A 3D model provided visual coordination and simulation of the construction progress. Image courtesy of POWERCHINA HEEC Ltd.

The State Grid Corporation of China is developing and promoting 3D design standards to digitalize processes for lifecycle substation management throughout the country.

The Miluo western 220kV substation is the organization’s CNY 120 million ($17 million) pilot initiative and the first substation to use 3D digital modelling throughout construction, operations, and maintenance.

This article was originally published as part of the PEI print edition in 
Smart Energy International Issue 4-2020
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Located in Hubei province, the substation will significantly improve the grid structure in the Miluo area, covering 16km2 and enhancing the reliability of power supplied to 160,000 residents.

POWERCHINA Hubei Electric Engineering (HEEC) won a bid as lead designer to implement 3D collaborative modelling in accordance with the State Grid’s design standards and to deliver digital twins to the owner.

The project presented numerous site challenges, including a complex surrounding landscape lined with large residential houses that restricted the layout of the substation facility.

To accommodate the compressed footprint, the spatial location of each building structures, electrical equipment, and cable trenches – required multiple contributing engineering disciplines in close collaboration.

Working against an aggressive 10-month schedule to complete construction, HEEC had to effectively coordinate with each construction organization to safely deliver the project on time.

“The pilot program set a great example for using digital twins to support future state grid projects”

Faced with these design and construction difficulties, the team required integrated building information modelling, reality modelling and simulation and visualization technology to apply 3D digital standards and achieve full lifecycle digitalization. To accurately plan the project, HEEC used oblique photogrammetry, captured using an unmanned aerial vehicle, and ContextCapture, reality modelling software from US headquartered Bentley, to survey the substation site and generate a 3D reality mesh.

Using geospatial reality modelling helped establish a digital context for the project, visually capturing landscape, vegetation, rivers, lakes, roads, and houses surrounding the project area to support substation site and corridor planning.

“ContextCapture generates high-precision reality models automatically and can visually reflect various information to help make decisions,” said Wei Wang, executive assistant, senior engineering, at HEEC.

He added that compared to traditional 2D drawings, using the reality modelling application provided reliable environmental information to rationalize the substation layout amid the constrained site.

HEEC relied on the accuracy of the 3D reality model to visualize and analyze the existing conditions, optimizing the incoming and outgoing corridor lines while also minimizing impact on agricultural land and houses bordering the substation.

Using the reality mesh enabled the team to avoid demolishing six houses and reduce the area occupied by the substation by 22%, saving 0.94 hectares when compared to the original design scheme. As a result, HEEC saved CNY 2.5 million through the optimal substation layout and reduced earthworks for bored and cast-in-place piles by 63m3 to save an additional CNY 90,000.

The compressed substation layout, while optimal from an environmental and residential perspective, required multiple engineering disciplines to collaborate to avoid collisions in the tight space.

The electrical and civil engineering groups shared data and information through 3D models in discipline-specific digital applications that were then imported into the comprehensive substation model available within the connected data environment.

Integrating structural design software and analysis helped refine the architectural model to achieve less than 1% deviation in accuracy between the designed and actual steel material, optimizing the steel frame with just eight tonnes of steel to save CNY 120,000 in material costs.

By establishing collaborative 3D design workflows within the connected data environment, the team created an optimal engineering model, which identified and resolved clashes in advance, resulting in zero changes during underground construction. “Through comprehensive collision inspection of the underground facilities, design errors are found in advance and about 30 construction reworks are reduced,” says Wang.

The engineering design model, combined with the reality model, forms the substation digital twin where construction drawings and material quantities can automatically be extracted.

HEEC explored various methods to use the 3D design model to digitally guide construction. The team relied on mobile applications to enable on-site construction staff to access and check the substation model and associated drawings.

Various forms of data and dynamic simulation were integrated, allowing construction crews to visualize equipment installation and better understand the construction process.

Aerial image capturing helped to establish a digital context for the project, visually capturing the surrounding area. Image courtesy of POWERCHINA HEEC Ltd.

Working in a connected data environment with these mobile digital solutions provided on-site workers with easy access to the 3D design model, improving workflow and communication while effectively guiding construction to save 15 working days.

Integrating 4D construction sequencing provided visual coordination and simulation of the construction progress to track and manage the construction schedule.

Using a dynamic construction simulation application, HEEC performed a comparative analysis between the planned construction schedule and actual on-site process to effectively manage changes in real time.

“We can systematically and comprehensively manage and control the progress of the project, analyzing the progress deviation at all times to control the possible risks,” explains Wang.

Full construction digitalization of the Miluo substation was completed 30 days ahead of schedule and creating a digital twin of the substation reduced total investment of the project by CNY 6.3 million.

As China’s first substation project to use 3D design standards and digital twins during construction, HEEC has set a blueprint for the future. “The pilot program implemented standards during construction that helped to improve design quality and set a great example for using digital twins to support future state grid projects,” says Wang.

About the author

Amit Trehan is Industry Marketing Director, Utilities, at Bentley Systems.

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