Data Power

AN ADVANCED FAULT DATA/INFORMATION PRESENTATION IN POWER SYSTEMS

Ozgur Gonen Noah Badayos

Mladen Kezunovic Biljana Matic Cuka

Visualization sciences Electrical and Computer

Electrical and Computer Electrical and Computer

Engineering

Engineering Engineering

Texas A&M University Texas A&M University Texas A&M University Texas A&M University

College Station, TX, College Station, TX,

College Station, TX, College Station,TX, 77840,

77840,USA 77840,USA

77840,USA USA

*****@***.****.*** ********@****.***

*******@***.****.*** *******@***.****.***

and computed information developed for various analysis

Abstract

applications and different utility groups.

To help make the power system more reliable huge

amount of data generated from different Intelligent The paper starts with providing background on fault

Electronic Devices (IEDs) located in substation of power analysis and IED data. The goal and implementation of

system should be collected, analysed and displayed. Easy some automated analysis applications are discussed next.

way of accessing and viewing recorded data or information The needs for presentation of field recorded data and

obtained through automated analysis is commonly lacking information obtained from automated analysis is outlined

in the existing power systems. Nowadays data and related and some implementation examples are discussed in the

information presentation is one of the most important following sections. Conclusion, Acknowledgement and

requirements in power engineering. Many users find that References are given at the end.

their work is more efficient when using versatile

data/information presentation software. The emphasis in this 2 IED DATA USED FOR FAULT ANALYSIS

paper is on implementing user-friendly, device independent

The main purpose of the fault analysis in the context of

data/information presentation with ability for remote access

this paper is to precisely determine spot on the transmission

too.

line where fault occurred and evaluate performance of the

equipment involved in fault clearing. Such analysis can

1 INTRODUCTION

provide information like fault type, confirmation whether a

This paper focuses on specific class of mostly software fault has in fact occurred, assessment of the accuracy of the

solutions in power systems, namely the ones related to fault location algorithms embedded in relays, performance

automated fault analysis for monitoring, maintenance and of the switching elements (circuit breakers) responsible for

control applications. This class of solutions collects data isolating faults, etc [4]. After a fault in power system takes

from Intelligent Electronic Devices (IEDs) in substations, place automatic actions of controllers responsible for fault

organizes it in appropriate databases, and in newer detection and classification (protective relays) and related

applications processes the data automatically to extract switching equipment (circuit breaker) status is immediately

information relevant to different utility groups such as seen by an operator in the control center who will take note

operators, protection engineers, and maintenance personnel. of the fault event and inform other staff like protection

group or maintenance [5]. The consequences of mentioned

The approach for automated collection and analysis of events are reconstructed from data collected by recording

IED data has been offered in the past by several vendors of devices located in substations, and the views of the

the solutions for power industry [1]. However, most of the data/information explaining the events and consequences

focus in the past was on implementing data collection and are displayed in the staff offices that are quite remote from

integration, which are only the first step towards analysis substations. Various groups, such as protection engineers,

automation [2]. Automated analysis, which is a new system operators and maintenance staff are then in a

technology not previously widely used in the power industry position to take further actions. The protective engineers

has been deployed only in the last decade and on a very start analyzing faults in more details. They visually inspect

limited scale [3]. recorded data and also check and compare IED records

before making a decision about nature of the fault and

The latest developments are an extension of the related equipment (protective relays and circuit breakers)

previous ideas but they explore two distinct directions: a) actions. In the case of permanent fault the maintenance

making the analysis more integrated across data from group is requested to go to the field, assess any damages,

different IEDs, and b) providing more elaborate tools for and fix the damage as needed. For this group it is extremely

viewing the original IED data and results of the analysis important to have information about precise location of the

using advanced computer graphics. This paper focuses on fault and surrounding circumstances such as terrain, type of

new solutions for graphical representation of recorded data supporting transmission line structures (towers) and

performance of the switching equipment (circuit breakers).

Knowing this information ahead of the time helps

maintenance crews preparing for the repair job and making

sure the job is completed efficiently so that the transmission

lines can be brought back to service as quickly as possible.

It can be seen from the above that proper data presentation,

ability to easily compare signals generated from IEDs and

good fault location presentation are important in trying to

minimize outage time.

The IEDs used to collect the data recordings in

substations considered in this paper are: digital protective

relays (DPRs), circuit breaker monitors (CBMs) and digital

fault recorders (DFRs). Those IEDs provide detailed

Figure 2. List of signals in CBM recordings

information about fault type, fault location, power quality

disturbance, operation of protective relays and operation of

DFR is a device with an ability to capture and store

circuit breakers.

short transient events, longer-term disturbances and trend of

input quantities such as RMS, frequency, harmonics, power

DPR is designed to calculate operating conditions on an

and power factor [10]. This device records huge amount of

electrical circuit and trip (open) circuit breakers when a

data. Figure 3 shows typical signals recorded by DFRs and

fault is found [6]. The DPRs respond to conditions like

used in the analysis.

sudden change in impedance, over-current or voltage,

reverse power flow, over- and under- frequency, and they

would trip for faults up to a certain distance away from a

substation but not beyond that point. The DPR records and

generates huge amount of data relevant for the analysis.

Figure 1 shows summary of data recorded and/or generated

by a typical DPR [7].

CBM is developed at Texas A&M University and main

purpose is to monitor circuit breaker (CB) condition on-line

[8]. CB is an automatically-operated electrical switch

designed to disconnect and hence protect an electrical

circuit (transmission line) from damage caused by overload

or short circuit [9]. Figure 2 shows list of the signals that are

recorded by CBM.

Figure 3. Input signals for DFR analysis application

Figure 4. Interconnection diagram of substation IEDs

Figure 1. Summary of data in DPR files and reports

the status and timing of that operand is validated. If not, a

failure or misoperation is identified and diagnosis is

initiated to trace the reasons by the logic of cause-effect

chain [13].

CBMA (Circuit Breaker Monitor Analysis) is an

application based on analysis of records of waveforms taken

from the circuit breaker control circuit using a Circuit

Breaker Monitor (CBM) device. It enables protection

engineers, maintenance crews and operators to quickly and

consistently evaluate circuit breaker performance identify

deficiencies and trace possible reasons for malfunctioning.

It can automatically analyse switching operations of large

Figure 5. AEA System architecture

number of circuit breakers under complex switching

conditions [14].

The developed system takes IED data as shown in

Figure 4 and supports client/server architecture shown in

Implementation architecture for each of the three

Figure 5. The part that resides on a PC in the substation

solutions is shown in Figures 6-8 respectively.

includes the Automated Event Analysis (AEA) Client which

interfaces to the CBM, DPR and DFR devices connected to

the Substation PC [11]. The server side resides at remote

location and consists of AEA Server software integrating

three automated analysis applications (CBMA, DPRA,

DFRA), database and web application.

3 DATA/INFORMATION FROM AUTOMATED

ANALYSIS APPLICATION

An IED alone typically may record an enormous

amount of data, but the case usually is that the output cannot

Figure 6. DFRA Architecture

sufficiently aid any utility personnel in making complete

interpretation of an event without information coming from

automated analysis of recorded data. To address the

different needs of different utility personnel, it is important

that the integrated substation data undergo further

processing to produce more useful and readable reports

containing information pertinent to the task at hand. Thus, a

few automated analysis applications were developed as

summarized below:

DFRA (Digital Fault Recorder Analysis) - provides

automated analysis of DFR event records. The analysis

looks at all the monitored circuits and identifies the one

with the most significant disturbance. For that selected

circuit, DFRA performs signal processing to identify pre-

Figure 7. DPRA Architecture

and post-fault analogue values, statuses of the digital

channels corresponding to relay trip, breaker auxiliary,

communication signals, etc. The expert system determines

fault type, faulted phases, checks and evaluates system

protection performance. At the end, the analysis program

calculates the fault location [12].

DPRA (Digital Protective Relay Analysis) - is an expert

system based analysis application which automates

validation and diagnosis of relay operation. Validation and

diagnosis of relay operation is based on comparison of

expected and actual relay behaviour in terms of the status

Figure 8. CBMA Architecture

and timing of logic operands. If actual status and timing of

an operand is consistent and as expected, the correctness of

To present data/information, there is a need for two

types of graphical user interfaces: the desktop and web user

interface. The desktop user interface, which is meant to

support local user connected to the computer at a substation

site, may be used by protection engineers. The developed

user interface provides advanced waveform viewer, which

will be further discussed in the next section. Also this

application can be used for testing purpose since it provides

ability to change device connections and settings. That

means that a new IED can be easily connected, configured

and tested using this interface. The interface allows

determining which data will be deleted and which archived

in the database. On the other hand, the web user interface

can be used by protection and maintenance groups, as well

as the system operators. It requires only a web browser

coupled with cell phone to be used to access data from the

field (substations) at remote site (control centre or staff

offices). This interface has ability to show physical Figure 9. Signal waveforms display

environment of faulted area, which will be discussed later.

The fault location can be shown in 2D and 3D view as will

be elaborated in the following section. This

data/information viewing approach makes it easier to assess

fault location accuracy and handle related tasks.

4 DATA/INFORMATION DISPLAYING

In the fault analysis process, several utility groups are

involved: operators are the first to make note of the fault,

then protection engineers are asked to perform detailed

analysis of causes and consequences, and maintenance

crews are sent to inspect and if needed repair damaged parts

of the system caused by a fault.

Before protection engineers make final decision

regarding the fault, they usually visually inspect generated Figure 10. DFR report

analysis reports and data recorded by IEDs (signal

waveforms). The inspection of signal waveforms can be

improved by a few additional functionalities allowing easy

manipulation and viewing. The visibility of each signal can

be enhanced by providing several graphycal display

features: selection of signals to be viewed including an

option to remove some signals from the dispaly, comparison

of signal waveforms by displaying them superimposed in

the same view with a color code, user ability to move a

displayed signal to any other view by dragging its label, and

signal zooming to view further details. The user should be

able to see in single view a time sequence of all the signals

that occured during the same event and got recorded by

IEDs. An example is shown in Figure 9.

The reports generated by IEDs are usually difficult to

interpret, as shown in Figure 10. Because of that, automated

Figure 11. Report for protection engineers

analysis applications are developed and implemented. As an

example of the analysis application for each IED, the

To improve presentation of data/information,

module that generates reports specialized only for

customized techniques may be combined with the standard

protection engineers is developed. Such automated analysis

ones typically used for data/information presentation in

report contains only essential information as shown in

other applications unrelated to power systems. Commercial

Figure11.

software for power system presentation may be combined

with automated analysis software to improve access and

make data/information presentation more user friendly and

understandable. For instance, the results of fault data

analysis that point out to the fault location in the electric

circuit representation of the power system network may be

combined with geographical and model data about the same

network producing more comprehensive views of the

troubled area. An example of using Power World

commercial software to represent power system network

and enhancing it with custom designed software to

accurately determine fault location is shown in Figure 12

[15]. The same results for fault location may be overlayed

on the earth satellite pictures obtained from Google Earth,

as shown Figure 13 [16]. This way, in case of outage it is Figure13. Satellite view of fault location area

easy not only to determine where the fault location may be

in the electrical network but also to know what to expect

from the physical terrain surrounding actual equipment

around fault location. This information is important for the

maintenance crews that are supposed to patrol the area,

locate the fault, assess possible damage from the fault, and

fix the problem. To give even better information about the

equipment and area characteristics, a 3D model of the

equipment and physical area may be developed as shown in

Figure 14. This model allows maintenance crews to view

the area from different angles allowing better assessment of

what may be involved in repairing transmission line

structures (towers), and what equipment and parts may be

needed to complete the job. This versatility of graphical

options for representing data/information associated with

field recordings, electrical networks, and physical outline of

the equipment is not available today and yet offers Figure 14. 3D view of fault location area

significant benefits to various utility groups.

5 CONCLUSION

Besides the examples shown in this paper, some

additional graphical views of the switching equipment are This paper introduced new concepts of utilization and

developed by the authors and reported earlier [17]. presentation of substation data/information. It emphasizes

the importance of good data/information presentation when

attempting to reduce outage time in power systems and

make the remedial process easier. The following are major

conclusions:

Desktop viewing of signal waveforms captured by

recording devices in substations allows utility personnel

to deal with test and evaluation tasks for individual

recording devices, which is very important to be able to

maintain and evaluate performance of the all-digital

monitoring solutions

Web browser viewing of recorded data and information

produced through automated analysis allows utility

personal located in control canter and/or other offices

remote from the substations to maintain timely

awareness of the critical events in power system such as

occurrence of faults

The graphical interfaces can significantly benefit from

Figure 12. Power world fault display

mixing the data/information derived from recorded

signals with other data such as satellite images of

certain geographical area or 2D and 3D views of

various power apparatus obtained from advanced Analysis of Circuit Breaker Operation, IEEE Transactions

equipment models. on Power Delivery, Vol. 20, No. 3, pp 1910-1918, July

2005.

6 ACKNOWLEDGMENT [15] Demo Software. Power World Corporation. ND. 4

Nov. 2007

The authors would like to thank the following /demosoftware.asp>.

organizations for funding the developments reported in this [16] Explore, Search and Discover. Google Earth. ND. 4

paper: EPRI (through TC agreement with CenterPoint Nov. 2007 .

Energy and HydroOne), PSerc and DOE-Current [17] M. Kezunovic, E. Akleman, M. Knezev, O. Gonen, S.

Technologies Corp. Special thanks are due to Mr. Don Natti," Optimized Fault Location", IREP Symposium 2007,

Sevcik from CenterPoint Energy for providing data to test Charleston, South Carolina, Aug 2007.

the various solutions mentioned in the paper.

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