Simultaneous Fault in a Power System

Kimberly Y. AboboBSEE – V from EECE Dept. MSU-

IITIligan City, Philippines

kimberly.abobo@gmail.com

Reden Leon L. BadellesBSEE – V from EECE Dept. MSU-

IITIligan City, Philippines

redenleon.badelles@gmsuiit.edu.ph

Mohammad Yusoph M. MutiBSEE – V from EECE Dept. MSU-

IITIligan City, Philippines

mohammadyusoph.muti@gmsuiit.edu.ph

Abstract— The paper presents on how to solve the fault currents and voltages at chosen breaker points when simultaneous occurs. MS-Excel use as data input and where the output is to be display. And with MATLAB-software used to perform the algorithm in solving when simultaneous fault occurs. It opens an .xlsx file where input data is stored. It then let the user choose to what type of fault connection occur in the pre-define chosen sample circuit. After defining suitable boundary conditions for different type of faults using the impedance matrix parameters for the series-series, admittance matrix parameters for the parallel-parallel and the hybrid matrix parameters for the series-parallel connection for finding the positive, negative and zero sequences. The suggested procedure proves useful to analyze any combination of faults without limit of type and phase of fault. A simple test system is considered to illustrate the accuracy of the algorithm. The output is then displayed through the excel file again, showing the currents and voltages of the chosen breaker where the fault occurs.

I. INTRODUCTION

The fault analysis of a power system is required in order to provide information for the selection of switchgear, setting of relays and stability of system operation. Faults usually occur in a power system due to insulation failure, flashover, physical damage or human error. These faults may either be three phase in nature involving all three phases in a symmetrical manner, or may be asymmetrical where usually only one or two phases may be involved. Occurrence also of simultaneous fault is possible in which it is the difficult part. Simultaneous faults may be one of the following connections:

Series-Seriesa) Single line to ground at F and Single line to ground at F’b) Single line to ground at F and Two Lines open at F’c) Two lines open at F and Two lines open at F’Parallel-Parallela) Double line to ground at F and Double line to ground at F’b) Double line to ground at F and One line open at F’c) One line open at F and One line open at F’

Series-Parallela) Single line to ground at F and Double line to ground at F’b) Single line to ground at F and One line open at F’c) Two lines open at F and Double line to ground at F’d) Two line open at F and One line open at F’

By the application of the theory of two-ports it is possible to extend the method of symmetrical components to calculate the fault at two nodes in the network. Apart from a single fault, this method also enables us to determine the conditions for any type of fault in a different location in the network. Generally we can use this method for the same or different types of two simultaneous faults.

II. TESTING

The assumptions made in the program is limited to the following:

The program is limited to a fix power system The connections of generators and transformers

are fix The shunt reactors, loads and resistances are

neglected Only Z parameters are formulated, Y and H

parameters are derived from Z parameters. Fault impedance is assumed zero Manual closing of excel file to work properly

III. CONCLUSION

With the two-port network theory applied to the power system components provides a transparent solution of two simultaneous faults. The formation of equivalent circuit and elements of the matrix Z,Y,H was derived. The computation of any affected phase via ratio of the isolation transformers in solving the faults voltages and currents at point F and F’. The results are accurate enough though there are some constraints that is being recognize as stated above in the testing section.

REFERENCES

[1] Magabo, A & del Mundo, R. Simultabeous Faults

IV. RESULTS AND DISCUSSION

The results above are the voltages and currents at circuit breakers B & C. SLG fault at F’ occurs at phase b and phases a and b are open at F.

The results above are the voltages and currents at circuit breakers B & C. DLG fault at F’ occurs at phases b and c and phase b are open at F.

The results above are the voltages and currents at circuit breakers B & C. SLG fault at F occurs at phase b and DLG fault at F occurs at phases a and c.

Based on the three results, it has an accuracy of more than 95% due to assumptions and and rounding off the results.