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Management of sub-transmission and distribution system in power utilities

It would be ideal to model low voltage network emanating from each and every distribution transformer. However, the network data would be acquired in phases due to the large number of network entities and the large number of low voltage consumers. In the first phase, data collection of sub-transmission network (33kV or 66kV) and 11kV distribution and sample low voltage (0.4 kV) system including consumers should only be taken up. The sample low voltage network would be from high density, medium density and low-density pockets and covering different categories of consumers. This will serve the basis for determining the overall losses and improvements required in the entire low voltage network. In the subsequent phase, complete low voltage network could be taken up, if required.

Data collection and mapping of the network would require a survey of the entire geographical area over which the network is spread out. This survey would consist of the following tasks:

• Create a digitised background map of the area, which could be one or both of the following:
  Geo-reference satellite imagery procured from NRSA
  Survey of India Maps
• Survey entire area locating and collecting attribute data of each and every entity, viz.,
  Pole
  Overhead Conductor segment
  Underground Conductor segment
  11/0.4kV distribution transformer sub-station

The poles, consumer location/service poles, sub-stations etc. shall be located to within an accuracy of ± 100meters relative to the base map. This could be done either with a Differential Geographical Positioning System (DGPS) or other techniques using Electronic Distance /Angle measuring Equipment based on lasers or combination of these techniques.

Plot the above points of entities on the digitised maps. Model the network using a network mapping software and build customised queries on network database.


Fig. 2

Figures 2 and 3 show the views of a distribution network with attached Information and distribution network with Land base Map


Fig. 3

GIS for day-to-day Operation & Maintenance
Interfaces that use the querying facility available with the RDBMS in the network-mapping environment will provide the accurate and reliable information to the utility operational staff on the spatial and non-spatial attribute data of the network created in the GIS. Customised interfaces can be delivered as also the staff can be easily trained to design and create their own interfaces. The information can be in the nature of an inventory report of any type of network entity (poles, conductors, underground cable segments etc.) or location information etc. As a real world example, the facility could be used to point out all the poles and the conductor segments located along a road, which would be effected due to say, widening of road or construction of an over bridge. The actual topology around the identified area could help in planning an alternative permanent route for the affected section or planning a temporary section during the period the construction work is going on.


Fig. 4

Figures 4 and 5 show the views of a query showing all the through poles of a particular type.


Fig. 5

However, monitoring of the distribution system on a real time basis and also to introduce a certain measure of automation in to the distribution system will mean investing in a Supervisory Control and Data Acquisition system (SCADA). Integration of the network mapping and the network analysis software with SCADA will prove to be a tool of immense benefit to the power distribution system utility in improving the operating efficiency and consequently customer satisfaction.

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