Supervisory Control And Data Acquisition (SCADA) Laboratory for Research & Training in Distribution Automation Mini S. Thomas, Parmod Kumar Abstract: This paper reports a unique SCADA Laboratory facility for power systems at Jamia Millia Islamia, New Delhi. It has been designed to function as a research and training center for utilities, faculty members & students. The paper covers the functioning of the SCADA/EMS laboratory facility, based on Distributed-processing technology. The SCADA laboratory is currently providing hands on experience to students and practicing engineers and is giving them an insight into the contemporary SCADA systems. This lab is the first of its kind to be functional in India and may be unique. Keywords: SCADA systems, Distribution Automation, Ethernet, Intelligent Control, Laboratory, Real Time Systems, DCS

I. INTRODUCTION Power is a critical infrastructure for the growth of Indian economy. Acceleration in the economic growth will depend upon a financial and commercially viable power sector that is able to attract fresh investments. Currently electrical energy constitutes about 20% of the total annual energy consumption on a worldwide scale with an ever-rising demand. The power sector in India at this juncture is plagued by a number of problems. These include inadequate generation capacities, poor capacity utilization, very high transmission losses and poor project implementation. Plant load factor in most of the plants has been very low compared to the power plants in other parts of the world. The sector has been bogged down by resource constraints. Not withstanding the massive increase in generation capacities over the past decades, the history of the Indian power sector has been punctuated by shortages, massive pilferages and a demand-supply gap, which has been growing. The shortages have been so chronic that, at times fears have been expressed about a negative impact on industrialization due to these shortages. It is thus imperative that power utilities look at increasing efficiencies in distribution networks, which have among the highest transmission and distribution losses in the world at upwards of 30 per cent. Distribution automation is a tool for enterprise-wide management of an electric utility system. In other words, distribution automation, if properly applied, provides for efficient operations enhances operational outputs and translates into economic benefits. Prof. Mini S. Thomas wishes to thank the All India Council for Technical Education (AICTE), for providing the funds for the project. Mini S Thomas is working as Professor in Electrical Engineering, Jamia Millia Islamia, Jamia Nagar, New Delhi, INDIA 110025 ([email protected]) Parmod Kumar is working as Professor and Head, Department of Electrical Engineering, Delhi College of Engineering, Bawana Road, Delhi, INDIA 110042 ([email protected])

Distribution automation through SCADA systems directly leads to increased reliability of power for the consumers and lower operating costs for the utility. It results in forecasting accurate demand and supply management; faster restoration of power in case of a downturn and a quick, alternate arrangement for power for important/emergency locations. The utilities are in a better position to undertake both active and reactive power management and with better anticipation of trouble and greater trouble-shooting through remote access. Predictive maintenance results in reduced cost of maintenance of power system devices, thereby extending their life. Distribution automation through SCADA also reduces human influence and errors. Although many utilities are talking about distribution automation, this has not taken off the way it should have. There are many reasons for this condition. First of all, the lack of adequate knowledge among utility workforce, about SCADA and distribution automation and the immense advantages the implementation will bring about in the power sector. Hence there is an immediate need for proper training facilities in SCADA and distribution in India, for the distribution reforms initiated by the Ministry of Power to go ahead smoothly. Cost factor is also a hurdle, as the cost of a complete distribution automation system for a major city is Rs 30-50 crore, but the general observation is that once a proper proposal is made, finances will flow automatically from sources. The SCADA laboratory at Jamia Millia Islamia has been set up with the view of providing students and practicing engineers with hands on learning experience on SCADA system, and its applications to the management, supervision and control of an electric power system. The setting up of this laboratory is of utmost importance because SCADA systems, though used extensively by the industries, are the proprietary item of each company and hence very few technical details are available to students and researchers. This laboratory is providing research facilities in the form of hardware and software for adaptive and intelligent control of integrated power systems. Research work on preprocessing data at the RTU level using Fuzzy Logic and Fuzzy-Genetic algorithm has already earned recognition [1, 2]. The significance of the laboratory is highlighted by the developments in substation automation, which is revolutionizing the automation scenario in power systems [3]. One of the unique features of the SCADA/EMS laboratory, that makes it the only one of its kind, is the use of a distributed processing system, which supports a global database. The use of such a system was favored against that of personal computers with data

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II. DESIGN OF THE LABORATORY Large SCADA systems are used in a wide range of applications like power station control, transmission, distribution automation, and smaller SCADA systems are used for industrial automation. In the proposed lab we wanted to give a general idea about SCADA systems which would be applicable to any of the above mentioned processes, in particular for substation automation. Hence designing the specifications for the laboratory was quite challenging and satisfying. SCADA for power systems, distributed in wide geographical areas, is an integrated technology comprising of the following four major components [7]: (i) Master Station: It is a collection of computers, peripherals and appropriate input/output (I/O) systems that enable the operators to monitor the state of the power system (or a process) and control it. (ii) Remote Terminal Unit (RTU): RTU is the “Eye, Ear and Hands” of a SCADA system. The RTU acquires all the field data from different field devices, processes it and transmits the relevant data to the master station. At the same time, it distributes the control signals received from the master station to the field devices. (iii) Communication System: It refers to the communication channels employed between the RTU and the master station. The bandwidth of the channel limits the speed of communication. (iv) Human Machine Interface (HMI): HMI refers to the interface required for the interaction between the master station and the operators/users of the SCADA system. The proposed laboratory has all the above components of the SCADA system with on-line monitoring & control facilities as shown in Figure-1. The master station has two engineering consoles for project implementation and four operator consoles for system monitoring. The SCADA hardware includes a distributed processing unit (DPU), a remote terminal unit (RTU) and a number of analog, digital and pulse input/output units and field equipment. The communication interface includes the Profibus and Modbus modules, and the LAN in the laboratory is through an Ethernet highway. The system software has the facility for easy online configuration for mimics, trends, reports etc. and for web navigation. An 11KV substation, which is supplying power to the Faculty of Engineering and Technology, is being monitored. The prototype model of a 400KV transmission line and on-load tap changer transformer (with auto-transformer and stepper motor) have been developed, monitored and controlled through the SCADA system, to enable the students to have a feel of a real power system. III. SYSTEM ARCHITECTURE The architecture of SCADA system used in the laboratory, among the various processors connected to the data-highway, is of distributed function type. Distributed architecture was preferred as this is modular and expandable in future. The SCADA system used in the laboratory is microcomputer based with functional and database distribution. It has open ended system architecture comprising of the system hardware,

the system software and human machine interface, which are discussed in detail below:

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Figure-1: Overview of the Laboratory

A. SYSTEM HARDWARE: The system hardware comprises of the processing units, the DPU and RTU, two engineering stations and four operator stations. Each of the hardware components is discussed in detail in the following sections. 1. Distributed Processing Unit (DPU): The DPU is configured around a 32-bit Restricted Instruction Set Computer (RISC) processor AC800F with 4 MB memory as shown in Figure-2. It can support up to 100 master less RTUs. At present there is only a single RTU communicating to the DPU. The DPU has a capability of handling more than 1000 inputs and outputs, but it is presently configured for 216 inputs and outputs (digital, analog and pulse). The RTU, DPU and the input/output units are interconnected through the Profibus module. The DPU has the Modbus module for dedicated communication with Intelligent Electronic Devices (IEDs). 2. Remote Terminal Unit (RTU): The SCADA/EMS laboratory has a single RTU that can be stationed at a remote location. Presently in the absence of a sufficiently remote field, the RTU is functioning inside the laboratory itself. The RTU is also equipped with I/O channels (digital, analog and pulse) for capturing the field data, and has the modem for communicating on RS485 link. Like the DPU, the RTU is also configured around a 32-bit RISC processor AC800F. The RTU communicates to the master SCADA system (DPU) through a Profibus. Since the DPU and RTU have the same

hardware configuration and are at the same location, they can act as a redundant system at any time, to depict the actual control room experience.

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The DPU and RTU are currently performing the Data acquisition, system monitoring and control and the Sequence of Events Recording (SOE) functions in the laboratory: 3. Input/Output Units: At present the system has 216 input/output channels, including that of both the DPU and RTU. The analog inputs comprise of the signals coming from the voltage and current transducers connected to the various field devices like the 3-phase transmission line, 3-phase load, etc. The digital inputs/outputs are the capacitor bank on/off positions in the substation and the circuit breaker positions on the transmission line and the load. Apart from these, there are pulse inputs and outputs. 4. Data Highway: The laboratory incorporates industry standard networking. It has an Ethernet data highway (coaxial cable) operating at 10Mbps and is currently supporting a network of four operator stations and two engineering stations along with the DPU and the RTU, all connected in bus topology. The DPU passes real time data to the operator and engineering stations via the Ethernet through customized software. The I/O units are connected to the processor through the Profibus. The Modbus module connects the Intelligent Electronic Device, the Energy Analyzer, to the AC800F. The Modbus is incorporated in the system for performing dedicated tasks and for better understanding of the industrial buses. 5. Operator and Engineering Station: The SCADA system has six Pentium-IV Computers (running in the environment of Windows 2000) acting as the operator stations and engineering stations, so that, at a given time, a maximum of 10 students/trainees can work in the laboratory, two on each station, one station is left for faculty members and R&D work.

Each of the four operator stations provides a customized, interactive, graphic user interface, designed using modern software programming techniques. The entire field can be monitored and controlled from the operator stations. Presently, as the field equipments being monitored are not very vast, each operator station covers the entire field, but in case of a vast field, each operator station can be configured to perform dedicated monitoring of different sections of the field. Two Pentium IV computers are serving as the engineering stations for the system. The engineering station runs the engineering software, programmed using Visual Basic 6.0. The commissioning, adding new hardware, changing the tag settings, and associated tasks are performed at the engineering station using the engineering software. B. SYSTEM SOFTWARE: Currently the laboratory utilizes two system software programs for better understanding and proper utilization of the product available in the market. The first one is hardware specific and dedicated software, whereas the other one is an open-ended system software, which can communicate with any hardware device. This is to make the laboratory much more generalized, rather than constrained to a specific hardware. The SCADA software being used in the laboratory has provision for online configuration facilities like creation, modification, and deletion of process parameters in database, mimics, trends and reports. A web navigator has been designed using Java, to enable process management via Internet. The software has secured control facilities for executing individual digital output points or group of predefined points with a single command. It is capable of supporting standard power system software programs like MATLAB and EDSA. The dedicated software used in the system, Freelance 2000, consists of two main modules: Digivis, the operator software and Digitool, the engineering software. Digivis software offers a user-friendly graphical interface in accordance with MSWindows standard. It provides a comprehensive, standard and free display logging, graphics and display facilities including trend archiving, system diagnostics, etc. Both free display and graphic displays are user-defined and are created using the graphic editor in the Digitool. The archived trend and log files are viewed using Digi Browse. Digi DDE (Dynamic Data Exchange) permits to convert data to ASCII format, making it readable by third party softwares. The Digitool, also known as control builder, is operated in configuration mode where, the project is structured, configured and documented. Configuration can be processed off-line. The project objects are assigned to the hardware structure as part of the system configuration, and can then be downloaded when the connection is later made on-line. Digitool can handle all types of IEC 61131-3 programming languages like the Function Block Diagram (FBD), Instruction List (IL), Ladder Diagram (LD) and Sequential Function Chart (SFC). All the back end programming is done in Digitool using functional blocks along with the appropriate logic functions. Digitool is a highly extensive module with several useful features such as visual and sound alarms, trend display, time stamping etc. Report of all field alarms and system alarms along with time stamping, description, state and current value is generated. Alarms (visual as well as audio) can be set and displayed as per the requirement. All

unacknowledged alarms remain in flashing mode till they are acknowledged. Trend display is another useful tool of this software. By trend display we mean the display of variation of different parameters such as voltage, current, frequency, temperature etc. with time. The software can be configured to give both the past and the current trends. From these trends, we can predict the next trend also. These trends appear in the form of colorful graphs and can be given oscilloscopic form by choosing appropriate scales. This feature makes the software more user-interactive. This allows the students to reconstruct the sequence of events in case of a fault. Open ended software: SCADA portal is an open system software, which enables one to develop highly interactive HMI for remote control and PLC applications. It combines the unique usability features found in HMI with simple integration of control equipment and a variety of IEDs. It can communicate with locally and geographically distributed devices through communication protocols like OPC and Modbus. The applications in SCADA are based on object oriented principle. In the SCADA lab, we have configured SCADA portal using both OPC and Modbus protocols. C.HUMAN MACHINE INTERFACE (HMI). HMI refers to the communication between Man and Machine and is of utmost importance in modern computer based control systems. The HMI in the laboratory has been developed to make it highly descriptive, interactive and user friendly. This was done in order to enhance the student’s perception of electrical power systems and their performance. The control elements of the power system and other field devices are graphically modeled on a color monitor. The graphics have been developed in almost an exact replication of the real time field setup, depicting all the field devices exactly as their layout in the laboratory. The control fields have been designed in the form of buttons having different color schemes for depicting different operating conditions such as red for “off” and green for “on”. The different visual alarms keep flashing on the top of the screen, till they are acknowledged. The HMI has been designed using both the softwares available, the Digivis and SCADA Portal. IV. FIELD DESIGN The foremost task in the designing of the laboratory was, defining the power system to be monitored and controlled. This was done taking into account adequate scope for expansion of the system in future, and the latest facilities available in instrumentation and monitoring areas. A number of big industrial houses involved in power system SCADA were contacted, and detailed discussions were carried out with the experts in the field. Also a study of the available industrial SCADA systems was done. Finally, the power system to be monitored, the configuration of the laboratory and the specifications for the field device were finalized. The laboratory field presently comprises of the following: • An 11KV Substation feeding the Faculty of Engineering building, Jamia Millia Islamia. • 3 phase transmission line model, complete with reactive and capacitive compensation. • Energy Analyzer

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Prototype model of on load tap changer (OLTC) using stepper motor and autotransformer. • RTD, level Sensors, transducers, contactors Substation monitoring: Provision has been made for the monitoring of an 11kV/440V substation at Jamia Millia Islamia. The substation is located about 150m from the SCADA Laboratory. Exclusive cabling has been laid from the substation up to the SCADA Lab with proper earthing. Voltage, Current, frequency, phase angle and power factor transducers have installed and real time values from the L.T side (440V) of the Transformer have been made available in the SCADA Lab. The substation has 8 capacitor banks installed for power factor corrections, which are automatically switched on depending on the power factor. The On/Off positions of the capacitors are also fed in the DPU as digital inputs.

Figure-3: The three phase transmission line set-up with autotransformer and stepper motor with drive.

Three-phase Transmission Line: The transmission line model as shown in Figure-3 was built to simulate the real time distribution conditions in the laboratory, so that students could get a hands on experience of phenomenon such as Ferranti Effect, Series and shunt compensation etc. by performing experiments on the system. The transmission line model kept in the laboratory is a scaled down Π-model of a three-phase transmission line. The actual field parameters of the existing line were obtained and were scaled down to 230V, 5A range. The parameters for a 10-section Π-model were computed and the actual inductance values per section obtained. The inductances were designed and wound in the lab itself and the capacitors were obtained readymade. The entire section bearing the capacitance and the inductance was enclosed in wooden boxes with covers. After assembling the lines, testing was done and satisfactory results were obtained with Ferranti effect and other line parameter studies. Each of the 3 phases of the transmission line is connected via autotransformers. The Isolators perform the switching operation and are energized from the operator stations. Current and voltage transducers are connected to sense the incoming voltage and current of each phase, depicting the current and potential transformers on the actual line. Figure-4 shows the transmission line graphics on the HMI screen.

To give the students a fair idea of control devices, a 10kgcm torque stepper motor with autotransformer has been used as an On-Load-Tap changer, connected to the transmission line model. The stepper motor has been mounted over the autotransformer and can be driven by the operator console with pulse inputs.

Figure-4: Transmission line model graphic

A 3-phase resistive-inductive/capacitive load has been designed and developed to act as the power system load. V and I transducers as well as contactors are connected between the transmission line and the load to measure the voltage drop in the transmission line and also to perform switching operations of the load. The reactive and capacitive compensation of the line during full load and light load conditions are clearly demonstrated using the careful variation of the capacitive and inductive loads. Energy analyzer: The SCADA lab has an Intelligent Electronic Device (IED), a three-phase energy analyzer, connected to the incoming 3-phase supply through the Modbus module to the system. It can monitor up to 25 parameters and is currently configured for the Frequency, 3 phase currents (Ia, Ib, Ic), three phase voltages (Va, Vb, Vc), power factor, real power and reactive power. It directly measures the phase and a neutral voltage, frequency, phase currents and computes other quantities such as voltage between lines, phase power factors, phase active and reactive energies and three phase system energies etc. V. COMMISSIONING Commissioning of the laboratory involved the following main tasks: • Physical wiring of the devices • Earthing • Tag allocation • Software customization • Graphic design Once all the field devices including the transmission line model were finalized and obtained in the laboratory, the main

task was to connect them to the DPU and provide proper grounding schemes. The connection of the various analog and digital devices to the different Input/output channels in the DPU has already been described in the earlier sections. Ferrules bearing the appropriate tags have been attached to all the wires connecting the devices to the I/O channels, for easy identification and tracing, in case any change has to be made. The entire system has been earthed as per industrial standards. Tag allocation for various devices was an easy task as memory mapping in the system is automatic and a device connected to the appropriate channel is identified by the system on its own and the users can provide the tag of their own choice. Software customization was done by generating Functional Block Diagrams (FBD) for each of the field devices and then applying the appropriate logic. Audio and Visual alarms were set to indicate different conditions in the devices for e.g. when the Transmission Line current exceeds a particular limit, both audio and visual alarms are generated. Graphical trends were generated for constant monitoring of the different parameter changes with time. Different parameters such as voltage, current, frequency etc. have been plotted in different colors for easy monitoring. Apart from the trends, a second by second record for each of the parameters is maintained in the system. No external circuit/device is employed for this function as all the data coming from the DPU is already time stamped. All the graphics as mentioned earlier have been designed in an exact imitation of the actual field devices and their layout. The actual monitoring of the field is done through the Digivis module of the software. The graphics are highly interactive and easy to understand. VI. CONCLUSION The SCADA/EMS Laboratory has been designed and commissioned to facilitate the understanding of real time monitoring & control of systems for Electrical Engineering students and professionals. The Laboratory is first of its kind where the students will get hands on experience on the on-line monitoring and control of the Electric Power System. The laboratory was conceived and designed after extensive consultation with Industries and utilities. The components of SCADA systems, master station, RTU, different communication channels and a variety of field equipments are available in the laboratory. The data acquisition is with time stamping, which will lead to sequence of events monitoring. A 3-phase transmission line model with on-load tap changer and static VAR are the highlights of the field equipments. The laboratory gets on-line data from the 11KV substation feeding the Faculty of Engineering. The laboratory has two engineering stations and four operator stations at present, with 216 Input/output units, which can be expanded to 1000. Overall, this laboratory will provide the undergraduate and postgraduate students with a better understanding of industrial SCADA systems, especially as SCADA systems at present are proprietary items of each company. It is proposed to add redundant data highway using fiber optic cable soon. The SCADA Laboratory is primarily used for regular research and training programs for the benefit of Faculty and students of Jamia, in order to give them hands on experience on SCADA systems. Another major emphasis is on doing industrial consultancy and research for the benefit of Industrial

houses. In addition, there are regular training programs for practicing engineers on SCADA systems. The courses are modular and would suit both practicing and fresh engineers. The SCADA lab has already trained a large number of engineers from various electricity boards in India and practicing engineers from the Industrial automation sector. Overall, the SCADA lab designing and implementation was a challenging, passionate and fruitful experience. VII. ACKNOWLEDGEMENT The authors wish to thank Mr. Somendra Kumar, General manager, ESPL, for the necessary advice from time to time in implementation of this project. Thanks are also due to M/s ABB and M/s Industrial IT solutions for the help rendered. VIII. REFERENCES [1] Parmod Kumar, V.K.Chandna, Mini S.Thomas, “Intelligent Algorithm for Pre-Processing Multiple Data at RTU”, IEEE Transactions on Power Systems, Vol.18, No:4, November 2003, pp 1566-1572. [2] Parmod Kumar, V.K.Chandna, Mini S.Thomas, “Fuzzy-Genetic Algorithm for Pre-processing Data at RTU”, IEEE Transactions on Power Systems, Vol. 19. No: 2, May 2004. [3] John D. McDonald, “Substation Automation IED, Integration & Availability of Information” IEEE Power & Energy Magazine, Vol-1, No.2, March/April-2003, pp-22-31. [4] S.P. Carullo, C.O. Nwankpa, “Interconnected Power Systems Laboratory: A Computer Automated Instructional Facility for Power System Experiments”. IEEE Transactions on Power Systems, Vol 17, No: 2, pp215-222, May 2002. [5] K.K. Tan, T.H.Lee, C.Y.Soh, “Internet-based Monitoring of Distributed Control Systems-An Undergraduate Experiment”, IEEE Transactions on Education, Vol45, and No: 2, pp128-134, May 2002 [6] B. Qiu and H. B. Gooi, “Web-Based SCADA Display Systems (WSDS) for Access via Internet,” IEEE Transactions on Power Systems, Vol.15, No.2, pp681-686, May2000 [7] “Fundamentals of Supervisory Systems,” IEEE Tutorial Course, 1991, 91EH0337-6 PWR. [8] “Automating power distribution”, Alfred Manohar, ABB, http://www.blonnet.com/businessline/2001/08/01/ stories/040156ma.htm

IX. BIOGRAPHIES Mini. S. Thomas (M-88, SM-99), graduated from University of Kerala in 1984, completed her M.Tech from IIT Madras in 1986 (both with gold medals) & PhD from IIT Delhi in 1991, all in Electrical Engineering. Her employment experiences include Regional Engineering College, Calicut, Kerala, Delhi College of Engineering, New Delhi and presently as Professor in the Faculty of Engg. & Tech., Jamia Millia Islamia, New Delhi. Mini S. Thomas received the prestigious ‘Career Award’ for young teachers, instituted by AICTE, Govt. of India, for the year 1999. She has published over 20 papers in International/National Journals & conferences. Her current research interests are in SCADA/EMS systems and intelligent protection of power systems. Parmod Kumar has received his B.E., M.E., and Ph.D in the year 72,75 and 1982 respectively. After post-graduation in Measurement and Instrumentation, he joined M.P.Electricity board, M.P. (INDIA), as assistant Engineer and commissioned telemetry and SCADA instruments at sub-station, power stations and central control room. In 1983, he joined central electricity authority as a Deputy System Engineer and designed and configured the load dispatch centers for electric utilities. Subsequently, he served on various capacities to Indian Railway Construction Company, ERCON, ESPL, ESTC, and then entered in academic life in 1991. His area of interest is smart and intelligent system design, operation and control.