Substation Load Share

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Communication and Load Balancing Using SCADA

Model Based Integrated Substation

Abstract With the increase in automation, the industrialcontrol systems are automated with computers. Computer

control and monitor the industrial operations that exist in the

physical world with virtual simulation tools. In this paper, we

present a SCADA (supervisory control and data acquisition)

based fully automated master station in the integrated

substations environment. The idea is, to enable all the substations

to communicate with master station and to balance the load

through SCADA model. The scenarios we are taking into the

consideration include automatic load balancing. Load is balanced

in two modes namely, manual mode and automatic mode. This

model helps the engineers and research scholar to test their

system before the real implementation. This model for integrated

substations drastically reduces the time latency if compared with

conventional model. It reduces the time as well as human

intervention in the critical tasks such as responding to faults, load

balancing actions, etc. The proposed model is fast, scalable,

flawless and robust.

Keywords SCADA, Master station, integrated substation,automatic load balancing.

I. INTRODUCTIONIncreasing progress towards digital technology leads to

the electric substation automation. In which digital

communication takes place between electronic transducers,

digital protective relays, and other component of the

automated substation. In conventional substation the point to

point wiring were used for transferring the analog data. This

data is not suitable for high speed transmission. Many

researchers in the world are doing study for making electric

substation automated. New development in the field of

microelectronics have led to the novel design and testing of

many equipment of the automated substation. The devices

which have been developed includes like microprocessorbased digital relay, microprocessor based fault event recorder,

digital alarm sequence recorder and digital current and voltage

transducers. These types of devices are generally capable of

sending and receiving the data in the digital form. Further step

in substation automation is to develop the communication

network like local area network (LAN), Wide area network

(WAN), or on internet bases with in the substation and other

devices are connected such as SCADA system [1].

The purpose of the paper is to incorporate a SCADA

based communication network between master station and

substation and also to balance the load in the substation. The

proposed model has the advantage to operate in real time. This

is done by directly connecting the integrated output obtained

through different IEDs, digital relays and energy meter etc. to

SCADA model. With this, SCADA model will display the real

value of the process occurring in the substation. On the basis

of obtained real time values the SCADA model will work.

This model has many advantages as it reduces the cost ofhardware connection while providing the fast, convenient

protection, and data transfer capability. Main focus is on real

time information i.e. the state of the substation can be obtained

at any instant. Hence, this increases the overall reliability of

the substation [6].

This paper includes the study of following, as listed below:-

(1) In this paper, we study the digital technology used in

station (WAN or internet) communication network, which is

developed to integrate the protection, control and dataacquisition using SCADA model.

(2) This paper proposes a SCADA based model to

communicate the master station and the substation as well as

to balance the load between different substations. It includes

master station from where the main control is done.

Substations are divided in to four zones. The communication

is done in a fast effective way.

(3) In addition, to balance the load, the operation is carried out

by two modes of operation namely; manual mode and

automatic mode. With the help of any of the mode the load

can be balanced.

II. CONVENTIONAL SUBSTATIONFor long period, the conventional substation was built on a

set of a standalone system. Each subsystem requires separate

wire sets and physical connection from the switchyard to themaster station. In conventional substation the monitoring and

control is done from the central location but the information

obtained at the master station is limited. Mostly systems are

standalone and non-remote accessible. Standalone systems are

characterized by inherent redundancy in data acquisition and

control circuits [1]. Each sub system has its own separate

Neha Kardam

School of Engineering,Gautam Buddha University,

Gr. Noida, [email protected]

M. A. Ansari


Gr. Noida, India

[email protected]

Farheen


Gr. Noida, India

[email protected]

978-1-4673-6150-7/13/$31.00 2013 IEEE 1256


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input and output circuits. Figure 3 shows the conventional

substation panel/rack wiring. It shows how complex wiring is

used in conventional substation for data communication.

Conventional substations are made using standard

design. High voltage switchgears are put in combination with

copper cables for all the interfaces between the primary and

the secondary equipments [1]. According to the substation

size, its location and by its control and monitoring complexity,

the large numbers of cables used are decided. These cablesused are of different lengths and sizes according to the use.

They are installed in substation and are cut in specific length

with respect to the requirement. If in case any fault occur

or any malfunction arise in substation then these cables gets

damaged.

Fig.1.The conventional substation

In such conditions cables are replaced by new cables

and again they are cut in to specific lengths, so this becomes

the labor intensive process. This is true especially in the case

where old substations are rebuilt when insulation deteriorate.

The distances that cable wires are needed to cover between

different equipments in the substation are exposed to

electromagnetic transients [1]. This leads to possibility of

equipment damage and event failure.

Hence such failures in the substation prevail to the

unhealthy protection and control operation. In some cases for

the purpose of the safety issues the open CT circuits are used

while the primary is energized. Under these circumstances the

secondary e.m.f. is so high that it may danger to the peoples

life.

Fig.2. Conventional substation panel/rack wiring.

III. SCADA SYSTEM USED IN SUBSTATION AUTOMATIONSince early 1980, SCADA system are recognised and came

into existence [3].SCADA system are the industrial control

system. These system works on computers. They control andmonitor the process that exists in the physical world. SCADA

systems have three important components, which are as

follows:

A. Master station behaves as a centre to monitor and controlthe data obtained from the zone station.

B. Zone station is working as a mediator. As it takes datafrom the substation and sent the data to the master station.

Master station responds according to the data obtained and

sent back to zone station. Zone station sent the response of

master station to the substation equipments.

C. Equipments are used to make the communication betweenthe master station and the zone station [4].

Initially SCADA systems were dominated by the zone

station which is equipped with RTUs that has proprietary

protocol [4]. With the advancement of the digital technology,

SCADA systems are connected with various components suchas RTU, IEDs, Energy meters, I/O modules and gateway with

different protocols. Gateway is defined as the network node

which is equipped for interfacing with the other networks with

different protocols. Gateway can communicate with the

impedance matching devices, RTUS, rate converters IEDs,

energy meters, and fault isolators are connected to provide thesystem interoperability. Gateway should have redundant

communication port [4]. Gateway is essential features for

routers; it can do arithmetic and logical calculations. Gateway

can be connected to two or more control station with different

protocols for communication. Gateway is also connected tohuman machine interface (HMI) which act as a replacement of

the control panel of the substation. Intelligent Electronic

Device (IED) is the microprocessor based controllers in power

system. Its function is to receive data from the power

components and then to issue the control commands such as

Protectionpanel

Protectionpanel

Protectionpanel

Protectionpanel

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tripping circuit breaker or sensing alarm etc. In zone station,

IEDs are installed to communicate with the gateway according

to the specified protocol standard. Human machine interface(HMI) is a computerized device with which user can interacts

with the SCADA system. In HMI system, user can provide the

input and the system can provide the output to the user in

response to input. Local HMI means single computer with the

application of HMI [4]. For substation automation the standard

protocol has been provided namely, IEC 61850. With the helpof IEC 61850 the communication can be established between

local HMI and gateway. Figure 4 shows the communication

between the master station and the zone station.

CONTROL CENTER

-- - - - -Fig.3.Zone Station Configuration [4].

IV. WORKING WITH WONDERWARE INTOUCHA wonderware intouch, Human machine interface (HMI)

finds application in the industrial environment, where

electrical components can be represented graphically. Plant

operator monitor and control the industrial process with this

user friendly graphical interface. An intouch HMI applicationdefines a tag as a data item [5]. Tag can be used to make the

specific component accessible as data item from a

manufacturing environment [5]. Intouch consist of three main

components namely:

A. The intouch application managerIt is used to organize the applications that we create. It is

also used to configure the following: Window Viewer as an

NT server, Network Application Development (NAD) for

client and service based architecture, Dynamic Resolution

Conversion (DRC).

B. Window MakerWindow Maker is the development scenario, where object

oriented based graphics are created. These windows can be

connected to the industrial I/O systems for different

applications.

C. Window ViewerWindow Viewer is the runtime scenario. In this the

developed work in Window Maker can be made to run or

executes.

Historical data, real trends, and alarm events etc can beobtained with the help of Wonderware intouch. Each tag is

configured while preparing the model. Type of tag is defined

according to the type of tag input. Script is implemented in the

application key of the model for balancing the load, and to

find the real trends for each zone. Sliders are used to define

the working voltage range of the substation.

V. PROPOSED SCADA MODELThe proposed SCADA model is prepared in Window

Maker application of wonderware intouch software. The

developed model is run or executed in Window Viewer

application of wonderware intouch software. Several windowsare prepared to make the model. It is the replica of powersystem control station which exists in the physical

environment.

User id and password is needed to open the power system

grid. Once the power system grid is opened, the home page

appears. Home page consist of the main master station and is

connected with four different zones namely zone 1, 2, 3 and 4.

Master station is the one from where the main control is

executed. When particular zone is clicked then the separate

window will appear. Each zone has its own substation

environment. From home page, the main page for substation

control can be opened. In main page master station is

connected to four zone stations. In this windowcommunication takes place between master station and zone

stations. From home page load balancing window can be

opened. In load balancing window there are three boards. First

board consists of master station and each button for four

substations. Second board is used for manual balance for load.

It consists of different buttons for load balance and reset

button for switching OFF all substations. Third board is used

to balance the load automatically.

VI. RESULTS AND DISCUSSIONBelow are the screen prints of the proposed SCADA

model. The developed model is obtained from Window

Maker. When the developed model is executed in Window

Viewer, we get the following results in the form of screen

print.

A. Communication Between Master Station and Zonestations

Figure 4 shows the main power system grid. Before

entering to the power system grid, user password is required.

GATEWAY

METERENERG

Y

I/OMODUL

ES

IED IED

S

HMI

SWITC

H

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B. Load Balancing In SubstationLoad balancing window consist of master station board,

four substations and two boards of load balancing operation.

The load balancing is done in two modes, which are as

follows:-

1)Manual mode It is represented by load balancing board asin figure 9.

2)Automatic mode - It is represented by automatic loadbalance board as in figure 9.

Master station consists of four buttons as s1, s2, s3 and s4.

S1 is substation 1 similarly all substations are defined. Theworking voltage which we have taken into consideration for

substation is between 0 to 60 KV. If voltage increases above

60kv then substation turned OFF. In figure 9 below the entire

substation are in OFF mode.

Fig.9. All substations are in OFF mode

1. Manual mode:In figure 10, substation 1, 3 and 4 are turned ON

manually while s2 load exceeds so it is turned OFF

automatically. In such condition load is balanced manually by

clicking s1s2 button on load balancing board. Pink colorshows that load has been shared between substations. For

example; load has been shared between s1 and s2 as shown in

figure 11 on master station board.

Fig.10. s1s3s4 substations are ON while s2 is faulty

Fig.11. Manual load balance between s1 and s2.

Similarly if s3 load is exceeded as shown in figure

12, then it is balanced by single click on s2s3s4 button asshown in figure 13. Load is shared by s2, s3 and s4. The same

way if any of the substations load exceeded then it can be

balanced manually by entire four substations, by single click

on s1s2s3s4 button.

Reset all is used to turned OFF all the substations

simultaneously to 0kv.

Fig.12. s1, s2 and s4 are turned ON while s3 substation faulty

Fig.13.s2 load balanced by s2, s3 and s4.

2. Automatic Mode:In automatic load balance board, when set all is clicked

then the entire substations are turn ON. It will run

automatically. When any of the substations load exceeds or

become unbalanced then the entire substation will balance the

load as shown in figure 14.

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Fig.14. Load is balanced automatically.

VII. CONCLUSIONIn this paper, we have reviewed the conventional

substation and substation automation using SCADA. SCADA

based substation model has been presented. In addition,

substation communication and load balance has beenanalyzed. SCADA model can help in the development of the

substation automation.

It includes:-

Time saving while balancing load. Saving in the maintenance of the cost and failure

identification.

Flexible operation, easy to adapt. Handy interface. Entire information of the state of the

substation is available at a single location.

Reduction in space of the control centre.Although the system is very good and outperforms

the current state of art, yet there are problems like too manyrequests from the substation to the master station may lead toconjunction problem. If the master station fails, whole system

goes down. It is expensive to maintain this type of computing,as it requires IT professionals to maintain the master stationand other technical issues.

ACKNOWLEDGMENT

We are very thankful to the Dean of School ofEngineering who encouraged us to work on this project andunder their valuable guidance this work was carried out. Theywere the constant source of encouragement in the completionof our research work. This valuable guidance is not onlyuseful in completion of our work, but it is a constant source ofinspiration for us in our future life.

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