CC BY
13
TO THE QUESTION ON DISTRIBUTION OF LOADING BETWEEN
POWER UNITS TES
Farhadzadeh E.M., Muradaliyev A.Z., Farzaliyev Y.Z.
•
Azerbaijan Scientific-Research and Design-Prospecting Institute of Energetic AZ1012, Ave. H.Zardabi-94
e-mail:[email protected]
ABSTRACT
Practical realization of existing programs of calculation of distribution of loading between power units TES being in working order demands authentic power characteristics. In conditions of increasing ageing the core and auxiliaries of power units, maintenance of reliability of power characteristics in itself represents serious problems. The method of distribution of loadings between power units TES in view of their technical condition, based on registered technical and economic parameters is developed. Practical approbation of this method testifies to essential advantage of a recommended method, as in comparison with uniform distribution of loading between power units, and in comparison with the intuitive approach to distribution of loading.
INTRODUCTION
A problem of distribution of loading between the same power units (EB) TES well-known [1]. Corresponding algorithms and programs of calculation are developed. Practical realization demands, first, authentic power characteristics, that in conditions of increasing ageing the core and auxiliaries EB in it represents a serious problem [2]. In this connection heuristic approach when because of an operational experience, loading EB appointed seldom applied.
In these conditions, the great value got with methodical support to management TES in the form of recommendations on expedient distribution of loading between EB depending on reliability and profitability of their work.
These recommendations received by estimations of integrated parameters (B) reliability and the profitability of work EB calculated on actual values of technical and economic parameters EB TES [3]. We shall notice that desire simultaneously to raise reliability and profitability of work in some cases is amazing, since for maintenance of reliability of work additional expenses are required. In addition, it is true. However, in considered statement it is a question only of operational expenses, which at greater reliability, naturally, is less.
Method of calculation of distribution of loadings. As initial data for calculations serve:
n - the general number same EB
nb - number being in working order EB, nb < n;
Pmin, s - minimally safe load EB;
Pn0M - rated power EB;
In - an integrated parameter of reliability and profitability of work EB; Pav=P Z/nb - average loading on one EB, where P - loading TES;
Calculation of distribution of loading between nb EB spent in following sequence:
1. The relative size of factors of the importance of the technical condition (TC) i-th EB under the formula defined
b,= B
1 Bv
(1)
b
where i=1, nb; Bs B^ =
b
L b-
j=i
; B+ h B- -accordingly, positive (+) and negative (-) values Bi;
+ — + nb and nb - accordingly number being in working order EB with B h B";
2. Are defined minimal (bmin) and maximal (bmax) value of realizations of an integrated parameter bi under formulas:
bmin = min (bi, b2,......bnb)
bmax = max (bi, b2,......bnb)
(2) (3)
It is obvious, that bmin <0, and bmax> 0;
3. Intervals of possible decrease are defined (AP-) and increases (AP+) average loading EB under formulas
AP pcp Pmin, s
AP+ = P -P
AP P noM P a
(4)
(5)
4. If AP- < AP+ calculation of distribution of loadings between nb EB in view of their reliability and profitability is spent under the formula:
Pi = Pav + AP"-bi
(6)
5 If AP-> AP , under the formula:
Pi = Pav + AP+ bi
(7)
EXAMPLES OF CALCULATION OF DISTRIBUTION OF LOADING BETWEEN EB TES IN VIEW OF THEIR TC
1. On fig.1 the fragment of monthly result of the analysis of technical and economic parameters and recommendations in the basic directions of increase of overall performance EB is resulted.
=i
The basic directions of increase of an overall performance of power units in_month 20_year
Results of calculations have allowed to establish and recommend: 1. Technical and economic parameters of power units (EB), not meeting shown requirements for month
EB
Technical and economic parameters
The name
Relative deviation
Actual value
Recommende d value
The maximal electric loading Share el. energy for own needs Average loading
Operating ratio established capacities The specific charge of conditional fuel
-1,439 -1,333 -1,330 -1,310 -1,186
220,00 5,50 160,00 11,10 344,00
270,00 4,10 179,29 44,84 329,61
The specific charge of conditional fuel Operating ratio established capacities Share el. energy for own needs The maximal electric loading_
-1,072 -0,996 -0,857 -0,571
342,80 19,20 5,00 250,00
329,61 44,84 4,10 270,00
Average loading
-0,296
175,00
179,29
7
Average loading
-0,365
174,00
179,29
2. Factors of the importance TC
ÎB are equal
EB 1 2 3 4 5 6 7 8
Factor of the importance of 0,486 - - 0,482 0,126 0,255 0,604
the TC 1,318 0,634
3. To group "bad" concern 2 and 3 EB. Decrease in their loading in inverse proportion relative sizes of factors of the importance of the TC is recommended.
4. Least effective of operating EB should consider 2 EB. This EB is recommended to switching-off on scheduled repair, and preliminary - in a reserve or to the greatest possible decrease in loading
5. To group "good" concern 8, 1 4, 7, and 6 EB. Increase of their productivity to proportionally relative sizes of factors of the importance of the TC supposed.
6. To the most effective is 8 EB. Its work with as much as possible admissible productivity is expedient.
2
3
6
Fig.1. Fragment of monthly result of the analysis of technical and economic parameters and recommendations in the basic directions of increase of overall performance EB.
2. Results of calculations of relative values of factors bi under the formula (1) describing TC EB are resulted in table 1
Table 1. Realizations of relative sizes of factors of the importance of TC EB
Serial number of power units
N (i) 1 2 3 4 5 6 7 8
bi 0.249 -0.675 -0.325 0.242 - 0.064 0.13 0.309
Results of calculations distribution of loading between EB TES for of some values Pav are resulted in table 2.
Table 2. Results of calculations distribution of loading between EB TES for of some values Pa
Loadings Pav, MWt Conditional numbers of power units
1 2 3 4 5 6 7 8
110 115 96,5 103,5 114,9 - 111,3 112,6 116,2
130 140 103 117 139,9 - 132,6 135,2 142,4
150 164,9 109,5 130,5 164,8 - 153,9 157,8 168,6
170 189,9 116 144 189,7 - 175,2 180,4 194,8
190 214,9 122,5 157,5 214,7 - 196,4 203 220,9
210 232,4 149,2 180,8 232,2 - 215,8 221,7 237,9
230 247,4 182,7 207,3 247,3 - 234,5 239,1 251,7
250 262,4 216,2 233,8 262,3 - 253,2 256,5 265,5
Experience of calculations of distribution of loadings between EB shows, that application of formulas (6) and (7), despite of their faultlessness, insufficiently full use adjusting intervals EB (AP+ and AP"). Essentially greater effect turns out, if instead of formulas (6) and (7) to use formulas (8) and (9), looking likes:
P = P -AP--^ = P - (P - P. (8)
i av ^^ i av V av nim,s / i V /
mi n 111111
Pi = Pav + AP+ = Pav + (Pnom - PJ^ (9)
bin
where i=1,nb
Thus the formula 8 is used, if AP- /bmin < AP+ /bmax . If Ap- /b_ > Ap+ /b , the formula
1 mm max nun max 1
(9) is used. Results of calculations of distribution of loadings between EB TES under formulas (8) and (9) are resulted in table 3.
Table 3. Recommended distribution of loading of power station between EB for of some values Pav.
Loadings Pep, MWt Conditional numbers of power units
1 2 3 4 5 6 7 8
110 117,4 90 100,4 117,3 - 111,9 113,9 119,2
130 144,8 90 110,7 144,6 - 133,8 137,7 148,3
150 172,1 90 121,1 171,9 - 155,7 161,6 177,5
170 199,5 90 131,5 199,2 - 177,6 185,5 206,7
190 226,9 90 141,9 226,5 - 199,5 209,3 235,8
210 254,3 90 152,2 253,9 - 221,5 233,2 265
230 281,6 90 162,6 281,2 - 243,4 257 294,2
250 290,2 140,9 197,5 289,9 - 260,4 271,1 300
We shall define an interval of change of loading EB at the first and second ways of calculation of distribution of loadings. We shall assume, that AP- < AP+. At calculation by the first way:
- The bottom boundary value of loading (P) according to the formula (6) will be equal:
P(1) = P + AP-- b -
— av min
- The top boundary value of loading (P) according to the formula (7) will be equal:
P(1) = p +AP-- b
- The size of an interval of change of loading calculated under the formula:
A- p(1) - p(1) =AP" (b - b )
1 — ^^ \ max min /
(10)
At work as the second (2) ways size of an interval of change of loading (À2) it calculated under the formula:
A = P(2) - P(2) = AP
(
b_ - b
A
max min
min J
(11)
Degree of change of an interval of loading EB we shall define from parity A2 and A1
A2 = b -1
A mn
(12)
Thus, the interval of change of loading increases in |b Jn| = ^ 675 = 1.48. If Ap" > Ap+, similar calculations allow to establish, that
Ai _ b 1 - 1/ - 3 23
A _ "max /0.309 _ 3 23
(13)
Essential excess A2 above A1 testifies to doubtless economic advantages of the second way.
ACCOUNT OF CHARACTER OF CHANGE OF NUMBER OF THE POWER UNITS THAT ARE BEING IN WORKING ORDER IN TIME.
As an example on fig.2 dynamics of change nb within a year is resulted.
As change nb the casual character caused by automatic switching-off EB, their switching-off under the emergency application, in a reserve or on scheduled repair follows from fig.2 monthly have in many respects. Inclusion and switching-off EB demands revision of distribution of loading between EB. The basic stage thus is the estimation of relative values of integrated parameters (B), describing reliability and profitability of everyone EB. As the initial information for calculation Bi with i=1,nz last results of measurement and calculation of technical and economic parameters EB. The special program preparing this information is developed.
It is natural, that at calculations that part of these data which reflects the TC being in working order nb EB is used only. It is necessary to have in view of, that planned loading PES
specified and known not less than for 15 minutes before execution. This feature makes the basic difficulty of operative management of operating modes EB. Fluctuation of loading can be operatively considered at constant sizes Bi c i=1,nL The block diagram of algorithm of definition of loading EB in view of their reliability and profitability is resulted on fig.3.
Data input nb, N(i), b(i) with i-1,nb
Input of loading TES, P'
i r
- av p;/nb
P,-(Pcfp-90)/bmm
P2 =(300-Pafv)/bmax
Fig.3 The Block diagram of algorithm of calculation of distribution of loading between EB TES
ESTIMATION OF ECONOMIC EFFICIENCY
The basic purpose of the account of reliability and profitability of work EB at distribution of loading YES, is decrease in operational expenses and first of all, the charge of fuel. The sparing mode of operation insufficiently reliable and economic EB by restriction of their loading allows not only to lower the charge of fuel on TES, but also to reduce speed of deterioration and an idle time in emergency repair. Most operatively and precisely efficiency of the account of reliability and profitability EB can be estimated by calculation of the charge of conditional fuel. We shall consider some features of these calculations.
1. Economic profit (5UZ) in the form of relative reduction of size of the charge of fuel can be
calculated by comparison of the charge of conditional fuel at identical actual (f) loadings EB equal f..
Pav (designate it through UI;1) and recommended (r) in view of reliability and profitability of work of loadings EB Pav (we shall designate it through U^).
8Ur = 100 Us1 U^2 % s U
where U^i and Uz,2 can be calculated:
. For each hour (h) daily production schedule TES under the formula:
nh
„(h) _-n(f)
(14)
h). = P(f) - At Y U(m)
,,1,i av,i i / ; av,j j=1
nb
U<h). = Yp(r) -u(m) -At.
£,2,i ¿.j i,j av,j j
(15)
j-1
where i=1,24; Uj - average value of the specific charge of conditional fuel of j-th EB for preceded month; At<1; - For each day (d) month:
24
(16)
- For each month (m) year:
Ud) = Y U s,u i=1 24
UZ,2 = Y US,2,i i=1
nb
U^ =YP(f). - AT -U(m) - At.
s,1 Z-1 av,j j av/ j
j-1
nb
Uim = YP(r). - AT -U(m) - At.
£,2 ¿.j av,j j av '"j
j-1
If to consider, that cost 1 t. conditional fuel on 01.01.2014r. was equal So=229$. That economic benefit in cost expression calculated under the formula:
(17)
Sz = (Uz,1 - UL2) So
(18)
In table 4 settlement, values are resulted 8UZ and Sy for of some Pav for an interval of time 1 hour.
I f
Table 4. Parameters of efficiency of uniform distribution of loadings EB for of some Pav and At=1hour.
P A av 110 130 150 170 190 210 230 250 270
SUI, % 0,23 0,42 0,54 0,62 0,7 0,75 0,8 0,53 0,3
Si, % 137 296,4 433,2 570 707 821 980,4 752 456
As one would expect with increase Pav 8UZ and Sz increase, reach the greatest value equal:
P • lb 1 + P • b
-q _ nom | mm | mm max
Pav
and further decrease.
According to table.1
b
-b
max ^ min I
(19)
300 - 0.675 + 90 - 0.309
Pav max =-= 234МWt
avmax 0.309 + 0.675
Thus, the most economic mode TES takes place, when Pav/nb = Pav = Pavmax . This
dependence of change SUZ = f(Pav) and Sz = f (Pav) it is typical and does not depend on technical and economic parameters. Their change conducts only to change Pav, max.
CONCLUSION
1. The new method of distribution of loadings between power units TES, considering reliability and profitability of each power unit is developed;
2. At formation of structure of working power units, distribution of loading is practically instantly calculated for each step of daily production schedule TES;
3. Change of structure of working power units demands recalculation of factors of the importance of a technical condition;
4. Economic benefit of distribution of loading a recommended method makes approximately 0.45% from total expenses for fuel.
REFERENCE
1. Arzamastsev D.A., Bartolomey P.I., Holyan A.M. The Management information system and optimization of modes of power supply systems.-M.: Higher school, 1983.208 p.
2. Duel M.A., Fursova T.N., Kanyuk G.I. Automation of definition of power characteristics of the equipment. Power, 2013, №2, p. 13-19
3. Farhadzadeh E.M., Farzaliyev Y.Z., Muradaliyev A.Z. Increase of reliability and profitability of boiler installations of block power stations., Power system, 2015, №8.
