Design and Costs Estimation of Electrical Substations Based on Three-Dimensional Building Blocks

G. Bebis et al. (Eds.): ISVC 2010, Part III, LNCS 6455, pp. 574–583, 2010. © Springer-Verlag Berlin Heidelberg 2010

Design and Costs Estimation of Electrical Substations Based on Three-Dimensional Building Blocks

Eduardo Islas Pérez, Jessica Bahena Rada, Jesus Romero Lima, and Mirna Molina Marín

Instituto de Investigaciones Eléctricas, Av. Reforma 113 Col Reforma, Cuernavaca, Morelos, México, 62490

{eislas,jesbahrad,jesus.romero,mmolina}@iie.org.mx

Abstract. Substations design is a fundamental engineering component in power network construction. The benefits obtained for having adequate tools and de-sign systems are related mainly to cost savings, reduction of construction prob-lems and faster throughput of projects. In this paper we propose an approach based on three dimensional building blocks to construct virtual substations. The building blocks can become 3D standards for advanced engineering, automated drawing, data extraction and reusability of designs. Therefore these substation designs can improve quality and reliability of the design process. With virtual substations we can use them to help on making decisions about construction site selection and community and government acceptance. Finally 3D visualization and walkthrough can be used to improve construction, commissioning, opera-tions and maintenance of distribution and transmission electrical substations.

Keywords: Building Blocks, 3D Environments, Electrical Substations Design, CAD Tools.

1 Introduction

In this paper a system for designing electrical distribution substations (SIDSED) is described. The system uses different levels of building blocks to ease the design proc-ess and facilitate the estimation of costs of new electrical substations. The building blocks are based on three levels of abstraction; buildings blocks in the highest level are composed from building blocks in lower levels. Each building block has an asso-ciated cost obtained from a concepts catalogue with unit prices. The system was developed for CFE (Electricity Federal Commission) which is the main utility for generation and distribution of electricity in Mexico.

Using different levels of abstraction allow human designers the flexibility to devise a substation design using different levels of complexity and plasticity. For instance, if it is needed to change radically the design of a new substation an engineer can use basic elements from lower levels of abstraction (transformers, high-voltage circuit-breakers, lightning rods, structures, foundations, ducts banks, etc). Also, if a new de-sign of a substation is required quickly, the designer may use modules, which is a group of elements in superior levels of abstraction (line bay, transformer bay, control room, edge wall, etc). Once the configuration of a substation has been completed,

Design and Costs Estimation of Electrical Substations Based on 3D Building Blocks 575

human designers can estimate the cost for that substation and they are able to make decisions about the involved costs, type and size of equipments and future develop-ments for that electrical substation.

2 Traditional Design for New Substations

Figure 1 depicts a flow diagram about the current process for designing a new elec-trical substation. Human designer bases new designs on information and data from developed projects such as: topographical data, old CAD drawings and budget data to generate new CAD drawings, costs estimation and tender documents for a new substation.

•Topographical data•Soil Mechanics

Substation Technical

Specificacftions

Existent Projects •CAD Drawings (AutoCAD Files)

•Cost Estimation (Excel Files)

Human Designer

Data Analysis

New Projects•New CAD Drawings (AutoCAD Files)

•New Cost Estimation (Excel Files)•New Tender Documents (Doc Files)

Cost Engineer

Fig. 1. Flow diagram for traditional substations design at CFE

3 System Requirements

CFE asked for several requirements to meet the needs of 13 distribution divisions. The requirements for SIDSED were established taking into account that it will be used in all CFE´s Divisions across the country. The main solicited requirements were:

R1. The system must consider the whole design process for 115-KV substations. R2. The system must be able to design 3D normalized arrangements (H, ring, main

bus and main-bus transfer-bus). R3. The system must have interoperability with costs engineering software in order to

obtain the costs for building substations. R4. The system must have 3D visualization and walkthrough to give information

about equipments (transformers, high-voltage circuit-breakers, etc.), building elements (foundations, ducts banks, walls, etc.) and verify security distances be-tween components.

576 E.I. Pérez et al.

R5. The system must generate drawings, concepts catalogue and costs estimation documents.

R6. The system must generate a visualization file to share the substation with personnel without the necessity of having the system or any software used for development.

4 Related Work

Substations design is a fundamental engineering design component in power network construction. Puget and Enriquez dealt with several concepts related with good prac-tices for substations design [1] [2]. However, due to complexity in designing an elec-trical substation the process can be tedious and time consuming; therefore the design time can be prohibitively long. In recent times, with the aid of two dimensional CAD systems, substation’s design time has been reduced considerably. During these years, other industries have adopted three dimensional modeling for example: process plant design, mechanical design, manufacturing, architecture, civil engineering, medicine, etc. There are a lot of software packages, hardware tools and information related to 3D and virtual environments [3]. The benefits of 3D design and modeling in these in-dustries are well documented [4]. Reduction of change orders, concurrent engineering designs, elimination of interferences, increased quality of design, accurate material requirements, faster project throughput, visualization and construction sequencing have all shown quantifiable benefits [5].

Aberden [6] describes in a full study the benefits obtained with the migration from 2D to 3D, mainly reducing the change of orders and reusing existing parts and morph-ing an existing part into a new one. With respect to reusing parts in the design proc-ess, there are recent works which discuss problems involved in design reuse [7] [8]. However, most studies on the topic of reuse have predominately dealt with problems involving computer software and architectural reuse [9], [10], [11], [12]. Griss and Nazareth have shown that reusing design components is useful to reduce costs and shrink development time [13] [14]. In our approach, we reuse electrical and civil components as building blocks in order to ease the design process. Additionally the system estimates the costs for building new electrical substations.

5 System Description

In order to accomplish with the specified requirements, SiDSED was developed hav-ing three modules: engineering design module, costs engineering module and visuali-zation module (see Figure 2).

In the engineering design module, human designers use the building blocks to design a new electrical substation, taking into account some topographical data. Af-ter that, the cost of an electrical substation is estimated with the costs engineering module. Finally, with 3D visualization and walkthrough module, designers can make decisions about aspects related with construction, operations, maintenance and training.


SIDSED

SubstationTechnical

Specificacftions

Visualization Module• Three dimensional walkthroughRoamer y FreedomSoftware

Products• Electromechanical and civil drawings• Estimation costs of projects, equipment and materials•3D Visualization and walkthrough

•Topographical data

•Soil Mechanics

Tender Bases•Documents•Drawings

Building Blocks Library

Costs Engineering Module• Concepts Catalogue• Estimattion CostsOPUS Software

Subestations Configuration Volumetric calculation

Design Engineering Module

AllPlanAllPlan SoftwareSoftware

• Security distances • Interference detection

Fig. 2. SIDSED Configuration

H Arrangement

Ring Arrangement

Level 3 Level 2 Level 1

Abstraction Levels

Substations Arrangements

Fig. 3. Schematic diagram at different abstraction levels


5.1 Three-Dimensional Building Blocks Scheme

The 3D building blocks library was developed using a CAD software tool, which was selected from several software tools options to fulfill the established requirements for the system [15]. The 3D models were associated at different levels of abstraction and stored in a library embedded in the design engineering module.

The schematic diagram of building blocks at different abstraction levels is shown in Figure 3. It can be seen from the figure that each building block at level 1 is a basic element. In level 2 there are building blocks formed by elements from level 1, which are represented by horizontal rectangles. In the third level of abstraction, the horizon-tal rectangles are put together in order to have building blocks represented by vertical rectangles, which finally are used to design the physical arrangements of substations (H, ring, main bus and main bus-transfer bus). It is important to mention that each building block has associated its costs in such a way we can obtain the costs of the whole substation.

6 System Modules

6.1 Design Engineering Module

This module is divided in two processes: volumetric calculation and substations con-figuration. For volumetric calculation the soil movement is estimated in order to cre-ate terraces, levels and profiles in the construction site and estimate the associated costs depending on several factors (terrain type, soil volume, unit costs, etc.). The ob-jective of the substations configuration process is to build normalized substations in-cluding bays, control rooms, edge wall, ducts banks, etc. With the final design of the substation, the civil and engineering CAD drawings can be generated; a list of all elements of the substation are generated and linked with their costs. With these in-formation can be generated the documents related with tender bases. The updating of CAD drawings and costs estimation will be made automatically when the substation design is changed, avoiding the time consuming activities to maintain all information updated.

6.2 Costs Engineering Module

In this module the list of all elements generated in the design module are linked auto-matically to estimate the costs for building that substation. The associated costs for each building block are stored in a catalogue of concepts which describes the techni-cal specifications and costs based on their unit prices.

6.3 Visualization Module

This module consists of visualization and walkthrough around the virtual electrical substation in order to make decisions about layout design, types and sizes of equip-ments and constructive elements. The main objectives of this module are: to detect and avoid interferences between elements and verify security distances between compo-nents. It is also helpful to show the design to be approved by other government sector.


6.4 Three Dimensional Building Blocks Library

For creating the 3D library we build and grouped together 3D elements at different levels of abstraction. As we can see in Figure 4, the first level consists of building blocks of basic elements, such as transformers, high-voltage circuit-breakers, light-ning rods, structures, foundations, duct banks, etc. (see Figure 4, level 1). Each of these elements has associated its unit price through a link with the concepts cata-logue. In the second level are the building blocks that are formed by elements of the first level, for instance, the transformer-perch building block is composed by a trans-former, a transition perch, foundations, and groundings. The H structure with dis-connect blades is formed by an H structure, blades, a motoperator, foundations and grounding (see Figure 4, level 2). Finally, the third level is formed by building blocks in the most superior abstraction level, for example: line bay, transformer bay, control room, edge wall, etc (see Figure 4, level 3). This 3rd level is the most used abstraction level in the design process because it has all the necessary equipments for a specific function. For example, the control room has all equipments and materials inside of a standardized control room. If the designer needs to design a novel control room then he/she needs to use the 1st and 2nd abstraction level. It is very important to mention that each building block in the three abstraction levels has associated its unit price in such a way that at the end, the costs estimation for the whole substation is obtained.

Level 1

Level 2

Level 3

Fig. 4. Building Blocks at different levels of abstraction

Because building blocks were obtained from experienced human designers; these were developed in such a way that these can be used in different types of arrange-ments (ring, transfer bus, H, etc.). Therefore using these building blocks, the engineer can design a great variety of electrical substations very quickly.


7 Costs Estimation and Design of Electrical Substations

SIDSED is being used for development and costs estimation of new substations at CFE. To estimate the associated costs to build a new substation each building block has associated unit prices from a concepts catalogue. By designing a new substation based on those building blocks we will know a priori the total cost for that substation. As an example in Figure 5 is shown the costs estimation of a building block in the 3rd level integrated by 2 building blocks in the 2nd level of abstraction. In this example the cost involves an H structure, a high-voltage circuit-breaker, blades, motoperator, foundations and grounding. The cost of this building block is estimated in almost 250,000 pesos.

Fig. 5. Estimation Costs for a building block in the 3rd level

In Figure 6 a) and b) are shown images and drawings from the Valle Verde sub station (i.e. top view, edge wall, control room and transition perch). Valle Verde sub-station is configured in an H arrangement. Figure 7 shows images from La Reina a main-bus substation arrangement. Figure 8 shows La Diana, an encapsulated GIS sub-station, this substation is being designed in three levels in a completely novel way because it is located in a very populated area in Mexico City and it has spatial restric-tions requirements. The system will help to make decisions about the convenience of each substation and which is the best equipment distribution and configuration based mainly on their estimated costs among other criteria such as: 3D interferences, addi-tional future bays, etc.


a) 3D Design b) CAD Drawings

Fig. 6. Valle Verde Substation


Fig. 7. La Reina Substation


Fig. 8. La Diana Substation


8 Results

The results obtained with this approach is a library of 120 building blocks in the first level of abstraction, 30 elements in the second level and 15 in the most superior and complex level of abstraction. Additionally human designers in Distri-bution Department are working in the development of electrical distribution sub-stations based on different arrangements (main bus, H, ring and main bus-transfer bus) used at CFE. With the building blocks library human designers will be able to design other normalized arrangements as well as generating fully new substations configuration.

Once the 3D virtual substation is designed the CFE´s Divisions obtain the follow-ing benefits:

• Volumetric calculation for soil movement. • The civil and electromechanical CAD drawings. • The costs estimation of substations based on the concepts catalogue. • A three-dimensional visualization to navigate around the substation and to take

3D measurements in order to verify security distances between components. • Costs estimation documents to help in the elaboration of tender documents. • Visualization files to review the completeness and exactness of substations.

Some of the benefits obtained with SIDSED are the following:

• Reduction in time. In a preliminary study the first group of designers is tak-ing in average 75% less time to design a new substation.

• Cost savings. The cost savings for CFE is related with reducing the change of orders or modify a substation design when is it in the construction process.

• Standardization. Improving the standardization process of substations through the use of a standardized building blocks library besides using a unique concepts catalogue with standardized unit prices.

• Design sharing to review. Facilitate the process of reviewing and project acceptance.

9 Conclusions and Future Work

Some of the benefits obtained with the use of this type of approaches are related mainly with cost savings through design automation, reduction of construction prob-lems and faster throughput of projects. The building blocks can become 3D standards for advanced engineering, automated drawing, data extraction and reusability of de-signs. With virtual substations we can use it for site selection, community and gov-ernment acceptance and 3D visualization and walkthrough can be used to improve construction, commissioning, operations and maintenance.

Nowadays we are training personnel and implementing SIDSED in the first three Divisions at CFE and in a near future it will be implemented and used in all CFE’s Divisions along the country.


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