1. M. Kezunovic (P.I.) S. S. Luo D. Ristanovic Texas A&M University
Fault Location in Transmission Networks Using Modeling, Simulation and Limited Field Recorded Data
M. Kezunovic (P.I.)
S. S. Luo
D. Ristanovic
Texas A&M University
PSerc Review Meeting
College station, Nov. 7, 2002
PSERC

2. Overview
Objectives
Testing procedure data requirements and test results
Potential problems and improvement
Design and User documentation
Conclusions
Future Research
This presentation includes three parts:
Part I introduces the summary report
Part II introduces the technical report
Last section is conclusion. Mainly introduce the status of the project

3. Objectives Defining procedure to be used for testing
Defining requirements regarding input data
Testing using fault data collected from Center Point Energy
Testing using fault data collected from other utility
Analyzing and evaluating the performance and proposing potential improvements
Improving the software and developing user interface
Developing the design and user documentation for facilitating future upgrades and practical use of the software

4. Testing procedure Using static system model
Obtaining the fault data file from utility and then converting into COMTRADE format
Producing the input data file based on the available DFR files
Checking the corresponding substation interpretation files based on the DFR configuration and system file
Running the software and obtaining the estimated location
Comparing the estimated result to the actual or calculated result
When using updated system model
Extracting parameters from the model and producing the topology data file before executing the above steps
System file refers to the one consisting of the topology, load and generation data of the system and short circuit parameters given in the specific format, such as PSS/E format, hlppssemodel.sav

5. Data requirement When using static system model Fault case data
fault data file in COMTRADE format (DFR raw data is need to be converted)
fault report (optional)
actual fault location (optional)
System data
Load flow and short-circuit model including topology
Interpretation file for each monitored substation

6. Data requirement, Cont.
Input data file generated by user based on available DFR files
Necessary fault information including the fault type, affected fault circuit
Options how to produce a list of possible faulted branch candidates
Algorithm parameter file
Including iteration number, crossover and mutation possibilities, population number…
When the more accurate model is required
Additional real power flow data is needed

7. Testing 15 fault cases obtained from Reliant Energy H&LP were tested
Power system simulator PSS/E is utilized
PSS/E models in versions 26, 27, 28 are tested
Sensitivity of results under different options is analyzed
Static model and tuned model are used

8. Testing
Using fault data collected from TVA or other utility to test fault location
The item was changed because data is not obtained
Instead, different power system simulation software was used
CAPE is a new selection
PSS/E system model is converted into CAPE database
Short circuit results obtained from the PSS/E and from CAPE are compared
The fault location software is customized for CAPE
Test result is not available because current version of CAPE is not perfect

9. Test results (1) Case # Number of DFR triggered
Actual or calculated fault location
Estimated fault location
Error 1 2
0.40 mile
0.2 mile
0.2
3.32 miles
0.3 3
3.49 miles
3.15 miles 4
2.50 miles
2.47 miles
0.0 5
2.0 miles
1.18 miles
0.8 6
1 mile
0.1 mile
0.9 7
2.8 miles
6.1 miles
3.3 8
3 miles
5.7 miles
2.7

10. Test results (2) Case # Number of DFR triggered
Actual or calculated fault location
Estimated fault location
Error 9 1
66.0 miles
66.9 miles
1.0 10
3.8 miles
0.4 mile
0.9 11 3
2.36 miles
2.13 miles
0.2 12 2
7.77 miles
6.54 miles
1.2 13
6.2 miles
1.6 14
4.77 miles
3.0 15
7.09 miles
0.7

11. Problems and improvements
Some factors affected estimated fault location accuracy:
Fault cycle
Faulted branch candidates
Phasor calculation
Model
GA result
Statement work mainly presents all activities for the project.
Defining the procedure to be used for testing the fault location software----one of two primary goals of the project is to evaluate the performance of the software.To get a comprehensive assessment, a more systematic testing is needed.
Defining the requirements regarding the input data needed for testing----It refers to the requirements for various power system
Testing the fault location software using fault data collected from RE HL&P----
Testing the fault location software using different power system simulation software----

12. Problems and improvements
Fault cycle
- Problems
For each triggered DFR, correct cycle to calculate the during-fault phasor should be used.
For several triggered DFRs, the the same cycle to calculate the during-fault phasor should be use
- Improvements
The criteria of determining fault cycle is improved
Additional measurements are taken to avoid using different fault cycles
In the user interface part, a new feature is added for user to specify the exact fault cycle
This is a schedule of the project. Note that the task #4, the original task is to use the fault data obtained from other utilities. Because of lack of the fault data from other utilities, the schedule is changed slightly. The task is to use new system simulation package instead of the PSS/E to test the fault location software

13. Problems and improvements
Branch Candidates
- Problems
The produced list of candidates must include the faulty branch, which creates a large number of choices
- Improvements
Additional options are added for user to choose the method of producing candidates
user can check the detail list of possible faulted branch candidates and edit it before the fault location software runs

14. Problems and improvements
Phasor calculation
- Problems
• Waveform includes DC offset and high frequency
components, which affects the accuracy
Improvements
Using improved Fourier algorithm for obtaining the during-fault recorded phasor
Filter the noise contained in recorded waveforms
The section is to introduce the technical report. There are six parts: Introduction.
Background mainly presents the former activities before the last review meeting. These activities include
1.testing the initial version of the fault location software through using the fault data obtained from the RE HL&P,
2.analyzing the performance of the fault location algorithm and software
3. Implementing the identified improvements. These improvements include correction of the phase sequence, correct calculation the fault inception cycles, correcting the design problems, algorithm improvements and model improvement. For the algorithm, signal processing is introduced to remove the noise found from the recorded waveforms, improved Fourier algorithm is introduced to eliminate the DC component. For GA algorithm, some measures are taken to overcome the small population problem, convergence problem, search space problem and so on. For model problem, a tuning strategy is applied to get a better updated model. To facility the usage of the fault location software, user interface was developed.
4. Several versions of interim testing reports were submitted.
Activities refers to the activities since last review meeting
Results refers to the results obtained from the new version of the fault location software which utilizes the new strategy of tuning system model
Next step-activities for coming months
Conclusion

15. Problems and improvements
Model
- Problems
The static PSS/E model provided by utility may not reflect the real system operation condition when a fault occurs
Tuning generator and load power as well as tuning the system topology is required
- Improvements
Using different version of PSS/E model with different topology and parameters
Tuning static parameters. Two situations are considered:
No additional real data is available. The concept of pre-fault phasor matching is introduced. Some cases show that tuning is effective
Additional real data is available, generator and load power scaling is utilized
Activities
Developing the graphical user interface
In order to facilitate the usage of the fault location software and further upgrades , a limited user interface was developed. Much benefits
Tuning the static system model
Converting PSS/E data into CAPE database

16. Problems and improvements
Genetic algorithm convergence
- Problems
Fixed iteration number may not always approach the final solution
For different runs, GA result may vary within a specific range
- Improvements
• Using fitness scaling to solve the small population
• Using multi-point crossover to increase the search space
• Using new replacement of “weak parent” to make GA more
robust
• Studying behavior of the fitness value add a criteria using
the average fitness
• Adding a feature to give an exact result after using GA limit
search range in the user interface part

17. Design and user documentation
Limited development of user interface for practical use
Fault location software design documentation and user’s guide are produced for software upgrade

18. Conclusion(1)
The test results show that the scheme of matching waveforms to locate a fault is feasible
Multiple triggered DFRs are helpful for improving location accuracy
It is suggested to use all the recorded currents and voltages for matching
It is suggested to use the same fault cycle to calculate during-fault phasors for each DFR

19. Conclusion(2)
Tuning system model and making it fit the operation condition when the fault occurs helps producing more accurate results, especially when additional real data is available.
It is suggested that the fault resistance is set within a reasonable range, especially in 345KV system
Producing a right list of faulted branch candidates before running fault location software is very helpful

20. Future research How to obtain and incorporate more accurate model data
How to make the user’s knowledge more useful
How to incorporate an iterative approach between running the program and having the user look at the results and make some practical choices
How to interface the program to variety of short circuit programs
How to obtain more data for further evaluation of the performance

21. Thank you!