Russian
AUTHER BIOGRAFY
USEFULL LINKS
INTERNET SEARCHING
ELECTRONIC LIBRARY
Protsenko Aleksandr Viktorivich
Electro technical faculty
Department: Eloctrosuply of the enterprises and cities .
Scientific supervisor: professor, doctor of technical sciences of EPG Kovalev Aleksandr Petrovich
Master degree theme: "Valuation of vitality loading knots of industrial enterprise".
Introduction.
For the first time in the world the concept of survivability was formulated by Russian admiral Stepan Osipovichem Makarovym is ability of a vessel to continue fight, having damages to various fighting parts.
 In power survivability is understood as property of object to resist to indignations, not supposing their cascade development with mass infringement of a feed of consumers
As push to development of methods of an estimation and forecasting of chained failures in energy system (ES) the failure that has happened November 9, 1965 in USA, which has resulted to that in territory with the population about 30 million person more than on 10 submission of the electric power was stopped, has served.
The damage from failure has made more than 100 million dollars. Followed after that ten fine (from the economic point of view), but similar failures on the country were finished July 13, 1977 by failure in New York. Within 25 hours life of New York was paralyzed. The damage from consequences of this failure has made more than 1 billion dollars [1,2]
After 26 years, August, 14, 2003 at 16 11 minutes on local time because of damage on a line Niagara - Falls without an electricity has remained almost all east part of Northern America, i.e. 50 million person [3].
It is possible to tell about each of the listed failures, that given energy system has lost survivability. Survivability of electro power system (EES) depends on its(her) structure, a configuration, reliability of an electric equipment, means of relay protection and uncrushing automatics, and also from qualification of the attendants, a stock of stability, a reserve of active capacity etc. [5].
At operation EES occurrence of so-called chained failures because of consecutive refusal in operation of several switches is observed at switching-off of damage [6]. Chained failures were observed in 25 EES and two OES the former USSR. For 5 years it was fixed 75-chained failures. In 81 % of cases chained failures occurred because of damages to a network and refusal in functioning protective switching devices [7]. On chained failures it is necessary 90 % of economic damage[9].
A depth chaired failure is understood as a level of frustration of functioning of installations energy system at failures and infringements in work [6,7,8]. As parameter of survivability frequency of occurrence of system chained failures with various depth of infringement of electro supply [7] can serve.
Urgency.
At the present stage of development of engineering and technology for an estimation of reliability of circuits of systems of electro supply (SES) the wide circulation was received with element methods of calculations of reliability. In these methods it is supposed, that SES consists from separate independent (in sense of the analysis of reliability) elements, functional dependences between parameters of separate elements of the device [1-4] are excluded from consideration.Considered SES consist of elements: transmission lines, transformers, switches, separators, disconectors, automatic switches etc. As units of the circuit we shall understand physical items SES which are directly connected not less than to three directions of transfer of energy, i.e. usually it is modular trunks or section of switching centers etc. [3].
The purpose.
For SES in work [4] concepts are entered: refusal such as « breakage of a circuit » and refusal such as "short circuit" ("KZ". In work [3] except for the listed kinds of refusals it is offered to take into account and transition of failure through the switching device. Factors, which would be expedient for taking into account at calculations of reliability ÑÝÑ, are listed in [5]. In work [6] it is proved, that is inexpedient to divide refusals to which the electric equipment while in service more than on three kinds is exposed.Results of researches.
In the given work the following kinds of refusals of elements of the circuit are considered : refusal such as "short circuit", refusal such as « breakage of a circuit » and refusal in operation (the latent refusal).All other refusals, which met in SES, the industrial enterprises of Ukraine, appeared on the order less often selected and consequently in calculations were not taken into account.
The listed kinds of refusals should be carried to the following types of an electric equipment [6].
1. Refusal such as "short circuit". Such kind of refusal can occur in all elements of the circuit through which passes a current of loading in a normal mode of operation. Short circuits (KZ) in such elements are disconnected by the basic relay protection in which operative range there is a considered element of a network, or reserve with endurance of time. Overlapping of isolation in the most protective switching device in these calculations it is not taken into account, as such damages meet on the order less often, than KZ in elements of a network protected by these switching devices.
2. For protective switching devices we shall take into account two kinds of refusals:
à) Refusal of the switch such as « breakage of a circuit ». To such refusals we shall carry false and excessive switching-off of switches as a result of action of relay protection, which are liquidated with the help of manual switching (i.e. without means of automatics), and also automatic switching-off of switches as a result of damages to secondary circuits of relay protection;
á) Refusal of the switch in operation. These refusals come to light as a result of routine inspections of switches: a drive, the coil of switching-off, äóãîãàñèòåëüíîé chambers, contact system, the opportunity of overlapping (blocking) of isolation is estimated at external and internal over voltage, ways of outflow of a current are checked. Is examined relay protection, contacts of relays, operative circuits of a feed, work of the device of automatic repeated inclusion (AAI), devices of automatic input of reserve (AIR) etc are checked protection..
All refusals revealed as a result of preventive maintenance which could result in refusal in operation of the switch at occurrence KZ in an operative range of its relay protection, will be worn out in special magazine and this information is used for definition of parameters of a stream of refusals of system of switching-off of the switch.