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Магистр ДонНТУ Козырева Екатерина Владимировна

Katerina Kozireva

Faculty: Electrotechnical (ETF)

Department: Electrical Power Plants (EPP)

Speciality: "Electrical Power Plants" (EPP)

Theme of master`s work :

The analysis of transients of electric motors of own needs of thermal power station on the basis of discrete mathematical models

Scientific Supervisor : Dr. Sc. (in Engineering), Professor Vitaliy F. Sivokobylenko

Autobiography	Abstract

ABSTRACT

master's thesis on

The analysis of transients of electric motors of own needs of thermal power station on the basis of discrete mathematical models

INTRODUCTION

Reliable and economic operation of modern thermal and nuclear power plants to a large extent depends on the reliability of the mechanisms of their own needs. The main drive of the most critical auxiliary mechanisms ES are asynchronous and synchronous motors 6 square. 95% of the power required for personal needs account for electric motors [1]. The continuous increase in unit capacity units leads to an increase in installed capacity of the motor load, the unit power and starting current of blood pressure and diabetes, which in some cases difficult to ensure a successful and dynamic stability of the self-propulsion load short-circuit and short-term low voltage [6]. This could lead to accidental throttle power and decrease reliability of the entire power system as a whole. In some transient conditions (switching power supply to another source, disabling short circuit, etc.) in the engines may experience shock currents and moments exceeding the permissible and significantly reduce the term of their service.

HOT TOPICS

For further improvement and development of multimachine power systems are relevant to develop and create of these systems, a high degree of adequacy of a real object and allows to investigate the features of transitional and emergency regimes, shorten design and cost of natural experiments [2]. With the help of digital mathematical models seem possible to optimize the transients in mathematical methods of electricity supply systems, taking into account the characteristics of the existing developed equipment. Thus one of the basic requirements to mathematical models is maintenance of their numerical stability and comprehensible expenses of machine time for calculations of transitive modes [7]. For the decision of this problem one of approaches is application of the discrete models based on the decision of the differential equations by implicit numerical methods of integration [1].

PURPOSE OF WORK

The work purpose is working out of discrete mathematical models of transformers, asynchronous and synchronous engines for the analysis of transients in systems of own needs 6 kV EPP. For achievement of this purpose the decision of following problems is required:

1. Creation of a method of definition of parametres of multiplanimetric equivalent circuits of transformers, asynchronous and synchronous engines on the basis of the set catalogue data;

2. Creation of discrete mathematical models on the basis of the full differential equations for basic elements of system of own needs EPP. Implicit methods of integration should be applied To the decision of the differential equations with use of program MathCAD 14;

3. Working out of mathematical models of multimachine system of an electrical supply of own needs EPP on the basis of discrete mathematical models of the scheme and taking into account their interconnection among themselves;

4. Mathematical modelling and the analysis of transients in systems of own needs EPP (s. c., a break of a food, group выбег and engine self-start).

THE MAIN CONTENT OF WORK Recently, due to the rapid development of computer technology, as well as due to the increased requirements for the accuracy of modeling in the design and creation of highly reliable systems, electrical plant, thermal power plants and other critical installations with large blood pressure and diabetes significantly increased interest in models of mathematical methods of electricity supply systems based on the full equations Park Goreva for cars and for all elements of the supply network [3]. Topical is the creation of universal models, allowing to study both short-term (AR, ABP, shorts) and long (start, automatic starting of pumping jacks) transients in a group of machines based on their mutual influence, given the dependence of the parameters of the displacement currents and saturation of magnetic circuits. Consider the calculation of parameters and simulation of induction motor starting. The advantage of multiple-equivalent circuits ac machines is in the universality of their use for calculating the transient and steady-state modes 9]. In addition, information about their options very convenient for storage in memory and used in calculations on the computers [4].
Figure 1 - Equivalent Circuit of asynchronous motor with deep groove with two-planimetric rotor (figure is animated; a quantity of personnel - 4; the number of repetitions - nfinitely; the volume- 42.6kb)

The calculation of the parameters of a two circuits of induction motors engineering techniques. Calculation is performed in relative units as follows: Adjust the nominal values of efficiency and power factor:

1) Define inductive reactance of the scattering stator

2) Find the load current, which is taken to be equal to the current magnetization
3) Find the inductive reactance of the branches of the magnetization
4) Determine input resistance of the engine at rated speed at Sн
5) Determine the input resistance of the engine start-up with S = 1
6) We find the conductivity of the rotor at the rated slip
7)Accepted parameters of the first circuit of the rotor equals the resultant resistance of the rotor in the nominal mode
8) We find the conductivity of the rotor at start-up
9) The parameters of the second circuit of the rotor is found as the difference between the resultant conductivity of the rotor at S = 1 and the conductivity of the first circuit of the rotor at S = 1
The parameters obtained by the method of engineering, said by solving a system of nonlinear algebraic equations (SNAE). To do this, compile the program for calculating the parameters of equivalent circuits of a more accurate method. Sub-calculating the input resistance, stator current, torque AM:
Sub-calculating the maximum point:
Sub-calculation of losses in AM:
Refine the parameters of equivalent circuit by solving SNAE using block making Given - Minerr package MathCad. Equation is the condition of coincidence between the calculated and catalog current stator torque at S = 1 and S_Н, as well as losses in nominal mode:
Check now match the calculated values of currents, moments and the efficiency with catalog:

THE MAIN CONTENT OF WORK

Recently, due to the rapid development of computer technology, as well as due to the increased requirements for the accuracy of modeling in the design and creation of highly reliable systems, electrical plant, thermal power plants and other critical installations with large blood pressure and diabetes significantly increased interest in models of mathematical methods of electricity supply systems based on the full equations Park Goreva for cars and for all elements of the supply network [3]. Topical is the creation of universal models, allowing to study both short-term (AR, ABP, shorts) and long (start, automatic starting of pumping jacks) transients in a group of machines based on their mutual influence, given the dependence of the parameters of the displacement currents and saturation of magnetic circuits.

Consider the calculation of parameters and simulation of induction motor starting.

The advantage of multiple-equivalent circuits ac machines is in the universality of their use for calculating the transient and steady-state modes 9]. In addition, information about their options very convenient for storage in memory and used in calculations on the computers [4].

Figure 1 - Equivalent Circuit of asynchronous motor with deep groove with two-planimetric rotor

Figure 1 - Equivalent Circuit of asynchronous motor with deep groove with two-planimetric rotor (figure is animated; a quantity of personnel - 4; the number of repetitions - nfinitely; the volume- 42.6kb)

The calculation of the parameters of a two circuits of induction motors engineering techniques. Calculation is performed in relative units as follows:

Adjust the nominal values of efficiency and power factor:

1) Define inductive reactance of the scattering stator

Inductive reactance of the scattering stator

2) Find the load current, which is taken to be equal to the current magnetization

The load current, which is taken to be equal to the current magnetization

3) Find the inductive reactance of the branches of the magnetization

The inductive reactance of the branches of the magnetization

4) Determine input resistance of the engine at rated speed at Sн

The input resistance of the engine at rated speed at Sн

5) Determine the input resistance of the engine start-up with S = 1

The input resistance of the engine start-up with S = 1

6) We find the conductivity of the rotor at the rated slip

7)Accepted parameters of the first circuit of the rotor equals the resultant resistance of the rotor in the nominal mode

Parameters of the first circuit of the rotor

8) We find the conductivity of the rotor at start-up

The conductivity of the rotor at start-up

9) The parameters of the second circuit of the rotor is found as the difference between the resultant conductivity of the rotor at S = 1 and the conductivity of the first circuit of the rotor at S = 1

The parameters of the second circuit of the rotor

The parameters obtained by the method of engineering, said by solving a system of nonlinear algebraic equations (SNAE). To do this, compile the program for calculating the parameters of equivalent circuits of a more accurate method.

Sub-calculating the input resistance, stator current, torque AM:

Sub-calculating the input resistance, stator current, torque AM

Sub-calculating the maximum point:

Sub-calculating the maximum point

Sub-calculation of losses in AM:

Sub-calculation of losses in AM

Refine the parameters of equivalent circuit by solving SNAE using block making Given - Minerr package MathCad. Equation is the condition of coincidence between the calculated and catalog current stator torque at S = 1 and S_Н, as well as losses in nominal mode:

Check now match the calculated values of currents, moments and the efficiency with catalog:

Check match the calculated values of currents, moments and the efficiency with catalog

Figure 2 - The characteristic Engine Launcher
Calculate the auxiliary factors for DE:
Compose in the form of the Cauchy system of differential equations AM:
System DE we will solve at first known obvious methods, for example, by means of a method of Runge-Kutta, and then this decision we will compare further to results which have received by means of implicit methods. The sequence of calculation is indicated in the main program AD_RK_1, which also shows the above routine. Start time ask, for example 6 seconds. When calculating step 0.314 radians, and knowing that one second equals 314 rad, start time will be 1884 rad and 6000 will require steps.
The result of calculation starting AM received the following graphics:
Figure 3 - Starting characteristics of the phases
Figure 4 - Speed AM during start
Figure 5 - Electromagnetic torque
Figure 6 - Power Engine
CONCLUSIONS As a result of the master plan to develop a universal mathematical model for transient analysis of electric auxiliary power plants based on discrete mathematics. With this program may be the consideration of electric motors in different modes.

Figure 2 - The characteristic Engine Launcher

Figure 2 - The characteristic Engine Launcher

Calculate the auxiliary factors for DE:

The auxiliary factors for DE

Compose in the form of the Cauchy system of differential equations AM:

System of differential equations AM in the form of the Cauchy

System DE we will solve at first known obvious methods, for example, by means of a method of Runge-Kutta, and then this decision we will compare further to results which have received by means of implicit methods.

The sequence of calculation is indicated in the main program AD_RK_1, which also shows the above routine. Start time ask, for example 6 seconds. When calculating step 0.314 radians, and knowing that one second equals 314 rad, start time will be 1884 rad and 6000 will require steps.

The result of calculation starting AM received the following graphics:

Figure 3 - Starting characteristics of the phases

Figure 3 - Starting characteristics of the phases

Figure 4 - Speed AM during starFigure 4 - Speed AM during start

Figure 4 - Speed AM during start

Figure 5 - Electromagnetic torque

Figure 6 - Power Engine

Figure 6 - Power Engine

CONCLUSIONS

As a result of the master plan to develop a universal mathematical model for transient analysis of electric auxiliary power plants based on discrete mathematics. With this program may be the consideration of electric motors in different modes.

BIBLIOGRAPHY

1. Перхач В.С. Математичні задачі електроенергетики. – Львів: Вища школа, 1989. – 464 с.

2. Сивокобыленко В.Ф., Лебедев В.К. Переходные процессы в системах электроснабжения собственных нужд электростанций: Учеб. Пособие. – Донецк: ДонНТУ, 2002. – 136 с.

3. Сивокобыленко В.Ф. Переходные процессы в многомашинных системах электроснабжения электрических станций: Уч. пособие/- Донецк, ДПИ, 1984. – 116 с.

4. Официальный сайт кафедры “Электрические станции” Томского политехнического университета. (Электронный ресурс) http://www.elti.tpu.ru

5. Электрическая часть электростанций и подстанций: Справочные материалы для курсового и дипломного проектирования. Учеб. пособие для электротехнических специальностей вузов/ Крючков И. П., Кувшинский Н. Н., Неклепаев Б. Н.; Под ред. Б. Н. Неклепаева – 3-е изд., перераб. и доп. – М.: Энергия, 1978-456 с.

6. Сивокобыленко В. Ф., Костенко В. И. Математическое моделирование электродвигателей собственных нужд электрических станций. Учебное пособие. – Донецк: ДПИ, 1979. – 110с.

7. Ойрех Я. А., Сивокобыленко В. Ф. Режимы самозапуска асинхронных двигателей. – М.: Энергия, 1974. – 96с.

8. Сивокобыленко В. Ф., Павлюков В. А. Расчет параметров схем замещения и пусковых характеристик глубокопазных асинхронных машин. – Электричество, 1979, №10.

9. Сивокобыленко В. Ф., Лебедев В. К. Определение параметров схем замещения для анализа режимов работы синхронных двигателей. – Электротехника, 1982, №12.

10. Сыромятников И. А. Режимы работы синхронных и асинхронных двигателей/ Под ред. Л. Г. Мамиконянца. – 4-е изд., перераб. и доп. – М.: Энергия, 1974. – 96с.

COMMENT

When writing this Abstract master work was not completed. The final work can be obtained from the author or supervisor since December 2010.

Autobiography	Abstract