Water Based Renewables

How to digitize penstocks leading to powerhouse of a hydropower plant from the site maps?

Benefits: The condition, load, flow rate etc. in a penstock can be monitored real time if the digitized shape files and its attribute tables can be connected to a set of sensors which can measure and send the status of vital parameters, important for condition monitoring of the pen-stocks in large scale hydro power plants. The portability of the monitoring system is another reason for installation of such real-time monitoring systems. A GIS map can be used in any type of device if the map-codes can be exported to another device. Most of the tools used for GIS nowadays offer such features in their digitization module. The entire digitized maps of the power plant will also enable to identify vulnerable points and erroneous portions which can be rectified by adopting to required mitigation methodologies.

Tools Required: Map Window Software, Knowledge of pipe network analysis.

Methodology: The entire process to achieve the objective can be divided into:

1.Digitization of the sitemaps

2.Preparation of attribute table for condition monitoring

1.Digitization of the sitemaps

After the collection of site maps of a hydro power plant,the pen-stocks are identified and digitized using point and line shape file. The points are used to represent junction and lines are used to depict the length of the pen-stocks. The source and sink of the entire pen-stock is also represented by the point shape file connected to the line shape-files.

The colour, size and style of the point and line shape files may be chosen randomly by the users.

In case of Map Window software, the following steps are adopted to digitize the pen-stock network:

a)The projected coordinate system is selected or defined by going to the Settings sub menu under the File menu.

b)The scanned picture of the site map is imported into the software by using ‘Add Layers’ sub menu under the File menu.

c)After that the point shape-files were used to digitize the junctions of the pen-stocks. The junctions are taken as the points where two or more pen-stocks converges or disperses.

d)The line shape files are used to digitize the pen stock length. For both point and line shape file generation the menu item: ‘Create Shape-file’ is used

e)For each type of shape file (point and line) one layer is created under which all the line and point shape files,generated during the digitization process,are stored.

f)The colour, size and style was adjusted by right clicking on the layers, for which such properties has to be changed, and then going to the ‘Property’ sub-menu.

2.Preparation of attribute table for condition monitoring

Once the map is digitized successfully, the next step is to create the attribute tables linked to the shape files. Here the parameters which will be monitored is represented by the columns whereas the rows will depict the shape file for different pen-stock junction or length. The steps used to create the attribute table and the corresponding columns is explained below:

a)The attribute table, shown after right clicking on the layers representing the  point or line shape files , is used to store the data for the parameters which were selected for monitoring the pipeline condition.

b)Here each parameter is represented by separate columns of the attribute table where as the rows were used to depict the data for the parameter measured for that pen-stock junction or length.

c)The columns can be added by clicking on the ‘Add Field’ sub-menu found in the Attribute Table window.Rows will be automatically generated once and when a new shape file is created.

d)The data for the parameter can be added real-time or manually. For real time data collection, the attribute table of the shape files are connected to the external data base of the instrument or data logger used for monitoring the parameter. The tables in the external data base must be same as the attribute table with same number of columns and rows. To connect to an external data base, the sub-menu ‘Connect Database’ can be used which can be found under the File menu.

After the creation of attribute table, the data stored can be used to depict the condition of the pen-stocks directly through the digital map created from the scanned picture of the site map. The same digital map can be exported to a platform independent code so that monitoring of the pen-stock network can be possible from any device.