THE OPEN UNIVERSITY OF SRI LANKA DEPARTMENT OF ELECTRICAL & COMPUTER ENGINEERING

ECX4232 POWER SYSTEMS I

ACADEMIC YEAR – 2013/2014

Academic coordinator: Dr. KAC Udayakumar Course coordinator : Dr. KAC Udayakumar Contact Phone: (011) 2853 777 ext. 628 E-mail kauda@ac.ou.lk

Course Information The course consists of

Three assignments #1, #2,and #3 (2nd, and 3rd assignments will be sent you latter). The assignments should be submitted on or before due dates. The late submission of the assignments will not be accepted.

Two Continuous Assessment Tests (CAT): There will be two CAT on the dates specified in the activity diary and both of them are open book types

Laboratory Experiments : There are two laboratory classes (compulsory)

Day schools: There are three-day schools on the dates specified in the activity diary. Although day schools are not compulsory, you are advised to attend to these day schools.

Final examination: This will be closed book type. The question paper will be of duration 3 hours.

Moodle class This course will be available under the section ‘Electrical and Computer Engineering’ in the NODES –OUSL web site. Instructions for logging in: You should go to the NODES –OUSL page (http://ousl.nodes.lk/) and log in.

Username : your National Identity Card number

Password : s-user (for first time users)( use all simple letters)

: use your “changed password” (if you have logged in before and already changed your password)

Syllabus of the course

Power generation methods Hydro, coal, nuclear etc. Combined cycle etc. Power generation from renewable sources, Non-conventional types of power generation, Power station practice, Station support auxiliaries, Substations-equipment, layout, etc. Circuit breakers - types, principles of operation, Isolators, CTs, PTs, reclosers

Overhead lines

Mechanical characteristics, Materials and construction, Distribution line construction and special features, Insulators and insulator strings

Under ground cables Types construction features, installation, jointing etc.

Power distribution Ring and radial feeders, Calculations of voltages and currents

Analysis Symmetrical components, Per-unit representation

Faults Analysis of symmetric faults, Analysis of unbalanced faults

Protection Basic types of protection for generators, transmission lines, distribution systems, bus-bars, substations etc. Simple computations involving CTs and PTs

All assignments should be submitted on or before the deadline in A4 format

For the format of the cover page please refer the moodle class

ASSIGNMENT 1

(Date of submission: refer the activity diary) Question 1 You are requested to prepare a table to explain functions, rated characteristics symbol and circuit diagram of elements of power system listed below: AC generator Transformer Auto-transformer AC Motor Over head line

Under ground cable Current transformer Voltage transformer Circuit breaker Isolator

Surge arrester Reactor Capacitor

The table should consists of four columns: element of power system, symbol, circuit diagram, function, rated characteristic Question 2 Write a report (approximately 1500 words) on “Options available to increase the power generation in Sri Lanka for next 15 years”. Your report should include followings: Introduction

i. Present status of generation ii. Load growth iii. Use of conventional sources of energy iv. Use of non-conventional (renewable) sources of energy v. Conclusion vi. References

The report should critically analyze technical, economical and environmental aspects of the sources that you select.

The report should be word processed (font: Times New Roman, size: 12) and submitted separately to the ECX4232 Moodle class. Question 3

i. Describe briefly “thermal rating of conductor” ii. A three-phase, 50 Hz over head transmission line with horizontal configuration

consisting four conductors per-phase is shown in figure Q1. Outside diameter of each conductor equals to 29.644 mm. Per-unit length resistance at 200 C equals to 0.0619 Ω/km. Temperature coefficient of copper is 0.0068 0C-1

14.5 m 14.5 m

40

cm

Figure Q1

a) Calculate GMD and GMR

b) Determine per –unit length inductance and capacitance

c) If the length of the transmission line is 200 km and ambient temperature is

420 C calculate per-phase parameters of (R,XL and Xc) equivalent pi model

of the line

(state any assumptions you make)

(o=8.85x10-12

Fm-1

, o=4 x 10-7

Hm-1

)

Question 4

i. Certain power plant consists of four generator units and step-up to 230 kV using two parallel connected transformers. Sketch a suitable bus-bar arrangement for the step-up substation and justify your answer.

ii. The power generated by the power plant is transmitted through the double circuit over-head transmission line and step-down to 33 kV at grid substation. Then, four 33 kV distribution lines deliver this power to four load centers at different locations. For the purpose of power factor improvement two capacitor banks are installed at two load centers. Sketch single- line diagram and circuit diagram for this power systems using standard symbols.