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ELEC6114 Power Systems Analysis Coursework The layout of a power system under consideration is attached as Appendix 1; this is based on a real life installation, although the data has been modified. The system consists of the main supply point, a number of interconnected busbars, several induction motors, some non-rotating loads, interconnecting cables and some local generators. The relevant data for all system components is supplied in Appendix 2. Six busbars in the system have been identified as points A, B, C, D, E and F - while additional locations half way through connecting lines as G, H, J, K, L, M and N - and you will be asked individually to consider a particular combination of those locations. Information about your assigned unique locations is enclosed in a file ELEC6114 PSA data 2013.pdf on the modules web page and will be referred to as points X and Y below. Part 1

Using the ERACS software create a model of the system. Make sure all system components are properly represented. Although this part of the assignment assumes that all students have the same system to study, it is vital from the point of view of gaining confidence in running the software that you prepare the data individually on your own, rather than copying if from someone else. Save your model as a basic configuration. Having generated the model, use the Loadflow module to calculate the steady state conditions of the network. Reflect on your results if they appear correct. Make necessary modifications and improvements if errors found.

A group of induction motors is to be connected to the network and all possible locations (A, B, C, D, E and F) are assumed to be feasible. You should connect this group to point X (your individual location as described above). The data for the group of the machines (represented as a single machine) is included in Appendix 2. Add this load to point X, save your data as a new configuration and run the Loadflow again. Consider carefully how the load flow has changed and be prepared to discuss your findings with other students at a seminar later in the Semester. Note also that it may be necessary to upgrade some parts of the system to make sure that no component is overloaded. Should this be the case make the necessary changes (e.g. add a parallel cable) and save the modified version.

Using the same data you used for the group of the new induction motors (that is taking the same P and Q as consumed by the motors), assume now that the new load is non-rotating. Modify your model data accordingly and save as the third configuration. Run the Loadflow and compare your results with those obtained previously; have some results been predictable?

Finally, with reference to the lectured part of the course, consider the economic aspect of connecting the new load of induction motors. What can you say about possible increase of costs following the installation? Part 2

Use the three generated models (the basic configuration, the second one with an added induction motor and the third with the non-rotating load) to study the following types of faults after a fault has been applied to point Y (that is one of the points you have been assigned: A, B, ..., F, G, , or N):

three phase, single phase to earth, phase to phase, two phase to earth.

Therefore you should obtain four sets of results for each of the three configurations. Study carefully your results and prepare for a discussion during a seminar later in the Semester.

The main purpose of the seminar will be three-fold:

first, to establish the differences between fault behaviour in the system after the fault has been applied at different locations and to explore how the type of the added load (rotating or non-rotating) influences this behaviour;

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secondly, to identify how various types of faults affect the performance; and finally, to try to decide (as a joint effort of a group of students taking this module) if

there is any advantage of connecting the new induction machines to one particular point (A, B, C, D, E or F) in preference to the remaining five locations.

Finally, for the case of a three-phase fault applied to the basic configuration only, consider if an approximate simple analytical estimation of the fault currents would be possible, perform such calculations and compare your result with the ERACSs analysis. Report

You are expected to prepare an individual report covering all aspects of the work you have done. The report should be structured as follows: a cover page should contain the coursework title, your name and ID number, followed by an

executive summary; this summary must fit on the cover page and is limited to 500 words; the main body of the report, limited to 15 pages, which should focus on your findings,

detailed discussion, observations and must finish with conclusions (limited to 500 words); the font size should not be less than 11; appendices containing:

o copies of the load flows for the three networks as generated by ERACS; o results produced by ERACS for the four types of faults for the three configurations of the

network (in other words 12 pages of such results); o analytical calculations for the three-phase fault for the basic configuration (these

derivations could be attached as hand written notes if preferred).

When preparing your report please observe the following requirements: do not copy text from books or lecture notes; make sure that your executive summary delivers a short but otherwise a complete message; prepare summary tables or consider other means of presenting your results succinctly; focus on your findings and observations; refer in the main text to all appendices.

To guide you through the process you might consider the following issues: How does the addition of the new load affect the system performance? Does it matter if the new load is rotating or non-rotating? Are there any noticeable differences between the effects of the different types of faults? Are all numerical results explainable? Is it possible to assess the accuracy of the numerical calculations? How accurate is the analytical approximation in predicting the three-phase fault? Have you observed anything unusual or unexpected in your results?

Please note that the above questions should not be answered directly but serve simply as guidelines to assist you in preparing the report.

Please note that you are expected to complete your work by the end of week 9 and hand in your report by 4pm on Tuesday 3rd December 2013. Any delay in handing in the report will incur a penalty in the form of reduced final mark (at a rate of 10% reduction for each working day of late submission, up to 5 working days, no submission is allowed after that; extension requests must be made in advance). The report should be submitted for marking in the Zepler Reception (Building 59). Please write clearly: ELEC6114 Coursework and do not forget to put your name on the cover.

The Seminar will be organised in week 11, when you will have an opportunity to present your results and discuss them with other students and supervisors. The overall mark will be made up of 45% for your report and 5% for your presentation and your contribution to the final discussion during the Seminar. The total contribution of the coursework is 50% (the other 50% coming from the examination marks). Professor J.K. Sykulski Dr E. Sykulska October 2013

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L4 L5 L3

~ ~ ~

IM IM IM IM

IM IM IM

Load Load

T1

T2 T3 T4 T5

G1 G2 G3

11 kV 11 kV

3.3 kV

3.3 kV 3.3 kV 3.3 kV

415 V 415 V 415 V 415 V

IM1 IM2 IM3

IM4 IM5 IM6 IM7

3.3 kV L2

L1

L6 L7

Ld1 Ld2

IM

T6

3.3 kV

415 V

IM8

A B C D E

F

G

H J K L

N

Main intake Standby intake App

en

dix

1

M

4

Appendix 2 The Main intake (the grid) may be represented as an equivalent large generator and the suggested values which need to be defined in ERACS are: Three Phase Fault Infeed = 90 MVA; Three Phase Fault X/R Ratio = 14 Single Phase Fault Infeed = 90 MVA; Single Phase Fault X/R Ratio = 14

All components of the power system in Appendix 1 are available from two libraries, one of which is provided for you in the form of a .csv file that you need to download from the course web site (PSA_Assignment_lib_Lib.csv) and import into ERACS, and another one that is available within the ERACS environment as ERAs Reference Library. The components are recognised by the key word. The parameters necessary to conduct the load flow and fault studies will be automatically picked up by the programme, but each element needs to be defined to be recognised. The system components are as follows:

Transformers Name ERACS key word Rating [MVA] Voltage ratio [kV]

T1 T001_PSA 3.5 11/3.3 T2 T002_PSA 0.75 3.3/0.415 T3 T004_PSA 1 3.3/0.415 T4 T006_PSA 1.25 3.3/0.415 T5 T006_PSA 1.25 3.3/0.415 T6 T006_PSA 1.25 3.3/0.415

Generators Name ERACS key word Rating [MVA] Voltage [kV]

G1 GMIN_PSA 1.863 3.3 G2 GMIN_PSA 1.863 3.3 G3 GMIN_PSA 1.863 3.3

Note for all generators: Generator model should be set as Parks Equations, Generator type P,Q, Group Assigned Power (MW) 0.76, Group Assigned Reactive Power (MVAr) 0.56

Induction motors

Name ERACS key word Rating [MVA]

Group Assigned Power [MW]

Voltage [kV]

IM1 M001_PSA 0.76 0.45 3.3 IM2 M1.2 1.5 0.45 3.3 IM3 M001_PSA 0.76 0.4 3.3 IM4 M003_PSA 0.196 0.135 0.415 IM5 M004_PSA 0.119 0.075 0.415 IM6 M002_PSA 0.142 0.12 0.415 IM7 M002_PSA 0.142 0.12 0.415 IM8 M110 0.11 0.07 0.415

Cables Name ERACS key word Length [km] Voltage [kV]

L1 C229_PSA 0.8 3.3 L2 C229_PSA 0.6 (2 in parallel) 3.3 L3 C229_PSA 0.1 3.3 L4 C229_PSA 0.15 3.3 L5 C229_PSA 0.2 (2 in parallel) 3.3 L6 C230_PSA 0.175 3.3 L7 C230_PSA 0.175 3.3

Note for all cables: The Rating Selector should be set to Air

Loads

Name ERACS key word P [MW] Power factor Nr in parallel /MW multiplier Voltage [kV]

Ld1 Ld1_PSA 0.5 0.8 1/1 0.415 Ld2 Ld2_PSA 0.4 0.8 1/1 0.415

The additional induction motor connected at point X (that is point A, B, C or D): Name ERACS key word Rating [MVA] Group assigned Power [MW] Voltage [kV] IMX M1.5 2 0.8 3.3