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Dissertation:
Master's work subjekt:
"Estimation of loading knots vitality"
Actuality
For the first time in the world the concept of survivability has been formulated by Russian admiral Stepan Osipovich Makarov as a vessel ability to continue fight, having damages in various fighting parts [1].
In energetic under vitality of an object to resist to indignations is a property of an object to shut out their cascade development with massive violation of feed users [2].
Vitality of the electroenergy system (EES) depends on its structure, configuration, reliability of electrical equipment, facilities of relay defence and antidamage automation, and also from qualification of auxiliary personnel, supply of stability, reserve of active power and etc. [4].
During the EES exploitation there is appearance of the so-called chain failures from the successive refusal in work of a few switches in case of setting off damages [5].
Chain failures were observed in 25 EES and two OES of the former USSR. For 5 years 75 chain failures have been fixed. In 81% cases chain failures took place because of the damages in a network and the refusal in functioning of protective commutation vehicles [6]. 90% of occur in national economy harm is an open-chain failure [7].
Under the depth of a chain failure it is understood the level of disorder in the functioning of units at failures and violations in work [5,6,8].
Frequency appearance of system chain failures with the different depth of violation of electrical supply can serve as the index of vitality. [6]
Therefore the work, directed toward the substantiation of selection is the best, from such point of view as to reliability and vitality, scheme of electrical supply of a consumer, is actual. The correct selection of the consumption scheme will make it possible to practically not allow the appearance of cascade emergencies in power systems.
The purpose of the work is
To give the comparative estimation of the distributor apparatus scheme with one and two systems of collecting tyres. Namely, to determine the vitality of substation in the dynamic and static behavior.
The scientific value of the work
The work gives the comparative estimation of substation with one and two systems of assembled tyres in the dynamic and static behavior.
The state of the question
Vitality of substation is defined by means of system of the linear differential equations of the given kind:
 =P(t)A,
where A-matrix intension transitions; a-vector-line; P(t) a-vector-line.
The formula for definition of frequency of occurrence of chained failures which can occur at SC in a protected element of a network and refusal in operation of some protective switching devices through which emergency current has passed looks like:
 , (1)
where  j - parameter of an independent stream SC in j element of a network;
s.i - parameter of a stream of refusals in operation ³ protective switching device. Here the index s specifies that the stream of refusals in operation ³ protective switching device is considered;
 i - an interval of time between routine inspections of system of switching-off ³ protective switching device together with its relay protection or systems automatic inclusion of a reserve;
m - number of protective switching devices through which emergency current has passed, thus action of their basic relay protection in necessary or the number of section switching devices with MRS, given up in switching on;
n - number of units of the electric equipment receiving the electric power from the given unit of loading.
The formula (1) is right under the performance of a condition: time intervals between occurrences SC in an element of a network and time intervals between refusals in operation of protective switching devices do not contradict with exponential functions of distribution of probability with parameters accordingly j, s.i and besides the condition is observed here:
In case the terms of preventive systems maintenance of switching-off the protective switching devices will be identical (i.e.  ) then the formula (1) will be as follows:
 (2)
The probability of occurrence of cascade failure Q(t) during time t can be defined as follows:
 (3)
Thus, using the theory homogeneous Markovsky processes the system of the linear differential equations for the estimation of vitality of schemes MRS has been received.
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