SVG Interface for an Electrical Network Switching Training Aid

Paul J. Nolan1, Michael Murphy2, Arthur Byrne2 and Domhnall Walsh3

1 Atlantic Simulation and Training Technologies, Galway 2 DTTS, Electricity Supply Board, 3 National University of Ireland, Galway, Ireland

Keywords: svg, xml, user interface, electric network, training


One-line diagrams are used extensively in the electric utility industry to show installed equipment (generators, transformers, busbars, circuit breakers) and interconnecting transmission and distribution networks. Such diagrams are used both in planning and operation applications. The electronic display of such diagrams has replaced hard copy. Traditionally such diagrams have shown static data (e.g. network parameters) or are annotated to show calculated results shuch as results of a load flow, short circuit calculations and so on. AutoCAD (DXF or DWG) or native GIS Formats have been used. The advantage of using XML for common data exchange has been recognised though the XML-based Power System Information Exchange programme agreed by EPRI (Electric Power Research Institute) for CCAPI (Control Center Application Program Interface).

Increasingly applications are being delivered via web interfaces. Users demand that their web applications display and interact with rich graphics. Moving from the static bitmaps of today's web toward more scalable, dynamic and interactive web content is demanded. The answer is Scalable Vector Graphics (SVG), which allows us to describe two-dimensional graphics, such as utility one-line diagrams, in terms of an XML grammar. These can be manipulated with CSS or XSL(T) style sheets or processed directly as XML, using advanced styling functionalities such as color gradients and filter effects. SVG is the W3C-recommended, XML-based, standards-compliant alternative to similar proprietary formats. Developers can create Web displays that integrate data-aware graphics on top of maps. Raster as well as vector data sets can be included and in addition to the usual panning, zooming, and object selection, animations and sophisticated interactivity can also be incorporated. Thus the static one-line diagram for a power system becomes a scalable and dynamic interactive web document.

Much of the time and expense invested in training electrical network technicians in the area of power generation and distribution is given to teaching and testing the technician on his/her knowledge of standard electrical procedures. Due to the potentially drastic consequences of any error while carrying out electrical switching operations in a high voltage environment, trainers must ensure that technicians have an adequate understanding of the procedures involved. This requires a considerable amount of "On The Job" training. It also involves very considerable time being spent performing paper-based exercises where switching plans are developed to meet specified criteria.

This paper describes the replacement of the paper-based exercises for developing switching plans with an electronic version using SVG. The system, NOSTRA (Network Operation Switching TRaining Aid) was developed for ESB's (Irish Electricity Supply Board) network training school. The web-based package is designed both as an instructional aid and as an assessment tool. The SVG diagram, comprising a synthetic system with a mixture of both 3 phase and single phase distribution network (including underground cable), transformers, switching kiosks and so on, can be zoomed and panned. A lookup function allows individual pieces of equipment to be identified on the map. Hyperlinks on the network diagram connect to digital photographs describing the equipment at each location.

The web based interface allows users to select a particular exercise and subsequently a second HTML window is used to enter the switching plan. The plan uses a standard task grammar requiring the user to specify who is performing each action, the location at which the action is being carried out, the particular device involved and the name of the operation. Each of these is selected from a drop down list box which are populated with all the various possibilities. As each step in the switching plan is entered, the user may navigate through the diagram, look up hyperlinked material (e.g. procedural manuals, safety rules, photographs of equipment and so on. The SVG diagram is annotated with additional graphic symbols (e.g. earth symbol added) or with colour or other changes to show changing status. Various levels of feedback are possible and switching exercises can be arbitrarily complex, including alternative correct solutions. At the end of the exercise a switching plan conforming to the company's standard is printed. All user inputs are logged to a database.

The paper details the technical details of the implementation and the decisions involved in distributing the processing between JavaScript on client side and ASP on the server. Details on the integration of a CLIPS-based expert system, used to analyse partially correct plans, with the SVG display is also discussed. The experience with the prototype system and future plans are also discussed.

contact info:
Paul J. Nolan and Domhnall Walsh
Atlantic Simulation and Training Technologies (ASTech)
Unit 2, Campus Innovation Centre
Upper Newcastle, Galway, Ireland