Electrotechnical faculty
Speciality: Electrotechnical systems of electrical consumption
Master's work theme:
Scientific supervisor: Shlepnyov Sergey
In the last some years are given to questions of quality of electric energy very much a great attention. The electric power is used in all spheres of human life, possesses a set of certain properties and directly participates in creation of other kinds of products, influencing their quality. Last years there were many TVs, computers and other devices working on a direct current through the secondary power supply. They worsen quality of electric energy in a power line.
The work actuality is connected with absence of the analytical decision of problems of an estimation of electromagnetic compatibility and can help to open to experts theoretical aspects of a problem of improvement of quality of electric energy. The main objective – to investigate voltage in electric networks of Donetsk. The idea of work consists in use of techniques of the likelihood modeling, allowing to describe casual processes. Scientific value of work – development of the theory electromagnetic compatibility in a range of definition of characteristics of casual processes by means of statistical likelihood methods of calculation.
Electromagnetic compatibility of means - ability to function in the established electromagnetic conditions and not to create inadmissible electromagnetic hindrances for other means [1].
It is necessary to improve various ways electromagnetic compatibility if at least one indicator electromagnetic compatibility does not correspond to the normalized. It is enough to calculate or measure these indicators in these cases before improvement electromagnetic compatibility.
In the given work nonlinear characteristics therefore difficult use of analytical methods of an estimation which consider electromagnetic compatibility are considered[3]. Thereupon it is expedient to pass to statistical multifactor modeling which will be stated in more details.
Practically the majority of the meeting law of distribution – the normal law which the main feature that other laws are similar to it. One of work problems – to learn, whether submits voltage to the normal law.
Parameters of normal distribution have been found. On the basis of results we will draw a conclusion that change of voltage in time represents non-stationary casual process, and simultaneously with it submits to the normal law.
The normal law is represented in Fig. 1.
Fig. 1: The normal law (the given image is animation with following parameters quantity of shots – 7; quantity of cycles of repetition – 5; volume in kilobytes – 26,4)
The second way of research of voltage – research by means of correlation function and its characteristics. The analysis of the weighed and accepted data is executed - average value and dispersal is not to constants. Results: voltage – non-stationary casual process; that it is better to investigate function of Correlation of features, is necessary to increase realization number.
The correlation function is represented in Fig. 2.
Fig. 2: The correlation function
Now two basic ways of quality maintenance of pressure are known:decrease in losses of voltage and voltage regulation.
Decrease in losses of voltage is reached:
1. Choice of section of conductors of electric mains on conditions of losses of voltage;
2. Application of longitudinal capacitor indemnification of jet resistance of a line;
3. Indemnification of jet capacity for decrease in its transfer on electric systems, by means of condenser installations and the synchronous electric motors working in a mode of over excitation.
Voltage regulation can be carried out in the next ways: by means of the transformers established at enterprise, equipped with the device of automatic control of factor of transformation depending on loading size and by means of the intermediate transformers equipped with various factors of transformation.
1. The primary goals of maintenance Ems are formulated. Check придерживания norms of GOST 13109-97 on one-minute deviations of voltage is executed.
2. The concept a voltage deviation is in full opened; its influence on electric equipment work, responsibility and indemnification measures is considered.
3. The analysis of quality of voltage taking into account multifactor modeling is made. It is possible to assert that change of voltage represents non-stationary casual process for which studying it is necessary to write down daily schedules.
4. The basic problems connected with regulation of voltage in city networks are analyzed, and also recommendations about improvement of its quality are made.
5. It is planned to receive daily schedules that will allow to specify results of practical researches and to choose recommendations for the organization on improvement of quality of voltage.
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