The heart of this complete supervisory control and data acquisition (SCADA) solution is CMC's application software OSKER (Open Scada Kernel), which adheres to POSIX and ANSI C standards. It is based on a distributed architecture and supports the Oracle relational database management system (RDBMS).

OSKER provides corridors to the external world for easy access to SCADA data and functions, through service libraries. A wide range of customisation is possible through configuration editors for different features. It supports a powerful rule-based facility with an online rule editor to trigger actions like alarms and report generation, message display and device control. It is a highly user-friendly, expressive and effective X / Motif-compliant, fully graphic interface. This rich user interface provides multiple windows and features like zooming, panning, layering and de-cluttering.

The software consists of a set of closely interacting software modules that carry out the functions of real-time data acquisition and supervisory control, data processing, handling operator interactions and report generation.

The functions of the SCADA system are:

	Acquiring data from field equipment
	Processing the acquired data
	Generating alarms and events
	Automatic and supervisory control
	Presenting the data, alarms and events to the operator
	Logging the data
	Generating reports
	Supporting online configuration of the system
	Group control
	Interlocking through software as a back-up to the field interlocks (an interlock is a device or instruction that coordinates two or more processes and prevents one operation from interfering with another)
	Redundant hot standby for both the host and the front-end processor (FEP)

OSKER sub-systems are:

	Data acquisition sub-system
	Calculation / conversion sub-system
	Analog point monitoring sub-system
	Discrete point monitoring sub-system
	Accumulated value sub-system
	Situation monitor sub-system
	Control sub-system
	Display sub-system
	Log sub-system
	Reports sub-system
	Switchover sub-system

Data acquisition sub-system
This sub-system resides in the FEP. It handles data acquisition from and control to the field. Tele-metered parameters like voltage and current are captured using remote terminal units (RTUs), which are connected to suitable field instrumentation like meters, transducers, etc. The acquired data is processed to make it relatively protocol-free and is updated in the local database. The changed data (report by exception) is sent to the main sub-system.

The dual-redundant FEP provides a high reliability to the field interface. When the host system fails, the FEP continues to acquire data from the field and buffers it locally. After the re-establishment of communication with the host, this buffered data is uploaded. This provides the end-user with the exact timing details of status events.

Multiple dual-redundant FEPs can be connected in a system to cater to a large number of communication channels.

Calculation / conversion sub-system
Some of the analog, discrete and accumulated values received from the field may be raw values. They are converted to engineering values, based on pre-defined equations, using linear, non-linear look-up tables. Each point in the system can have a separate equation depending on its field connectivity.

Engineering values received from the field are updated without going through a conversion process. All these points are validated against their pre-defined reasonability groups. The converted analog values are checked for zero suppression and the appropriate values are suppressed to zero.

Some new values are calculated on the basis of those received from the field. The software makes it easy to create an arithmetic equation through a user-friendly expression builder. Total power import, power consumption, etc, can now be calculated. Such an intelligent calculation engine avoids the connection of every point in the field, providing a cost-effective solution. The calculated values are also checked for their validity. Reasonable values are passed on for further processing.

Analog point monitoring
Analog values received from the calculation / conversion sub-system are validated against the operator-defined alarm limits. Alarms of various priorities are generated, based on the level of violation. These violation conditions are user-definable through friendly graphical menus. When a value returns from an alarm range to a normal range, the existing alarm is made non-persistent and an event is generated.

Values acquired from the field as well as those calculated in the software pass through the analog point monitoring sub-system. Low limit violation; high limit violation, very high limit violation, etc, are a few cases for analog point monitoring.

Through the MMI, the operator can block the generation of alarms at any individual point. The new value is intimated to the log / report and display sub-systems.

Discrete point monitoring sub-system
Circuit breakers, isolators and field points with specific status definitions, fall into this category. These devices change state from one position to the other. Some of these positions are defined as abnormal states. These definitions vary, depending on the point types and on the position of the device in the power network.

When a device goes into an abnormal state, an appropriate alarm is generated and displayed. When the device comes back to normal, an event is generated and the alarm is made non-persistent.

Accumulated value sub-system
Different types of accumulated values are received from the calculation / conversion sub-system (hourly, daily, etc.). If the accumulated value is not within the limit, this information is passed on to the log, report and display sub-systems for further action. Specified accumulated types are reset. Based on this information, the relevant alarm / event information is generated.

Situation monitoring sub-system
This sub-system has the ability to drive certain software programs, depending on the status of the field. The situation is expressed as a combination of analog, discrete and accumulated value information. In case a pre-defined situation is detected in the field, the information is passed on to the control and display sub-system for further action.

Control sub-system
A control command is an operation executed to forcibly change the status of a device. This could be a supervisory (given by the operator) or a closed loop (given by the system) control.

Display sub-system (MMI)
Monitoring and control of the user interactions with the field, is done through the man-machine interface (MMI). This full-graphic user-friendly interface provides acquired data through single line diagrams (SLD) and tabular formats.

The MMI is based on a Windows graphical user interface (GUI). It supports features like concurrent display of multiple windows, resizing and positioning of windows, and multiple page display screens with scrolling.

Features of different components of the MMI are:

Real-time display
This display consists of a real-time data presentation to the operator in full-graphic pictorial form, single line diagrams / schematics, tables, lists, icons, graphs, text, user-defined symbols and dynamic data display. Dynamic data on these pictures and tables are updated with the latest data on change.

Digital images in .gif and .xmp formats can be incorporated as part of the pictures. The module has various graphical features like zooming, layering, de-cluttering, etc., for advanced navigation.

Trend display
The MMI supports plotting values against time for analog values. Parameters like points and duration are user-selectable for each trend graph. The MMI performs automatic scaling of X and Y axes. Four parameters can be displayed for a trend, simultaneously, in one window. Each parameter is displayed in a different colour for better comprehension. Trending can include both historical and current data in the same window. This makes it convenient for the user to compare the current value of a point with its historical data. A maximum of four trend windows can be opened, allowing a total of 16 trend graphs on one screen.

Log sub-system
This sub-system logs analog, discrete and accumulated values. In addition to this, it also logs some computed values like average, minimum, maximum, etc., using special functions over a set of analog values. Apart from acquired and calculated data, alarms and events are also logged into the system.

Reports sub-system
The sub-system generates reports on system data. The software supports easy report configuration, with which a set of new reports can be configured for each application. The operator can create and print reports on any logged data, on demand. The system can be configured for periodic automatic printing of certain reports.

Configuration sub-system
This sub-system provides the necessary user interface to configure the data to be monitored and controlled. A set of user-friendly graphical editors makes it easy for the user to add / modify / delete various points and their attributes, including the generic and field attributes.

Switchover sub-system
The system has a high degree of fault-tolerance, to handle failures at various levels in the hardware and software modules. Redundancy is provided for all critical modules of hardware, such as FEP, master system and software modules. If critical components fail — including a critical software task in the active system — the standby system takes over within a few seconds.

In addition to these subsystems, OSKER also supports features like Windows MMI and WAP clients.

Windows man-machine interface
Win-MMI is optimised to use the real-time multi-tasking features of Windows NT, 9x and Windows 2000, and is installed using a client-server architecture. The Win-MMI client allows the operator to configure and monitor the system over a LAN.

Standards
The software adheres to the following international standards

	IEEE's operating system interface specifications: POSIX 1003.1a, 1003.2, 1003.1b
	X / OPEN portability for porting on to various hardware platforms
	MIT X11 X-Window system, ANSI for user interface
	MIT X11 X-Window system, ANSI for user interface
	TCP / IP, Ethernet, IEEE 802.1, .2, .3 and .10 standards for LAN
	IEC TC 57 / industry standard protocols for RTU communications
	Inter-control centre communication protocol (ICCP), defined as TASE-2
	NFS (IEEE 1003.8) for resource sharing
	SQL (ANSI X.3.135) for the database interface

Wireless access protocol (WAP) client support
A WAP client interface for SCADA is capable of displaying the required analog and discrete information to a user of mobile phone. In contrast with remote MMI, a WAP-enabled MMI displays critical information to a moving user over a cell phone on a click. Programmable alerts are given to the mobile user in case of alarms or events.

Technical architecture, hardware and software platforms
Hardware platforms

	Alpha servers
	Intel server
	Xeon servers

Software platforms

	Linux
	Tru-Unix 64
	SCO Unix

Solution architecture

Strengths
OSKER is an engineering solution specially created to meet the complex demands of a system operator with the responsibility for ensuring the quality and reliability of a power system. It has a completely distributed architecture with client-server technology as its driving concept, which facilitates easier expansion of the system, based on the expanding needs of the network. Highly parameterised and configurable, OSKER makes it easy for the operator to add, delete and modify the data and picture definitions.

OSKER has been field-proven in various environments, such as load despatch and distribution automation, combining different sets of architecture and complexity. The open architecture makes it convenient to configure OSKER for different sets of platforms.

Benefits

	Three-level hierarchical SCADA system
	Online migration of WRLDC and two SLDC systems
	Connectivity to existing ABB proprietary Indactic-33 protocol-based RTUs
	Connectivity to existing Siemens proprietary RP-570 protocol-based RTUs
	First regional load despatch centre to have a SCADA system in India

Experience
CMC has more than 300 engineers with vast expertise in design, development and implementation of several data acquisition and control system services, and solutions ranging from rugged and compact RTUs for data acquisition to advanced PLC-based closed-loop plant monitoring and control systems.

Indicative client list

	Load dispatch automation for:
		Tamil Nadu Electricity Board – Phase I
		Tamil Nadu Electricity Board – Phase II
		Andhra Pradesh State Electricity Board – Phase I
		Andhra Pradesh State Electricity Board – Phase II
		Andhra Pradesh State Electricity Board – Phase III
		Karnataka Electricity Board – Phase I
		Karnataka Electricity Board – Phase II
		Karnataka Electricity Board –- Phase III
		Kerala State Electricity Board
		National Hydro Power Corporation (NHPC)
	Railway traction SCADA for:
		Nagpur-Durg section
		Jolarpati-Salem section
		Chakradarpur section
		Chennai-Villipuram section
		Nagda-Bhopal section
	Eastern Region Electricity Board power grid augmentation project Load despatch systems at:
		West Bengal State Electricity Board
		Orissa State Electricity Board
		Bihar State Electricity Board
		Damodar Valley Corporation
		POWERGRID
		ERLDC
	Generation plant local monitoring system for:
		NTPC, Dadri (gas and thermal)
		NTPC, Patna, Vindhyachal, Kawas
		NTPC, Patria, Allahabad, Nagpur
	Distribution automation prototype for the Andhra Pradesh State Electricity Board
	Distribution automation for:
		WBSEB - Jalpaiguri circle
		Andhra Pradesh State Electricity Board – Gachibowli Substation
		Rajasthan State Electricity Board - Jaipur City – Phase I
		Rajasthan State Electricity Board - Jaipur City – Phase II
	Generation data acquisition and monitoring system (GDAMS) at the NTPC head office, New Delhi
	Y2K compliance for GDAMS for NTPC, Head Office, New Delhi
	Generation data acquisition system for NTPC, southern region
	Generation plant information system for Spectrum Power Generation Ltd, India
	Equipment monitoring system for Neyveli Lignite Corporation (NLC)
	National protocol development for the Inter-Load Dispatch Centre Communication
	Consultancy for the interim National Load Despatch Centre (NLDC)
	Data acquisition system for the Indian government's department of energy (DoE)
	WRLDC: Interim augmentation project for SCADA facilities at the Western Region Load Despatch Centre, Mumbai, India
	Substation automation for the Andhra Pradesh State Electricity Board
	Airfield lighting computer control system at Changi International Airport, Singapore
	Load management system for Landis & Gyr, USA

Case study
Interim augmentation project for SCADA facilities at the Western Region Load Despatch Centre, Mumbai

Contact
CMC Ltd
CMC Centre
Old Mumbai Highway
Gachibowli, Hyderabad – 500 032
Tel: 91-40-23000401 / 501
Fax: 91-40-23000509