EE 374 Phase 1 Solution

1 INTRODUCTION

This document presents the project definition of the EE 374 Fundamentals of Power Systems and Electrical Equipment course. Here are the important points about the project:

• This is not a group project. Each student must submit his/her own work.
• The project contains two phases. You will be given some tasks in the ”Project Work” section of this document. Your code should accomplish these tasks. In Phase 1, you are expected to implement a PYTHON function. In Phase 2, an improved PYTHON function must be created. You will submit the final version of PYTHON function and a report.
• If you have a question concerning the project, contact course assistants via e-mail first.
Please add both of the assistants as email recipients.

Important Dates:


2 PROJECT INFORMATION

Electricity is generated in bulk and transmitted to consumption areas via HV overhead lines. Therefore, the selection of transmission line and tower plays an important role in transmission system planning. Geometry of the conductor positions plays an important role in the calculation of electrical parameters of a transmission line. In practice, there are many types of transmission towers.



Figure 1: 735 kV transmission lines Figure 2: Double circuit 6-bundle carried on V-guyed towers, 4-bundle 765 kV transmission line (Quebec, Canada)


Figure 3: 380 kV transmission tower in Turkey during construction


Figure 4: Zhoushan Island overhead line with the tallest power pylon in the world with 380 m. (500 kV 4-bundle)








Figure 5: Spacer for a 6-bundle Figure 6: Spacer for an 8-bundle transmission line,
transmission line. 1100 kV China



There are many other specifications in transmission line and transmission tower design. However, the most important properties in terms of power system analysis are explained above. Some extra information is given below:

• The purpose of colorful spheres or cone shaped indicators in transmission lines are to inform helicopter pilots about transmission lines.
• The purpose of the shape of insulators is to make the surface flashover path longer.
• The purpose of ground wires is to protect the phase conductors from lightning strokes. Also, they provide a path for return currents.
• The higher the system voltage, the longer the insulator length.

As you expect, there are more parameters that can affect the design of a tower; however, those are out of scope of this course. In this project, you will need only basic parameters as input that are listed here:

• number of circuits
• number of bundle conductors, where bundles form a regular polygon
• bundle distance, which is the length of the edges of the polygon that a bundles forms (in m)
• length of the line (in km)
• name of the ACSR conductor
• location of the phases with respect to the origin
• a library of ACSR conductors and their parameters

Note that the library parameters will be given in Imperial Unit System and you should convert those values to SI units. Also, note that the system is 50 Hz. With these raw input parameters, we expect students write a function to calculate the electrical parameters of a line in per unit. To compute these parameters, Geometric Mean Distance (GMD), Geometric Mean Radius (GMR) of the line are found first. You will be introduced with these concepts in the following weeks of the course. You are not required to know these information in the first phase of the project.

Figure 7: Definition of phase locations in input file.

In your input file you will be given x and y coordinates of bundle centre for each phase, where distances are given in meters with respect to origin. The definition of these x and y coordinates are described in Figure 7, i.e. position of dark green circles. In Figure 7 red circles are representing the conductors and dark green circles are representing the centre of each bundle.

3 PROJECT WORK

In this project you will be given a random transmission tower’s specifications in a text file. Also, you will be provided with a library of ACSR conductors. In Phase 1, you are supposed to find a tool to preprocess the raw input data given in text format into a useful format for Phase 2 applications. In other words, you will create a function file that reads formatted data from text in PYTHON environment. In Phase 2, depending on these data your code should calculate the resistance (R), reactance (X) and susceptance (B) of the overhead line in per unit quantities.

These information will be valid for the transmission line to be modeled:

• You will be given only 3-phase systems (no single-phase systems)
• All phases consist of the same bundle orientation and same type of conductors
• Lines are transposed. The transposition rule is as follows.

Transposition cycle section Position 1 Position 2 Position 3
1 Phase A Phase B Phase C
2 Phase C Phase A Phase B
3 Phase B Phase C Phase A

• There will be no double circuits in this project.

3.1 Phase 1

Tasks:

• Create a PYTHON function that reads the raw input data, which are listed in the previous section, given in the text file.
• The code must find the conductor name that is given in the input text file from the library and extract the necessary information about the conductor type from there, namely outside diameter, AC resistance at 20°C, and GMR of the conductor.
• Your function must give the outputs in SI Units, i.e. all lengths in meters. So, make the necessary unit conversions.
• Your function must take the input file and library paths in string format as the inputs of the function.

Evaluation:

• You must parse all the raw input data correctly and in correct format. (string for the conductor name, double for other parameters, Ex: student ID = 1234567)
• You must submit your function in a way equivalent to this format. Note that the order of the input and output variables is important (-10 Points for wrong function format):
[𝑆𝑡𝑢𝑑𝑒𝑛𝑡 𝐼𝐷, 𝑆𝑏𝑎𝑠𝑒,𝑉𝑏𝑎𝑠𝑒, 𝑁𝑏𝑢𝑛𝑑𝑙𝑒,𝑑𝑏𝑢𝑛𝑑𝑙𝑒, 𝑙𝑒𝑛𝑔𝑡ℎ, 𝑐𝑜𝑛𝑑𝑢𝑐𝑡𝑜𝑟 𝑛𝑎𝑚𝑒, 𝑜𝑢𝑡𝑠𝑖𝑑𝑒 𝑑𝑖𝑎𝑚𝑒𝑡𝑒𝑟, 𝑅𝐴𝐶, 𝐺𝑀𝑅𝑐𝑜𝑛𝑑𝑢𝑐𝑡𝑜𝑟] = 𝑡𝑒𝑟𝑚𝑝𝑟𝑜𝑗𝑒𝑐𝑡(𝑡𝑒𝑥𝑡_𝑝𝑎𝑡ℎ, 𝑙𝑖𝑏𝑟𝑎𝑟𝑦_𝑝𝑎𝑡ℎ)
• The function is going to be called with two inputs and at the end, it must return a list in the above format.
• Upload .py file of your code to ODTUCLASS directly, first.

3.2 Phase 2

In this part, you are expected to submit a PYTHON function and a report. Your code must execute all the tasks in Phase 1, so refine your code.

Tasks:

• Your PYTHON function should calculate the electrical parameters of the line, i.e., series resistance & reactance (Ω), and shunt susceptance (℧). (Include the effect of earth on shunt capacitance calculations.)
• Then, you must calculate these quantities in per unit using the base values given in the raw input text file.
• Write a maximum 5-page report on your observations. The report should not include explanation of your code rather it should include the followings:
– The employed method, why and how you used it.
– Any method/assumption/etc. you used to improve accuracy performance.
– Test results.
– Your observations on how changing the inputs in the text file affects the line parameters.

Evaluation:

• You must submit your function in this format where the data type of the output variables is double. (Ex: student ID = 1234567) Note that the order of the input and output variables is important (-10 Points for wrong function format):
[𝑆𝑡𝑢𝑑𝑒𝑛𝑡 𝐼𝐷, 𝑅𝑝𝑢,𝑋𝑝𝑢, 𝐵𝑝𝑢] = 𝑡𝑒𝑟𝑚𝑝𝑟𝑜𝑗𝑒𝑐𝑡(𝑡𝑒𝑥𝑡_𝑝𝑎𝑡ℎ, 𝑙𝑖𝑏𝑟𝑎𝑟𝑦_𝑝𝑎𝑡ℎ)

• The function is going to be called with two inputs and at the end, it must return a list in the above format.
• Upload .py file of your code to ODTUCLASS.
• Save your python code as a pdf by following the steps. File → Print → Enable “color printing”
→ Click the “print” button → “Select Microsoft Print to PDF” under the printer tab.
• If you cannot do the above, save your code as a PDF using any method you want.