RESULTADOS DE PROYECTO DE MEJORA CONTINUADescripción completa
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LUF, CONCENTRACION MICELAR CRITICA
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CMC (COORDINATED MASTER CONTROL)
CMC CMC ensu ensurre prope roperr coor coordi dina nati tion on betw betwee een n Auxi Auxili liar arie ies, s, boiler and turbine to attain efficient and safe running of the plant. In thermal power units the turbines are fast responding components& boilers are having transport lag & thermal inertia Hence delayedly delayedly respond respond with variation variation in command command.. Turbine will be able to control the load or th.pre. quickly by changing the position of control valves. The other parameter are to be controlled by boiler master. The mode of operating the units as follows. (1) CMC ² coordinated coordinated mode mode (2) BOILER follow follow mode- Boiler Boiler follow turbine turbine (3) (3) Turbi Turbine ne foll follow ow mode mode-- Turb Turbin ine e foll follow ow Boil Boiler er (con (const stan antt Pr. Pr. Mode) (4) RUNBACK MODE.
Definitions:
1)
CMC:
Basically to control internal parameter·s of unit like (1) M S Pressure, (2) Load. Also to coordinate sensitive turbine and slow response of boiler auxiliaries, Good for network and Unit stability. Both Boiler and Turbine control ON Auto. 2)
BFM:
Boiler follow turbine. Turbine on Load control- Boiler ON Autocontrol pressure with BLI as feed forward. MW demands are met by Turbine firstly and lesser importance to unit stability. 3)
TFM:
Turbine follow Boiler. Boiler Master on manual control. Pressure control. Turbine maintains pressure by varying MSCV ,Unit load depends on steam output from boiler Best for unit stability
RUNBACK MODE. under runback conditions the firing for the boiler must be reduced to preset values, as close as possible to the tolerable limits. Therefore the swings of firing rate caused by the action of the PID controller must be avoided. As consequence of this condition the system has to switched to pure feed forward to control where the firing rate set point is directly proportional to load capability signal. To avoid any mismatch between steam production of the boiler and the turbine load turbine has to be switched to initial pressure control.
04)
RUNBACK:
In R/B mode boiler controls give command in proportion to unit capability. Turbine ² Pre. Control. R/B mode sets in automatically. 05)
BOILER MASTER: Basically a pressure controller F/F
Pre. Set point Actual pressure + BM
FEED FORWARD SIGNAL GNI OUTPUT - CMC BLI - B.F.M PRTD - T.F.M GET BYPASSED - R/B
06) G N I :
Control tracking generator or set Generates increase/decrease rate.
point
control
module.
Target to GNI: CMC : Load dispatch center or unit- master [frequency corrected] BFM
: Boiler demand (BM O/P)
TFM
: Actual Load.
R/B
: Unit capability.
07) UNIT CAPABILITY:
Capability to produce MW at that instant, W.C signal depends on the number of auxiliaries in service and their contribution is expressed as MW signal, which they can support.
08) FGMO:
Free Governing mode of operation Intro duce critical external parameter i.e. freq. of network to our control system. To ensure stability of network or grid it is necessary to have frequency regulation in CMC/EHC. But frequency is network parameter, which cannot be controlled by few units in the network. Total disturbance in network will be passed on to the units having regulation by the many units do not have regulation. 09) CMC TABLE Mode
Boiler controls
BFM
Throttle Pressure
CMC
Pressure
TFM
RUN BACK
MW & Pressure [Manual at KORBA] Produces steam as per unit capability
BOILER FOLLOW MODE 1. Turbine on load control 2. Boiler master on Auto-controls throttle steam Pressure with steam flow as feed forward. Varying fuel I/P (firing rate) in the furnace. In this mode boiler has to supply the steam for whatever load has been set from Turbine desk. In this way if the throttle steam reaches a limit (1 0 kg below the set throttle steam Pr.) ´limit Pr. Engagedµ condition comes and load would be scarified to maintain/restore the throttle steam Pr.
BOILER FOLLOW MODE
P
+
-
PR.
B
PID
PI
T
FUEL FIRING DEVICE
G MW
+ MW SET PT.
-
U
F F
SELECTION OF BOILER FOLLOW MODE ( BFM)
1. Put air control on auto (at least one FD fan) 2. Put feeders speed control on auto after varying fuel master(FM) output and making feeder speed controller error zero. 3. Vary Blr. Master O/P so that FM error becomes zero. Then put FM on auto. 4. Make throttle pr. Set point and actual pr. Difference zero. 5. Put BM on auto. If unit in turbine follow or coordinated mode change over to boiler follow occurs under following condition :turbine goes to manual because of any reason or operator action Pr CMC - Pr Lim > 60MW
TURBINE FOLLOW MODE: MODE: -
1. Boiler manually controlled 2. Turbine master On Auto -controls throttle steam Pre. (With steam flow as feed forward) by varying load. In T.F.M Pr. Controller comes into picture and the throttle Steam Pre. Varies the opening of MSCV to maintain the set throttle steam Pre.
TURBINE FOLLOW MODE
PR. SET PT.
B
P
+ PI
MW SET PT. FUEL FIRING DEVICE
T
G N
+ PI
-
-
F
SELECTION OF TURBINE FOLLOW MODE ( TFM)
1. Boiler master on manual. 2. Throttle pressure deviation zero. 3. Turbine in auto. 4. Press. Turbine flow push button along with manual release on CMC desk and turbine goes to initial pressure mode from LMT mode by itself. 5. Now load set point can be changed by varying the boiler master manually.
+
Unit Tar get Load
+
Fr eq. Deviation corr ection
Boiler
CMC LOOP basic
Turbine
Logic Unit Load Capability
Min
R un back
Load Rate (Set)
Min
Permissive Load Rate form turbine str ess evaluator (ESE)
Track ing integrator
Guidance load signal
+
+
PID
Boiler Contr oller
-
Thr ottle Pr. err or
PR.CORRECTION CK T.
±
-
+
P TURBINE CONT.
+
Pr essur e Set Signal
PI
Turbine Contr oller
Steam PR. BOILER
GEN
MW
CMC controls the plant treating boiler and turbine as a unit. It aims is to generate desired µMW¶ O/P through coordinate regulation of boiler I/P & O/P (turbine I/P). Turbine must not increase load without taking firing /boiler inertia in consideration. CMC coordinate sensitive turbine & slow response boiler & Auxiliaries. IN CMC Boiler master on Auto Turbine master on Auto Unit master - Receiving load demand from ALDC or Manually from desk. In cmc sets the MW set point which will be pursued by boiler master by taking throttle pressure error as final trimming input signal. Turbine will control the MW by taking mw error as input. Th.pre. error will not be effecting the the mw till it is beyond limits. Boiler master will change the air & fuel to provide the desired steam. The respond will be slow when compared to turbine response. So it may be reemphasized that this mode of operation gives maximum stability to the units with optimum response taking boiler & turbine as a unit. Pressure correction curve is basically a bridge between the slow boiler & fast responding turbine control. Performance of CMC largely depends on the proper tuning of the curve. Tuning of the curve varies with boiler & fuel .
Pressure Correction in CMC Under
normal operating conditions including small load (pressure) variation boiler and turbine are controlled independently as per set point from GNI. Any unbalance in power generation and power consumption due to frequency variation in FGMO , throttle pressure may increase or decrease which may cause dangerous condition in the boiler. If DP (Set throttle pre.- Actual throttle pre.) variation goes below set point ( - ve pressure deviation) , boiler storage capacity is used. However, any large variation in throttle pressure shall restrict the Turbine output till the Boiler has produced the additional output to match the increased demand. Similarly in case of +ve pressure deviation turbine output will increase. MW
15MW 2 Kg - DP 15MW
1 Kg
1 Kg
2 Kg + DP
Note:Note: THROTTLE PRESSURE (DP) correction starts at +/- 1Kg and acts upto +/- 2Kg. It will add or subtract +/- 15 MW to the GNI output, thereby generating pressure corrected GNI output to EHC.
FREQUENCY
INFULENCE ON CMC
K F Min Unit Master
+
O/ p +
Fr equency & Pr. Connected GNI O/P to EHC
GNI +
P
-
-
Adder
--
Max Min n M I N
1.5 %
Pr e. Corr ection M A X
Delay
+ +Adder
MW
Fr equency connected GNI O/P
P
Th.Pr e. Set.Pr e
F/F Boiler master PI+D
10 MW
3012 3992
20 MW
Air master master
Fuel
Fr equency inf luence M I N
LDC Unit Master
M A X
+ + -
LOAD UNIT
MAX
P
Turbine load limiter CM C
UNIT Capability M I N
TFM BFM
MAX
MIN
UNIT load rate
Tar get of unit
M I N
UNIT COORDINATER GNI
R un back limit
MIN M A X
LIMITING BLOCK
Actual MW Boiler demand
TSE u pper mar gin
+
TFM
M I N
TSE lower mar gin
+
D action
P
BFM
+
P
Del ay
P
BLI
CMC
PA FA N A PA FA N B
PRTD M I N
Capability + -
load
F(x)
BFM
PULV A -J
TFM
R un back in action
CMC LOOP ST#II K ORBA
Set.Pr e Th.Pr e
F/D +
+
-
Boiler master PI+D
Air master master
Fuel
PR (CMC set Pt to turbine)
Max
Load Setter
Min
Max / Min. Limiter
+
(
EHC TSE Inf luence
+
+
f)
Load
Load R efer ence
+
+ + +
GNI Load +
25MW
+
Delay
+
Thr ottle Pr essur e Set.
0. 2HZ 0. 125 HZ 40MW
+
-
Boiler Master
CMC LOOP
+
Fr eq
-
Load Limiter
+
Actual Pr essur e
M I N
Fr equency Inf luence ON
Pr essur e Corr ection
Fr equency Unloading Character istic
Load contr olle r
TOTAL COAL FLOW
28.6% 85.7% B
TOTAL OIL FLOW X001 X
XM03 Y1
Y
XP01 Y2
P
-
PT3
X001
A
A
+
B
P
+
3X1.01
MW GENER ATED Y2 Y1 +
XP01
B/M O/P
AIR
CV Corr ection loo p mani pulates the coal f low measur ement signal by incr easing or decr easing it, to show less coal is going when coal quality is bad and mor e when coal is good the effect is limited to 85% to 100% of actual coal f low
+
MIN
P
CV CORRECTED COAL FLOW
FUEL
MASTER
CV CORRECTION LOOP A
B
J
TOTAL FUEL FLOW
BOILER DEMA ND
Max
AIR MASTER LOOP
X N01 X N01
Max TOTAL AIR FLOW HK7715D
Y
XP01
P
PI
W
R L
R S04 OXYGEN MASTER
Ui XM02
80%
X N01
Max TOTAL AIR FLOW
+
-
AIR MASTER
FDA
20% +
§
+
X N01
MIN AIR FLOW
FDB
(E = 0..1)
AIR FLOW DEMA ND
Ua = Ui
E
O2 Correction loop manipulates the total airflow measurement by increasing or decreasing O2 master to show less air/more air is flowing. This influence is limited to 30% of the total air flow [Presently]
O2 TRIM -
A section station and a setter for oxygen set point are provided to achieve the desired excess air. If variable O2 set point (SP) is selected, set point is generated by a function generator which is a function of max ( air flow SP and total air flow). In other mode SP is set from UCB. O2 in flue gas is compared with this SP and error is fed to PI controller, output of which is limited between 0.8 and 1.2% of total air flow.
SELECTION OF CMC 1. Put air control on auto (at least one FD fan) 2. Put feeders speed control on auto after varying fuel master(FM) output and making feeder speed controller error zero. 3. Vary Blr. Master O/P so that FM error becomes zero. Then put FM on auto. 4. Make throttle pr. Set point and actual pr. Difference zero. 5. Put BM on auto. 6. Increase /decrease unit master output so that it becomes equal to actual load. (wait unit load set value and load value matches as shown in the CMC panel digital indicator). 7. Form TG desk put turbine control on auto. 8. Press coordinated push button along with manual release on CMC desk.
FEED RATE
CURVE GENERATOR Generator UCB Set Point
Max Mill PA Flow
+ Controller
HAD MILL PA FLOW GENER ATION CURVE
-
CURVE GENERATOR SETTINGS XU01 CAR D HAD SET POINT FOR PA FLOW AS PER FEED R ATE
