GIS for distribution Network Management : An Introduction

You are well aware of the problems facing the distribution utilities to meet the day-to-day requirements of the power consumers, such as system management for quality power with minimum losses, monitoring of AT&C losses, optimum inventory management, maintaining a proper customer complaints and grievance system, effective workforce utilization, etc. The day- to-day challenges before distribution utilities in the country include lack of updating of dynamic data uniformly throughout the utility (since data is created by meter readers/line men), lack of correct consumer data base, non-availability of MIS for middle and top management, which leads to faulty
planning, consumer hardships and revenue leakages, non-feasibility of energy audit, delays in project implementation, etc. Thus, utilities urgently need to address issues such as

• non-availability of network information, and consumer and technical database;

• non-existence of regular updating system;

• non-availability of any IT-enabled tool to provide the required analytical reports correctly and quickly; and

• non-existence of records of day-to-day changes in the system.

The distribution company cannot work efficiently and economically without the availability of consumer and technical database as analysis and improvement of the system will not be possible. Geographic Information System (GIS) provides the solution the utilities are looking up to.GIS has the potential to revolutionize the reform process in areas like consumer indexing, distribution network mapping, asset and work management, enhancing billing and collection efficiency and managing consumer relationships. Therefore, GIS is a valuable tool for improved decision-making through efficient MIS. In fact, many utilities are using GIS for preparing an inventory of the existing network, gaining easy access to network details and consumer data, data analysis and network improvement, load growth projections, etc.

GIS based customer indexing and asset information management system could provide the requisite managerial inputs for decision making. This could form the basic application to which all other business processes would be  integrated.

GIS would help utilities in the following ways:

• Visualization: GIS can visualize the actual network, as it is laid out on ground. It helps provide a snapshot of the locations of substations, lines and cables in relation to their geographical bearings. It also plots the locations of consumers with respect to their feeding networks (starting with the source and ending with the end-user).

• Convenience: GIS is user friendly and provides ease of data entry. Since the data are digitised, several interactive applications are possible that permit automated mapping, facilities management and network solutions.

• Flexibility: With GIS, utilities have the flexibility of choosing the other systems to share or exchange data with (i.e., Network Analysis, Inventory,Trouble call analysis); and

• Better comprehension.

Advantages of GIS as an Effective IT Support System

For power utilities, the primary objective of using Global Positioning System (GPS) and GIS should be to:

• enhance the efficiency of transmission/distribution system in terms of quality of power;

• increase revenue earning;

• reduce T&D losses (both technical and commercial) as well as outages; and

• merge the functions of independent offices into the mainstream operational hierarchy with the help of organisation-wide networking.

You may like to know: For what purposes can GIS be used in distribution systems management? These are listed in Box.

Box : GIS Applications in Management of Power Distribution Systems

• Inventory of existing network.

• Easy access to network details.

• Easy access to consumer data.

• Data export for analysis and network improvement of the existing system.

• Load growth projection.

• Handling customer inquiries.

• Fault management.

• Planning of routine maintenance.

• Network extensions and optimization.

• “What if” analysis.

• Network reconfiguration.

• Improved revenue management.

• SCADA integration with GIS.

• Right of way and compensation.

Thus, utilities should be equipped with comprehensive IT roadmap to integrate GIS application with other business processes. Fast, accurate and reliable data can be made available due to advances in the IT area with GIS as an important component unifying the geospatial data with the electrical data. This would also provide transparency in Distribution Management. The GIS environment hosts many presentation techniques that enable fast and accurate interpretation of results from power flow results to short circuit analysis. Proper selection and implementation of GIS will enable the Distribution Company to reap many benefits (Box ).

Box: GIS Benefits

• Improving financial viability.

• Reduction of T&D losses.

• Improving customer satisfaction.

• Increasing reliability of power supply.

• Improving quality of supply.

• Systems approach with GIS.

• Transparency through computerization.

Now that you have some idea of the usefulness of GIS, you would like to know: What is GIS? How exactly can it be applied for distribution system management?

What is GIS?

Geographic Information System (GIS) is a computer system capable of assembling, storing, manipulating, and displaying geographically
referenced information by integrating databases, optimizing data layering and timely data updates. In the context of power distribution, GIS is a digital representation of the geo-coordinates of customers, network elements and important landmarks on the relevant area’s geographical map having suitable resolution, along with their attributes.GIS essentially has five components: Hadware, software, data, people and methods (Fig.).

Various Components of GIS

1. Hardware is the computer and peripherals on which a GIS operates.Today, GIS software runs on a wide range of hardware types, from
centralized computer servers to desktop computers (used in stand-alone mode) or networked configurations.

2. Software: GIS software provides the functions and tools needed to  store, analyze, and display geographical information. The key
software components are:

• Tools for the input and manipulation of geographical information,

• A database management system (DBMS),

• Tools that support geographical query, analysis, and visualization, and

• A graphical user interface (GUI) for easy access to tools.

3. Data is possibly the most important component of a GIS. Geographical data and related tabular data can be collected in-house or purchased from a commercial data provider.

4. People: GIS technology is limited without the people who manage the system and develop plans for applying it to real-world problems. GIS users range from technical specialists who design and maintain the system to those who use it to help them perform their everyday work

5. Methods: A successful GIS operates according to a well-designed plan and business rules, which are the models and operating practices unique to each organization.

GIS provides information such as the location (e.g., where is the customer, line, cable, DTR, feeder, substation, etc.?), topology, which describes the spatial relationships between adjacent features (e.g., what land use is adjacent to each of these customers, lines, cables, DTRs, feeders, substations, etc?),attributes (e.g., what are the capacity, numbers, voltages, crossings, etc.?), dimensions (e.g., what is the area and perimeter?), etc. GIS organizes geographic data into a series of thematic layers (Fig. 11.3) and tables. It links locational (spatial) and database (tabular) information and enables the user to visualize patterns, relationships and trends.

Fig. : Example of layered datasets for weather-based decision making about power distributionLet us now understand how utilities can map and prepare GIS for various applications. But before that you may like to review the concept of GIS.


GIS Based Mapping of Electrical Network

You have learnt that the Geographic Information System is a system of mapping of the complete electrical network. The question we address now is:How is the mapping done? What are the systemic requirements? For this we first need to understand what kind of data is required to map in a GIS.

All GIS data are made of two components:

• Geometric data and

• Attributes data.

Geometric data refers to the geometry of geographical features such as locality boundary, street boundary, plot boundary, building features, etc. Geometric data could be one or both of the following:

• Geo-referenced satellite imagery,

• Maps generated by surveys, e.g., Survey of India maps.

The geometric data is usually acquired using a variety of technologies with one of the following two accuracies:


“Coarse Mapping” specifications are used at the planning stage the world over.Attributes (tabular) data refers to the information associated with the geometric data such as locality name, street name, nature of occupation of a plot, elevations, etc. It is descriptive data that is linked to map features(e.g., points, lines, etc.).

Examples of attribute data relevant for a power utility are given below.

•Consumer data such as category wise number of consumers and

•connected load including the Bulk Consumer details such as

− contract demand,

− maximum demand,

− energy consumption, and

− supply voltage.

Network data

− source(s) of power supply/grid substation(s) supplying power to the area,

− existing substations, and

− existing lines.


•Demand data

−peak demand MW/MVAR − simultaneous and non simultaneous, and

− annual Energy Consumption data.

Sub-Transmission System

− existing 66-33/11 kV substations and existing 66-33 kV lines,

− under construction substations, and

− under construction 66/33/11 kV lines.•

•Distribution System

− 11 kV lines,

− distribution transformers, and

− LT lines.

Operational parameters

− Substation equipment status,

− 66/33 kV feeder breakdowns,

− failure of distribution transformers,

− tripping on 11 KV feeders/lines, and

− consumer outages.

Electrical network details

− single line diagrams with conductor sizes, lengths, transformer locations, capacitors, consumer location and load, etc.,

− parameters of equipment, devices and conductors, and

− load data such as peak load, diversity factor, power factor, etc.

• LT network

− section length,

− conductor size of each section,

− connected load for each group of consumer,

− number of consumers in each group, and

− total connected load on the transformer.

• Equipment parameter data

The schematic diagrams for existing substations have to be prepared with information of power transformer rating and numbers, impedance values,

bus-bar scheme, isolators, circuit breakers type, e.g., minimum oil/bulk oil/ SF6/Vaccum and type of installation (indoor/outdoor), number of incoming and outgoing feeders, CTs and PTs, details of taps and normal tap position, spare bays, etc.

•Load data covering the monthly, daily and yearly details of energy/peak power in the electrical system as well as the following information is required:

− peak load on each transformer/feeder and corresponding actual voltage,

− diversity factor at various voltage levels,

− power factor at various voltage levels, and

− load factor and loss load factor at various voltage levels.

Finally, the above points of entities are plotted on digitized maps. The network is modelled using a network mapping software and customized queries are built on the network database. Several layers of information such as the following are contained in these map representations.

•The first layer corresponds to the land background containing roads,landmarks, buildings, rivers, railway crossings, etc. (Fig.).

Fig.: a) The Drawings of the Street Map of an Area; b) The Drawings of the Electricity Distribution Network; c) The Map of the Area overlaid with Electricity Distribution Network; (Source: http:// www.gisdevelopment.net/...)• The second layer corresponds to the distribution network coverage. The low voltage system and customer supply points with latitude and longitudes are overlaid on the satellite images and/or the geographical maps of an area.

• The next layer could contain equipment information, viz. poles, conductors,transformers, etc. Most of the electrical network/equipment has a geographical location and the full benefit of any network improvement can be had only if the work is carried out in the geographical context.

• The “attribute data” is attached to each of the entities using a backend“database”.

GIS can be used to produce and visualise layered data sets . Data in a GIS are referenced to geography; they have real- world locations and could overlay one another. This process gives an entirely new perspective to data analysis that cannot be seen in a table or list format.

Thus, GIS consists of the following:

1. Database – for storage and retrieval of information. The database forms the foundation of the GIS system. All the information about
the GIS system is stored in the database.

2. Base map – for geo-referencing of the network system.

3. GPS points – for picking up the actual location (latitude/longitude) of various network components.

4. User interface – for accomplishing various tasks of reports, query, analysis.

In a nutshell, we can say that the GIS technology

• integrates common database operations (data query and statistical analysis), with the unique benefits of visualization and conceptual
spatial analysis offered by maps;

• optimizes data layering (spatial overlays for object relationship identification),

• allows for effective and timely data management (particularly data
updates).

GIS can be used to derive diverse information for efficient technical and commercial management of a power distribution utility, e.g., capacity analysis,investment cost estimation, estimation of yearly peak loads of medium and low voltage transformers, calculations of power flow, and technical and commercial losses in the network, and so on.Proprietary software tools, like SMALLWORLD, PTI, and POWERON, among others, can leverage the GIS database by offering a basket of customised solutions that range from load flow and power loss analyses, network reinforcement, reconfiguration and line design, capacitor and substation placement, relay and fuse co-ordination, etc., to outage and supply complaint management, and job planning and control. The computerized integration of information with the spatially dispersed links has the ability to greatly enhance the decision making process and documentation.

Systemic Requirements

A robust GIS solution for a distribution utility comprises the following:

• GIS application and database software should be OGC (Open Geospatial Consortium) Compliant,

• Differential GPS survey of entities and consumers and overlaying on satellite imagery should be on the following scales:

− Urban/Cities/Metros on 1:1000 scales.

− Semi urban on 1:2500 scale−

•Rural area on 1:5000 scale (the survey in rural areas may be restricted to the corridor of HT/LT lines survey rather than
covering the entire rural area).

The map resolution should be as follows:

− spatial resolution less than or equal to 2.5 metre ground sample distance (GSD) per pixel for urban areas.

− spatial resolution less than or equal to 10 metre GSD per pixel for rural areas.

• Door-to-door survey of customers and collection of data should be carried out.

• Utility HQ/Circle HQ as Data Centre should be equipped with servers and networked with Utility HQ, Divisions, Subdivisions, etc.

• GIS System Testing and Commissioning should be done for given
concurrent users.

The utility must be ready for integrated IT enabling and the necessary basic IT hardware and software including networking must be in place.

Hardware Requirement

• Server of adequate sizing for enterprise-wide deployment for storing maps and geospatial data.

• Application server and web server.

• Desktops at different user locations.

• Enterprise-wide WAN and LAN at different locations with proper security and connectivity.

Software/Application Platform Requirement

GIS solutions would primarily consist of Database and Applications software.The application package should work in LAN/WAN/Internet/Intranet environment. As already stated, GIS application and database software should be OGC (Open Geospatial Consortium) compliant, time tested, widely deployed at multiple utilities world-wide and in India, from a reliable supplier of high reputation and long standing recognition in the field of geographical information.The programming application should be developed using the latest
non-proprietary Object Oriented Programming language (OOP), i.e., visual Basic etc., and it should be possible to customize the application to suit user requirements. No proprietary development languages should be required for GIS software solutions, which should be configurable and parameter driven. In such an event, advantage can be taken of product enhancements without the programming and re-programming challenges encountered in a system that is driven by an application programming interface (API). GIS software should be truly open with all geometry, network facility model, business rules validation, and version management stored in an open, standard relational database.

Software must have dynamic capability to establish relationship between the entities. It should be designed to be scalable and flexible, taking advantage of innovative memory management and a Dynamic Display Cache for rapid data access and display. Software must be able to show and/or give error messages in case of incomplete network. The system administrator should be able to assign the password for using specific features of application software and database. The system should have an open architecture and the Spatial Data Engine should work on all industry standard Cross-platform support like UNIX/Windows/Linux, etc.

The core functionalities of the GIS are given in Box .

Box : Core Functionalities of the GIS

The GIS should be able to:

• Create layers from all supported data sources including coverage feature classes, shape files, computer-aided design, raster, and geo-database feature classes, or tables containing x, y coordinates.

• Create group layers from multiple data sources including vector overlays on top of raster data/images.

• Provide Data Preview facility before loading it and Drag and Drop layer from the preview window to the map.

• Provide inbuilt industry standard Reports Generation tool both at Server and Desktops.

• Provide the facility to label features based upon fields or expression of two or more fields.

• Carry out registration, rectification and storage of different formats of data in a single database.

• Support Topological-editing capabilities.

• Define rules for Topology like rules to make sure that no polygon overlaps another polygon in the same data, polygons should form a

continuous surface with no voids or gaps, lines in a data should connect to one another, dangling and pseudo nodes removal.

• Create Bookmarks, i.e., facility to Create, Edit and Move To Bookmarks. (Bookmarks will be created to store the information of the
display Extents of the map.)

• Provide Back-up recovery module for managing the backup and recovery operations of the database.

• Provide software support for back-up storage copy of the Customer information, for use in case of any corruption of current data.GIS application architecture should

• provide a framework and the necessary programming interfaces to enable complex GIS applications to be developed and integrated with applications that already exist within the utility,

• support the distribution of the functionality of GIS application across a number of components which interacts as separate process via process communication and control mechanism.

• create Single Line Diagram (SLDs) of electrical sub-transmission network.

Source Code should follow structured programming practice. Internal documentation should be a part of the programs. Comments in the programs should be written to aid understanding and should provide supplementary information. Also the comments for the modules (prologue) should form the beginning of the module. These prologues should have the following information:

• Module functionality or what the module is doing.

• Parameters and their purpose.

• Assumptions about the input, if any.

• Global variables accessed and / or modified in the module.