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UWE Bristol Engineering showcase 2015

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Phan Giang Thai Ngoc<br />

BENG (HONS) ELECTRICAL AND ELECTRONIC ENGINEERING<br />

Project Supervisor<br />

DR. HASSAN NOURI<br />

Investigation into impact of pre-insertion resistors in Circuit breakers<br />

Modelling representation and concept<br />

Once when in use (open / close), switch time break causing<br />

impacts to the circuit, called the overvoltage. The<br />

methodology of analyzing the effects of the pre-insertion<br />

resistor and pre-insertion inductor on the 138 KV<br />

transmission line was modelled and simulated using PSCAD.<br />

The full model of the transmission line circuit with bus line<br />

and all component in PSCAD shown in the figure.<br />

Result:<br />

In this study, the 138 KV transmission line with break<br />

time switch is built in PSCAD. The pre-insertion<br />

impedance is considered in this project. The different<br />

value of components are changed in many case. The<br />

result in PSCAD is shown that:<br />

I. Overvoltage in circuit which has break time switch<br />

II. Uncontrolled overvoltage in transmission line<br />

III. Controlled overvoltage in transmission line<br />

I. Pre-insertion resistors<br />

II. Pre-insertion inductor<br />

IV. Comparison<br />

Project summary<br />

This project present the analyzing of pre-insertion<br />

impedance in a 138V transmission line using<br />

PSCAD/EMTDC. 50 ohm resistors and inductors 20mh<br />

turn is inserted into the circuit. Overvoltage will be<br />

measured at remote bus and capacitor bus what call<br />

phase to phase overvoltage and ground to phase<br />

overvoltage. A comparison is shown to see the best<br />

method for different cases.<br />

Project Objectives<br />

• PSCAD Familiarization<br />

• Understand the 1-phase circuit.<br />

• Understand the 3-phase circuit<br />

• Understand the circuit with break time<br />

switch<br />

• Understand the transmission line<br />

• Analyzing the waves voltage in<br />

uncontrolled and controlled voltage.<br />

• This project will study the analyzing and<br />

the comparison the voltage in circuit.<br />

The complete line model consists of several<br />

sub model representing the following<br />

elements:<br />

1. Transmission line and circuit components.<br />

2. Break time switch are installed the closed<br />

function.<br />

3. Pre-insertion resistors and pre-insertion<br />

inductor with different values<br />

4. Voltage wave table.<br />

Ground to phase uncontrolled overvoltage wave<br />

Ground to phase pre-insertion resistor overvoltage<br />

wave<br />

Project Conclusion<br />

Over 3 study optimal control circuit voltage of<br />

transmission lines with break time switch.<br />

Three ways are: fixed inductor, pre-insertion<br />

resistor and inductor pre-insertion. Each<br />

method has its own advantages and<br />

disadvantages. Finally, pre-insertion inductor<br />

is chosen as the most complete method to be<br />

used.<br />

Phase to phase pre-insertion resistor overvoltage<br />

wave<br />

Pre-insertion inductors.

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