = Transformer Sound Pressure Level at IEEE

Locations (dBA)

Surface Area = IEEE Measurement Surface Area in

m2 = 1.25 x Transformer Height x Measurement

Perimeter (B2)

(20)

Calculating Transformer Noise Level

with Setback from Property Line

Step 2: Calculate Sound Pressure Level at a Specific

Location

Assuming hemispherical sound wave radiation

LpR = Lw – 10 Log10 (2

π

R²)

(B3)

Where:

LpR

= Sound Pressure Level at the Specified

Distance, R (dBA)

Lw

= Transformer Sound Power Level (dBA)

R = Distance from Transformer to Location in m.

This resulting Lp calculated from Step 2 will provide

(21)

Calculating Transformer Noise Level

with Setback from Property Line

The maximum allowed sound level at a property line is 53 dBA. The property line is 122 meters from the

transformer. The height of the transformer is 6.1

meters and the perimeter is 18.3 meters. What should the maximum allowable sound pressure level of the

transformer be at the IEEE locations?

LpR = 53 dBA, R = 122 m, h = 6.1 m, p = 18.3 m Using equation (B2) Surface Area = 1.25 x h x p = 1.25x (6.1 m) x (18.3 m) = 139.5 m2 Rewriting equation (B3) Lw = LpR + 10 log10 (2πR2)

⇒ Lw = 53 dBA + 10 log10 (2π(1222)) = 102.7 dBA

Using equation (B1) Lw= LpIEEE + 10 log10 (Surface

Area)

⇒ LpIEEE = 102.7 dBA – 10 log10 (139.5) = 81.3

dBA The maximum allowable sound pressure level of the

(22)

Summation of Levels of Multiple

Sources

# o f I d e n t ica l So u r ce s

d B a d d e d t o

s i n g l e l e v e l

2

3 d B

3

5 d B

4

6 d B

5

7 d B

(23)

B B A P o w e r T r a n s f o r m e r - 1

Transformer Noise

Sources & Characteristics

Ramsis Girgis

Tutorial Session

IEEE Transformer Committee

(24)



Sources / Components of transformer noise



Characteristics of each noise component



Relative magnitudes of no-load and load noise



Is Load Noise an issue?

(25)

B B A P o w e r T r a n s f o r m e r - 3 

No-Load Noise



Core Noise



Cooling Equipment Noise



Load Noise

Sources of Noise in a Transformer

(26)

S o u

r c e s

&

F r e q

u e n

c y S

p e c

t r u m

(27)



Caused by Magnetostriction of core material

 Mainly 120 Hz, 240 Hz, and 360 Hz with some 480 Hz

 100, 200, 300, and 400 Hz for 50 Hz operation

 Relative magnitudes are determined by core material & flux density

 An unexpectedly high level of a frequency component would indicate

core / tank resonance

(28)

Frequency Spectrum of Core Noise - 1

10 20 30 40 50 60 70 80 2 5_3 1 . 5 4 0 5 0 6 3 8 0 1 0 0 1 2 5 1 6 0 2 0 0 2 5 0 3 1 5 4 0 0 5 0 0 6 3 0 8 0 0 1 0 0 0 1 2 5 0 1 6 0 0 2 0 0 0 2 5 0 0 3 1 5 0 4 0 0 0 5 0 0 0 6 3 0 0 8 0 0 0_1 0 0 0 0_1 2 5 0 0_1 6 0 0 0_2 0 0 0 0 Frequency, Hz S o u n d p r e s s u r e l e v e l , d B

(29)

Frequency Spectrum of Core Noise - 2

0 10 20 30 40 50 60 70 80 90 2 5 3 1 . 5 4 0 5 0 6 3 8 0 1 0 0 1 2 5 1 6 0 2 0 0 2 5 0 3 1 5 4 0 0 5 0 0 6 3 0 8 0 0_1 0 0 0

Frequency (Hz)

S o u n d P r e s s u r e ( d B )

(30)



Caused by Fans and Pumps

 Moderate levels of low-frequency (<100 Hz) fan-blade / Motor noise component(s)

 Remainder is wide-band noise

(31)

Frequency Spectrum of Fan Noise

0 10 20 30 40 50 60 70 80 25 31.5 40 50 63 80 100 125 160 200 250 315 400 500 630 800 1000 Frequency, Hz S o u n d P r e s s u r e l e v e l , d B

(32)



Caused by the winding leakage flux



Producing vibrations of the windings and tank



Exclusively 120 Hz



100 Hz for 50 Hz operation

(33)

B B A P o w e r T r a n s f o r m e r - 1 1

Frequency Spectrum of Load Noise

0 10 20 30 40 50 60 70 80 1 2 3 4 5 6 7 8 9 1 0 11 12 13 14 15 1 6 1 7 1 8 19 20 21 22 23 2 4 2 5 26 27 28 29 30 Fr equency (Hz) S o u n d P r e s s u r e l e v e l , d B

(34)

R e l a

t i v e

m a g

n i t u

d e s

o f n

o - l o

a d a

n d L

o a d

N o i s

e

(35)

Magnitudes of No-Load & Load Noise, N. America

Transformer No Load Noise Load Noise (Load - No Load) Noise

# dBA dBA dBA

1 66.7 44.1 _-22.6 2 72.9 60.6 _-12.3 3 69.2 58.1 _-11.1 4 _59.7 _58.5 _-1.2 5 72.5 56.6 _-15.9 6 _65.4 _70.5 _5.1 7 _79.6 _79.1 _-0.5

(36)

Magnitudes of No-Load & Load Noise, Europe

Tested values of Noise Pressure Level, dBA

XMER No Load Load Load - No Load

# MVA Phases HV Noise,dBA Noise,dBA Noise,dBA

1 300 3 400 61.0 62.8 _1.8 2 200 3 116 55.4 65.0 _9.6 3 20 3 110 39.4 42.9 _3.5 4 25 3 110 43.8 49.5 _5.7 5 31.5 3 110 46.2 48.1 _1.9 6 40 3 110 43.8 53.0 _9.2 7 22 3 116 49.8 42.3 _-7.5 8 25 3 110 45.8 43.2 _-2.6 9 294 3 330 53.0 59.0 _6.0

(37)

I s L

o a d

N o i

s e a

n I s

s u e

?

(38)

Why hasn’t load noise been an issue



Historical requirements (No-Load Noise only)

 No-Load noise has been considered the dominant noise component



Magnitude of Load noise was not recognized

(39)

Load Noise vs Load (

40 Log I p.u.

)

P.U. Load

Load Noise Reduction

0.9 -1.8

0.8 -3.9

0.7 -6.2

0.6 -8.9

(40)

Is Load Noise likely to become an issue ?



Requirements for “low noise” transformers

 Resulted in designs with no-load noise lower or equivalent to load

noise



Locating substations in heavily populated communities

 With strict limits on the total noise of a transformers

(41)

Summary

 Contributors to Transformer noise are:

 Core noise: Multiples of 100 / 120 Hz

 Cooling system noise: Low frequency and wide band noise

 Load noise: Purely 120 Hz

 Load Noise has become an important issue for electric utilities

 Load noise can become the more dominant noise in low noise transformers

 Some customers added Load noise to their Specifications in past 2 years

(42)

1

Audible Sound of Transformers

under some special Conditions

Christoph Ploetner

Panel Session

IEEE Transformer Committee

Monday, March 20, 2006

(43)

Topics



DC-biasing current in transformers



Transformer operation with

non-sinuso

non-sinusoidal

idal currents

currents



Noise aspects of oil-immersed

shunt reactors

(44)

3 3

DC-biasing

(45)

B(t) B(t) B, B, ΦΦ, v, v H, H, ΘΘ, i, i I_DC I_DC B(t) B(t) B, B, ΦΦ, v, v H, H, ΘΘ, i, i B_DC B_DC B B dt dt d d vv==−− ΨΨ ~~ DC DC I I __

DC-biasing: phenomenon

w

wiitthhoouut t DDCC--bbiiaassiinng g ccuurrrreenntt wwiitth h DDCC--bbiiaassiinng g ccuurrrreenntt

B B dt dt d d vv==−− ΨΨ~~ magnetic equivalent magnetic equivalent Φ

Φ_{_air}_{_air} ΦΦ_{_core}_{_core} Φ Φ Θ Θ model model v(t) v(t)

~

i(t) i(t) Φ Φ_{_core}_{_core} Φ Φ_{_air}_{_air} V_DC V_DC

(46)

5

DC-biasing: waveshapes

without DC-biasing current

10 A 0 A 2.0 T 0.0 T -2.0 T 0.3 A 0 A 2.0 µm -2.0 µm 0 µm -0.3 A

with DC-biasing current

2.0 T ~ total flux ~ core flux 2.1 T f l u x d e n s i t y c u r r e n t m a g . - s t r i c . 2.0 T 1.75 T time time

(47)

DC-biasing: harmonics

without DC-biasing current with DC-biasing current

0 1 2 3 4 5 6 7 8 9 harmonic order v 0 1 2 3 4 5 6 7 8 9 harmonic order v c u r r e n t m a g . - s t r i c . flux density: v = 1 current: v = 1, 3, 5 … mag.-striction: v = 0, 2, 4, 6 … flux density: v = 0, 1 current: v = 0, 1, 2, 3, 4 … mag.-striction: v = 0, 1, 2, 3, 4 … f l u x d e n s i t y

(48)

7

DC-biasing: noise spectrum

noise harmonics: v = 1, 2, 3, 4, 5 … 0 2 4 6 8 … harmonic order v 0 2 4 6 8 … harmonic order v noise harmonics: v = 2, 4, 6, 8 … 70 50 30 10 dBA 1.7 T 1.7 T 71 dBA 83 dBA

(49)

DC-biasing: waveshapes (3-phase / 5-limb)

-2.0 µm 0 0 -2.0 T 0 2.0 T -2.0 T 0 2.0 T c u r r e n t m a g . - s t r i c . f l u x d e n s i t y y o k e , r e t u r n 1 A -1 A time f l u x d e n s i t y l i m b s

(50)

9

DC-biasing: waveshapes (3-phase / 5-limb)

-4.0 µm 0 4.0 µm 0 50 A -50 A -2.0 T 0 2.0 T -2.0 T 0 T 2.0 T c u r r e n t m a g . - s t r i c . time f l u x d e n s i t y y o k e , r e t u r n f l u x d e n s i t y l i m b s

(51)

DC-biasing: noise spectrum (3-phase / 5-limb)

with DC-biasing current without DC-biasing current

1.3 T 1.5 T 1.7 T 1.3 T _{1.5 T} 1.7 T 50 dBA 70 dBA 50 70 dBA

(52)

11

DC-biasing: noise increase

0,0 5,0 10,0 15,0 20,0 25,0 30,0 0,0 5,0 10,0 15,0 I_DC / I0 [pu] d e l t a L [ d B ] 1.6 T 1.7 T

(53)

DC-biasing: principal schemes and examples (1)

1. DC Current injection in a single winding (applicable to all core types)

Examples

 unsymmetrical switching of a power electronic device

connected to a transformer winding (HVDC, inverter, converter)  transformer inrush V_AC ~ I_DC c o n v e r t e r i n v e r t e r load

(54)

13

DC-biasing: principal schemes and examples (2)

Examples

 vagrant earth currents caused by

 DC electric railroad systems

 cathode protection applications

 Geomagnetic Induced Currents (GIC)

 HVDC system with ground return

2. DC Current injection via the transformer neutral

(applicable to transformer banks, 5-limb core type, shell type)

3 x I_DC/3

XFMR 1 XFMR 2

(55)

DC-biasing: HVDC system with ground return

YY 1-3 YD 1-3 YY 4-6 SR 2 SR 1 SR 4 SR 3 YD 4-6 - 500kV / - 3 kA + 500 kV / 3 kA YY 7-9 YD 7-9 YY 10-12 YD 10-12 Bipolar operation + 500 kV / 3 kA Monopole operation with ground return 0 kV / 3 kA

(56)

15

DC-biasing: measures to avoid biasing

 use 3-phase 3-limb core, other transformer design measures

only restricted effective

 implementation of a control loop for DC-current (HVDC,

inverter, converter)

 installation of a resistor between transformer neutral and

ground

 isolation of transformer neutral together with and installation of

an 3-limb earthing transformer close to the affected unit

 installation of a blocking device between transformer neutral

and earth (bridgeable capacitor)

(57)

(58)

17

Non-sinusoidal currents: waveshape examples

Winding current of a HVDC transformer

(59)

Non-sinusoidal currents: sound increase

F_ax

F_rad

Calculation rules have to be applied for each harmonic component and each pair of harmonics

 Force

 Sound pressure

 Sound level difference

f

F

p

~

⋅

B

x

G

f

_vol r r r

=

2

~

I

F

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

⋅

+

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

⋅

≈

∆

base base f f I I L 20 lg 20 lg 2

(60)

19

))

)

cos((

)

(cos((

2

1 )

sin(

)

sin(

~

)

(

t

I

t

I

t

I

t

F

m n m n m n m m n n m n ω ω ω ω ω ω

+

−

⋅

=

⋅

1 each harmonic current component produces a force (noise)

component of double frequency

2 each pair of harmonic currents I_n und I_m gives two force (noise)

components with frequencies being the sum and the difference of the harmonic current frequencies

))

2 cos(

1 (

2

1 )

sin(

~

)

(

t

I

2

t

2

I

2

t

F

ω

=

⋅

−

ω

(61)

given harmonic spectrum

Non-sinusoidal currents: example (HVDC transformer)

harmonic noise spectrum

assumption: 74 dBA @ sinusoidal current

noise increase for harmonics 5, 7: 15.7 dB

total noise: 89.7 dBA

order current 1 1344 5 240 7 152 order 1 5 7 1 2 6 8 5 4 10 12 7 6 2 14 order 1 5 7 1 74.0 85.2 83.7 5 81.7 74.7 72.2 7 81.2 56.6 69.8

(62)

21

Non-sinusoidal currents: noise spectrum (HVDC transformer)

test bay measurements

on-site measurement (not calibrated)

no-load noise load noise

2 4 6 8 10 12 14 16 18 harmonic order

20 22

70 dBA

(63)

Oil-immersed

Shunt reactors

(64)

23

Oil-immersed shunt reactors: design, operation

operation

 power (current) determined by line voltage

 operation always at “full load”

general design

(65)

Oil-immersed shunt reactors: noise sources

 winding noise (Lorentz force)

 gap noise (Maxwell force)

 core noise (magnetostriction)

F_stric F_gap F_ax F_rad gap limb package win-ding limb package Φ_(t) yoke F_stric

(66)

25

Oil-immersed shunt reactors: noise spectrum

70 dBA

2 4 6 8 10 … _{harmonic order}

reactor 1 reactor 2

2 4 6 8 10 … harmonic order

 spectrum comparable with transformer no-load noise spectrum

 characteristic A-weighted harmonics are usually of order 4 and 6

 “tinny” sounding noise may indicate a problem with the gapped core

(67)

 DC-biasing causes high noise increase up to

25 dB @ 1.7 T. The noise spectrum is unique.

 Non-sinusoidal currents (HVDC) do increase the noise

level up to 18 dB.

 Reactor noise spectrum is similar to transformer

no-load noise spectrum. Characteristic harmonics are usually of order 4 and 6.

Conclusions

(68)

1

IEEE/PES Transformers Committee

HVDC Converter Transformers & Smoothing Reactors Subcommittee March 20, 2006

The Audible Sound produced by Dry-type Air-core Reactors Presented by

Klaus Papp

(69)

• Dry-type Air-core Reactor Design and Applications

• Audible Sound Generation by Dry-type Air-core Reactors • Sound Radiation and Methods of Mitigation

(70)

3

Dry-Type Air-Core Reactor

(71)

(72)

4

Winding design principle

open style winding encapsulated style winding

(73)

Multilayer dry-type air-core reactor 1 winding 2 winding conductor 3 duct stick 4 spider 5 terminal 6 support insulator 7 mounting bracket

(74)

6

Thyristor co ntrolled shunt reactors and filter reactors for SVC stations

TCR

3 rd 5 th 7 th 11 th

Filters

Q

(75)

SVC station

(76)

8

HVDC smoothing reactors and AC filter reactors for HVDC converter stations

AC Bus Thyristor Valves AC-Filters and C-Shunt HVDC Smoothing Reactor 5 th / 7 th 11 th / 13 th

(77)

HVDC Converter Station

(78)

10

Sound Generation by Dry-type Air-core Reactors

The audible sound of an air core reactor is caused by the vibration of the winding due to the electromagnetic forces produced by the interaction of the current flowing through the winding and its magnetic field.

2

i

F

i

B

F

≈

⋅

⇒

≈

(Hz) (A) 100 500 currents 60 Hz (Hz) (N) 100 500 forces 120 Hz

60 Hz current 120 Hz e xciting force

⇒

(79)

Sound Generation by Dry-type Air-core Reactors (Con’t) (Hz) (N) 100 500 forces 120 Hz 240 Hz _{360 Hz} 600 Hz (Hz) (A) 100 500 currents 60 Hz 300 Hz (A) currents 0 Hz 300 Hz (N) forces 300 Hz 600 Hz

60 Hz + 300 Hz current 120 - 240 - 360 - 600 Hz exciting forces

DC + 300 Hz current 300 - 600 Hz exciting forces

⇒

(80)

12

Example: Sound spectrum of an HVDC Smoothing Reactor

(81)

Sound Generation of a Dry-type Air-core Reactor (Con’t)

deflection due to electromechanical forces magnetic field plot

The deflection of the winding is proportional to the electro-magnetic force a_x i s o f r o t a t _i o_n a l s y _m m e t _r y coil height 2400 mm avg diameter 2900 mm radial built 290 mm turns no. 160

(82)

14

Animation of a breathing cylindrical winding

(83)

ρ π

E

D

f

₀

=

1

f ₀….breathing mode frequency D ….winding diameter

E ….Young’s Modulus (of wi nding material)

ρ … density (of winding material)

Example: encapsulated coil,

winding material aluminum D = 2900 mm → f ₀ = 470 Hz

(84)

16 2 0 2 2 2 0 4 1 1 ⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛ + ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎣ ⎡ ⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛ − = ω ω ω ω ω d K F V frequency (Hz)

V…vibration speed ω= 2πf, f ….vibration frequency

F… vibration force ω₀ = 2πf _0, f ₀ …breathing mode frequency K … structural stiffness d … damping (p.u. of critical)

Log (V / F) 30 40 50 60 0 100 200 300 400 500 600 700 800 900 1000 1100 1200

(85)

x

c

p

=

ρ ₀ ω

Vibration Speed - Sound Pressure

ρ₀ is the air density in kg/m3;ρ₀= 1.2 kg /m3 c is the speed of sound in air in m/s; c = 340 m/s ωx is the vibration velocity in m/s

ω = 2πf is the acoustical angular frequency in s–1 x is the vibrational amplitude in m

Example: x = 1 µm, f = 1000 Hz → L_p≈ 100 dB

dB

x

c

L

_p 0 ₅

10

2 log

20

₋

⋅

=

ρ ω x v = ω x

(86)

18

Sound Power and Sound Power Level

2 2 0

c

S

x

W

=

ρ σ ω

W is the radiated sound power in W L_W is the sound power level in dB ρ₀ is the air density in kg/m3

c is the speed of sound in air in m/s S is the sound radiating surface in m2 σ is the radiation efficiency (no unit) ωx is the vibration velocity in m/s

ω= 2πf is the acoustical angular frequency in s–1 x is the vibrational amplitude in m.

Watt

W

L

_W ₀ 12 0

10 ,

log

10 =

−

=

(87)

0.01 0.02 0.03 0.04

v

L_W= 103 dB

L_W(A) = 87 dB(A)

single-phase air-core shunt reactor

Q (60 Hz) 40 Mvar current 1400 A (rms) winding dimensions: height 2400 mm avg. diameter 2900 mm radial built 290 mm Radiation pattern

(88)

20

Sound pressure field of vibrating winding

m m

v

20 40 60 80 20 40 60 80 4 0 4 0 4 3 4 6 4 6 4 6 4 9 4 9 5 ₂ 5 2 5 2 5 5 5 5 5 5 5 ₈ 5 8 5 8 6 1 6 1 6 1 64 6 7 7 ₀

(89)

1 2 1 2 2 2 log 20 , ~ ~ , ~ A A L L A W x W A x → _W = _W +

x is the vibrational amplitude

A is the cross sectional area of conductor

- increase conductor cross section - avoid breathing mode resonance

ρ π

E D f ₀ = 1

- provide reactors with sound shields or sound enclosures

- provide sound walls or buildings

Options for Mitigation

(90)

22

Sound Shield Options

1 .. resin fiberglass shell 2 ..sound absorbi ng liner

(91)

example for Sound Enclosure

(92)

24

Sound Enclosures for Thyristor controlled Reactors

(93)

Sound Enclosures for Thyristor controlled Reactors

(94)

26

sound shields for HVDC smoothing reactors

(95)

P o w e r T e c h n o l o g y P r o d u c t s - 1 - 0 0 6

Sound Level

Measurement methods

Ramsis Girgis Tutorial Session

IEEE Transformer Committee

(96)

Sound Pressure Measurement method

 Most commonly used method today

 Actually measures (Transformer noise + Ambient )

 Ambient noise is corrected for within limits

 Included in the measured values are:

 Sound reflections from walls of test area

 IEC allows correcting for room sound reflections but ANSI does not

 Sound standing waves

 Near field effects

 When measuring Load noise, the measured value also includes Load

(97)

Sound Intensity Measurement Method

 Directional measurement of sound pressure level

 Measures the noise emitting from the transformer only

 Does not include ambient noise, including load noise of the booth transformer,

sound reflections, standing waves

 Does not include near field effects

 Avoids changes in ambient noise level

 A must use for very low noise transformers, unless transformer / reactor is

tested in a low sound room

 A much more accurate measurement for transformer noise

 Especially when measuring the frequency spectrum

(98)

-Reference to Sound Intensity measurement method in IEC

IEC Standard # 60076 - 10 "Determination of Sound Levels"



Sound intensity measurements have the following advantages

over sound pressure measurements:

 An intensity meter responds only to the propagating part of a sound

field and ignores any non-propagating part, for example, standing waves and reflections.

 The intensity method reduces the influence of external sound

(99)

Sleepless in New York City?

Donald C

Donald Chhuu, C, Con on EEdisdison on of of NYNY, I, Inncc..

Low Noise Tr

a

n

sform

er

Requirements

(100)

C

o n E

d i s

o n O

v

e r v i

e w

C

o n E

d i s

o n O

v e r v

i e w

NYC and Westchester County

Area: 660 mile

22

(Electric

& Gas

)

Popu

lation:

9,097,254

–

3.2 m

ill

ion el

e

ctric c

us

tom

ers

–

13,050 MW 2005 peak

–

In some areas, load density

> 2,000 MW per mile

22

NYC and Westchester County

Area: 660 mile

22

(Elec

(Electric & Gas)

tric & Gas)

Population: 9,097,254

–

3.2 m

3.2 mil

illion e

lion electric custom

lectric customers

ers

–

13,050 MW 2005 peak

–

In some areas, load density

> 2,000 M

(101)

(102)

D

e n s e U r b a n E

n v i

r o n m

e n t

D

e n s e U r b a n E

n v i

r o n m

e n t

3 3

(103)

T y p i c a l 1 3 8/1 3 k V Su b s t a t i o n

138/13 kV 65 MVA

Syn Bus Syn Bus Breakers

To Network Load Transformer Breakers Circuit Switcher Syn Bus

(104)

H i s t o ri c a l T ra ns f or m e r N o i s e

R e q u i r e m e n t

H i s t o ri c a l T ra ns f or m e r N o i s e

R e q u i r e m e n t



New York City Noise Code – Octave band noise specification

with annoyance criteria



Locate substations in commercial zones next to major roads



Industry standards: transformer no-load and cooling

equipment (pumps & fans) noise

Isolated areas: 65 – 85 db(A)

Urban areas: 60 - 65 db(A)

Residential: Main tank in enclosed room

with radiators in ventilated area



New York City Noise Code –

New York City Noise Code

– Octave band noise specification

Octave band noise specification

with annoyance criteria



Locate substations in commercial zones next to major roads



Industry standards: transformer no--load and cooling

Industry standards: transformer no

load and cooling

equipment (pumps & fans) noise

Isolated areas: 65

Isolated areas: 65 –

– 85 db(A)

85 db(A)

Urban areas: 60

Urban areas: 60 -- 65 db(A)

65 db(A)

Residential: Main tank in enclosed room

with radiators in ventilated area

(105)

T y p i c a l Su bs t a t i o n A r e a 1 9 7 0s

(106)

Co m m e rc i a l – Re s i de nt i a l Z on e

(107)

5 T r a ns f o r m e r V a u l t s I n -L i n e

(108)

T r an s f o r m e r L o a d N o i s e

Fi e l d Me a s u r em e n t s

T r an s f o r m e r L o a d N o i s e

Fi e l d Me a s u r em e n t s



Survey: 6 transformers from 4 different

manufacturers



Power Loading: 30-50 % of nameplate rating



Voltage: 105 % of nameplate rating

68 – 78 db(A)



Survey: 6 transformers from 4 different

manufacturers



Power Loading: 30--50 % of nameplate rating

Power Loading: 30

50 % of nameplate rating



Voltage: 105 % of nameplate rating

68

(109)



Midtown Manhattan



Mixed residential and

commercial



Limestone veneer,

granite base



Louvers lit to appear

as storefront



Planters in sidewalk



Midtown Manhattan



Mixed residential and

commercial



Limestone veneer,

granite base



Louvers lit to appear

as storefront



Planters in sidewalk

M a n h a t t a n Su b s t a t i o n De s i gn Co nc e p t

M a n h a t t a n Su b s t a t i o n De s i gn Co n c e p t

(110)

N Y Ci t y M 1 R N o i s e Pe r fo r m a n c e

Re q u i r e m e n t (So u n d Pr e s s u r e L e v e l )

N Y Ci t y M 1 R N o i s e Pe r fo r m a n c e

Re q u i r e m e n t (So u n d Pr e s s u r e L e v e l )

39 39 Above 4,800 Above 4,800 41 41 2,400 2,400 –– 4,8004,800 47 47 1,200 1,200 –– 2,4002,400 53 53 600 600 -- 1,2001,200 59 59 300 300 -- 600600 66 66 150 150 -- 300300 74 74 75 75 -- 150150 79 79 20 20 -- 7575

Maximum Average Sound Level Maximum Average Sound Level

(db) (db) Manufacturing Zone

Manufacturing Zone Octave Band Freq. (Hz) Octave Band Freq. (Hz)

(111)

T r an s m i s s i o n Sy s t e m V o l t a g e

Re qu i re m e nt s (Ov e re x c i t a t i o n )

T ra ns m i s s i o n Sys t e m V o l t a ge

Re qu i re m e nt s (Ov e re x c i t a t i o n )

30 30 311 311 363 363--380380 Continuous Continuous 328 328 328 328--362362 10 10 --381 381--400400 345 345 0 0 --Over 400 Over 400 Continuous Continuous 130 130 130 130--145145 30 30 124 124 146 146--152152 10 10 --153 153--160160 138 138 0 0 --Over 160 Over 160 (minutes) (minutes) Lower Lower Range Range Class (kV) Class (kV) Duration Duration Limits (kV) Limits (kV) Voltage Voltage Voltage Voltage

(112)

T y p i c a l A r ea St a t i o n N o rm a l

Op e r at i n g Co n di t i o n

T y p i c a l A r ea St a t i o n N o r m a l

Op e r at i n g Co n di t i o n



140-145 kV HV bus voltage



Non-summer loading: Four transformers loaded

to approximately 30 % of nameplate rating (65.3

MVA)



Summer loading: Four transformers loaded to

approximately 80 - 90 % of nameplate rating

(65.3 MVA)



NLTC: 125.4 kV position



LTC: 12L position (12.558 kV position)



Power factor: 0.93



140--145 kV HV bus voltage

140 145 kV HV bus voltage



Non--summer loading: Four transformers loaded

Non

summer loading: Four transformers loaded

to approximately 30 % of nameplate rating (65.3

MVA)



Summer loading: Four transformers loaded to

approximately 80

approximately 80 -- 90 % of nameplate rating

90 % of nameplate rating

(65.3 MVA)



NLTC: 125.4 kV position



LTC: 12L position (12.558 kV position)



(113)

T y p i c a l A r ea St a t i o n Co nt i n g e n c y

Op e ra t i n g Co n d i t i o n

T y p i c a l A r ea St a t i o n Co nt i n g e n c y

Op e r at i n g Co n di t i o n



138-140 kV HV bus voltage



Summer loading: Three transformers loaded to

approximately 143 % of nameplate rating (65.3

MVA): 93.8 MVA for 8-hours



NLTC: 125.4 kV position



LTC: 16R position (15.468 kV position)



Power factor: 0.93



138--140 kV HV bus voltage

138 140 kV HV bus voltage



Summer loading: Three transformers loaded to

approximately 143 % of nameplate rating (65.3

MVA): 93.8 MVA for 8

MVA): 93.8 MVA for 8--hours

hours



NLTC: 125.4 kV position



LTC: 16R position (15.468 kV position)



(114)

L ow N o i s e T r a ns f o r m e r De s i g n s

L ow N o i s e T r an s f o r m e r De s i g n s



65 MVA, 132-13.8 kV Transformer



93 MVA, 132-27 kV Transformer



65 MVA, 132/65-13.8 kV Transformer



234 MVA, 138 kV +/- 25° Phase Angle Regulator *



234 MVA, 335-136-13.8 kV Auto-transformer *



420 MVA, 335-136-13.8 kV Auto-transformer



150 MVAr, 345 kV Shunt Reactor (Future)

* New designs for 2007-08



65 MVA, 132 --13.8 kV Transformer

65 MVA, 132

13.8 kV Transformer



93 MVA, 132 --27 kV Transformer

93 MVA, 132

27 kV Transformer



65 MVA, 132/65 --13.8 kV Transformer

65 MVA, 132/65

13.8 kV Transformer



234 MVA, 138 kV +/ -- 25

234 MVA, 138 kV +/

25°° Phase Angle Regulator *

Phase Angle Regulator *



234 MVA, 335 --136

234 MVA, 335

136--13.8 kV Auto

13.8 kV Auto--transformer *

transformer *



420 MVA, 335 --136

420 MVA, 335

136--13.8 kV Auto

13.8 kV Auto--transformer

transformer



150 MVAr, 345 kV Shunt Reactor (Future)

* New designs for 2007

* New designs for 2007--08

08

(115)

Re v i s e d 2 0 0 5 N Y C N o i s e Co d e



New law provides for maximum sound levels

measured, with the windows open, within a

residence in either a mixed use or residential use, or

within a commercial building.



New law provides for maximum sound levels

measured, with the windows open, within a

residence in either a mixed use or residential use, or

within a commercial building.

(116)

Co m p a r i s o n o f N Y C Z R v s . N Y C

N o i s e Co d e L i m i t s (So u n d Pr e s s u r e )

Co m p a r i s o n o f N Y C Z R v s . N Y C

N o i s e Co d e L i m i t s (So u n d Pr e s s u r e )

30 40 50 60 70 80 31.5 63 125 500 1000 2000 4000 8000

Octave Band Frequency (Hz) S o u n d L e v e l ( d B )

ZR Property line M1R ZR Property line M1