the utilization of digital fault recorders

2040 IEEE TRANSACTIONS ON POWER DELIVERY, VOL. 22, NO. 4, OCTOBER 2007

The Utilization of Digital Fault Recorders inProtection System Analysis on Tenaga Nasional

Berhad Transmission SystemAbdullah Asuhaimi Mohd Zin, Senior Member, IEEE, and Sazali P. Abdul Karim

Abstract—The protection system is a very critical element in apower system. It is security to the power system for isolating onlythe faulty plant as fast as possible. A simple fault can lead to a cas-cade of tripping if it is not isolated accurately and fast enough bythe protection system. Furthermore, protection system analysis is acomplicated task for inexperienced engineers. Most of the analysisrelied mainly on the relay indications which could lead to incorrectanalysis due to the uncertainty of the correct relay operations andtime tagging. Therefore, it is an urgent requirement to explore pro-tection system analysis to improve system reliability. This paperdescribes a method of early detection of protection system failuresin Tenaga Nasional Berhad’s Transmission Grid using digital faultrecorders. The method has demonstrated to be more accurate, thusenabling faster decision making and shorter interruption time.

Index Terms—Digital fault recorder (DFR), hidden failures, pro-tection system analysis (PSA).

I. INTRODUCTION

THE importance of monitoring the performance of powersystems has steadily increased over the years. Conse-

quently, evaluation of system disturbances has become morecomplex and the monitoring of an equipment’s performancehas become essential for power system reliability to ensurecompetitive power supply in the deregulation industry [1].

In the electrical industry, the economic factor plays an impor-tant role to preserve continuous business with the consumers.Domestic and industrial consumers are more sensitive to theavailability of electricity supply being fed to their premises.In this new era of business globalization, whenever wide-areapower outage occurs in a country, the power system reliabilityand security will always be the first to be inspected by the powersystem regulator.

II. RECORDER AS AN ANALYSIS TOOL

The main objective of protection system analysis is to assistutility engineers to examine the behavior of secondary equip-ment in order to improve the reliability of the power system.

Manuscript received April 3, 2006; revised December 19, 2006. This workwas supported in part by Tenaga Nasional Berhad and in part by UniversitiTeknologi Malaysia for this research. Paper no. TPWRD-00190-2006.

S. P. A. Karim is with the Tenaga Nasional Berhad, Kuala Lumpur 59200,Malaysia (e-mail: [email protected]).

A. A. M. Zin is with the Faculty of Electrical Engineering Uni-versiti Teknologi Malaysia, Johor Bahru 81310, Malaysia (e-mail: [email protected]).

Color versions of one or more of the figures in this paper are available onlineat http://ieeexplore.ieee.org.

Digital Object Identifier 10.1109/TPWRD.2007.905456

TABLE IDIGITAL FAULT AND DISTURBANCE RECORDERS INSTALLATION

Unfortunately, only a few engineers can interpret the recordedwaveform traces captured during faults and disturbances. Theengineer should first have experience in power system opera-tion, network configuration, and power system protection. Forthose who have experience but have not undergone relevanttraining, they cannot interpret the significance of the recordedwaveform traces. Even the most technically trained engineerswill face difficulties in understanding the problems if they donot have experience in fault and disturbance analysis.

Protection system analysis using fault records has been useto identify the source of any tripping in a power system. Un-fortunately, the digital fault recorder (DFR) has not been ex-tensively applied due to a lack of training. Moreover, with somany DFR models from different manufacturers, the task be-comes more difficult. Failure to understand protection systemoperations and the fault’s characteristics can cause a time delayin power-supply restoration to the consumers.

A. Recorder’s Definition

In order to optimize the application of the recorders as arecording device, Tenaga Nasional Berhad (TNB) has definedand categorized two types of recorders, namely the DFR andthe digital disturbance recorder (DDR). By adopting these twodefinitions, TNB is able to decide the strategic locations for in-stalling each recorder in TNB’s Transmission System. The listof fault and disturbance recorders installed in TNB’s Transmis-sion System is shown in Table I.

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ZIN AND KARIM: UTILIZATION OF DIGITAL FAULT RECORDERS IN PROTECTION SYSTEM ANALYSIS 2041

B. Digital Fault Recorder

A DFR is defined as a device to graphically record all of thevoltages and currents as well as protective relays’ operationsduring any fault condition and switching transients using a fastsampling rate. The fast sampling rate shall be at least 2000 Hzand above. The recording time shall be up to 4 s [2], [3].

III. DIGITAL DISTURBANCE RECORDER

A DDR is defined as a device to graphically record all ofthe voltages and currents as well as protective relay operationsduring any power system disturbances, including fault condi-tion, power swing, power system frequency deviation, and otherinformation related to dynamic system performance using fastand slow sampling rates. The fast sampling rate must be at least2000 Hz and above. The slow sampling rate can be as low as100 Hz. Both fast and slow sampling rates shall be used at thesame time. The recording time for the fast sampling rate shallbe up to 4 s and the slow sampling rate shall be up to 60 s [2],[3].

IV. REVIEW OF EXISTING ANALYSIS TOOL

As the power system grows, the protection system’s relia-bility and selectivity have become a very critical issue comparedto the last century. The evolution of numerical protection tech-nology contributes to the complexity of protection system anal-ysis. Therefore, a DFR is a very important tool for protectionsystem analysis. One advantage is to confirm the correctness ofprotection operation compared to the normal utilities practiceand any special rectification that needs to be done.

In 1992, Rodriguez et al. [4] presented a paper on modularapproach for fault diagnosis. They described the application ofneural networks in order to detect the faulty elements in a powersystem taken from alarm messages. They used these alarm mes-sages to formulate a model classification representing the be-havior of the protection system.

There is some literature which discussed the protectionsystem performance information to identify the faulty sectionand confirmation of protection operations. Mc Arthur et al. [5]discussed the combination between an expert system and modelbased to identify the accuracy of the protection schemes. Theprinciples are based on correct protection operation schemesand modeled for any given disturbances. The model needs to beupdated to the latest power system status in order to perform thecorrect diagnosis. The findings were extended by Chantler etal. [6] in 2000, which used DFR to identify the fault’s section.They utilized power system modeling to analyze the protectionsystem reactions corresponding to tripping.

Dongyuan et al. [7] introduced an integrated power systemprotective relaying fault information system in 2003. With thisapproach, the relay and fault recorder information are capturedand stored in the local management computer located at the sub-station. All of this information is sent to the control room for theoperator to make a decision. This approach requires all of theprotective relays to be upgraded to digital relays.

A. Protection System Performance

When discussing protection system analysis, it is all aboutselectivity and speed [6]. Fast fault clearing time is essential

Fig. 1. Example of the consequences due to protection system failures.

to minimize the impact of any system fault. Protection relayoperating times may vary from a fraction of a cycle to severalcycles for the transmission system and may exceed 1 s for thedistribution network.

The protection system is a very important device to ensurethat the consumer receives a secure electricity supply. This isone reason why most of the power utilities devote serious atten-tion to protection system performance. Furthermore, conductinga protection performance audit for each operation becomes rou-tine. This audit is essential for protection system analysis.

Failure to detect protection failures prior to any system inci-dent can lead to component failures. Fig. 1 provides an exampleof the consequences resulting from the protection system fail-ures.

Protection system analysis requires vast experience and in-depth knowledge on how the protection systems operate. Con-sequently, all protection operations must be recorded and syn-chronized in order to detect any failure in the protection system[8]. This approach can be used to measure the performance ofthe protection system being installed.

From the power system’s point of view, the protection sys-tems fail to protect if:

1) the main protection does not operate correctly;2) the fault is cleared by the backup protection;3) the fault clearance time is beyond the standard require-

ment.Analysis on the protection system will further improve the

effectiveness of each protection scheme installed. This will re-veal the protection hidden failures and, hence, reduce the im-pact during any tripping. Simultaneously, the analysis will re-veal protection failures which could prevent a cascade of trip-ping that might lead to a major blackout. Some of the protectionsystem hidden failures could directly affect the power systemperformance. Protection system hidden failures are defined as “apermanent defect that will cause a relay or a protective schemeto incorrectly and inappropriately remove a circuit element(s)as a direct consequence of another switching event” [9]. Nor-mally, the protection failures will occur when the power systemis under stressed conditions, such as during or immediately after


Fig. 2. Artificial neural networks.

faults, undervoltages, overloads, or as a consequence of anotherswitching event [10].

B. Protection System Analysis Tool Development

Recently, TNB has embarked on a project to develop a pro-tection system analysis tool with Universiti Teknologi Malaysia(UTM). The newly developed tool utilized the information ex-tracted from the existing DFR. Each tripping waveform traces,together with the associated protection devices’ operationstatus, are analyzed and then compared to the TNB’s protectionpractices [3].

Most of the power utilities in the whole world have been op-erating their power systems in different ways due to various re-quirements imposed by their regulators. In a transmission net-work, the system operators have to follow predetermined rulesstated in their National Grid Codes. Therefore, different philoso-phies and practices have been adopted in order to fulfill theabove requirements.

Protection system analysis is a systematic approach to iden-tify the operational behavior of the protection system compo-nents. It incorporates protection basic rules, namely reliability,

selectivity, and speed. This research utilizes the recorders’ infor-mation where all power system data during flashovers are cap-tured.

The protection system analysis (PSA) module will analyzethe protection system response using the data that have beensampled by the selected DFR at a substation level. The datasampling rate being used by the selected DFR for this researchis 5 kHz. This approach will produce 100 arrays of data forevery one cycle (20 ms for a 50-Hz system) of information.As a result, the PSA module will analyze the data for every0.2 ms in a matrix form as shown in the analog and digitalmatrices below.


Fig. 3. Kg. Awah–Paka Line 2 tripping on September 14, 2005 at 14:37:10.

TABLE IIDIGITAL INPUTS CONFIGURATION FOR MAIN1

AND MAIN2 ARE DISTANCE PROTECTION

where

red phase voltage at the “ ” data sampling;

yellow phase voltage at the “ ” data sampling;

blue phase voltage at the “ ” data sampling;

red phase current at the “ ” data sampling;

yellow phase current at the “ ” data sampling;

blue phase current at the “ ” data sampling;

neutral current at the “ ” data sampling.

TABLE IIIDIGITAL INPUTS CONFIGURATION FOR MAIN1

DIFFERENTIAL AND MAIN2 DISTANCE


Fig. 4. Impedance locus measured by a distance relay using mho characteristic.

TABLE IVPROTECTION SYSTEM ANALYSIS

wheredigital input no 1 at “ ” data sampling;

digital input no 2 at “ ” data sampling;

digital input no 3 at “ ” data sampling and so onuntil .

The two matrices from before consist of a set of analog anddigital signals’ reaction during a power system fault that hasbeen recorded in a specified sampling time. The values will be

used to calculate the time response of the protection systemand the total fault clearing time. All of these time-responsevalues will be validated against the predefined value accordingto the protection philosophies being adopted in TNB using anartificial neural network (ANN). The ANN has 23 inputs and7 outputs with 2 hidden layers to calculate the accumulatedweights. The architecture of the ANN is shown in Fig. 2. Thelists of digital inputs used are tabulated in Tables II and III.The output of the ANN that has been introduced in thisresearch should produce a report similar to that practiced bythe medical profession (i.e., the normal “medical checkup”report for human beings). This approach was selected becauseit has the capability to check for any symptom before a majorproblem hits the power system.

This simplified, yet useful report will help the nonprotectionengineer to understand the next course of action to be takenrelated to the protection system. In order to verify the aboveconcept, actual tripping data shown in Fig. 3 have been testedto identify the protection system hidden failures using the PSAmodule. An example of a report produced by PSA is shown inTable IV.

The normal practice of power utilities for this kind of faultis usually treated as a normal operation since it does notcause any load loss and the fault can be cleared successfully.Although the fault is transient in nature and the power supplyis restored automatically, PSA has successfully detected aprotection system hidden failure in the Main 1 protection.In this example, the Main 1 protection failed to isolatethe fault. However, the fault was cleared by the Main 2protection. The PSA report recommends that the maintenancecrew check the Main 1 operating characteristics. From thesite investigation, it was found that Main 1 is a distanceprotection and Main 2 is a current differential protection.Further analysis was conducted, and it has been ascertainedthat the failure of Main 1 to isolate the fault was due to ahigh-resistance path created by a tree encroaching into thezone 2 of distance protection. Approximately 22 ms beforethe final isolation by current differential, the impedance fallsinto zone 1 as shown in Fig. 4. However, it is not sufficientfor the distance relay to make any decision to trip. The


Fig. 5. Impedance locus measured by a distance relay using quadrilateral characteristic.

normal time required by a typical distance relay to trip isbetween 30 to 40 ms.

In order to increase the Main 1 sensitivity for this kind of faultin the future, it is recommended that the utility must replace itwith a quadrilateral characteristic distance protection as shownin Fig. 5. Using the same reach settings, it has been proventhat a quadrilateral characteristic can improve the distanceprotection sensitivity for a high impedance fault. Therefore,the PSA has detected a protection system hidden failure in theMain 1 protection that is related to the incorrect selection ofthe distance protection characteristic for the Kampong Awahsubstation.

V. CONCLUSION

Protection system maloperation is often a contributing factorto most major power outages despite system constraints asdiscussed in [11]. Although a major blackout is an occasionalevent, the impact from a single incident might cost more thanU.S.$ 1 billion. The selection of an appropriate protectionscheme must be carefully evaluated in order to prevent anydamage in the power system. In that respect, TNB has imple-mented protection schemes to cater to all types of faults, such aslightning strike and tree encroachment, which are common intropical countries such as Malaysia. The fault and disturbancerecorders installed in the TNB transmission grid system havemade significant improvements in the operation of the powersystem. With this newly developed tool (PSA), TNB is able toidentify the protection system hidden failures before any majordisturbance appears in the power system. In conclusion, PSAis a valuable tool for decision making, particularly to networkdispatch operators of TNB, Malaysia. Ultimately, reducedoperating costs for every disturbance in the power system willbe achieved.

REFERENCES

[1] S. P. A. Karim, “Fault diagnosis in transmission system,” M.Elect. Eng.dissertation, Universiti Teknologi, Johor Bahru, Malaysia, 1995.

[2] S. P. A. Karim, K. M. Isa, and A. H. A. Bakar, “Tenaga NasionalBerhad experience on the application of fault and disturbance recorder,”presented at the Fault and Disturbance Analysis Conf., Atlanta, GA,May 4, 1999.

[3] Protection & Control Code of Practice, 2nd ed. Kuala Lumpur,Malaysia: Tenaga Nasional Berhad, 2003.

[4] C. Rodriguez, S. Rementeria, C. Ruiz, A. Lafuente, J. I. Martin, andJ. Muguerza, “A modular approach to the design of neural networksfor fault diagnosis in power systems,” in Proc. Int. Joint Conf. NeuralNetworks, Jun. 7–11, 1992, vol. 3, pp. 16–23.

[5] S. D. J. Mc Arthur, J. R. McDonald, S. C. Bell, and G. M. Burt, “Expertsystems and model based reasoning for protection performance anal-ysis,” in Proc. Inst. Elect. Eng., Colloq. Artif. Intelligence Applicationsin Power Systems, London, U.K., 1995, pp. 1/1–1/4.

[6] M. Chantler, P. Pogliano, A. Aldea, G. Tornielli, T. Wyatt, and A.Jolley, “The use of fault-recorder data for diagnosing timing and otherrelated faults in electricity transmission network,” IEEE Trans. PowerSyst., vol. 15, no. 4, pp. 1388–1393, Nov. 2000.

[7] S. Dongyuan, W. Xinghua, and D. Xianzhong, “Road to the integratedprotective relaying fault information system,” in Proc. IEEE PowerEng. Soc. General Meeting, Jul. 13–17, 2003, vol. 1, pp. 23–26.

[8] A Working Group of the Relaying Practices Subcommittee of the IEEEPower System Relaying Committee, “Application of fault and distur-bance recording devices for protective system analysis,” IEEE Trans.Power Del., vol. 4, no. 3, pp. 1625–1630, Jul. 1989.

[9] S. Tamronglak, “Analysis of power system disturbances due to relayhidden failures,” Ph.D. dissertation, Virginia Polytech. State Univ.,Blacksburg, 1994.

[10] M. G. Adamiak, D. Novosel, B. Kasztenny, V. Madani, J. Sykes, and A.G. Phadke, “Wide area protection and control—today and tomorrow,”Proc. IEEE Power Eng. Soc. Transmission and Distribution, pp. 1–7,May 2006.

[11] S. H. Horowitz and A. G. Phadke, “Boosting immunity to blackouts,”IEEE Power Energy Mag., vol. 1, no. 5, pp. 47–53, Sep./Oct. 2003.

Abdullah Asuhaimi Mohd Zin (M’88–SM’97) received the B.Sc. degree fromGadjah Mada University, Indonesia, in 1976, the M.Sc. degree from Universityof Strathclyde, Strathclyde, U.K. in 1981, and the Ph.D. degree from the Uni-versity of Manchester Institute of Science and Technology, Manchester, U.K.,in 1988.

Currently, he is a Professor and Head of Electrical Power EngineeringDepartment, Faculty of Electrical Engineering, Universiti Teknologi Malaysia,Johor Bahru. He authored or coauthored more than 90 technical papers. Hisresearch interests include power system protection, application of neuralnetwork in power system, arcing fault in underground cables, power qualityand dynamic equivalent of power systems.

Dr. Mohd Zin is a corporate member of The Institution of Engineers,Malaysia (IEM) and a member of the Institute of Electrical Engineers (U.K.).He is a registered Professional Engineer (P. Eng.) in Malaysia and CharteredEngineer (C.Eng.) in the United Kingdom.


Sazali P. Abdul Karim is currently pursuing the Ph.D. degree at UniversitiTeknologi Malaysia, Johor Bahru.

He is actively conducting the fault analysis courses for power utilities in AsiaPacific, Middle East, and Europe. He has more than 17 years of experience intransmission protection systems, specializing in fault investigation with TenagaNasional Berhad (TNB), a power utility company in Malaysia. His work hascontributed to a significant reduction of system minutes. His research interestsare protection system and fault signature analysis.

Dr. Abdul Karim received an award from the Malaysian Government whichwas presented by the H.M. the King for his contribution in analyzing theprotection system during a power crisis which saved the country from a majorblackout. He also received international recognition when his paper “TenagaNasional Berhad Experience on the Application of Fault and DisturbanceRecorders” won the 1999 Best Paper Award at the Fault and DisturbanceAnalysis Conference in Atlanta, GA. He is currently a member of Boardof Engineers Malaysia (BEM) and a Corporate Member of The Institutionof Engineers Malaysia (IEM). He is also a registered Professional Engineer(P. Eng.) with Board of Engineers Malaysia, The ASEAN Federation ofEngineering Organization, The Asia–Pacific Economic Cooperation, and TheInternational Engineer Register.

the utilization of digital fault recorders

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