| Abstract |
The design trend in developing new, and expanding developed geothermal fields use Modular Fluid Collection and Disposal System (FCDS) and Power Plants due to the rugged terrain and or ample distance that makes long pipelines uneconomical to connect these plants to the main initially developed site, As this small (usually 20Mwe) modular Plants increase in a field, unmanned operation of its FCDS is a good economical option. This would require full automation rising a PC based SCADA, wherein a supervisory computer would automatically log and send data to the main plant for monitoring and recording purposes, by personnel from the main site (i.e. Ohaaki Plant, NZ). A plant trip of one module may not have a significant effect on the total capability of the grid it is serving due to its small capacity. The modular plants, which were intended to be load plants, are affected by the total loading of the ttiain plant anti the grid hence it has been experiencing load fluctuations. The scope of this paper covers only the basic automation of the wellhead motorized valves, making it load following. Good control of the wellhead motorized valve results in a minimum wastage of vented steam and ultimately, the longevity of the production field. The proposed system is PC based and employs intelligent instruments which are readily available and are now in use in the industry. One major feature of the system is the use of discrete control signals instead of analog signals, which would eliminate hunting due to the time delay in the delivery of steam from the wellhead to the separator. |