Graphic-Analytical Method for Detecting the Relay Protection

False Tripping Zones

Pavel Pinchukov

and Svetlana Makasheva

Power Engineering Institute, Far East State Transport University, Seryshev Street, Khabarovsk, Russia

Keywords: Traction Power Supply System, Catenary Feeder, Relay Protection, R-X Diagram.

Abstract: The relay protection devices of a traction power supply system should work correctly and steadily to provide

uninterrupted traffic. High intensity of heavy haul traffic significantly increases a load on all elements of the

traction power supply system. Heavy haul traffic causes several problems in catenary feeder’s relay protection

operation. Increased currents values while the heavy haul traffic can reach values of short-circuit currents. In

this case, the relay protection devices will tripping false and switch off a supply line without any damages.

Unnecessary relay protection false tripping leads to a pause in heavy haul traffic and brings significant

financial loses. Experimental long-term observation suggests that the current relay protection detuning

technology is not well optimized and needs to be improved. Identification of operating conditions of the relay

protection devices at the particular railway section was clarified by current research. Proposed the graphic-

analytical method allows simplifying the relay protection detuning from the traction load characteristics. That

makes it possible to reduce the number of cases of the relay protection false operation. The method based on

the comparison between the real load areas and the installed relay protection characteristics. Examples of the

successful correction of protection parameters in order to tune out from the load zone are shown in details.

1 INTRODUCTION

It is difficult to overestimate that electricity is

critically important for a modern person’s life. The

electricity is an irreplaceable resource for human’s

needs for almost all types of activity. It is worth to

noting that a presence of electricity in modern

production processes is natural and familiar to all

consumers. In this regard it is of interest that, if the

consumers assess any prospects for development of a

production processes, they usually take as granted the

electricity existence and do not think about such

possibility problems with a power supply like a power

interruption or a poor power quality. At the same

time, power outages are perceived by consumers as

something out of the ordinary (Makasheva et al.,

2020).

Nevertheless, reliability and uninterrupted power

supply are two major conditions for economy and

efficient of production processes (Esen and Bayrak,

2017; Makasheva and Pinchukov, 2016). When an

emergency situation appears in a power supply

https://orcid.org/0000-0001-9461-6620

https://orcid.org/0000-0002-0329-3836

system, it is necessary to quickly eliminate an

accident and then restore the power supply.

Currently, a responsibility for timely

disconnection of a damaged part of an electrical

system is assigned to the relay protection (RP)

devices. In turn, the automatic reclosing devices are

in charge of the inclusion the undamaged part of

power supply system (Alstom, 2011; Ciufo and

Cooperberg, 2021; Hill, 1994; IEEE, 2016; Ma and

Wang, 2018). RP should respond only to a damage

that occurs in the protected area. To do this, relay

protection devices are assigned a strictly defined

algorithm and trigger conditions.

Also, it is important the RP devices to satisfy two

major requirements (Alstom, 2011; IEEE, 2016; Saha

et al., 2010):

 Should trigger only while the emergency

modes, and disconnect only an area with a

damage;

 Should not trigger in the load modes.

If the RP triggers in the load mode, the

undamaged area of the power supply system

Pinchukov, P. and Makasheva, S.

Graphic-Analytical Method for Detecting the Relay Protection False Tripping Zones.

DOI: 10.5220/0011947800003612

In Proceedings of the 3rd International Symposium on Automation, Information and Computing (ISAIC 2022), pages 397-404

ISBN: 978-989-758-622-4; ISSN: 2975-9463

 2023 by SCITEPRESS – Science and Technology Publications, Lda. Under CC license (CC BY-NC-ND 4.0)

397

disconnects and a forced consumers interruption

occurs up to the moment of automatic reclosing

operation. In some cases the power supply

interruption leads to power outages and a violation of

the operating conditions of electrical consumers.

Such a RP functioning is regarded as a false operation

and named as a false tripping (Alstom, 2011; IEEE,

2016; Saha et al., 2010).

Responsible consumers suffer from power

outages because even a short interruption in the

power supply can lead to the technological process

destroying, can associate with a risk tohuman life and

health, and can bring significant material losses

(Alstom, 2011; Mason, 1956; Saha et al., 2010). The

electric rolling stock of the AC electrified railways is

a very good example of the responsible consumer

which needs an uninterrupted power supply for a non-

stop transportation process. Taking into account

technical needs and importance of the railway

transport, the RP false tripping is unacceptable.

Concern for the PR false tripping was prompted

by increasing of incorrect RP functioning cases while

heavy hauling especially for Far Eastern Railways of

Russia (Pinchukov and Makasheva, 2019). It is

tempting to consider RP functioning in view of new

data from railway observation practice based on

automated monitoring systems (Andrusca et al.,

2021; Makasheva, 2016; Mariscotti, 2022).

Many researchers studied problems of

determining parameters of the RP devices as follows:

 A wealth of information about the RP basic

theory and main principles of operating are

available now. For example, main calculations

of tripping zones parameters and relay settings

are given in (Ciufo and Cooperberg, 2021; Hill,

1994; IEEE, 2016);

 New adaptive RP parameters for nowadays are

given in (Moyo et al., 2019; Sezi and Menter,

1999);

 application examples of RP operation

algorithms for AC railway lines are shown in

(Han et al., 2012; Makasheva et al., 2020;

Pinchukov and Makasheva, 2019);

 Protection aspects are described in (Andrusca

et al., 2021; Moyo et al., 2019) for the traction

power supply system operation under present

conditions for a normal mode and a short

circuit mode;

 There is some intresting, but scanty

information, that the modern feeder distance

protection and overcurrent protection can not

successfully protect from short circuits, that is

discussed in (Andrusca et al., 2021; Han et al.,

2012).

There is no doubt that the RP devices

characteristics determinate by standard methods of

calculation and tuning. The methods do not take into

account the increased currents while the heavy haul

traffic, therefore, the RP devices with parameters

selected in such a calculated way, do not work

correctly. Thus, it was found from the mentioned

literary analysis, that most previously

recommendations are given in general terms and

cannot take into account the influence of the local

characteristics of the real railway lines, especially due

heavy haul traffic. As a result, there is no method for

identification the reasons of the RP false tripping. It

would be interesting to consider ways for identifying

the RP false tripping zones for reducing the number

of the RP incorrect operation.

The present study is aimed at the complex analis

of the RP false tripping problem and finding possible

ways to detuning the parameters of the RP devises

from the load mode especially due the heavy hauling.

To begin with, the causes leading to the RP false

tripping cases need to be investigated. Then, it can be

possible to exclude incorrect functioning leading to

disruption of the transportation process and power

supply interruptions. There is a definite possibility

that creation a method can be used in RP parameters

detuning.

The results of monitoring system's database

analisis offer a unique opportunity to apply this data

to the RP detuning process. Data processing from the

monitoring systems set at real railway sections will

allow taking into account the regional local

specificity. So, now it is possible to take into account

the regional component while RP detuning and to

propose a quite simple and understandable detuning

method

Finally, the method to identify zones of RP false

operation and to eliminate false tripping by adjusting

the RP parameters can be proposed. Also,the findings

can be useful for the RP developers who interested in

creating of new algorithms for RP operating under

overload conditions.

2 METHODOLOGY

The motivation of this research is to define a

framework and conditions for correct detuning the

AC catenary feeder’s RP devices from the load mode

due the heavy hauling. This encourages to reduce the

number of cases of the AC catenary feeder’s RP

devices due to a better choice of their parameters.

ISAIC 2022 - International Symposium on Automation, Information and Computing

398

The core of the research is the development of

method for graphic analysis of RP device parameters

and load parameters of a real railway section. The

facts of the existing theory were used as a basis for

testing the hypothesis that proposed technique for

analysis is suitable for the complex engineering task.

The detecting of the RP false tripping zones was

carry out by means of graphical analysis for the AC

railways power supply system. To begin with, one of

the inter-substation zones between the AC traction

substations was choosen. Then, the operation of RP

devices at 25 kV feeders catenary network at freight

direction was examined.

Statistic data from the monitoring systems

installed on the particular railway section have been

accumulated during the 2021-2022 years. During this

period, the intensity of heavy haul traffic increased by

by 1.25 times. Also, lots of cases when the well-

known algorithms for RP devices cease to work were

detected (Pinchukov and Makasheva, 2019).

The proposed methodology for decreasing the

amount of the RP false tripping at the AC catenary is

based on a five-step approach as follows:

 Accumulation measured data from monitoring

system and their representing in the R-X

diagram;

 Determination load characteristics of catenary

feeders for a particular inter-substation zone

while increasing traffic volumes and train

weights in the R-X diagram;

 Representation the set RP characteristics for

particular feeder in the R-X diagram including

simulation results;

 Identification areas of overlapping of

retractable RP parameters in the load zones

characteristics;

 Detuning RP parameters from the load zones

characteristics.

The first step of the process refers to the

monitoring system data acquisition and analysis.

Based on the analysis of the feeder’s current and

voltage data with heavy hauling conditions it can be

possible to perform an initial step of analysis to

extract meaningful insights and transform into the

graphical view. Next, each step of the proposed

technique was expounded in the sections that follow.

2.1 Research Object Structure

A particular section of the AC railway with installed

distance relay protection devices, as depicted in

Figure 1, was taken for further consideration as the

research object. The section is located on the eastern

freight direction of the Russian AC 25 kV electrified

railways.

Numbers from 1 to 8 in Figure 1 correspond to the

serial numbers of the protective set of relay protection

devices for the AC catenary feeders.

Traction

Substation 1

Traction

Substation 2

Sectioning

post

Power

System 1

Power

System 2

Second track’s catenary

Rail Circuit

Spark Gap

High-voltage breaker

First track’s catenary

Rail Circuit

Figure 1: AC 25 kV Electrified Railway Section.

Spark GapInsulator

Catenary Fider

(Track 1)

Catenary Fider

(Track 2)

Catenary Fider

(Track 1)

Catenary Fider

(Track 2)

Electric

rolling

stock

Traction

Substation 1

Traction

Substation 2

Power

System 2

Power

System 1

Figure 2: Simulation Model Scheme

Graphic-Analytical Method for Detecting the Relay Protection False Tripping Zones

399

2.2 Simulation Model

The simulation model of power supply system for AC

25 kV railway section ander consideration was

created by MATLAB-based graphical programming

environment Simulink 9.8 as shown in Figure 2.

As depicted in Figure 1 and 2 the section contains

AC traction network between two traction

substations. The model includes the equivalents of

two energy systems of limited capacity, two traction

substations, catenaries the first and second tracks, and

a rail circuit. The catenary pole is integrated into the

model for a short circuit simulation. It is possible to

simulate the breakdown of the cantilever insulator.

Also the model has the possibility to change the

operating mode of the spark gap. Simulation of

electric rolling stock is also provided. The model

allows to change both the location and power of the

electric rolling stock.

The model provides changing the parameters of

power systems and traction transformers at

substations. The results of the short-circuit mode

calculation are given for the power of 40 MVA

traction transformers at both traction substations. This

is the most common transformation power for traction

substations of AC electrified railways. The output

power of the power systems was setting in the range

from 1500 MVA to 2000 MVA that is closest to the

output power at a voltage of 110-220 kV nominal

level.

2.3 Data Acquisition and Analysis

The considered section has a automated system for

monitoring the parameters of normal and emergency

modes. All feeder’s measured data like voltage,

current and phase angle between them, are written to

the database in real-time mode (Makasheva, 2016).

The results full-scale measured and calculated

characteristics of the operating modes were put on the

R-X complex diagram. Thus, a data base from field

measurements in operating conditions for a load

mode was collected.

After that, the input resistances measured by RP

in short circuits mode were calculated. Then, data

were put on the R-X diagram as dots. Thus, the areas

at the R-X diagram that correspond to every single

measurement were completed. Next, the angular

characteristics of the distance protection zones while

RP tripping on the R-X diagram were put. After that,

the parameters of possible short circuits were

calculated based on simulation model and also put on

the same R-X diagram. Each time, step by step, new

data was gradually applied to the R-X diagram,

forming the so-called surface layers.

Finally, obtained three-layers R-X diagram makes

it possible to study the conditions of the RP

functioning and detect the RP false tripping causes.

3 RESULTS

Currently, the RP devices used at the considered

section of the AC railway contain four zones of

distance protection (DP) (Andrusca et al., 2021;

Moyo et al., 2019; Pinchukov and Makasheva, 2019).

Three of them react to metal short circuits at a

catenary feeder and have the pie-shape. The forth DP

zone has a quadrilateral shape. The forth zone reacts

to short circuits that occurs through a large contact

resistance. That can arise, for example, while a short

circuit occurs through a catenary pole body (Alstom,

2011; Saha et al., 2010). First and second zones are

used as main protections for the catenary feeder and

the third one reserves the adjacent protection in case

of their failure. An example of the step-by-step

constructing of R-X diagram with comprehensive

characteristic as a graph with several layers are

described below in details.

3.1 Two-Layer Diagram

Load parameters of the 25 kV catenary feeder were

measured experimentally in real operation conditions

for AC railway section at the most freight track. The

RP characteristics was calculated and analysed based

on the measured data. Based on the measured

characteristics of current, voltage and the phase angle

between them, the characteristics of the feeder’s relay

protection were calculated in a well-known way by

means of the classical method for calculating DP

characteristics as shown in (Alstom, 2011; IEEE.

2016; Saha et al., 2010).

RP input resistances in load mode are shown for

one of feeders in Figure 3. The field of red dots in

Figure 3 is consists of the values R-X characteristics

of the DP in the operating load mode. They are

obtained on the basis of the measured parameters. The

field forms the first layer of the R-X diagram, in other

words, the layer of the measured RP characteristics.

The second layer is formed by the angular

characteristics of the DP from the first to the fourth

zones, named in Figure 3 as ‘DP 1st zone’, ‘DP 2nd

zone’, etc. The protection zones were recommended

by manufacturers of RP terminals. Graphically, these

areas are shown as sectors bounded by colourful lines

in Figure 3.

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400

Figure 3: R-X Diagram for AC Catenary Feeder.

Thus, there are two layers were applied in Figure

3 as below:

 The first layer is the measured characteristics

(as the area of red dots);

 The second layer is the set distance protection

parameters adopted in operation (as the colored

pie sectors named DP).

In order to find out whether the DP was correctly

tuned from the load mode, it was needed to plot both

the load area and the short circuit area on the same R-

X diagram. As shown in Figure 4, there are two zones

in the R-X diagram.

Figure 4: Calculated Short Circuit and Measured Load

Mode Parameters.

The red dots area is named as the ‘load zone’.

Each red dot was measured by DP in the load mode

and then plotted to R-X diagram as the DP input

resistance value. The grey dots area is named as the

‘short circuit zone’. Each grey dot was calculated for

DP in the short circuits mode by means of simulation

modeling and the classical well-known calculation

method for the DP parameters (Alstom, 2011; IEEE.

2016; Saha et al., 2010).

Summary, both areas form the two-layer

superimposition at the same R-X diagram. As shown

in Figure 3 and 4, the short circuit zones and the load

zone do not overlap. Thus, the distance protection

should work correctly. Meanwhile, several cases of

the DP false operation have been recorded at the

feeder during the observation period. Operating

experience shows that the DP was tripped false not

once. Thereby, such analysis of Figures 3 and 4 does

not give a clear answer to the question why the RP

false operation still occurs. Further, to find out the

answer, it will be also necessary to analyze the

operation of automatic reclosing devices.

3.2 Number and Causes of Automatic

Reclosing Trips

The statistics facts of automatic reclosing (AR) in

cases of RP devices tripping for the feeder under

consideration for last 4 years were collected and

analyzed. The results are shown as pie chart-

diagrams in Figure 5.

Figure 5: Number of Automatic Reclosing Trips.

The pie chart diagrams in Figure 5 allow

interpreting the actions of the AR and the RP devices

Graphic-Analytical Method for Detecting the Relay Protection False Tripping Zones

401

in relation to load and emergency modes. In order to

find out the causes of false tripping, it is necessary to

consider a number of characteristics that can be

probably added as the third layer to the previously

constructed two-layer R-X diagram.

3.3 Three-Layer Diagram

The third layer was formed from the angular

characteristics of the DP zones, shown in Figure 6 as

colored lines.

The green line in Figure 6 is indicated the angular

characteristic of the DP 3th zone, which is currently

being operated on the feeder under consideration. The

red line is indicated the characteristic that is

recommended by manufacturers of RP terminals to

increase the efficiency and stability of their setting.

Figure 6 shows two angular characteristics of the

DP third zone. The green sector in Figure 6 is a DP

characteristic which is used on the catenary feeder.

Figure 6: Three-Layer Diagram.

This type of distance protection is used on the

entire Russian AC railway network. As shown in

Figure 6 there is practically no margin between the

zone of red dots and the zone limited by the green

sector. It means that there is no DP detuning from the

load zone. Thus, the common third DP zone’s

characteristic does not provide DP detuning from the

load zone.

So, when the third layer was applied to the R-X

diagram, it can be possible to finally identify the zone

of RP false tripping. It is shown in Figure 6 as the

purple oval. Also, the sector circled in red in Figure 6

is the DP characteristic which could provide detuning

from the load area.

Such a quadrangular characteristic is one of the

types of distance protection, which is used in power

systems. There are no devices in Russia with such

characteristics for catenary feeders. Therefore, their

development for areas with high load currents is

extremely important especially due heavy hauling.

4 DISCUSSION

Using the full-scale measurements and simulation

results as input data, it is possible to graphically

evaluate the RP characteristics for their better

detuning from the load modes.

The findings gave reason to suggest that the two-

layer R-X diagram does not able to qualitatively

figure out the relay protection parameters for

detuning from the load area. Therefore, the

assumption of the third layer applying’s advisability

gave a positive effect.

As Figures 1, 2 and 3 show, the main part of the

resistance values is concentrated in the first quarter of

the Cartesian coordinate system. They form areas

with the angles from 30 to 50 degrees. Therefore, the

first quadrant of the complex resistance plane was

limited for better clarity and understanding.

Notoriously, that automatic reclosure is used to

recover the original status of the network. Obtained

data point to facts, that after the successful automatic

reclosure, the voltage is reapplied to the contact

network both in the event of unstable short circuits

and in the event of a false tripping of the relay

protection. In most cases, the main reason for false

RP operation is the RP response to a significant

current load in normal mode.

As follows from Figure 5, the percentage of cases

of successful automatic reclosure for the investigated

feeder was over 80 percent during all four years. The

specified share of the successful automatic reclosure

is not typical for similar sections of AC railways that

have lower load intensity as described in (Han et al,

2012; Hill,1994.).

A significant percentage of successful automatic

reclosure indicates that automatic reclosing does not

occur in emergency mode, but in load mode. That

proves the absence of RP detuning from the load

mode. Accordingly, our findings clearly show the

existing problem in the mechanisms of detuning the

RP parameters from the load characteristics of inter-

substation zones with heavy haul traffic at the 25 kV

power supply system of the railway transport. Thus,

the observation of lots of successful AR cases also

constitutes the evidence that the reason of big

percentage is the RP false tripping.

Next, it was proposed to use the graph-analytical

method to analyse the reasons for the RP false

tripping. After preparation and selection of

measurement data, the two-layer R-X diagram was

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402

created, but it was found, that the two-layer diagram

does not allows immediately identify the reason of the

RP false tripping.

Thus, the problem was solved by simultaneously

considering all characteristics on unified R-X

diagram. Consequently, the shortcoming in the

currently used DP characteristic at catenary feeders

was identified. It was clearly proved that with the

heavy traffic and a further loads increasing, it is

almost impossible to ensure reliable DP detuning

from the load area.

As a result, the proposed graphic-analytical

method for detecting the relay protection false

tripping zones makes it possible to evaluate the

efficiency of the form of the DP angular

characteristic. The described method’s application

can be recommended on heavy haul traffic AC

railways areas of with AC/DC electric locomotives.

At the same time, the described method can be

also used for the RP detuning for power supply lines

of industrial or agricultural enterprises with similar

problems. To continue and develop research in this

direction it is advisable to use the considered

mechanisms to reduce the amount of RP false tripping

in the long term.

5 CONCLUSIONS

The results obtained in the present research

demonstrate that visualization and graphical analytics

can be applying for solving the specific engineering

task. Current results proposed a framework for

analyzing PR detuning and elimination of the RP

false tripping.

The obtained results lead to the following

conclusions:

 The electrical characteristics of catenary

feeders from monitoring systems databases and

revealed an increase in loads during heavy haul

traffic were collected and analyzed

 From the automatic reclosing cases analysis it

was confirmed that the automatic reclosing

does not occur in emergency mode, but in load

mode;

 Shortcomings of the applied DP type while the

heavy haul traffic were highlighted and

explained by visual means with a high

probability;

 New method for visually determination zones

of the load, the short circuit and the DP angular

characteristics was proposed and described in

details;

 It was found out that the existing DP devices

are almost impossible to detuning from the load

area in the conditions of the heavy traffic

increasing, therefore, an urgent need has been

identified for the development of new RP types

for the catenary feeders as soon as it possible.

The practical benefit of the proposed method lies

in its application to tasks of analyses the AC railway

catenary feeder protection. The proposed method will

further develop in the direction of improving the

distance relay protection detuning from the load

zones in relation to the existing and planned AC

railways’ sections.

ACKNOWLEDGEMENTS

This paper was made possible by Russian Railways

JSC as grant No.4663593 dated December 27, 2021.

The statements made herein are solely the

responsibility of the authors.

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APPENDIX

Figure: Fragment of measurements electrical parameters’ database for the catenary feeder by the automatic monitoring

system.

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