Abstract of Master's Work

"Improved overcurrent protection section of the mine complex electrical-based automatic suppression of the reverse flow of electric energy consumers"

Introduction

Mining is one of the most important industries, which determines the level of the energy potential of Ukraine. Improving the efficiency of mining operations is directly related to an increase in the number of electrical mines equipment, increased branching of the cable lines, the extensive use the power converters and thyristor voltage regulators in the vast majority of electric drive mining machines. All this not only requires the introduction of special technical means, but also significantly influences the operation of electrical power electrical installations and electrical precinct mine. Limited space in the underground workings and the track lighting considerably complicate the installation, maintenance and preventive maintenance of electrical equipment. Because of delays in removing interferences in electrical equipment, as well as a result erroneous actions of the personnel in mining electrical equipment having a short circuit (short circuit) [1].

A theme urgency

Mine is characterized by a large number of non-stationary (moved in the process) equipment, which included, as a rule, are operated induction motors (BP). This establishes the existence of an extensive flexible cables network. The existing tools for overcurrent protection of circuit breakers and starters enable high-speed detect a short circuit [2]. However, after the breaker emergency state power persists. The reason is the presence of reverse energy flows from the previously included BP consumers. In this connection it is relevant investigation processes power shaft, caused by the effect of inverse energy flows after the breaker.

The purposes and problems

The aim is improved overcurrent protection of electrical complex land mines on the basis of the suppression of the reverse flow of electric energy consumers. To address the goal set the following problems:

• electrotechnical complex (ETC) mine site is studies as an object of study;
• studying the percolation characteristics of short circuit in the ETC section of the mine and analyze the ways overcurrent protection;
• rationale for a set factors affecting the salvage point ETC caused by the inverse energy flows;
• mathematical models of processes in the ETC after a short circuit is developmend and this model is theoretical studied;
• experimental studies processes in the ETC;
• practical implementation of research results.

Prospective scientific novelty

It is proposed refinement of electrical parameters, due to reverse power flow induction motors in the process of a short circuit, including overshooting induction motor after breaker; obtaining information parameter for the suppression the reverse energy flow device.

Short-circuiting is the study subject

The main cause of short circuits in underground electrical installations are mechanical effects. Mine electric equipment and electric motors are mechanically strong envelope to protect them from the active part of the external influences. At the same time in underground mines operated flexible cables, membranes which have an insufficient mechanical strength. In the general case currents is arising and depend on the parameters of the generating power sources, configuration and electrical parameters of its constituent elements, the type of short circuit and the resistance of the short-circuit, the presence or absence of connecting the load.

When short circuit event total electrical resistance of the chain underground power system is decreases, which causes an increase in current network. The nature of current flow short circuit the network is largely dependent on the power supply system and resistance short-circuited. As a result of reduced current-limiting electricity properties , increase the power and duration of the short circuit feeding point from the stator AD.

Development of a mathematical model of short-circuit and steps backward energy flows from the electric consumer

To study the processes in the district after its power shaft breaker should be used equivalent circuit presented in Figure 1. This scheme provides for the inclusion of all induction motors parameters (M1 - Mn), such as active and inductive resistances of stator (RC, xc); given the active and inductive resistances rotors (R'r; X'r); inductive resistance of the chain magnetization (Ho ) emf rotation (ER), inducted on the stator of each BP rotating field rotor currents [3].

Figure 1 - Equivalent Circuits ETC land mines for the study of a short circuit after the breaker (figure animated, frame - 17; delay between shots - 500 ms; volume - 91,8 kb size - 767x498, repeating animation - infinite)

Animated image in Figure 1 allows you to graphically display the process flow of the three-phase short-circuit and reverse the action of energy fluxes at the crash point. As shown, the closure of the contact to a circuit load rectifier VC, in the studied area three-phase short circuit occurs Point short-circuit receives power from the transformer substation and at the same time from stator AD. After tripping breakers in AD, fueling point short-circuit carried out only on the AD emergency accession.

computer model study, the following equation: diagram of the current flowing from the supply transformer to the emergency point (Fig. 2),diagram of the current flowing from the stator AD emergency adherence to salvage a point (Fig. 3), diagram of the current at short circuit (Fig. 4):

<

Figure 2 – diagram of the current flowing from the supply transformer to the emergency point

Figure 3 – diagram of the current flowing from the stator AD emergency adherence to salvage a point

Figure 4 – diagram of the current at short circuit

Obviously, the alarm point cable connected to the AD, can be de-energized after the breaker voltage if the reverse energy flow of the engine would be dedicated to an artificial short circuit (on the input stator BP) or other load, for example, not pre-loaded three-phase Capacitor connection. The structure of the model, adapted to the conditions of these studies is shown in Fig 5. In particular the scheme of suppressing inverse energy flows through a chain of forced short-circuit on the input of BP in the event of a s.c. in the motor cable and the subsequent safety switch network [6].

Figure 5 - The structure of a computer model emergency treatment study and suppression of the reverse energy flows through a chain of forced short-circuit at the input of AD

Conclusion

Determination of the functional capacity of the suppression of the reverse energy flows on the basis of modeling in the design scheme is the subject of further research. The results of modeling can be taken as a basis for justification of the parameters on which the device should respond suppress EMF rotation AD.

References

1. Риман Я.С. Защита подземных электрических установок угольных шахт. / Я.С. Риман. – М.: «Недра», 1977. – с. 5-11.
2. Бильдей Е.Е, Виляева Е.П Исследование особенностей влияния обратных энергетических потоков на аварийные процессы в электротехническом комплексе шахты после защитного отключения // Х международная молодежная конференция «Севергеоэкотех-2009»: материалы конференции (18-20 марта 2009г., Ухта): в 4 ч.; ч 1. – Ухта УГХТУ 2009.- 436 с.
3. Перехідні процеси в системах електропостачання: Підручник для вузів. Вид.2-е, доправ. та доп. / Г.Г Півняк, В.М.Винославський, А.Я. Рибалко, Л.І. Несен / За ред. Академіка НАН Украйни Г.Г. Півняка. – Дніпропетровськ: Національний гірничий університет, 2002. – с. 82 – 103.
4. Маренич К.Н. Обоснование структуры модели процесса короткого замыкания в электротехническом комплексе участка шахты / Маренич К.Н., Ковалева И.В. //наукові праці Донецького національного технічного університету. Серія «Гірничо-електромеханічна» Випуск 12(113). - Донецьк: ДонНТУ, 2006. – С. 179-185
5. Маренич К.Н., Ковалева И.В. Моделирование процесса короткого замыкания в низковольтном электротехническом комплексе шахты с учетом влияния электропотребителя // Наукові праці Донецького національного технічного університету. Випуск 7(128), серія електротехніка та енергетика. - Донецьк: ДонНТУ, 2007. - с. 146-149.
6. Маренич К.Н. Моделирование процесса короткого замыкания в электротехническом комплексе участка шахты во время выбега электродвигателя потребителя / [Маренич К.Н., Ковалёва И.В.]; под общ. ред. акад. НАН Украины Г.Г. Пивняка. - Донецк ООО «Юго-Восток, Лтд» 2005. – С. 84-88, - (Взрывозащищённое электрооборудование) (сб. науч. тр. УкрНИИВЭ)
7. Справочник энергетика угольной шахты / [Дзюбан В.С., Ширнин М.Г., Ванеев Б.К., Гостищев В.М.]; под общ. ред. Б.Н.Ванееа – [2-е изд.] – Донецк, ООО «Юго-Восток Ltd.», 2001, - Т1. – с. 339-411
8. Бильдей Е.Е, Виляева Е.П . Исследование функциональных возможностей технических средств подавления обратных энергетических потоков асинхронных двигателей // Х международная молодежная конференция «Севергеоэкотех-2010»: материалы конференции (18-20 марта 2010г., Ухта): в 4 ч.; ч 1. – Ухта УГХТУ 2009.- 436 с.
9. Lugo Nunez, David Rush. High power density and overcurrent protection challenges in the design of a three-phase voltage source inverter for motor drive applications. Blacksburg, Va. : University Libraries, Virginia Polytechnic Institute and State University, 2007. - 396с. [Electronic resource] - Access mode http://scholar.lib.vt.edu/theses/available/
10. Дьяконов В. П. MATLAB 6.5 SP1/7.0 + Simulink 5/6 в математике и моделировании / В. П. Дьяконов // Библиотека профессионала - M.: Солон-Пресс, 2005. - 576с [Electronic resource] - Access mode http://itbookz.ru/math/matlab/

Сomment

When writing this Autosummary Masters qualification work is completed. Completion date December 1, 2010.