TECHNO-ECONOMIC STUDY OF VARIANTS UPGRADING OF STAVROPOL GRID TRANSMISSION SYSTEM Текст научной статьи по специальности «Электротехника, электронная техника, информационные технологии»

A gricultural

Bulletin of Stavropol Region

UDK 621.313.004.67

№ 1(21)/1 Supplement, 2016

Vladimir Ya. Khorol skiy, Alexey V. Efanov, Andrey B. Ershov, Vitaliy N. Shemyakin

TECHNO-ECONOMIC STUDY OF VARIANTS UPGRADING OF STAVROPOL GRID TRANSMISSION SYSTEM

It presents technical and economic assessment of the possible upgrading of Stavropol grid transmission system, with the possibility of building ring girt between the transformer substations 110/35/10 kV «Novoaleksandrovskaya» and «Grigoropolisskaya.»

Key words: electric power system, economic indicators, calculation of reliability, the choice of the preferred solution.

Vladimir Yakovlevich Khorol'skiy -

Doctor of Engineering, Professor,

Power Supply and Electric Equipment Operation Department Stavropol State Agrarian University, Stavropol Тел.: 8-928-316-10-98 E-mail: Vladimir.Horolskiy@mail.ru

Alexey Valeryevich Efanov -

Ph.D in Engineering, Assosiate professor,

Power Supply and Electric Equipment Operation Department

Stavropol State Agrarian University, Stavropol

Тел.: 8-918-757-76-89

E-mail: yefanov@mail.ru

Andrey Borisovich Ershov -

Ph.D in Engineering, Assosiate professor,

Power Supply and Electric Equipment Operation Department

Stavropol State Agrarian University, Stavropol

Тел.: 8-918-750-54-01

E-mail: ershov157500@yandex.ru

Vitaliy Nikolaevich Shemyakin -

Ph.D of Engineering, Assosiate professor,

Power Supply and Electric Equipment Operation Department

Stavropol State Agrarian University, Stavropol

Тел.: 8-918-755-54-30

E-mail: Shi_ma@mail.ru

Improving the reliability of power grids due to the increase of electric load and an increase in the number of customers, increased requirements for security of electricity supply.

The situational circuit area of power grids is shown in Figure 1.

Transformer substation "Krasnaya Zarya" 2 transformers 110/10 kV 2.5 MVA

Transformer substation "Novoaleksandrovskaya" 2 transformers 110/35/10 kV 16 MVA

Power line 110 kV 1= 14.8km,AC-120

Stavropolskaya GRES 500/330/110 kV

Power line 110 kV l = 22.9km,AC-185

Transformer substation Transformer substation

"Razdolnaya" "Grigoropolisskaya" ;

2 transformers 110/10 kV 2.5 MVA 2 transformers 110/35/10 kV 16 MVA/'

*

Power line 110 kV I | Power line 110 kV

1 = 19.7 km, AC-185 1 = 22.9 km, AC-185

> со

II

Figure 1 - The situational circuit area of power grids

Power supply is carried out by a radial transmission lines from the Stavropolskaya GRES. Power lines 110 kV between the transformer substations are made on reinforced concrete supports using wires AC 120 and AC 185. Power lines are in 2 climatic region with a wall thickness of 10 mm of ice. In transformer substation used air circuit breakers, adopted circuit with switches and short-circuiting switch. At the transformer substation, «Krasnaya Zarya» has 2 transformers, the first - the worker, the second - a reserve for the transformer substation «Novoaleksandrovskaya» has 2 concurrent trans-

formers. In the transformer substation «Razdolnaya» and «Krasnaya Zarya» is set to 1 transformer.

Consider two variants of power supply: Variant 1 - using two radial transmission lines of 110 kV; Variant 2 - with the ring girt between transformer substations «Grigoropolisskaya» and «Novoaleksan-drovskaya».

Calculation of reliability and economic performance for the first variant is as follows.

1. According to the scheme of Figure 1 form the structural circuitry for calculating the reliability of the two radial transmission line of 110 kV [1, 4].

124 QTaCh and Practice

I ¿t Journal XK, Bulletin of Stavrapal Région

2. Let the necessary input data for the calculation of parameters of reliability.

For unscheduled outage accept ropl = 0.027 failures / km • year, TB = 4.52 hours.

Initial data for calculation of parameters of reliability transformer substation are in Table 2.1 [2]: roT = 0.015 failures / year, TB = 810-3 year / failure, to air circuit breakers roB = 0.03 failures / year, TB = 3 • 10-3 year / failure for switches and short-circuiting switches ro0K = 0.01 failures / year, TB = 0.810-3 year / failure.

Since the transformer substation «Krasnaya Zar-ya» is made in two-transformer version with working and reserve transformer is necessary to clarify the reliability of the transformer at this substation. Failure flow if this scheme is determined by the formula © = ©jKb2 + ®2Kb1, where KB - coefficient forced downtime KB = roT

For transformer coefficient forced downtime KB1 = KB2 = 0,015-8-10"3 = 0,12-10"3 and failure flow © = 0,015 • 0,12 • 10"3 + 0,015 • 0,12 • 10"3 = 0,36 • 105. failures / year. So, we get a very low failure flow for one transformer, and if there a substation transformer of reserve failure flow will be even less so in the calculation of the reliability of the substation transformer reliability may be unreported [3]. For substation «Krasnaya Zarya» œts = 0.03 + 0.04 = 0.08 failures / year; KB2 = 0.03-3-10"3 + 0.01-0.08-10"3 = 0.M0"3; for substation Novoaleksandrovskaya rots = 0.015-2 + 0.03 + 0.01 = = 0.07 failures / year; KB4 = 0.03-8-10"3 + 0.03-3-10"3 0.01-0.08-10"3 = 0.34-10"3; for substation «Razdol-naya» and «Grigoropolisskaya» rots = 0.015 + 0.03 + + 0.01 = 0.055 failures / year; KB6 = KB8 = 0.015-8-10"3 + 0.03^10"3 + 0.01-0.08-10"3 = 0.2240"3.

4. Found reliability radial transmission lines (I and II):

parameter flow sudden outages

COj = ¿CÙ; = 0,027(14,8 + 24,1)+ 0,04 + 0,07 = 1,16 i=1

failures / year.

n

CDjj = ¿(0 , = 0,027(19,7 + 22,9)+ 0,055 • 2 = 1,26 i=1

failures / year.

coefficient of downtime

KBl = ¿KBj = 0,027(14,8 + 24,1)0,52 • 103+ 0,1 • 103+

i=1

+ 0,34 -10~3 = 0,99 • 103,

KBn = ¿KBj = 0,027(19,7 + 22,9)0,52 • 10~3+ 0,22 • 2 • 103=

i=1

= 1,04 -10

5. Found capital contribution to network costs. Capital expenditures will find using specific parameters [2]

Kpin0 = qpm0 Lpni0 = 6,8^100^38,9 + 8,M0042,6 = 60958 thousand Roubles.

The project budget a transformer substation according to Table 7 of Annex B [2] Kts = (126,4 + 256,1 + 64,9 +109,4) • 100 = 556800 thousand Roubles.

The project budget of first variant grid transmission system with radial transmission feeder

^ = Kpl + K ts = 60958 + 556800 = 617758 thousand Roubles.

6. The calculation of total operating expenses. We use the formula Cy = Ca + C0 + C p The investment costs

n P 6

C=yK,-^- = 617758-= 37065,5 thousand

a t^ ;100 100

Roubles.

The maintenance expenses (QTn u QBn Annex B [2]) C0 = p0K1 =5,9^617758 = 34594,5 thousand Roubles.

The cost of transmission losses. Found cost of transmission losses in the network element according to the formula cz = + y z /hz :

For overhead transmission line cpl = 79 + 327000/3600 = 169,8 kopecks / kW • h;

For transformer substation

cts = 82 + 420000/3500 = 202 kopecks / kW • h;

Annual costs transmission losses in overhead transmission line will find the formula [5]

Clpl = Z(Spz/Unom)2RczL^zCpiz •10-5 =

2500N 110 ,

• 0,27 •

• 14,8 • 3100 • 169,8 • 10"5 + f32000] • 0,27 • 24,1 • 3100 •

2 I 110 J

• 169,8• 105 +1-2500-) • 0,17• 19,7• 3100• 169,8• 105 +

1110 J

+ | I0000] • 0,17• 22,9• 3100469,8• 10"5 = 3652,8 thou-

l 10 J

sand Roubles.

The cost of transformers losses (assuming Sp =

Snom):

Cts = [(Sp/Snom)2pkTCk + p xt,Cx]1°"5 =

= 2(12 • 22 • 3000 • 202 + 5,5 • 8760 • 202) • 10~5 + + 2(12 • 105 • 3000 • 202 + 26 • 8760 • 202) • 10~5+ + (12 • 80 • 3000 • 202 +19 • 8760 • 202) • 10~5 = 3475thou-

sand Roubles.

Final loss in a year

Cp = C lpl + C ts = 3652,8 + 3475 = 7127,8 thousand Roubles.

Total operating expenses in a year Cy = 37065,5 + 34594,5 + 7127,8 = 78787,8 thousand Roubles

z=1

A gricultural

Bulletin of Stavropol Region

№ 1(21)/1 Supplement, 2016

7. Find the supply-interruption cost

y = y oWle, Wle =fflsTB pcalc.

The calculations revealed that = 2,42. Тв = 4,4 h and Pcalc equate 37 000 kW, as the total full power of transformer substation is 47000 kV • A.

Wle = 2,42 • 4,52 • 37000 = 404747 kW • h.

Taking the unit cost of supply-interruption cost у0 = 30 Roubles /kW • h find

у J = 30 • 404747 = 12141,6 thousand Roubles.

8. Total annual costs of operating the electricity system of the first embodiment

Cta1 = Сy = 78787,3 +12141,6 = 90928,9 thousand Roubles.

We define operational reliability index and economic performance for the second variant if there is a reserve power line girt between transformer substations «Novoaleksandrovskaya» and «Grigoropolisskaya»

1. The operational reliability index for radial power network [3].

With parallel connection of elements flow outages determined by the formula

X Fm = 157,1 +142,8 +129,8 +118 = 547,7 failures / year.

2. Define the capital cost of the power supply system by the second variant

The cost of building a power supply system will be determined by the value of the radial power network plus girt.

K, = 617758 + 8,1 -100 • 24 = 637198

thousand

Found overall indicators compared variants power line

1. Net present value (NPV)

Net present value over 10 years of the project at the rate of discount E = 0.1

10 C 10 7964

NVP = Y —^--AK=y-- -19440 = 29886,6

£0(1 + E)m ¿0(1 + 0,1)' thousand Roubles.

2. Internal rate of return (IRR) of project

The method of successive substitutions define the internal rate of return (Table 1)

Table 1 - reliance NPV ot E

Е 0,1 0,2 0,3 0,35 0,4

NPV, thousand Roubles. 29495,4 13948,9 5180,9 2182,5 -218,3

Roubles.

Exceeding capital costs to the first variant

№L = K2 - Kj = 637198 - 617758 = 19440 thousand Roubles.

3. The operating cost: investment costs

n P 6

Ca = X K;-^ = 637198-=38232 thousand

a 100 100 Roubles.

maintenance expenses

C0 =p0K2 = 637198 •5,9 -37594,7 thousand Roubles 2 100

Yearly costs to cover the electricity losses in the network.

Since the girt is partitioned only activated during emergency and planned repairs, loss of electricity in the network element can be neglected Cp = 7127,8 thousand Roubles.

The total amount of the annual operating costs by the second variant of power supply

Cao = 38232 + 37594 + 7127,8 = 82954,5 thousand Roubles.

4. The supply-interruption cost

y2 = y0Wle = 30 • 2,06 • 10-3 • 4,52 • 47000 = 10,3 thousand Roubles.

5. Total annual operating costs, taking into account the supply-interruption cost by the second variant

Cte2 = C ao + Y2 = 82954,5 +10,3 = 82964,8 thousand Roubles.

6. The annual economic effect of modernization

cee = Ctai - cta2 = 90928,9 - 82964,8 = 7964 thousand Roubles.

As seen in Table 1, the project IRR in the range of (0.35-0.4). Refine it value by an iterative method.

Eirr = E, +-NVP(E|)-(E2 -E,) = 0,35 +

1 NVP(Ej) - nvp^;2) 2

2 187 5

+-¿IO^J-(0,4 - 0,35) = 0,395.

2182,5 - (-218,3)

Thus, the profitability of the project is 39,5 %. 4 The payback period. To calculate the payback period define the reduced annual costs over the life of the project

7964

F =-r = 7240 thousand Roubles.

1 (1 + 0,1)

7964

F2 = ——= 6581,8 thousand Roubles.

F3 =

(1 + 0,1)2

7964 (1 + 0,1)3

= 5983,5 thousand Roubles.

7964

F4 = ^ 4 = 5439,5 thousand Roubles.

F5 =

F6 =

(1 + 0,1)4

7964 (1 + 0,1)5

7964 (1 + 0,1)6

= 4945 thousand Roubles.

= 4495,5 thousand Roubles.

7964

F7 = -——- = 4086,8 thousand Roubles.

Fs =

(1 + 0,1)'

7964 (1 + 0,1)8

= 3715,3 thousand Roubles.

7964

F9 = ^ n^ 9 = 3377,5 thousand Roubles.

F10 =

(1 + 0,1)9 7964

= 3070,5 thousand Roubles.

(1 + 0,1)"

For the first 2 years the amount of economic benefit will be reduced

£Fm = 7240 + 6581,8 = 13821,8 thousand Rou-

3

bles, which is less than the value of additional capital investments AK = 19440 thousand Roubles.

Within 3 years of the project the amount of economic benefit will be reduced

Quarterly

Research and Practice Journal

Z Fm = 7240 + 6581,8 + 5983,5 = 19805,3

4

thou-

sand Roubles, that the large additional capital investments. Thus, the payback period is within 2-3 years. To refine its location use the above recommendations

1 gricultural

Bulletin ot Stavropol Region

„ 19440 -13821,3 „„„

Tpb = 2 +-- = 2,94 year.

pb 5983,5

The results show the effectiveness of the upgrading of electricity networks.

References:

1. Khorol'skiy V. Ya., Taranov A. M. Reliability of power supply. Stavropol: AGRUS, 2013 108 p.

2. Khorol'skiy V. Ya., Taranov A. M. Petrov D. V. Techno-economic calculations of electric distribution networks: proc. manual for schools. Stavropol: AGRUS, 2010. 108 p.

3. Gerasimenko A. A., Fedin V. T. Transmission and distribution of electrical energy. Rostov-on-don: PHOENIX, 2008.

4. The reference design of electrical networks / I. G. the Times-Chan, D. A. Faibisovich, I. M. Shapiro; edited by D. A. Faibisovich. M.: ENAS, 2006.

5. Vodyannikov V. T. Economic evaluation of energy APK. M.: «IPC EKMOS», 2002.