4.2 Calculation of option 2

_{Transformer type} ТM-6300/110. Their characteristics needed for calculation of the year losses – , ,

Year losses of energy in steel:

_Year losses of energy in copper in three-winding transformer defines as for each winding LV, НV, AV corresponding with their loads.

_{If in the catalogs for three-winding transformers there are losses of the short-circuit of the pair of HV and CH windings Pkz. BH-CH, then at the power of each winding equal to 100%. The total loss of individual windings is equal to:}

.

_{Transformer type} ТДТН-25000/110. Their characteristics needed for calculation of the year losses – , ,

_{Year losses of energy in steel}:

Year losses of energy in copper:

5 Technical and economic comparison of block diagrams of power

We carry out technical and economic assessment and comparison between the two circuits power system.

For each of the options being compared transformers planned most feasible wiring diagram of Uzbekistan at all voltages.

The economic feasibility of the scheme is determined by cost-effectively:

 

where K - investments in the construction of the power plant, USD;

Rn = 0.12 - normative coefficient of economic efficiency;

U - annual operating costs, USD / year;

We - the damage caused by electricity shortage, USD / year.

The training design comparison of options is made without prejudice, as this component involves the definition of supply reliability, probability and duration of outages, and other issues addressed in the literature. When comparing schemes is permissible to take into account the investment only different elements.

The cost of the transformers can be determined by the expression:

where K- (calculation.) - factory price of transformers;

α - coefficient taking into account the cost of bus systems, devices Gros protection, grounding, control cables to the control panel, construction and installation works, as well as materials.

Annual operating costs are determined by the formula:

U = A + and O + U(los.);

And where A + and O = [(R A + R O) / 100K-on depreciation and maintenance;

Ra and Ro - appropriations in%;

U(loss.) - The costs associated with losses of electricity:

where β - the cost of 1 kWh of electricity losses, USD / kWh;

    ΔW - power losses in circuit elements, kWh.

When the RGR allowed to take β = 0.0115 USD / kW ∙ h., R_a = 6.4%, R_o = 2%.

Deductions for depreciation and maintenance are:

For option 1:

For option 2:

Table 5- Feasibility comparison of options

Name of the element	The default value of a unit, thousand USD	1 variant				2 variant
		Number of units., NY	Amount, thousands of USD			Number of units., NY	Amount, thousands of USD
1. Transformer TРНДС-32000/35	69,6	2	139.2
2. Transformer TДТН-25000/110	72,3	1	72,3
4. The cell of 10 kV indoor switchgear	10	2	20
5. The cell of OSG 110 kV	20	1	20
Total:			251,5
6. Transformer TМ-6300/110	47					1	47
7. Transformer TДТН-25000/110	72,3					1	72,3
8. The cell of 110 kV indoor switchgear	30					2	60
Total:							179,3

Table 6 - The final result of the feasibility of comparison

Expenses	1 variant	2 variant
1 Estimated investment, thousands of USD	237.5	189,3
2 Depreciations and services, thousands of USD
3 The cost of energy loss, thousands of USD
4 These minimum cost, thousands of USD

The difference in cost between the options 1 and 2 is as follows:

that allows us to take as the most economical option 1.