Calculation and design of relay protection and automation of SES. Single-line power supply diagram

Contents

Source Data

Introduction

1 Determination of power consumption of the designed electrical installation

2 Selection of power supply circuit equipment

3 Calculation of dc currents

4 Selection of protection devices and automatic electrical installation devices

4.1 Calculation of protection for network sections

4.2 Calculation of APV and ALT

Conclusion

List of sources used

Introduction

Any electrical systems shall be reliable, economical, convenient and safe to operate and provide consumers with the required quality of electricity. Relay protection and automation devices play a major role in meeting these requirements.

The design of relay protection and automation is a complex process of developing and making decisions on the selection of the principles for performing relay protection. The issues of effective functioning of relay protection devices and automation of all elements of the protected circuit are also solved, starting from the selection of types and calculation of the set points of the designed devices and ending with their correct connection to operational current circuits and to current and voltage transformers.

Performing a course project on the course "Relay Protection and Automation," the student consolidates the acquired knowledge, as well as receives practical skills in designing RZiA, which are necessary for the further successful implementation of the course and diploma project.

2 Selection of power supply circuit equipment. Complete single-line electrical connection diagram.

Based on initial design data electrical connection diagram

includes the following attachments:

1) two supply overhead lines (VL) (TP No. 1) and two supply cable lines (CL) (TP No. 2) with a voltage of 10 kV connecting the facilities to the power system;

2) one cable line, voltage 10 kV;

3) two sections of busbars with section oil switches, disconnected in normal mode, at facilities 4 and 5;

4) two connections of power transformers.

Connection of cable and overhead lines, transformers to busbars with a voltage of 10 kV is carried out using oil switches.

To monitor the presence of voltage at inputs No. 1 and No. 2 are provided

single-phase voltage transformers, and three-phase transformers for voltage control on sections of busbars 10 kV.

Two busbar sections are provided for distribution of electric power at voltage up to 1 kV. Valve dischargers are provided to protect the overhead line from overvoltage. Connection of prefabricated busbars with voltage up to 1 kV to transformers is made with the help of input circuit breakers and a circuit breaker. Valve arresters are provided to protect against overvoltage of electrical equipment.

Consumers with voltage up to 1 kV are supplied via outgoing lines connected to collecting buses through circuit breakers.

4.2.2 Automatic switching on of reserve

To increase reliability of power supply to essential consumers, their two-way power supply is carried out. In this case, if one of the supply elements is damaged and disconnected, the consumers will continue to operate

by serviceable links of the power system.

Partitioned power supply circuit greatly simplifies relay protection, improves its clarity, increases residual voltages on buses

power substations at K3 in the distribution network and reduces K3 currents, allows in many cases to create the necessary modes according to the condition of voltage and power flows .

The automatic switching on of backup lines allows you to reduce the cost and simplify the power supply circuits. The use of ALT devices for overhead power transmission lines does not exclude the installation of APV devices on them and is considered as a reserving measure - the disconnected line is switched back on from the APV device, and if the operation of the APV device was unsuccessful, this line

is automatically disconnected from the receiving side and consumers with ALT devices are switched to power supply from another protection line, to which their own load is also connected.

We install the ATS device on objects 4 and 5, for reservation of objects of the 1st and 2nd category. Possible substation operation modes:

1) two power supplies for different sections are switched on, ALT switch is turned off;

2) one of the sources is ON, ALT switch is ON.

Conclusion

During the course project, short-circuit currents were calculated at all points of the protected network; the main types of protections on the lines (transverse differential directional protection, MTZ with independent instantaneous time delay, current cut-off without time delay) and on transformers (differential, gas protection, overload protection) were selected; set points for actuation of protections and relays were calculated; relay types (current relay PT40, RBM270, EV100) were selected.

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