Presented By:-Animesh Verma074003Student Electrical EngineeringFaculty of Engineering, DEI-Agra

SCADA A MYSTERY???INTRODUCTION

SCADA is not a specific technology, but a type of application.

SCADA stands for Supervisory Control and Data Acquisition, any application that gets data about a system in order to control that system is a SCADA application.

Some of the industries where SCADA is used are •Electric power generation, transmission and distribution•Water and sewage•Buildings, facilities and environments•Manufacturing•Mass transit•Traffic signals

WHAT'S COMING UP…A SCADA application has two elements

The process/system/machinery you want to monitor power plant, a water system, a network, a system of traffic

lightsNetwork of intelligent devices that interfaces with the

first system through sensors and control outputs gives ability to measure and control specific elements of the

first systemYou can build a SCADA system using several different

kinds of technologies and protocols. This white paper will help you evaluate your options

and decide what kind of SCADA system is best for your needs.

And a illustration of application with IEEE standard SCADA on power system.

VALUE OF SCAD TO YOU…Maybe you work in one of the fields I listed; maybe

you don’t. But think about your operations and ask:-Does your equipment need an uninterrupted power

supply and/or a controlled temperature and humidity environment?

Do you need to know — in real time — the status of many different components and devices in a large complex system?

Do you need to measure how changing inputs affect the output of your operations?

What equipment do you need to control, in real time, from a distance?

Where are you lacking accurate, real-time data about key processes that affect your operations?

DETAILED WORKING OF SCADA SYSTEMSA SCADA system performs four functions:

1.Data acquisition2.Networked data communication3.Data presentation4.Control

These functions are performed by four kinds of SCADA components:1.Sensors (either digital or analog) and control relays that

directly interface with the managed system.2.Remote telemetry units (RTUs): Small computerized

units deployed in the field at specific sites and locations.3.SCADA master units: Larger computer serve as central

processor. Provide human interface, automatically regulate managed system.

4.Communications network that connects the SCADA master unit to the RTUs in the field.

WORLD’S SIMPLEST SCADA SYSTEM

Obviously, a real SCADA system does more than this simple model. But the principle is the same.

A single circuit that notifies you of one event. Imagine a fabrication machine that produces

widgets. Every time the machine finishes a widget, it

activates a switch.The switch turns on a light on a panel, which

tells a human operator that a widget has been completed.

•First generation: "Monolithic"•No networks•Independent systems•proprietary protocols•Redundancy at data

•Second generation: "Distributed“•LAN introduced•Task division among stations•Reduced size and computational aids•Proprietary protocols

•Third generation: "Networked“•Use open system architecture•WAN introduced•Data sharing possible

SCADA ARCHITECTURES

Step:1 :Data Acquisition:- Begins at the RTU or PLC level and includes metered readings and Equipment status reports , which are communicated to SCADA as required.

Step:2: Data Transport

Step:3: HMI------SUPERVISOR

Step:3: Alarm handling

Step:4: Database Management System

STEPS INVOLVED IN SCADA

Data Acquisition Hundreds and thousands of sensors Two types (1) Discrete Input-----equipment status ON/OFF power ON/OFF Trip Wire alarms

(2) Continuous Input--Complex situations

Continuous changes in Voltage and current, fluid levels in tanks.

Advanced Systems (4 Threshold alarms) Major Under, Minor under, Minor over , major over

Usually done Using RTUs and PLCs RTU will telemeter the data PLC has computational capability does localized control PMU has GP system has synchronizing capability

Data Communication

Usually done over Radio, Modem or Dedicated serial lines

Recent trend on Ethernet and IP over SONET for Security LAN/WAN but not Internet

Converts Information into Protocol format

Standard protocols are IEC 60870-5-101 or 104, IEC 61850 and DNP3. These communication protocols are standardized and recognized by all major SCADA vendors

Fig 1: Block diagram of SCADA

Data Presentation

Through specialized computer known as HMI or HCI (Human Computer Interface)

Data processing, Log maintenance, Historical Trends.

Control if machine is braked down- Production can be stopped If machine is running good Production can be increased

Automatic control

Electricity production can be adjusted to meet demands on Power Grid

SCADA system ---communicates---processes----Human display.graphical representation, in the form of a mimic diagram

Fig2:- Block Diagram of a wireless SCADA

Communication using Wireless Network

REQUIREMENTS OF A SCADA SYSTEM

SCADA – RTU Sufficient capacity for future needs Rugged construction to Withstand temperature and humidity Continuous power supply (battery + External ) Non Volatile Memory (NVRAM) To store data when power is lost Real time clock for time stamping of reports

SCADA MASTER 24/7 Automatic Pager and Email Notification, avoid continuous

starring Detailed info display:- with understandable language. Extension Capability:- since SCADA is a Long term investment

(10-15 years) Back Up facility : If one master fails other should operate.

PMU Synchro phasor- phasor measurements that occur in same time Time Stamping Given by “GPS Radio clock” Theoretical accuracy is better than one Micro second

Fig3: Block Diagram of Phasor Measurement System

Where,PDC: Phasor Data ConcentratorsPMU: Phasor measurement UnitsWAMS: Wide Area Measurement Systems

Courtesy: anonymous, Fig3, http://www.macrodyneusa.com/model_1690.htm

PHASOR MEASUREMENT SYSTEMS

APPLICATION OF SCADA IN POWER SYSTEMTrans Power’s adoption of

new, centralized sub transmission SCADA architecture ((a) in Figure 2).

This relies on a PC full graphics terminal located remotely at each Area Control Centre (ACC) connected to National Control Centre (NCC).

Trans Power previously had implemented distributed systems Similar to (b) in Figure 2 (control did not have 100% overlap).

DISTRIBUTED & CENTRALIZED SCADA

Concern over the apparent reduction in reliability caused by the removal of a master station and consequent dependence on a single master.

Comparison of the differences between these two architectures is presented as a detailed example of the application of the composite reliability analysis algorithm.

The objective of the analysis is to calculate the expected amount of unsupplied energy attributed to a SCADA failure.

ANALYSIS ALGORITHM

Flow chart for analysis algorithm

1. Generate a SCADA and power system state based on individual component reliability’s and determines which busses the Operator has control of. 2. If there are no power system failures then there will be no load curtailments.3&4. If there is sufficient, available generation to meet the load then it may be possible to re-schedule this subject to circuit constraints. This is done using a dc load flow.5. This step is based on the linear programme based optimal power flow (OPF) The OPF minimizes load curtailment by rescheduling generation subject to branch and generation capacities.

ANALYSIS ALGORITHM CONTD…6. Compare whether loads curtailment and SCADA

control failure has occurred at the same bus or busses. This is perhaps a harsh simplification.The real question at this step is whether, given a load

curtailment, SCADA can restore the power system to full load?

For example in Figure 5 if a load curtailment occurs at bus 7 due to a circuit outage on its feed from bus 8 then SCADA control would be required at both busses 7 and 8 to restore the load at bus 7.

Whilst this is a straight forward example, analysis of this situation becomes more complex at more heavily meshed busses. Hence this is an area of ongoing study.

7. Accumulate the total power not supplied at busses where SCADA control has also failed.

Figure 5.IEEE reliability test system split into areas (loads and reactive power sources omitted)

Figure 4. SCADA communication topology for IEEE test System area 1

CONCLUSIONA brief startup of SCADA makes the concept

of this new process to be suggested as emerging trend in control systems.

Application of SCADA to power system reliability problem suggests the efficient operation with increased reliability.

With prime need of reliability and efficient optimized cost operation of big systems SCADA promises an advanced solution.

THANK YOU!