Electric utility operational support using GIS
System control
Distribution system control is the activity of issuing work control permits to ensure a safe
environment for the crews. The permits ensure that, when devices are opened to "kill" a line,
they will not be inadvertently closed in until the crew working in the area is clear. Tags are
placed on the devices, and the main function of the Control Center is to track these tags.
Given the geographic area covered by the Company, paper maps were considered ineffective
because hundreds of maps would be required if they were to be at a reasonable scale. Thus,
the Company elected to develop an electronic application that would allow the control
operator to view, zoom and trace facilities to determine control points for issuing work
control permits.
There are three steps in developing an application of this nature. The first is to determine the
"business process" which addresses the purpose of the application. Once that is established,
the "functional requirements" are developed to examine how the application will work.
From this, it is possible to then determine the "specific features" of the mapping system.
Business Process
The flow chart in Figure 1 defines the business process for the System Control application.
The tasks were divided into pre-job tasks that need to be done before the job can start, day of
job start tasks that must be performed before a crew can begin work, (e.g. permits issued,
devices tagged), and job complete tasks that effectively closes the job. The flow chart also
shows the interaction between the line crews and the System Control Center.
Figure 1. SCC/PIC Business Process
The process boxes should also be accompanied by textual explanations, for example:
Pre-job processes
Under normal circumstances a permit request is made in advance of the work being
performed. Usually 24 hours. The SCC will begin to fill in a card (e.g.: Live Line
Permit) based on the information collected from the applicant. The various permit
cards are pre-printed with a permit number already assigned. It is this permit number
that will be used as the unique identifier that will cross reference the applicable
graphic device symbols to the permit. The permit number will be re-keyed into the
applicable form by the SCC operator.
It is assumed that the applicant will, at minimum, know what feeder number they will
be working on. It will be the applicant's responsibility to provide enough information
to allow the SCC to isolate the limits of the work area.
Functional Requirements
As with the business process, the best way to determine functional requirements is to draw a
flow chart (Figure 2). This will help to identify the functions that will be performed by the
mapping system. The top row of boxes show the tasks performed by the operators as
identified in the business process. The second row of boxes identifies the specific map
related tasks performed by the operators.
Figure 2. SCC/PIC Functional Process
System Features
The numbered items in the lower boxes can then be used to develop specific system features.
These features need to be grouped into the following categories:
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Source Data - where from, collection procedures, links to other data
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Specific Attributes - what they do, edit rules
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Displays/Reports - what they look like, on what software
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Computer Hardware and Software - standard or special hardware, printer/plotter
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capabilities, software "platform"
Maintenance - where will it reside, who will maintain base files/data.
