Review on Design of Overhead Transmission Line by MATLAB Programming

Review on Design of Overhead Transmission Line by MATLAB Programming

Nishigandha Daware

PG Scholar [EPS],

Dept. of Electrical Shri Sai College of Engg. & Tech.

Bhadrawati, Maharashtra, India.,

Dr. Prakash Burade

Professor, Dept. of Electrical SITRC, Nashik, Maharashtra, India,

Abstract This project aims to develop a solution for designing transmission lines which will leave the manipulation and calculation part for computer and just by feeding some basic data we will get an optimized design of a new transmission line. Thus this project aims to bring a solution for engineers to the problems they are facing while designing a new transmission line. Transmission line design involves a lot of data manipulating and number of tedious calculations which take a major part of time required or devoted for planning and designing a new line. This software approach will provide a handy means for new ones entering in this field. The main objective of designing a high voltage transmission line is to transmit electrical energy at the lowest cost and with required reliability. Both electrical and mechanical design considerations are to be studied. Design of transmission line is a very complex task, since it includes designing of constantly changing parameters and design also includes very clear idea of the efficiency, regulation and losses. While designing transmission on lines various parameters are to be considered. They are as follows:

• Voltage selection

• Size of conductors and spacing between conductors.

• Choosing number and type of type of insulators.

• Sag and Tension.

• Span Length and Ground clearance.

• Calculation of R, L, C and self GMD.

  Key Words: Overhead transmission line parameters, Matlab Programming.

  1. INTRODUCTION

     Expansion of Transmission and Distribution network commensurate with the addition of generation capacity and growth in demand is required, in order to extend a reliable, stable and secure power supply. This needs an optimal and economical planning of the transmission system.

     Analysis of a Transmission system is technically complex, though in terms of economics and nance, it is not as great as Generation or Distribution. Typically for a given period, the investments in Transmission system are much less as compared to either Generation or Distribution. The objective of system planning is to evolve a power system with a level of performance characterized by an acceptable degree of adequacy and security based on a trade-off between costs and risks involved.

     Transmission planning is carried out to determine new Transmission facilities required over a planning horizon, timing of each addition / modification of the system and to select most suitable type for each new development stage.

     Capital cost requirements and investment plans associated with such plans should be developed

  2. TRANSMISSION PLANNING REQUIREMENTS Basic requirements for carrying a transmission planning

     study

     • Information on the existing transmission facilities: Collection of all the available information on the existing system forms the first stage in the planning process. Data required is as given below. Data is usually available in the records maintained at the substations. Basic parameters required are, line voltage, number of conductors per phase, size and type of conductor and shield wire, Line resistance, reactance and susceptance (positive negative and zero se- quince), Size and location of line connected shunt reactors, Size and location of series capacitive compensation.

     • Generation plan :

       It includes all data and information regarding generation (i.e. various plants and their generating capacity etc.)

     • Load Forecast

       Load forecast is the process, which involves estimation of future loads and ways in which these loads can be met. The existence of a load forecast that covers the planning period is essential to the overall planning task and is the foundation for all the planning studies. Load forecasts carried out on a state- wide, regional or national basis provide satisfactory input to the generation.

  3. PLANNING NORMS AND GUIDELINES

     Load is a constantly changing variable and since the load and generation must be matched at all times to maintain a reasonably constant frequency, the duties imposed on a transmission system are infinitely variable within the extremes of minimum load and maximum load. To this must be added the uncertainties associated with both the load forecast and the generation plan. This will enable the power system to operate without any constraints in the event of any changes occurring in the load forecast or the generation plan. Bulk transmission system connects major power plants to the regional load centers. This system delivers large blocks of power to the areas that contain large concentration of load. It normally operates at highest network voltage. This system also interconnects generating stations, and load centers. Bulk transmission system is operated as a meshed system and normally covers a wide geographical area.

     At the bulk transmission level, there are two basic system types, known as integrated and non-integrated. Major generating plants are connected to major load centres in a non-integrated system, whereas an integrated system also connects major generating plants to each other and connects major load centres to each other.

     1. Illustration 1

        Voltage selection depends on various factors. The reason we are considering it first is because in our program the programmer will enter the value of voltage and on basis of that the transmission data will be provided to the programmer.

        A transmission line transmits electrical energy in bulk from generating station to distributing station. The maximum generation voltage in developed countries is 33KV while in India it is 11KV. The amount of power that has to be transmitted through transmission line is very large, if this power is transmitted at 11KV or 33KV, the line current and power loss would be large. Therefore this voltage is stepped up to higher value by using step-up transformers. The transmission voltages in India are 132KV, 220KV, 400KV and 765KV. The voltages used as standards in India are 11kV, 22kV and 33kV for short transmission line, 66kV and 110kV for medium lines and 132kV, 166kV, 220kV and 400kV for long lines. Recently, 765kV transmission line is under running project. Also transmission system can be categorized as follows

        • High Voltage:

          The voltage upto 220kV is called as high voltage

        • Extra-high Voltage:

          The voltage between 220kV and 760kV is called as Extra- high voltage.

        • Ultra- high voltage:

          The voltage above 760kV is called as Ultra -high voltage

        • HVDC:

          Line to Line Voltage (kV)	Length of line Minimum	(kilometers) Maximum
          66	40	120
          110	50	140
          132	50	160
          166	80	180
          230	100	300

          Line to Line Voltage (kV)	Length of line Minimum	(kilometers) Maximum
          66	40	120
          110	<>50	140
          132	50	160
          166	80	180
          230	100	300

          This voltage is associated with DC and is above +/600kV. The corresponding maximum and minimum length of line according to standard volt-ages are given in the table: The system voltage in EHV system very much effect. The corresponding maximum and minimum length of line according to standard volt-ages are given in the table: The system voltage in EHV system very much effect the capital cost of transmission line.

          Table1: Table of Max/Min length of line according to standard voltages

          Selecting the transmission voltage the present and future expectable voltage of other lines in vicinity of the line under design are taken into account. The number of circuits in EHV system can be one or two.

          The weight of conductor material, the efficiency of the line, the voltage drop in the line and system stability depends upon system voltage. The choice of voltage therefore, a major factor in the line designs.

          Distance(km)	Number of Phases	Standard Working Voltage(kV)
          Upto 8	3	6.6
          Upto 16	3	11
          Upto 64	3	33
          Upto 116	3	66
          Upto 240	3	132
          Upto 480	3	220
          Upto 800	3	400

          Table 3: Table for Voltage Selection (According to Indian standard)

     2. Illustration 2

     The project "DESIGN OF TRANSMISSION LINE USING

     MATLAB" is a software project in which the coding is done on MATLAB. In this for simplicity purpose we have done topic wise programming and then the final program is designed so that in this, it recalls the individual programs sequentially

     Program:

     %final program for design of transmission lines clc

     clear all

     V=input(Enter the value of voltage in "kV"=); choiceoc

     Insulator Gmd

     Vr Spanlength Gndcl Sagtens Corona Skineffect

  4. CONCLUSION

This project is implemented through MATLAB programming. Mainly, we dealt with the study of Electrical parameters. This project will be fruitful in designing of trans- mission line as calculation part will be done by computer. In future this project can further be extended by considering tower design, thereby studying mechanical parameters. Various others factors can be included for the detailed study.

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