A Study on Long Power Transmission Line

✅ Paper Type: Free Essay	✅ Subject: Engineering
✅ Wordcount: 2364 words	✅ Published: 23rd Sep 2019

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Project Proposal

A STUDY ON LONG POWER TRANSMISSION LINE

ABSTRACT___________________________________________________________

In this ever changing advancing world, technology has an impact on everything, and Power System is no exception. This has caused a huge bump in power industry. For the quality of supply in long transmission line the area of power system needs to be upgraded. There are a number of softwares in the market which can simulate a virtual long transmission line but MATLAB SIMULATION can calculate the voltage profile precisely which is the main focused area of the project. In this given project, the researcher has to consider the differences in the simulated voltage and practical calculations. The main motto of this project is to get a thorough interpretation of readings, supplies, targets and a route of course for establishing the system in simulation software. The whole project is categorized into 2 main sections: one targets the coding for simulation in MATLAB Software while the other deals with the equations of fundamental qualities of electricity transmission in a power line such as RESISTANCE (R), INDUCTANCE (I), CAPACITANCE(C), VOLTAGE (V) and CURRENT(A). Specifically, the latter has to be simulated in the former for simulating and finding the differences.

CONTENTS_________________________________________________________________

ABSTRACT………………………………………………………………………………………………………………2

ACKNOWLEDGEMENTS…………………………………………………………………………………………3

CONTENTS………………………………………………………………………………………………………………4

INTRODUCTION……………………………………………………………………………………………………..5

INFORMATION ANALYSIS……………………………………………………………………………………..7

LAYOUT OF SYSTEM………………………………………………………………………………………………9

EXPLANATION OF HARDWARE AND SOFTWARE……………………………………………….10

CONCLUSION…………………………………………………………………………………………………………11

REFERENCES………………………………………………………………………………………………………….12

APPENDIX………………………………………………………………………………………………………………13

INTRODUCTION______________________________________________________

The conductors which are used to transmit large amounts of electrical energy over distances are known as Power Transmission Lines. Those lines that carry or transmit this energy over large distance are known as Long Transmission Lines. These transmission lines carry different voltages. On the basis of length to which these can carry the electrical energy, these lines can be categorized into three:-

Short Line- up to 50 kms, capacitance is negligible(C~0).
Medium Line- from 50 to 160 kms, capacitance is included, calculation is done by T-method or π-method
Long Lines- greater than 160 kms where distributed parameters are used.

These long transmission lines can carry voltages around 220/110 KV and from generating station to central main sub-station. In New Zealand, High Voltage Direct Current (HVDC) and 50 Hz frequency is used to transmit power.

Power lines usually contain many different devices like transformers, surge arrestors, switch gears, relays etc. conductors are used in Power transmission lines and widely used conductors are either (Aluminium conductor Steel Reinforced) or Copper.

In this project of long transmission line, the simulated and practical findings should be calculated for obtaining the desired results (like voltage, current, resistance, capacitance, inductance, etc.). Designing and simulating a long power transmission line in MATLAB and finding the voltage at different instances and points.

INFORMATION ANALYSIS______________________________________

LONG POWER TRANSMISSION LINES:-

Given below is a pictorial representation of long power transmission lines and instead of using lumped parameters, distributed parameters are used.

From the above figure, we can assume a small portion as differential length and ‘x’ is the distance from the receiving end of the line. So, the voltage is ‘V’ and current is ‘I’ at the distance ‘x’. Also, it can be seen from the figure that voltage is (v+dv) and current is (I+dI) at a distance (x+dx). Assuming

Ydx= shunt admittance

Zdx= series impedence

From figure,

(v+dv)-v = Izdx

dv = Izdx

dv/dx = Iz ………(1)

(I+dI)-I = vydx

dI = Vydx

dI/dx = vy ……….(2)

Diffrentiating both sides of (1) an (2) w.r.t x

d²v/dx² = z dI/dx ……….(3)

d²I/dx² = y dv/dx …………(4)

substituting the values of (1) and (2) in above equations;

d²v/dx² = zvy …………(5)

d²I/dx² = yIz …….(6)

the value of V in exponential form is given as

V= A₁ e^√(yz.x) + A₂ e^-√(yz.x)

Deriving V w.r.t x is given as

d²v/dx² = yz [A₁ e^√(yz.x) + A₂ e^-√(yz.x)]

The value of current ‘I’ can be derived from

I = ⅟[√(z/y) A₁e^√(yz.x)] – ⅟[√(z/y) A₂e^-√(yz.x)]

LAYOUT OF SYSTEM_______________________________________________________

The figure above illustrates the long power transmission line with all the parameters viz resistance, inductance and capacitance that are distributed properly. Then the series impedance and shunt admittance are denoted by Z and Y respectively.

The power lines used in this project is are 2 wired stainless steel power lines and almost 10 m long.
These lines will be approximately 6 cm apart.

EXPLANATION OF HARDWARE AND SOFTWARE__________________________

Different equipments used in this project are as follows:

A 230 V AC Power supply
Frequency Generator
Testing Probe
Cathode Ray Oscilloscope (CRO)

 FREQUENCY GENERATOR: – this equipment makes different types of waveforms as sine wave, square wave and we can measure different frequencies. This instrument is also used for simulation of sensors and other functional tests.

 TESTING PROBE: – It is a physical device which is used to connect to an electrical equipment for testing. These come in various configurations from simple to more complicated ones. The probe used in this project is a voltage probe.

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 CATHODE RAY OSCILLOSCOPE: – Cathode ray oscilloscope also known as CRO is a device used for getting different waveforms by inputting different values and resultant values can be seen on a screen of CRO and then can also be plotted on a Graph. In this project, it will be used for getting waveform of continuously changing voltages. It is also sometimes used for measuring voltage, current and even sometimes used for troubleshooting.

 MATLAB SIMULATION: – MATLAB 2014b is used for theoretical calculation and measurement. Mathworks Laboratory has developed this programming language. MATLAB is used globally for coding because of its easiness to get the result. MATLAB is also used to plot the voltage graph in this project.

CONCLUSION______________________________________________________________

To sum up with, it can be said that the researcher has to compare the voltage graph of practical and theoretical values and also theoretical values of transmission lines with practical ones. If we have the values of R,L,C we can easily calculate the practical values with the help of power line equations but MATLAB coding will be used to attain theoretical values.