Electric Utility Engineers have Traditionally Employed 2-D Computer-Aided Design (CAD) drawings to design substations, even after better technology was developed. Utilities have largely ignored advanced CAD tools, especially 3-D modeling features, even though they are the norm in many industries. For instance, the manufacturing industry has been using 3-D CAD models with associated bill-of-material (BOM) information in its design plans for years.
Progress Energy Carolinas (Raleigh, North Carolina, U.S.) believes the electric utility industry should follow similar processes. Progress Energy is in a good position to reap the benefits of the advanced technology as steady growth in the Carolinas leads to increased demand for electricity, which means building new substations. The utility currently serves 1.4 million customers in North Carolina and South Carolina over a 34,000-sq mile (88,060-sq km) service territory.
GROWTH FUELS DEMAND
To satiate growing demand, Progress Energy must plan, design and construct additional infrastructure including new substations and system-capacity increases. With an eye on cost and a commitment to quality of service, the utility requires detailed engineering drawings and concurrent design data reports. Accuracy and automation of CAD drawings helps to eliminate misinterpretations and construction delays during the project construction phase.
Automation of design and detailing with intelligent 3-D modeling instead of 2-D drafting is beneficial in enhancing engineering and production activity. In order to automate design and detailing, a system must be intelligent.
The Substation Modeling and Automation using Relational Database Technology (SMART) system, developed in Progress Energy Carolinas' Transmission Operations and Planning department, meets this challenge of intelligence. SMART system functionality provides a range of capabilities, including:
Intelligent 2-D/3-D CAD models for automatic generation of BOM reports
Synchronization of 2-D sectional and plan view drawings with a single 3-D substation model
Initial project estimate using intelligent one-line circuit diagrams
Flattened 3-D models that can be used with existing substations
Automatic updating of BOM information on standard drawings using pivot table technology.
THE CONVENTIONAL PROCESS
The method most utilities follow for substation design can add unnecessary time, cost and frustration. It usually incorporates two separate processes: an industry-standard 2-D CAD application for plan preparation and a standard BOM database for material and equipment information. These work-flow sequences typically require a user to manually search drawing indices and design data, which results in a cumbersome information-retrieval process.
According to substation engineering personnel, finding, retrieving and manipulating BOM data reports consumes the majority of effort for a project. All construction drawings are in a 2-D nonsynchronized format. For example, a breaker shown in the plan view is a totally separate element from the same breaker shown in the elevation view — even though both represent the same piece of equipment. Each occurrence of a design element must be updated separately from the rest. The result is a time-consuming and potentially error-prone process.
Additionally, standard construction drawings include static BOM information. This crucial catalog of parts and compatibles needs to be accurate for proper installation and future reference. Part changes in the warehouse database need to be updated on several sheets manually, making the process of drawing production and accuracy inefficient.
If savings of time and effort can be realized, then productivity can be maximized, errors can be minimized and duplication can be eliminated — all to the benefit of the organization. These motivations led Progress Energy to envision, design and develop the SMART system.
THE SMART SYSTEM
The primary objective of the SMART system is to provide linked data in the system that can respond to changes seamlessly and with minimal effort. To enable this dynamism, Progress Energy used 3-D parametric CAD models and linked them to appropriate database records. The utility designed the 3-D models from existing 2-D vendor and standard substation designs, then created 2-D and 3-D cell libraries. A cell library is a collection of 2-D and 3-D CAD models of standard equipment and structures that are used repeatedly.
Next, Progress Energy linked the cells to the corresponding data in the centralized database to create intelligent cell libraries for the user. Users choose the cells from these cell libraries to create and modify 3-D substation models. The designs then project specific construction drawings and plan views to generate a project BOM report automatically. Use of these pristine, intelligent cell libraries by end users enforces adherence to standards and informational consistency, which eliminates ambiguities. Figure 1 depicts a virtual 3-D model (a template) of a standard T&D-class substation that was built using cell libraries.
There are many benefits of using the SMART system. Most fall under two categories: reduced cost and reduced time. Progress Energy believes that a substation designed using the SMART system can take up to 30% less time than using the conventional process.
Other benefits of using the SMART system 3-D parametric models include enhanced visualization, flexibility in design parameters, ease of extracting 2-D views, design analysis and virtual prototypes. As you can see from Fig. 2, a single-phase regulator looks much more realistic when designed with the SMART system.
The SMART system is not just about good-looking models, but also accurate ones. Since accuracy of the BOM on standard engineering drawings is paramount to the success of the project, SMART uses automated pivot tables to accommodate real-time data changes made to the database records.
One critical component in substation design is an organization's standards unit, which ensures that equipment components, specifications, philosophies and design details will promote safety, efficiency, consistency and reliability, and will follow regulatory codes. Recognizing this, the standards unit is notified every time material coordinators add, manipulate or delete parts or equipment in the database. The SMART system enables a single-click refresh for pivot tables instantly showing changes in all corresponding drawings.
Progress Energy developed and tested this concept successfully with limited effort. This ensures that end users (engineering units) get up-to-date BOM data on project design drawings, thus improving consistency and accuracy. For customized projects, users can edit pivot tables to incorporate user-defined parts and equipment.
Since both plan and sectional views are required for substation orientation and configuration, Progress Energy designed the SMART system so that the system automatically updates both views once changes are made to the 3-D model. To do this, the system treats the 3-D model as the “parent object,” while a 2-D drawing is a “child object.” In other words, a transformer replaced in the 3-D substation model alone would be reflected in the plan and sectional views automatically, which saves time and ensures accuracy. Figure 3 illustrates the synchronized 2-D plan and sectional sheet views driven by the 3-D model.
Another aspect of substation design, the one-line diagram, is also greatly simplified by using the SMART system. The one-line circuit diagram is a simplified pictorial representation of a three-phase electrical circuit. It shows the components of the circuit as simplified standard symbols depicting devices.
Initially, for new substations and existing facility expansions, engineers use a one-line diagram to produce a quick project estimate for budgeting. In the SMART system, 2-D symbols are linked to the BOM database and then used to produce six standard one-line diagram templates. The user chooses the appropriate template to design a project-specific configuration. The system then will produce the corresponding project-estimate report almost instantly. This process eliminates the use of two distinct tools and options in the BOM report, providing process simplification. Figure 4 shows how a circuit switcher symbol would generate a BOM report with associated costs.
Another important capability of the SMART system is its ability to automatically generate a BOM. During the substation design phase, the user chooses and places the appropriate CAD models in a design file from the centralized intelligent cell libraries. Once satisfied with the design arrangement, a custom-built command triggers a query based on the models in the design file to generate a BOM report instantly. The graphic-driven report is editable, to include any design changes made by the user.
This concept enables Progress Energy to automatically gather material data for construction, through vector-based graphical models, all in one environment. Subsequently, the information is passed downstream to supply-chain systems for purchasing and inventory. To abide by work-flow management principles, the active link of the CAD models to the database is terminated after the project is released. Through automatic BOM generation, man-hours are reduced and productivity is increased. For example, a 3-D model of a load break switch stand, when placed in a file, will generate the construction BOM automatically.
A question arose as to how Progress Energy would handle brownfield (existing) substations, since those are completely represented in 2-D. The answer was to use the CAD application's built-in flatten-cell technique. This technique flattens a 3-D model in any given orthogonal direction (top, front and side views) and produces a 2-D cell. The flattening operation will not affect the object linkage to the BOM database. Figure 5 shows a V-switch on a feeder bus structure flattened in all three orthogonal views and the 3-D isometric view. Thus, the SMART system assists not only in new substation design, but also helps with design changes to existing substations.
Using the SMART substation design system will ultimately save the electric industry time, money and frustration. Integrated 3-D CAD models with automatic BOM data simplifies the process and reduces errors. Even in the initial project-estimate phase, the system allows for quicker and more accurate work based on one-line circuit diagrams. Synchronized 2-D plan and sectional views are created from a single 3-D model, and virtual 3-D prototypes can be created for design optimization and experimentation with alternative designs. The system also reduces latent human-performance errors and contributes to timely project completion by using current BOM information on standard construction drawings. Lastly, the SMART system can ease electrical clearance validation and enhance visualization.
The SMART system is a great advance for substation design, but Progress Energy is not stopping with what it has now. Ideas for future work include an enhanced version of the SMART system, as well as extending the SMART principle to other design units; applying the SMART functionality to future design standards; adding the capability for below-grade designs for foundations, grounding and conduit, and cable schedules; and integrating the SMART system with other design tools such as structure design, foundation design and ground-grid design.
While already well used in other industries, the application of 3-D design principles in a system design specifically for electric substations will create great benefits for utilities. Any system that can reduce time and cost should get a hard look from the industry, especially in a period during which all companies are watching the bottom line, while striving to provide increasingly reliable service at low rates.
The authors extend a special thanks to Rhonda Webb, a manager at Progress Energy Carolinas, and Terri Hopkins, a senior engineer at the utility, for their invaluable, continuous and strategic support for this automation project. Their vast experience in the utility industry helped the authors to understand the current processes and devise streamline processes that are user friendly to engineering personnel in a cost-effective manner.
Shiva Korremla is a rising engineer at Progress Energy. His job responsibilities include automating design processes utilized by the transmission engineering units by designing 3-D parametric CAD models of materials and equipment. He is also creating database linkages between graphical and nongraphical data by redesigning databases to be compatible to CAD applications. He received a MSME degree from the University of Texas at El Paso. [email protected]
Michael Goins is the project leader for the design automation effort at Progress Energy. His job responsibilities include leading the design automation effort by researching, testing and training. He oversees the job responsibilities of the design automation team and associated technologies. He received a bachelor's degree in computer information systems and is pursuing his MBA degree. [email protected]
Note: This article is based on a 2008 Southeastern Electric Exchange presentation.