What Structural Engineers Should Know about Substation Rigid Bus Design

Transcription

1 What Structural Engineers Should Know about Substation Rigid Bus Design Minnesota Power Systems Conference November 8, 2017 Paul Somboonyanon, P.E., P.Eng

2 Agenda Substation Rigid Bus System Design Guide Design Methods IEEE 605 vs. Rigid Bus Model Rigid Bus Modeling Summary Q&A

3 Substation Rigid Bus System

4 Substation Rigid Bus System Bus Conductor A-Frame Insulator Bus Structure

5 Substation Rigid Bus System Insulator Arrangements Single Double Delta

6 Design Guide IEEE 605 Design Guide IEEE Guide for Bus Design in Air Insulated Substations providing: Electrical design aspects Structural design aspects

7 Design Guide IEEE 605 Design Guide Loads Gravity Extreme Wind (ASCE 7-05) Ice

8 Design Guide IEEE 605 Design Guide Loads Ice with Wind (ASCE 7-05) Thermal Earthquake (IEEE )

9 Design Guide IEEE 605 Design Guide Loads Short Circuit

10 Design Guide IEEE 605 Design Guide Short Circuit Load tt ii ssss tt = 2 IIII cc [cos 2ππππππ + δδ ee TTaa cos δδ ] Eq. (17) AC Component Decaying DC Component

11 Design Guide IEEE 605 Design Guide Short Circuit Load

12 Design Guide IEEE 605 Design Guide Short Circuit Load

13 Design Guide IEEE 605 Design Guide Short Circuit Load

14 Design Guide IEEE 605 Design Guide Short Circuit Load FF tt = μμ 4ππrr 2 ii 1 tt ii 2 tt [dd 1 uu rr dd 2 ] Eq. (13) Additional resources: CIGRE 105, CIGRE 214, and IEC 60865

15 Design Guide IEEE 605 Design Guide Short Circuit Load

16 Design Guide IEEE 605 Design Guide Short Circuit Load

17 Design Guide IEEE 605 Design Guide Short Circuit Load IEEE 605 Eq.

18 Rigid Bus Design Design Methods: 1. IEEE 605 Design Guide 2. Static Rigid Bus Modeling 3. Simplified Dynamic Approach 4. Dynamic Rigid Bus Modeling

19 Rigid Bus Design Design Methods IEEE 605 Step 1: gather information Step 2: go through each design criteria Bus deflection limit Bus stress limit Insulator cantilever strength limit Step 3: obtain Allowable Span Length

20 Rigid Bus Design Design Methods IEEE 605 L Allowable Span L Allowable Span

21 Rigid Bus Design Design Methods Static Rigid Bus Modeling Analyzing rigid bus system using FEA software by checking Insulator strengths Bus stress and deflection Thermal expansion effect Joint deflection

22 Rigid Bus Design Design Methods Static Rigid Bus Modeling

23 Rigid Bus Design Design Methods Simplified Dynamic Approach Analytical Techniques to Reduce Magnetic Force from High Fault Current on Rigid Bus By T.A. Amundsen, J.L. Oster, and K.C. Malten considering: dynamic property of bus span

24 Rigid Bus Design Design Methods Simplified Dynamic Approach Pros: Easy to implement Potentially provide more cost saving Cons: Load reduction varies by span length No established design guideline of OLF

25 Rigid Bus Design Design Methods Dynamic Rigid Bus Modeling IEEE 605 Eq.

26 Rigid Bus Design Design Methods Dynamic Rigid Bus Modeling Pros: Provide more accurate results Potentially provide more cost saving Cons: Complex analysis Time consuming No established design guideline for OLF

27 IEEE 605 vs. Rigid Bus Model Comparison of Design Limitations Design Features IEEE 605 Model Insulator arrangements Single Double * Single * with design assumption

28 IEEE 605 vs. Rigid Bus Model Comparison of Design Limitations (Continued) Design Features IEEE 605 Model Check insulator strengths Cantilever Torsional Tensile Compressive

29 IEEE 605 vs. Rigid Bus Model Comparison of Design Limitations (Continued) Design Features IEEE 605 Model Check bus conductor fiber stress and deflection Simple arrangement Complex arrangement

30 IEEE 605 vs. Rigid Bus Model Comparison of Design Limitations (Continued) Design Features IEEE 605 Model Provide detailed results Include bus structures/foundations Allow quick modifications

31 Rigid Bus Modeling Model Considerations Bus Fitting Types Rigid Slip Expansion

32 Rigid Bus Modeling Model Considerations Bus Fitting Releases Rigid x y Rigid z * Releases in relation to insulator local axes

33 Rigid Bus Modeling Model Considerations Bus Fitting Releases Slip x y z Slip * Releases in relation to insulator local axes

34 Rigid Bus Modeling Model Considerations Bus Fitting Releases Expansion x y z Expansion * Releases in relation to insulator local axes

35 Rigid Bus Modeling Model Considerations Load Combinations 1. DL + Extreme Wind + Short Circuit 2. DL + Combined Wind/Ice + Short Circuit 3. DL + Seismic + Short Circuit 4. DL + Thermal

36 Rigid Bus Modeling Model Considerations Load Combinations Approach LRFD - checking insulator strengths ASD - checking bus stress, bus deflection, and joint deflection

37 Rigid Bus Modeling Model Considerations Load Combinations - Overload Factor (OLF) Loads Overload Factor (OLF) IEEE 605 ASCE 113* Utility Std DL or Ice Wind or Seismic Short Circuit Thermal * ASCE 113 Section recommends reducing insulator strengths by 50% when using LRFD load combinations

38 Rigid Bus Modeling Model Considerations Impact of Overload Factor to Cantilever Strength Maximum

39 Rigid Bus Modeling Model Considerations Impact of Overload Factor to Cantilever Strength 75% 95% 69% IEEE Std 605 ASCE 113 Utility Std Maximum Insulator Strength Usage

40 Rigid Bus Modeling Model Considerations Welded Connections IEEE 605, Section

41 Rigid Bus Modeling Model Considerations ANSI C37.32 Table 4

42 Rigid Bus Modeling Model Considerations Joint Deflection at Expansion Fitting

43 Summary IEEE 605 is a great source for substation rigid bus design. Different design methods are available. Rigid bus modeling provides more accurate results but several factors should be considered.

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