6.2.2 Analysis of structure of losses of power and coefficient of useful action of a network of an electricity transmission

Sizes of losses of power and the electric power it is the most important indicators of profitability of functioning of an electric network. It is necessary to estimate them in a normal mode of network work.

For the efficiency analysis work of a network will be determined percentage of losses of power and the electric power in elements of system of P2 concerning to useful power and W2 electric power by the following formulas:

= 15 МВт,

= 15·6700 =100500 МВт·г,

.

where R2-value of active power consumed by all users of the network;

W2 - useful electricity used by all users of the network;

і – the absolute and relative power losses in the i - th element of the network;

і – the absolute and relative losses in the i - th element of the network.

Power losses in the network are determined by the following formulas:

- In transmission line:

;

- In transformers:

,

where T - time customers per year, 8700 hours (60 hours for repairs);

– time of maximum loss (6.2).

The value of power losses in the network elements is determined according to Table. Annex B (Results Calculation of power losses).Power loss in transmission lines ( )and transformer ( )are determined by the parameters of the linear regime as the difference between the values of power at the beginning (Р^/) and end (Р^//) element (draw.6.2):

Power losses in steel ( )are determined by calculating the flux results. Results of calculation of power losses in transmission lines are given in table 6.7 , transformers - in the table 6.8. The value of power losses and power in each network element and their percentage composition are listed in table 6.9

Table 6.7 - Power loss in transmission lines

№ ЛЕП	Determination of branches according to current scheme	Р/ МВт	Р// МВт	МВт	Q/ Мвар	Q// Мвар	Мвар
1	Postnikovo-Stozhkovo	2,034	2,032	0,002	0,456	0,45	0,006
2	Stozhkovo-DavydovkaS (1dil)	13,632	13,515	0,117	6,86	6,612	0,248
3	Stozhkovo-DavydovkaS (2dil)	13,515	13,395	0,12	7,158	6,86	0,298
4	Stozhkovo - Davydovka	12,171	12,02	0,151	5,68	5,37	0,31
5	Davydovka - Gorniak (1dil)	6,616	6,616	0	2,721	2,72	0,001
6	Davydovka-Gorniak (2dil)	6,616	6,61	0,006	2,72	2,71	0,01
7	Davydovka-Gorniak (3dil)	6,61	6,516	0,094	2,71	2,615	0,095
	However, in power line network			0,49			0,968

The area networks Stozhkovo - 35 Davydovka -35 major loss of power and are 31% of total losses in the transmission line for active power and 32% for reactive power.On this site under tab. 6.6 the highest current density. Table 6.8 - Power losses in transformers. On a section of a network of Stozhkovo 35 – Davidovka-35 of loss of power the greatest also make 31% from all losses in power lines on the active power і 32% on reactive power.

On this section of a network according to tab. 6.6 the greatest current density

Table 6.8 - Power losses in transformers.

№ тр-ра	Determination of branches according to current scheme		Power losses in the copper							МВт		МВт		Power losses in the copper								Мвар			Мвар
			Р/ МВт		Р// МВт		МВт		Q/ Мвар					Q// Мвар		Мвар
1	ПС Горняк-110	Т1		2,032		1,98		-		-		0,052		0,45		0,36		-			-			0,09
3	ПС Довидовка -35	Т1		1,223		1,2		-		-		0,023		0,933		0,84		-			-			0,093
4		Т2		2,675		2,64		-		-		0,035		1,595		1,44		-			-			0,155
5	ПС Стожковоо-35	Т1		2,729		2,7		-		-		0,029		1,054		0,9		-			-			0,154
6		Т2		6,516		6,48		-		-		0,036		2,615		2,16		-			-			0,455
However, in power line network								0,025		0,15		0,175							0,487			0,46			0,947

Table 6.9 – composition of losses of power and the electric power in elements to system

Р2, МВт	W2, МВт·г	Name of items
			МВт	%	МВт·ч	%
15	100500	However, the net	0,665	4,433	4755,50	4,732
		- In LEP	0,490	3,267	3283,00	3,267
		- In May-MF	0,175	1,167	1472,50	1,465
		- In steel	0,150	1,000	1305,00	1,299
		- Bronze	0,025	0,167	167,50	0,167
Q2, Мвар	V2, Мвар·г	Name of items
			Мвар	%	Мвар·г	%
5,7	38190	However, the net	1,915	33,596	13750,5	36,005
		- In LEP	0,968	16,982	6485,6	16,982
		- In May-MF	0,947	16,614	7264,9	19,023
		- In steel	0,460	8,070	4002,0	10,479
		- Bronze	0,487	8,544	3262,9	8,544

These tab. 6.9 show that losses of the active power in power lines (3,267 %) exceed average ( =3%), and losses of the active power in transformers (1,167 %) on the contrary exceed statistical ( =2%). Power losses in steel of transformers of 1% also exceed power losses in copper of transformers which make 0,167%.

Exceeding of losses of power and the electric power in steel of transformers over losses in copper says that network transformers underloaded. The network works in conditions which differ from the project.