Coordinated master Control in Thermal Power pLant

CMC (COORDINATED MASTER CONTROL) Atul Anand Soni

CMC ensure proper coordination between Auxiliaries, boiler and turbine to attain efcient and sae running o the plant. (1)CMC – coordinated mode ()!"#$%& ollow mode' !oiler ollow turbine ()urbine ollow mode' urbine ollow !oiler (critical *r. *r. Mode) M ode)

CMC coordinate sensiti+e turbine  slow response boiler  Auxiliaries. $imited with help o turbine control (%-C) and %. CMC

!oiler master on Auto urbine master on Auto /nit master ' &ecei+ing load demand

1)

CMC3

!asicall to control internal parameter4s o unit li2e (1) M  *ressure, () $oad. Also to coordinate sensiti+e turbine and slow response o boiler auxiliaries, 5ood or networ2 and /nit stabilit. !oth !oiler and urbine control "6 Auto. )

!8M3

!oiler ollow turbine. urbine on $oad control' !oiler "6 Auto'control pressure with !$# as eed orward. M9 demands are met b urbine :rstl and lesser importance to unit stabilit. )

8M3

urbine ollow !oiler. !oiler Master on manual control. *ressure control. urbine maintains pressure b +aring MC; ,/nit load depends on

&/6!AC< M"0%. under runbac2 conditions the :ring or the boiler must be reduced to preset +alues, as close as possible to the tolerable limits. hereore the swings o :ring rate caused b the action o the *#0 controller must be a+oided. As conse=uence o this condition the sstem has to switched to pure eed orward to control where the :ring rate set point is directl proportional to load capabilit signal. o a+oid an mismatch between steam production o the boiler and the turbine load turbine has to be switched to initial pressure control. c ontrol.

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!"#$%& MA%&3 !asicall a pressure controller 8@8

*re. et point 

BM 8%%0 8"&9A&0 #56A$ 56# "/*/ ' CMC !$# ' !.8.M *&0 ' .8.M 5% !B*A%0 ' &@!

Actual pressure

>D) 5 6 # 3 Control trac2ing generator or set point control module. 5enerates increase@decrease rate.  arget to 56#3 CMC Ere=uenc

3

$oad dispatch center or unit' master

correctedF !8M

3

!oiler demand (!M "@*)

8M

3 Actual $oad.

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3 /nit capabilit capabil it..

>G) /6# CA*A!#$#B3 Capabilit to produce M9 at that instant, 9.C signal depends on the number o auxiliaries in ser+ice and their contribution is expressed as M9 signal, which

>H) 85M"3 8ree 5o+erning mode o operation #ntro duce critical external parameter i.e. re=. o networ2 to our control sstem. o ensure stabilit o networ2 or grid it is necessar to ha+e re=uenc regulation in CMC@%-C. !ut re=uenc is networ2 parameter, which cannot be controlled b ew units in the networ2. otal disturbance in networ2 will be passed on to the units ha+ing regulation b the man units do not ha+e regulation. >I)Mode CMC CM C

Boiler A!$% controls A!

%$BFM

Throttle Pressure

CMC

Pressure

TFM

,# B)C'

MW & Pressure [Manual at '$B)] Produces steam as per unit capabilit-

Input

Feed Forward

Input To turbine control

MW

Pressure error 

Steam Flow [BLI]

MW

Pressure error 

MW error  "#I $%P

MW error  (Load controller actie! MW error  (Load controller actie!

Throttle* pressure (Pressure controller actie!

Pressure error 

PT+ Turbine load set point

Pressure error 

Throttle* pressure (Pressure controller actie!

,#IT CapabilitSi.nal

BM B-passed

Pressure error 

Turbine controls

To Boiler 

Controls

!"#$%& 8"$$"9 M"0% 1. urbine on load control . !oiler master on Auto'controls throttle steam *ressure with steam Jow as eed orward. ;aring uel #@* (:ring rate) in the urnace. #n this mode boiler has to suppl the steam or whate+er load has been set rom urbine des2. #n this wa i the throttle steam reaches a limit (1> 2g below the set throttle steam *r.) Klimit *r. %ngagedL condition comes and load would be scari:ed to maintain@restore the throttle steam *r.

%$%C#"6 "8 !"#$%& 8"$$"9 M"0% ( !8M)

1. Pu Putt air air contr control ol on auto auto (at (at least least one FD fan) fan) 2. Put Put feeder feeders s sp speed eed cont contro roll on auto auto after after vary varying ing fuel fuel master(FM) output and making feeder speed controller error zero. . !ary "lr "lr. Master Master #$P #$P so t%at FM erro errorr &ecomes &ecomes zero zero.. '%en '%en put FM on auto. . Make Make t%rottle t%rottle pr. pr. et point point and and actual actual pr pr. Di*eren Di*erence ce zero. zero. +. Put "M on au auto. ,f unit in tur&ine follo- or coordinated mode c%ange over to &oiler follo- occurs under follo-ing condition / tur&ine goes to manual &ecause of any reason or operator action Pr 0M0 / Pr im  34M5

/&!#6% 8"$$"9 M"0%3 ' 1. !oile !oiler r manu manuall all  cont control rolled led . urbine urbine master master "n Auto 'controls 'controls thrott throttle le steam *re. (9ith steam Jow as eed orward) b +aring load. #n .8.M *r. Controller comes into picture and the throttle team *re. ;aries the opening o MC; to maintain the set throttle steam *re.

/&!#6% 8"$$"9 M"0%

-

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%$%C#"6 "8 /&!#6% 8"$$"9 M"0% ( 8M)

1. "oil "oiler er maste asterr on on ma manua nual. 2. '%r '%rottl ottle e pres pressu surre devi deviat atio ion n zer zero. . 'ur&in r&ine e in auto uto. . Press. Press. 'ur&ine ur&ine 6o6o- pus% pus% &utton &utton along along -it% manual manual releas release e on 0M0 desk and tur&ine goes to initial pressure mode from M' mode &y itself. +. 7o- load load set set point point can &e c%an c%anged ged &y vary varyin ing g t%e t%e &oile &oilerr master manually.

" &#M  ''

A section station and a setter or oxgen set point are pro+ided to achie+e the desired excess air. # +ariable " set point (*) is selected, set point is generated b a unction generator which is a unction o max ( air Jow * and total air Jow). #n other mode * is set rom /C!. " in Jue gas is compared with this * and error is ed to *# controller, output o which is limited between >.H and 1. o total air Jow.

Pressure Correction in CMC 8nder normal operating conditions including small load (pressure) variation &oiler and tur&ine are controlled independently as per set point from 97,. :ny un&alance in po-er generation and po-er consumption due to fre;uency variation in F9M# < t%rottle pressure may increase or decrease -%ic% may cause dangerous condition in t%e &oiler. ,f DP (et t%rottle pre./ :ctual t%rottle t%rottle pre.) pre.) variation goes &elo- set point ( / ve pressure deviation) < &oiler storage capacity is used. =o-ever< any large variation in t%rottle pressure s%all restrict t%e 'ur&ine output till t%e "oiler %as produced t%e additional output to matc% t%e increased demand. imilarly in case of >ve pressure deviation tur&ine output -ill increase. increase. MW

#$MW 2 K ! D" #$MW

# K

# K

2 K % D"

6ote3'  '=?#''@ P?@8?@ (DP) correction starts at >$/ 1Ag and acts upto upto >$/ 2Ag. ,t -ill add or su&tract >$/ 1+ M5 to t%e 97, output< t%ere&y generating pressure corrected 97, output to @=0.(B unit +)

RE'ENC INLENCE ON CMC K F Min Unit Master 

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Fre&'enc% Un"oadin3 Characteristic

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" Correction loop manipulates the total airJow measurement b increasing or decreasing " master to show less air@more air is Jowing. his inJuence is limited to > o the total air Jow E*resentlF

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%$%C#"6 "8 CMC 1. Pu Putt air air cont contrrol on auto auto (at (at leas leastt one one FD FD fan) fan) 2. Put Put feeder feeders s sp speed eed cont contro roll on auto auto aft after er varyi varying ng fuel fuel master(FM) output and making feeder speed controller error zero. . !ary "lr. "lr. Master Master #$P so so t%at t%at FM error error &ecomes &ecomes zero. zero. '%en put FM on auto. . Make Make t%rottle t%rottle pr. pr. et point point and actual actual pr. pr. Di*eren Di*erence ce zero. zero. +. Put "M on auto. 3. ,ncre ,ncreas ase e $decre $decrease ase unit unit mast master er outpu outputt so t%at t%at it &ecom &ecomes es e;ual to actual load. (-ait unit load set value and load value matc%es as s%o-n in t%e 0M0 panel digital indicator). C. Form orm '9 '9 desk desk put tur&in tur&ine e contr control ol on auto. auto. . Press Press coor coordin dinate ated d pus% pus% &utton &utton alon along g -it% -it% manual manual rele release ase on 0M0 desk.

FEED RATE

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