PCs already have a wide choice of communication options and connectivities to LAN. By using the high resolution, full graphic capability as available now, the operator can view the data in many forms such as tables, charts, trends, schematics etc. Some of the more powerful packages can even animate the monitored processes, depending on the data acquired. Most often required features of a good HMI are:
· Windows based operation
· Interaction through key-board/mouse.
· Pull down/pop-up menus.
· Text and graphic displays.
· Alarm management
· Procedure and comment facilities
· Password protection.
- Hardcopy facility
General
A typical single line diagram showing the different components of an Integrated Substation Control is shown in Figure 2. It shows typically how IEDs of different manufacturers are networked with say, a Harris SCADA/HMI system. Figure 3 shows only the architecture of the above system for a clear understanding of ISCS architecture.
Approach to ISCS
Advantages are many in adopting a full integration of all the operation, control and monitoring requirements of the substation into a single, intelligent automation system as proposed by ISCS concept. Before we could propose implementing such systems, we have to deal with several drawbacks emanating from different areas such as:
- Substation design
- Legacy system
- Lack of skills among operation and maintenance staff,
- Lack of expertise at the planning level to be able to justify advanced technologies,
- Lack of parity between cost and quality of power supply,
- Lack of funding and, - Lack of stable management philosophy.
Substations need to be designed with remote operable isolators and earth switches. Numerical IED-based protection should be specified with adequate confidence. The operation and maintenance staff should be given accelerated training in these areas to accept such technological changes. At the planning level, the engineers should be aware of the range of products available and should visit sites where they are applied to gain first-hand knowledge of such products. They should employ experienced and capable consultants to engineer such systems effectively to complete the project justification. Problem of funding may get solved with the proposed re-organisation of electricity boards. Cost justification for this project should be seen in the following areas.
- Power Quality Improvement: voltage control, var reduction, reactor and capacitor switching load transfer.
- Operational Reliability: Better monitoring of system conditions, load management, load shedding fault detection, isolation and restoration.
- Maintenance Scheduling: Better monitoring of breaker and transformer conditions, better fault information and sequence of operation, proactive condition based maintenance.
Avoiding many discrete devices for all the above purposes expected to provide considerable economic justification.
Conclusions
An attempt has been made in this paper to revisit some of the older concepts of substation control and to introduce the new concept of Integrated Substation Control. The evolution of the control philosophy and the control devices towards such integrated concept is described in detail. It is our belief and hope that the utility engineers and managers will get their substations ready for accepting the concept of Integrated Substation Control and thus utility operations towards the 21st century.
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