Communications systems, in one form or other, have always been a feature of Electrical Transmission Networks. The phrase commonly used is ‘System Control and Data Acquisition’ (SCADA).

In recent years there has been a significant change in the method of acquiring the data. Previously Power Plant control rooms would have individual alarms and indications ‘direct wired’ to the Control Room necessitating very substantial multi-core cable installations. Transmission networks would employ ‘Power Line Carrier’ to transmit the data from remote substations to centrally located Control Buildings.

Over the past 15 years or so these practices have changed dramatically. Control Centres now use powerful computers to acquire, assimilate, correlate and display incoming data. At the remote locations (be it for example turbine halls at Power Plants or Substations for Transmission Networks) the data is collected by computer based ‘Remote Terminal Units’ (RTU’s). The data collected by the RTUs is processed before onward transmission to the appropriate Control Centres. Data transmission is now, usually, by means of radio communication,
The advent of computer based communications systems facilitates the collection and analyses of substantially greater amounts of data than hitherto which can lead to a better understanding of network behaviour.

The use of SCADA is by no means restricted to Electrical networks. It has wide spread application in:

• The oil and gas sectors
• The water industry
• Rail networks
• The aviation industry and others

For Electrical networks the introduction of powerful computers at Control Centres enables the use of real time assessment and management of the networks. Energy Management Software (EMS) may be used better to determine generator scheduling and load dispatch requirements. On line security software may be used to determine operational constraints, preferred network configurations and potential hazards. Other on line software, such as load forecasting, may be used for planning purposes.

Java – Bali SCADA/EMS System
CONNUSA was appointed by PLN to review the existing SCADA facilities on the Java- Bali System and to recommend a new System which would meet the requirements of this System for the foreseeable future. The Terms of Reference for the Study were extensive. CONNUSA was involved in all aspects of the scope of work. Major areas of the scope of work included:

• Review overall operation of the Java- Bali System with regard to business and technical objectives
• Identify and prioritize required changes and enhancements to the existing facilities taking into consideration new technologies and facilities
• Identify and characterise the data to be exchanged between the PLN National Control Centre and four Area Control Centres and the most appropriate communication protocol for achieving this
• Identify and propose a suitable SCADA/EMS system for Implementation
• Prepare an Implementation Schedule and associated capital cost estimates
• Prepare Interim, Draft Final and Final Reports for the SCADA/EMS Plan

Power Plants and Substations
At all of the Power Plants and Substations, where CONNUSA has provided services relating to Supervision of Construction, the scope of work has included for communications equipment. This equipment includes RTUs and radio transmission facilities for SCADA purposes.

At new Power Plants the work has included all Control Room facilities, RTUs at appropriate locations and the communication media between these and the Control Room. At existing Power Plants the work has included the communications and SCADA facilities associated with the plant extensions and corresponding changes and additions to the Control Rooms.