Scientist, Regional Remote Sensing Centre- North
Electric substations are an important component of a typical power system. Sometimes managers have to struggle a lot to know even small things like when different transformers are installed at a particular substation or on which substation instruments are going to be obsolete. This results in poor infrastructure on one hand and redundancy at another. Advanced technologies such as GIS and GPS can help create an up-to-date interactive database regarding the assets and can help the managers to decide upon the future strategies in efficient manner.
Utility services are an important component of the physical structure of towns and there is a need for detailed information about the location and condition of their infrastructure and assets in such a way that it should facilitate planners and managers in all the phases of utilities management. A typical power system consists of four vital elements: a power station, which changes prime energy into electrical energy; transformers to raise the generated energy to the high potential required for economical passage through primary transmission lines; the transmission lines; the substations where the power is reduced to the secondary potential and the voltage used by the consumer. There is a need for the management to know the details of the infrastructure available at substations in such a way that they can retrieve the information as and when required in an efficient and quick manner.
Acquiring data in the conventional way is time consuming and costly. Recent developments in science and technology have provided powerful tools for mapping and data integration of infrastructure facilities such as GIS, GPS and remote sensing. These advanced technologies can be very effectively used to handle the present day complex problems related to optimum utilisation of available resources and infrastructure planning. GPS helps in getting the geographic location of any point on the earth with considerable accuracy and with the use of GIS, power companies can collect and store a large amount of data that can be readily accessed and analysed. It is a valuable tool not only for mapping facilities but also to improve decision-making and better management of infrastructure and planning. GIS is an important tool for spatial information integration and retrieval. For example, if management of a power company needs to know the date of installation of a given transformer, all they have to do is to click onto that transformer symbol. The attributes attached to this transformer will appear, where one of the attributes will show them the installation date. Consider that the same person now wants to have more complex information. He wants to see on the map, which are the 3 MVA transformers in a given area that were installed prior to a given date. The query facilities of the GIS will quickly process this information and show on the map only those transformers that qualify the criteria, hiding all other transformers that do not qualify it. So with the attribute information, it will also provide an insight in terms of their spatial distribution.
The integrated GIS database
A spatial layer containing the information regarding the substation name, its location, capacity and status has been prepared in ArcGISS for all the substations of Dehradun district of Uttarankhand state of India. The location parameters i.e. geographic co-ordinates were collected based on the location name in Survey of India toposheets. Once integrated in GIS, the prepared database can answer queries such as location and name of the proposed substations, their capacity etc. An example of the query showing existing and proposed substations is given in Figure 1.
Figure 1: Location map of all substations, Dehradun District showing the substations based upon their status i.e. existing or proposed
A detailed GIS database of the all 33 KV substations of Dehradun city consisting 21 parameters related to each substation was developed in ArcGIS. The following are the parameters for which the detailed information was collected: substation name, latitude and longitude of substation, Installed capacity, present capacity, capacity before upgradation, capacity after upgradation, lines from substation, lines to substation, transformer manufacturing company, date of testing, transformer panel type, transformer CTR, transformer cable capacity, transformer MF, transformer maximum load, feeder manufacturing company, feeder panel type, feeder CTR, feeder MF, feeder cable capacity and area fed by a particular feeder.
The location of each substation was collected with the help of GPS survey using DELL AXIM 5 PDA instrument with ArcPad software installed. The latitude and longitude information of the substation location collected by GPS survey was used to prepare coverage directly from the table.
The data collected from fields about substations, transformers and feeders was then incorporated in MS Access. Separate tables were prepared for the substation, transformers and feeders. Each table had a unique ID, for example SST ID was taken unique between substation table and transformer table. Similarly SST ID and TRF ID were taken unique between transformer table and feeder table. The unique IDs between these three tables were then used for joining the tables by firing a query in MS ACCESS.
The potential use
The developed GIS database can be used to access integrated information in a quick and interactive manner. An example of the use of the developed database is, if a senior management level person wants to know about the substations having transformers of 3MVA capacity. This query can be framed easily in a database query system and it will highlight only those substations which have 3 MVA capacities (Figure 2).
Figure- 2: Query showing substations with 3 MVA transformer capacities
In the same manner, the detailed database generated of 33 kv substations of Dehradun city can answer multiple queries based upon host of parameters as mentioned above. One example in Figure 3 highlights all the substations having transformers of the “Electra” company make as well as their installation date. It will also provide information regarding design life of various transformers and feeders. This information helps management to objectively assess in advance the future requirements i.e. which instrument needs urgent replacement or which can be replaced in future at a particular point of time.
Figure-3: a query showing all the substation having Electra company transformer
Hence, the integrated GIS database can help managers formulate the requirements for their establishments in advance and can help them use their resources optimally.