6.2 Analysis of results of calculation of modes of an electric network

6.2.1 Assessment of loading of lines of electricity transmissions

Power losses in lines of electricity transmissions depend on active resistance, so on section. At design of section of wires get out on the economic density of current (jek, Am/mm2). This density provides a minimum of the given expenses for a construction and network operation.

Results of calculations of currents on sites are presented in Addition B. To analyze current density in network power lines. Calculation of density of current (tab. 6.6) is carried out on a formula:

,

де – current of a site of a network (behind calculation data on EOM);

F_cт – the standard section of a wire a site of a network which is considered.

At Tm=6700 of (6.1) economic density of current makes for steel-aluminium uninsulated wires 0,8 Am/mm2.

Therefore, the condition has to be satisfied:

.

Table 6.6 – Calculation of density of current

Operational scheme		Brand wire	nкіл	кА	А/мм2	jР jЕК
Section
1	2	3	4	5	6	7
1	Postnikovo-Stozhkovo	АС-185/34	1	0,033	0,178	0,17	<0,8
2	Stozhkovo-DavydovkaS (1dil)	АС-150/27	1	0,234	1,560	1,56	>0,8
3	Stozhkovo-DavydovkaS (2dil)	АС-185/54	1	0,234	1,265	1,27	>0,8
4	Stozhkovo - Davydovka	АС-150/27	1	0,021	0,140	0,14	<0,8
5	Davydovka - Gorniak (1dil)	АС-150/27	1	0,114	0,760	0,76	<0,8
6	Davydovka-Gorniak (2dil)	АС-120/22	1	0,114	0,950	0,95	>0,8
7	Davydovka-Gorniak (3dil)	СА-70	1	0,114	1,629	1,69	>0,8

These tab. 6.6 specify that the calculation density of current on four sites of a network exceeds economic value.

On a site of a network of Davidovka Severna-110 - Stozhkovo-35 the calculation density of current exceeds economic value and makes 1,265 Ammm2 (wire brand the AS 185/34) і 1,56 Am/mm2 (the AS 150/27). On the Gornyak-110 PS Davidovka-35-network site density of current makes 0,95 Am/mm2 (the AS 120/22) and on a site of Davidovka-35-Gornyak-110 which is executed by brand of a wire of SA-70 density of current makes 1,629 Am/mm2.

Calculation current on these sites of an electric network doesn't exceed admissible (265 Am for SA-70, 450 Am for the AS 150/27, 450 Am for the AS 185/34,).

Due to the aforesaid, in the following section it is necessary to consider ways of increase of capacity of power lines, for example, to execute reconstruction of one overhead power transmission line for ensuring reliable power supply of the area. The increase in section of wires will allow to reduce power losses in an electric network.