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Abstract

Content

Introduction

The level of energy development and electrification reflect the state of the country's technical and economic potential. The energy sector provides electricity and heat to industrial enterprises, communal consumers, agriculture, transport, etc.

The development of energy is inextricably linked with the development of heavy industry. If the capacity of consumers of electricity is growing (and heavy industry is the main consumer of energy), then it makes sense to develop the power of power plants.

Outdated equipment should be replaced with new, modern, economical, in accordance with European standards. The increase in electricity consumption and the complexity of power supply systems require continuous improvement of power plants.There is a tendency to create automated control systems based on the use of digital universal and specialized computers.

In view of the importance of the correct and fast operation of relay protection, the main thing is the correct and optimal choice of protection operation parameters and its correct setting.

1. Relevance of the topic

In three-phase electric networks, during the operation of power supply systems, damage to electrical equipment and complex operating modes are possible. Damage caused by insulation failure, rupture of wires and cables of power lines, personnel errors during switching, lead to a short circuit of the phases between themselves or to the ground. When a short circuit occurs in a closed circuit, a large current appears, the voltage drop across the equipment elements increases, which leads to a general decrease in voltage at all points of the network and disruption to consumers.

Complex operating modes of electric networks arise, as a rule, as a result of accidents or after emergency shutdowns of equipment, with subsequent overloads and voltage deviations from nominal values. And although these modes are considered permissible for some time, they create the prerequisites for various kinds of injuries and disorders in the operation of electric networks.

In order to ensure normal operating conditions of electric networks and prevent the development of accidents, it is necessary to quickly respond to changes in the operating mode of the electric network, immediately separate the damaged equipment from serviceable equipment and, if necessary, turn on the backup power source for consumers. These functions are performed by relay protection and automation devices.

2. The purpose and objectives of the study

Research objectives: further improvement of digital relay protection systems and diagnostics of the main elements of own needs of power plants.

Object of research: elements of the system of own needs (transformers of own needs, asynchronous motors, synchronous motors.).

Subject of research: parameters that determine the criteria of operation, selectivity, as well as the nature and type of the selected equipment.

3. The current state of research and methods for the implementation of devices for relay protection of elements voltage 6 kV

Classical thermal power station (TPS) is a large industrial enterprise designed to generate thermal and electric energy [1 – 4]. Scheme of the main electrical connections of power unit No. 12 of the Starobeshevo PP.

The 220 kV open switchgear (220 kV outdoor switchgear) of the Starobeshevo PP was made by two partitioned working and bypass bus systems. The first and second working systems of 220 kV are sectioned by air circuit breakers, allowing to bring into repair a switch of any 220kV connection without disconnecting the connection itself.

On section A of 220 kV outdoor switchgear a bypass switch A is installed. On section B a combined switch B is installed, which can be used both as a bypass and as a bus connection. All 220 kV connections (blocks and lines) are connected to the bus bypass system, allowing the circuit breaker of any 220 kV connection to be repaired without disconnecting the connection.

Sectional, bypass, combined, bus-connecting switches 220 kV, 220 kV lines, 220 kV and 110 kV circuit breakers of 5TA – 5TB autotransformers are controlled from the control panels and panels of the main control panel. On the same panels are measuring instruments, synchronization and signaling devices of these switches.

At each power unit, two 6 kV sections are installed to power auxiliary mechanisms. The sections are fed through switches from the working transformer of their own needs 15.75/6/6 kV.

To reserve sections of 6 kV power units two bus systems of 6 kV backup power supply, powered by a transformer 110/6/6 kV 301T and 220/6/6 kV 302T, were made. 6 kV backup power supply buses are partitioned by circuit breakers through each pair of power units.

Ways to improve relay protection systems and diagnostics of the basic elements of the own needs of power plants and research tasks

The most common AED overload protection in most modern microprocessor-based protection devices or Siprotec 7SK81 terminals (Siemens, Germany); UZB – 301 (Novatek – Electro LLC, Russian Federation) RDC – 06 (Electrical plant Relss, Ukraine) uses the integral dependence of the stator current as a function of time [3 – 5]. However, this protective logic does not allow controlling the heating temperature of the stator windings and the AED rotor.

It is presented to consumers in three versions, the classification of which will be determined by the range of the rated current – 50 – 50 A, 10 – 100 A, 63 – 630 A. Each of these devices protects the three-phase motor from phase failure; with insufficient voltage in the network and with other mechanical deviations. The device operates with high accuracy and reliability. The device is a microprocessor – based automatic device that does not require operational power. In emergency situations arising in the mains voltage, the device, after restoring all the parameters, automatically performs a restart. If the problem arises in the engine itself, then the device blocks its restart.

Electronic relays of modifications RDC – 02, RDC – 03, RDC – 04, RDC – 05, RDC – 06 are microprocessor devices designed for control and integrated protection of industrial electric motors for various purposes.

Modifications of relays RDC – 04 and RDC – 06 are equipped with the latest copyright software Relsismotorconfig, which provides the most complete control of the condition of electrical machines. The price of products is set by the manufacturer and depends on the built – in functionality and the availability of copyright software.

List of sources

  1. Кацман М.М. Электрические машины. – М.: Высш. шк., 2000. – 324 с.
  2. Брускин А.Э. и др. Электрические машины и микромашины. – М.: Высш. шк., 2001. – 426 с.
  3. Данилов И.А., Иванов П.М. Общая электротехника с основами электрони-ки. – М.: Высш. шк., 2000. – 402 с.
  4. С.В. Усов. – Л.: Энергоатомиздат, Электрическая часть электростанций. 1987. – 616 с.
  5. Васильев А.А. Электрическая часть станций и подстанций 2-е издание, переработанное и дополненное. — Москва: Энергоатомиздат, 1990. — 551 с.
  6. Рожкова Л.Д., Козулин В.С. Электрооборудование станций и подстанций 3-е изд., перераб. и доп. Учебник для техникумов. М.: Энергоатомиздат, 1987. – 648 с.
  7. Андреев В.А. Релейная защита и автоматика систем электроснабжения Учебник для вузов. 4-е изд. перераб. и доп. — М.: Высшая школа, 2006. — 639 с.: ил.
  8. Неклепаев Б.Н. Электрическая часть электростанций и подстанций Учебник для вузов. — 2-е изд., перераб. и доп. — М.: Энергоатомиздат, 1986. — 640 с.: ил.
  9. Соркинд М.А. Асинхронные электродвигатели 0,4 кВ. Способы защиты от аварийных режимов. Новости электротехники, 2005, №4(34).
  10. Сивокобыленко В.Ф., Лебедев В.К. Переходные процессы в системах электроснабжения собственных нужд электростанций. Уч. пособие, Донецк, ДонНТУ, 2002. – 136 с.
  11. Гашимов М.А. Диагностирование эксцентриситета и обрыва стержней ротора в асинхронных электродвигателях без их отключения / М.А. Гашимов, Г.А. Гаджиев // Электротехника. – 1998. – №10. – С. 46-51.