Substation Design Document With Drawings

Substation Specifications

For a thorough substation design, you’ll need the following documents: a single-line diagram, a physical layout of the substation, section cuts taken from the physical plant, and wiring diagrams and schematics. Our group is tasked with finishing the substation’s design phase according to requirements that exhaustively address all equipment and relaying needs.

Alongside this, we will ensure that we are in accordance with IEEE standards by doing the following studies: AC study, DC study, and Lightning research.

Following the completion of the aforementioned phases, a complete design package is to be finalized.

Substation End Users

The people of Ames, who will depend on this design to power their homes and businesses, are the main end users of the substation. Nearby utility firms and power plants are additional consumers that rely on the substation’s operation as a component of the local power grid.

What Is Assumed And What Is Limited

Assumptions:

• The wind energy farm is rated at 138kV
• The ground on which the substation is to be built has already been leveled
• The equipment and relaying specifications provided by Burns & McDonnell are appropriately rated for the substation we are designing

Limitations:

• The design phase of the project must be completed by May 1st.
• The substation must service incoming lines of 138kV and outgoing lines of 69kV
• Battery bank must be rated at 125V DC and in accordance with IEEE 485
• Lightning protection must be in accordance with IEEE STD 998-2012
• All substation drawings are done using AutoCAD

Final Products and Services That Customers Expect

Among the project’s outcomes are a lightning study, schematics/wiring diagrams, a single-line diagram, physical layouts and sections, and an AC/DC study.

Single-Line Diagram

The substation’s overall design is depicted in the single-line diagram. All of the drawings have been created using AutoCAD, including this one. On the high-voltage side, there is a three-ring bus configuration depicted in the drawing, which comprises one transformer, all four breakers, and relaying equipment.

On the low-voltage side, there is a single breaker arrangement.

This diagram includes the incoming and outgoing lines, in addition to all of the connections in the substation yard. It merely displays the connected devices and equipment as well as the locations of the busses; it does not reveal the details of the cabling, such as the connections between individual ports.

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Physical Layout & Sections

The layout of the substation yard’s equipment is detailed in the physical layout. Additionally, it displays the perimeter fence, rigid bus, structures, road access, and substation enclosure.

Burns & McDonnell has received an AutoCAD drawing that includes all current and future equipment, along with detailed descriptions and any relevant standards.

General dimensions and equipment details are included in elevation section cut drawings.

Lightning Study

According to the IEEE STD 998-2012 Electro Geometric Model, which makes use of the empirical curves approach, the lightning study is carried out to assess and provide lightning protection for complete station protection against direct lightning strikes.

Here are the contents of this report:

• In order to design the lightning protection system, precise computations were performed.
• A synopsis of the shielding electrode groups’ orientation and protection outcomes
• Incorporating the maximum allowable heights of the lightning masts and shield wires into the suggested arrangement of the shielding electrodes

Further Study – Lightning protection guide

Lightning protection guide

AC/DC Study

Burns & McDonnell has been given the AC/DC calculations and their eventual ramifications, just like the Lightning Study. An examination of the substation’s power flow is part of the study, which is based on the AC and DC loads in the substation yard and enclosure.

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Schematics/Wiring

The schematics for the 69kV, 138kV, and 69kV line relays, as well as all of the transformer protection, have been completed following the creation of the AC and DC study. Along with this, the panel manufacturer has also received schematics and layouts for their use.

All of the connections between the enclosure’s equipment and the relays are shown in the wiring diagrams.

Figure 1-1 – Final Construction Package and Constituent Parts

Suggested Design

This section will address the preliminary design phases that yielded both successes and failures in the development of our original drawings; they were subsequently improved and rectified with customer collaboration and will be further detailed in Section 2.2.

Substation Design Layout

Following the schedule in Figure 1-1, the first task was to create an initial one-line layout for the substation. In the given specifications, the system contained the following elements:

1. Install three (3) 138 kV circuit breakers (B1, B2 & B3), to be used for the transformer high-side.
2. Install one (1) 69 kV circuit breaker (B4), to be used for the transformer low-side.
3. Install three (3) Coupling Capacitor Voltage Transformers (CCVT’s) (one per phase) on all three of the ring-bus exits.
4. Station surge arrester specification to be determined by substation engineer.
5. All substation equipment and bus should be rated for at least 2000A. All line conductors and equipment should be rated for at least 750A.
6. Install one (1) station service transformer on the 138-kV bus side of the 138/69kVtransformer MOAB to provide AC station service and relaying potentials.
7. New 3-phase 140-72-13.2, 100/134 MVA OA/FOA power transformer with Z1 = 5.6% on 100 MVA base.
8. Install one (1) 138kV motor operated air brake switch (A1).

Moreover, our system must initially be configured as a ring bus, as seen in Figure 2-1, and should be readily convertible into a breaker and a half for future growth, depicted in Figure 2-2.

Figure 2-1 – Ring Bus Layout

Figure 2-2 – Break and a Half Layout

Commencing the design process, our team concentrated on developing a single-line layout that conformed to the parameters provided by Burns & McDonnell, arranged in a ring bus configuration, consistent with the style seen in Figure 2-1. Building on this foundation, our team commenced the conversion to incorporate all requisite information for the final one-line diagram.

The preliminary design is depicted in Figure 2-3. All modifications to the original revision will be addressed in Section 2.2.1.

Figure 2-3 Initial Single-Line Design

Relay and Protection Design

Details on protection had to be added after the first Single-Line had been created. Additionally, this meets the client’s specifications. Burns & McDonnell supplied us with the electrical ratings of the components, which are displayed in AutoCAD cells, and the system consists of 10 relays wired for various protection systems and one wave trap used for communication.

Electrical component connections are illustrated in Figures 2-4 and 2-5.

Figure 2-5 – Color Coated Wiring Example for Relay Definitions

According to Figure 2-4, CT refers to a Current Transformer, whereas PT denotes a Potential or Voltage Transformer. When connecting a CT to a relay, as depicted by the red line in Figure 2-5, the connection can enter from either the left or right side of the relay and escape from the opposite side to be utilized in another relay.

When connecting a PT to a relay, nodes may be utilized to separate the connection from one relay to another, entering the relays from the bottom, as illustrated in Figure 2-6 by the blue line.

With these elements identified, a preliminary design of the single-line diagram was submitted, incorporating the protective systems. The outcomes of our team’s one-line design will be evaluated in Section 2.2.

Physical Design

Following to the development of the single-line, as illustrated in Figure 2-3, changes will be addressed in Section 2.2. The modifications to the original design of our single-line diagram serve as the foundation for the physical design, as drafting for the substation’s plan view commenced only after the one-line diagram was finalized.

This phase of the design is categorized into two segments: plan view and section cuts. The team was instructed to produce a plan view prior to developing the section cuts.

The plan view’s design is derived from the one-line diagram and represents a top-down perspective of the substation, encompassing all pertinent equipment and dimensions necessary for construction.

Figure 2-6 – AutoCAD Version of Plan View with Dimensions

Figure 2-6 presents the initial draft of our plan perspective based on the original single-line depicted in Figure 2-3. This area necessitated much information regarding the construction of a substation, particularly concerning appropriate connections and placements; hence, multiple revisions were undertaken prior to finalizing our design.

Following consultations with advisors from Burns & McDonnell, the group resolved to alter the single-line layout to establish a uniform design throughout all drawings, accommodating our client’s amendments aimed at simplifying and organizing our original design.

Figure 2-7 illustrates the newly submitted plan view.

Figure 2-7 – Revised Plan View AutoCAD Drawing

Upon completion of the plan view, the team concentrated on producing section cut views of the physical design. In Figure 2-7, the orientation of the section cut is indicated by the yellow circles in reference to the direction of the arrow.

These sectional images illustrate equipment heights and spacing information that are not depicted in the main plan view.

The sites of these incisions are illustrated in Figure 2-7. Figure 2-8 illustrates an example of a portion deleted from the initial revision stage.

Figure 2-8 – Section Cut Dwg# IASTATE-01-02 REV. 0

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