Joel Blair 

  Towns Holmboe 

AACSR: The Forgotten High Strength, Low Sag Conductor

What are the considerations, issues, and solutions presented when you’re faced with rebuilding a long transmission span across an ever-changing riverbed. This paper and presentation will explore how OG&E and CEC handled the rebuild of the Fixico-Kolache transmission line crossing the Canadian River. Specifically, we’ll discuss how the project was initiated, how CEC & OG&E developed solutions and selected the best option for everyone involved, how CEC & OG&E spanned the river by using a custom design with specialized conductor, and how construction turned the prints into reality. The washed out structure was discovered during regularly scheduled inspections as part of a program called Transmission Restoration. Transmission Restoration is a vital maintenance program at OG&E where inspectors inspect existing Transmission lines for areas of concern. CEC’s inspectors carefully assess each structure and make recommendations for repair, reinforcement, or replacement. The Fixico-Kolache 138kV Canadian River Crossing project emphasizes the importance and benefits of regular inspections of a utility’s infrastructure. We will also explore the decision making process for how to re-build the river crossing. OG&E and CEC evaluated multiple options for relocation of the line and we’ll showcase the reasons why each of those options was eliminated. Details considered in making the decision included time-frame, ROW issues, environmental considerations, and the desire to eliminate any structures being placed in the river bed. After the decision was reached to span the entire river bed, CEC and OG&E’s Transmission Engineers had to take this plan from conception to reality. After CEC’s survey crew provided a land survey showing the extents of the Canadian River, the group was now faced with a 2,200’ span. This long span presented many obstacles including vertical clearance, conductor spacing, structure strength, galloping, vibration, sag of the conductor, conductor strength, ice loading, constructability, and possibly FAA paint and lighting requirements. In order to avoid the FAA requirements and future maintenance they would impose, CEC and OG&E decided to use a special high strength AACSR conductor to reduce the sag and allow for shorter poles.

   Sanket Bolar 

  Javier Ruiz Leiva 

Understanding Online Partial Discharge Testing

Failure of equipment in a substation can lead to serious consequences resulting in unscheduled downtimes and potential loss of revenue. Maintenance testing can be carried out on equipment during scheduled outages taken at regular intervals of time. It is also important, however, to keep track of the equipment condition during operation by monitoring certain parameters based on the type of equipment. One parameter that can be monitored on a lot of electrical components is partial discharge activity. The term "partial discharge" refers to low energy discharges which occur in a dielectric. These discharges don't completely break down the dielectric and hence are called partial discharges. Partial discharge is not indicative of failure, but continuous PD activity deteriorates the insulation condition thereby, reducing the reliability of the electrical component and increasing the risk of equipment failure. Hence, online partial discharge testing can serve as a very important part of a predictive maintenance program. This paper will dwell on how online PD testing can serve as an important tool in detecting and tracking deterioration in equipment insulation. This paper will look at the theory of partial discharge and cover the various sensing techniques that are used to detect online partial discharge. Sample PD plots obtained from lab measurements corresponding to different types of partial discharge will be shared in this paper. Some case studies will also be included to highlight the importance of online partial discharge testing.

   Alex Bonnette, P.E. 

  Joe Carney 

  Joe Coffey 

A Study of How Enhanced Conductor Heat Dissipation from High Emissivity ACSS Allowed a Texas Utility to Make the Most of a Narrow Right of Way

This presentation and paper will detail a challenging project where Oncor Electric needed to upgrade capacity on an existing 138 kV route interconnecting to a neighboring utility. A narrow right of way made it difficult to achieve the required ampacity for this critical circuit using standard conductor options. The presentation will review the engineering analysis of the conductor/structure options considered, share the selected design, review project construction, and show in-service test results from after project completion.

   Alex Bonnette, P.E. 

  Joe Carney 

  Lance Holiman 

Engineering & Construction of a Transmission Line Within an Urban Area

The "Engineering and Construction of a Transmission Line within an Urban Area" presentation demonstrates the inimitable difficulties faced during design and construction within an urban environment. One example of an urban project is the Oncor: Denton Dr. - Maple Ave. 138 kV Line Rebuild located in Dallas, TX. Design was carried out by PEI and Oncor Engineering. This was an existing 69 kV wood monopole line with distribution and third-party utility underbuild. This line was rebuilt with new steel monopoles designed for 138 kV standards and to accommodate distribution and third-party utility underbuild transfers. Design challenges consisted of variations between Level "B" and Level "A" SUE (Subsurface Utility Engineering), construction outages, construction mobilizations, city approved working hours, and transfers of overhead third-party utilities within existing Right-of-Way (ROW). This presentation will discuss how coordination between multiple involved parties allowed for the project to be completed safely and successfully. Lessons Learned The Denton Dr. - Maple Ave 138 kV Line Rebuild project provided new experiences that will allow us to reinforce design approaches for similar future projects in dense urban areas. During the design phase, a greater emphasis was put on the locations of poles due to the dense nature of the environment we were constructing in. This is especially true for shared City ROW with other utilities. Foundations and poles were designed to fit within the parameters discovered by Level "B" (included "C" and "D") SUE. It was not reliable to depend on quality level "B" SUE for finalizing the design for this project. Quality level "A" SUE survey was utilized at the start of construction to reduce the impact on the public roads abutting the easement such as duration of traffic control, city permitting, sidewalk repair, etc. Due to the inaccuracy of the public utility information and additional unknown utilities found during level "A" SUE prior to construction, design modifications were made after construction documents were issued. Performing "A" SUE prior to issuing construction documents could have mitigated construction delays by allowing the engineers to have time to adjust the design to the existing conditions well ahead of the start of construction. Another method that proved beneficial, where pole spotting seemed undoable, was contacting the local municipality departments to obtain existing information about utilities within the area of work. For example, this aided in determining if an underground utility, such as a storm sewer or water line, was active or inactive. Another lesson learned was the need to establish a point of contact for the third-party utilities earlier on in the project. Establishment of a primary contact for third party utilities improved communication and coordination for distribution outages. Construction handled the coordination delays by sectionalizing distribution outages and reorganizing transmission construction crews. It was beneficial that Construction was involved early in the project scoping and design process to provide insight on potential project impacts or delays. Even with these precautions implemented in the design and construction phase, there was still unforeseen obstacles due to the nature of this project.

   Clinton Char, P.E. 

The Challenges of Fire Hardening the Southern California Edison Transmission and Distribution System

Due to various factors, the world’s climate is changing. In order to meet the challenges posed by climate change, utilities must recognize and prepare for these changes to ensure continued service reliability into the future. In California one of the most devastating results of climate change is the increasing frequency and intensity of wild fires throughout the state. The two worst fires in the state’s history have occurred over the past 2 years – Medocino Complex Fire (2018) where 459,123 acres were burned and the Thomas Fire (2017) where 281,893 acres were burned. As a result of the fires, electric utilities have lost a multitude of transmission and distribution lines resulting in millions of dollars in damage. To position itself to address climate change and the potential for increasing wild fires, Southern California Edison (SCE), has initiated a Grid Resiliency program to harden the SCE system against wild fires. The primary effort in the Grid Resiliency program is to look for pole materials and coatings which would increase the fire resistance of its poles. Composite poles, ductile iron poles, weathering steel poles, concrete poles were examined. Various coatings and wraps to protect new and in-service wood poles were also examined. An extensive evaluation process was conducted for each of the materials to ensure that the materials would perform well in everyday conditions. QUV testing, water intrusion testing, corrosive environment testing, strength testing and service life calculations were made to ensure that the materials would not degrade when exposed to the Southern California environment. Once it was determined that the materials would perform well under everyday conditions, the materials were subjected to fire testing to see how they would perform under simulated wild fire conditions. Two fire testing procedures were used to simulate wild fire conditions – ASTM Standard Test Method for Determination of Charring Depth of Wood Utility Poles Exposed to Simulated Wildland fires (DRAFT) and the RS Technologies Fire Testing. Upon being exposed to the fire testing, strength reduction calculations were made to determine the materials effectiveness to withstand fire conditions. Based on the testing results, SCE is making decisions on the materials which will be used to fire harden its system. The objective of this paper will be to provide the details of the materials which SCE has tested, the results of the testing and their effectiveness under simulated fire conditions.

   Sanchit Chitre, P.E. 

The Challenges of Fire Hardening the Southern California Edison Transmission and Distribution System

This presentation and paper will detail a challenging project where Oncor Electric needed to upgrade capacity on an existing 138 kV route interconnecting to a neighboring utility. A narrow right of way made it difficult to achieve the required ampacity for this critical circuit using standard conductor options. The presentation will review the engineering analysis of the conductor/structure options considered, share the selected design, review project construction, and show in-service test results from after project completion.

   Bartley Estes, CMS 

Supporting Design with Reality Capture Technology

Developments in reality capture and geospatial technologies are rapidly enhancing the approach to engineering and design in the utility sector. As current design workflows shift from 2D to 3D, precise preliminary design requires highly detailed existing information. Projects are now being “virtually constructed” before ever breaking ground, drastically reducing construction conflicts, change orders, and other issues that come along with conventional design workflows. To help achieve this, reality capture technologies are being leveraged to provide comprehensive and high-precision existing models. The general term “reality capture” encompasses many related technologies that capture the current state of something, like a project site. These technologies range from 3D laser scanning, photogrammetry, unmanned aerial systems, augmented reality, and many more. These new data capture methods are empowering designers to make more data-driven decisions. There is not one single reality capture technology that fits every situation. Choosing the right tool in the toolbox is key. Many times, this can be a blending of multiple technologies to produce the critical and actionable data needed to create a comprehensive preliminary design. Understanding how these different technologies translate to the world of design is crucial to the overall approach to a project understanding. This presentation will explore various reality capture technologies and discuss how each are implemented in preliminary design processes and 3D visualization. We will examine best-use practices for each and the benefits of their implementation.

  R. John Falkenrath, P.E., S.E.

  Greg Ade, PMP, CQA,

  Leo Padron, ASNT Level III, ISO - RAB/QSA

Teaming Up On Steel Pole Quality, And Why It Matters To You

Provisions and commentary for Chapter 10: Quality Assurance/Quality Control, of ASCE Standard: ASCE/SEI 48-11 Design of Steel Transmission Pole Structures, describe the basic roles and responsibilities of the Owner and the Fabricator relative to ensuring the quality of steel poles. However, as a standard, the document does not provide guidance or best practices for establishing and maintaining the working relationship between the parties responsible for quality working on the Owner's behalf and on the Fabricator's behalf. The Owner's specification for Quality Assurance and the Fabricator's Quality Control policy, procedures, and practices are the documents that establish the contractual relationship between the participants in ensuring quality, but do not provide the essential means of ensuring the system will be effective. This paper provides insights from both sides of the working relationship between an Owner and a Fabricator that have shown to be effective at ensuring steel pole quality. By establishing and maintaining a team approach to steel pole quality, the Owner and Fabricator have both benefited through reducing costs and maintaining schedules. If you are an Owner or a Fabricator involved with the quality of steel poles, you should ask yourself if costs and schedules are of interest to you. If they are, then this paper should matter to you.

   Brett Fisher 

  Tom Guess 

  Paul Barker 

  Jon Trout 

Reconductoring and Associated Lattice Tower Foundation Analysis and Modifications

In 2016, FirstEnergy (FE) initiated work to replace conductor and convert existing overhead ground wire to OPGW on three 69kV circuits in Pennsylvania. The project included 26 circuit miles of lattice towers and posed many challenges including an accelerated schedule, outage constraints, difficult access and the lack of existing lattice tower foundation capacity drawings. During the design phase of the project it was discovered the NESC 250C Extreme Wind loading case was causing uplift capacity issues on existing lattice tower foundations. FE, with the assistance of Burns & McDonnell (BMcD), completed a ground line reaction comparison of the existing configuration against the proposed design loading and identified each tower location where the new loading would exceed the existing configuration’s ground line reactions. FE and BMcD analyzed grillage capacities on 41 lattice towers which consisted of five different tower types. Grillage capacities were developed for these specific towers by following industry design practices. A geotechnical investigation was completed to characterize the native soil and backfill properties at the tower locations. The results of the analysis showed that the proposed loading increase would result in several of the grillages having insufficient uplift capacity. The factored capacities were compared with the extreme load case and were used to determine which structure foundations required modifications to provide adequate uplift resistance. Several mitigation options were developed to provide additional capacity to the existing foundations. The feasibility of each option was evaluated by representatives from engineering, construction, project management, real estate and transmission maintenance. Options were assessed and ranked considering cost, constructability, rights of existing easement agreements, aesthetics, land-owner impacts and long-term performance and maintenance. The uplift mitigation system included a bracket designed to attach to the existing tower leg near the ground that can accommodate connection to multiple anchor types. The attachment design had to account for induced stresses on the tower leg, additional bracing and reinforcement and constructability to properly install the anchors adjacent to the tower leg and foundation while securing the anchor to the bracket. The structural design of the attachment bracket required close coordination with construction, project management, real estate and geotechnical engineering. Several anchor systems were utilized to overcome varying rock depths and soil profiles. These anchor systems included grouted threaded rod rock anchors, helical anchors, stingray earth anchors and a hollow bar injection anchor system.

   Jean-Marie George 

Overhead lines under extreme heat and wildfire conditions

Wildfires can have multiple causes. Overhead lines often just happen to be on the path of a fire, and in this case it is critical to understand what may happen to the line and its components. Besides the risk of having phase ground faults resulting from intense arcing activity in the smoke and heat cloud, resilience is paramount and the amount of damage to lines is a direct consequence of line designs. Distribution overhead lines are obviously much closer to fires than transmission lines and therefore suffer much more of heat damage. Wood poles are clearly identified as a weak link under such circumstances but insulators can also become critical. Even for transmission lines the heat impact can be substantial but not necessarily immediately visible in the short term. Some specific physical characteristics of overhead line insulators need to be clearly identified and taken into consideration either to evaluate the risk of having a line drop during the fire or years later as a result of a weakening of the insulators which survived the fire in the first place. Another aspect of this problem is to review insulator design features assessing the risk of insulators to be a threat triggering fires on a normal day. Insulator failures can lead to line drops and subsequently trigger fires and catastrophic situations. This is true for either distribution or transmission lines. Hardening the grid means finding more robust line designs and insulators. In the aftermath of the Californian fires, this contribution is intended to help evaluating what can be done differently and what needs to be changed in the selection of insulators.

Chase Lansdale  

Kenneth A. Donohoo 

Case Study on an Alternative Approach to Distributed Energy Demand

Demand dispatch is an emerging science to providing grid services for controlling storage and flexible loads, such as air conditioners and water heaters. EPE is presenting analytics performed on a rural distribution system examining the impact to reduce 15-minute transients and overall system peak demand using control algorithms developed at the University of Florida and incorporated into engineering modeling software. The results show that it is feasible to control demand without any change being seen at the customer level, while also reducing peak demand by up to 5%.

   Srijib Mukherjee, Ph.D., P.E.  

Frequency Response and Dynamic Power Balancing in Wind and Solar Generation

Large scale deployment of renewable resources introduces significant complexity in performing load balancing and ACE/frequency regulation. Wind and solar energy are intermittent which may diminish rapidly while system load is increasing. This operating condition places an additional burden on conventional resources that are on-line and available for load balancing and ACE/frequency regulation to meet the challenges surrounding the aspects of uncertainty and variability that come with having variable generation in the system. There are two major attributes of intermittent generation that notably impact system operations – variability (generation changes according to the availability of the primary fuel, i.e. – wind or sunlight in this case resulting in swings of the plant output) and uncertainty (magnitude and time of the generation output is unpredictable). While variability is more of a function of regulation, uncertainty can be aligned more to the need for ramping requirements. The objective of this paper will be to understand the feasibility of ramp rate limits within the present CAISO’s conventional generation fleet to meet renewable requirements in 2020 and determine the additional ramp capability required with the integration of renewables to CAISO footprint. Moreover, statistical analysis will be done to characterize the ramp effects and determine the worst hourly changes with renewable energy penetration. The objective of this paper will be to understand the feasibility of ramp rate limits within the present CAISO’s conventional generation fleet to meet renewable requirements in 2020 and determine the additional ramp capability required with the integration of renewables to CAISO footprint. Moreover, statistical analysis will be done to characterize the ramp effects and determine the worst hourly changes with renewable energy penetration.

   Greg Parent, P.E., SE  

  Joshua Ratliff  

  Brandon Hubbard 

A Qualitative Measure of The Accuracy of Load Case NESC 250B

The National Electric Safety Code (NESC) specifies two load cases for structural design which include radial ice thicknesses in combination with wind pressures/wind speeds. These two load cases are NESC 250B and NESC 250D. Load case NESC 250B "Regional District Loads" is a non-probabilistic load case which originated in 1908. After several catastrophic failures in Iowa in the 1990's from ice and wind loading, engineers agreed that there was a need for a new load case which more accurately accounted for combined ice and wind loads. Engineers analyzed years of meteorological data and created load case known as NESC 250D "Extreme Ice with Concurrent Wind Loading". NESC 250D is a probabilistic load case with a 50 year Mean Recurrence Interval. Load case NESC 250D was first published in the 2001 edition of the NESC, but the NESC specified a Load Factor = 1.0 to be applied to the NESC 250D loads. For this reason, the NESC 250B load case with the NESC required load factors (Vertical = 1.5, Trans Wind = 2.5, Trans Wire Tension = 1.65) often results as the controlling load case. Since NESC 250B is not a probabilistic load case, a direct measure of reliability cannot be performed when this load case controls the structural design. However, the structural loads from NESC 250B with NESC required load factors can be compared to the structural loads from load case NESC 250D with a load factor of 1.0. This paper will discuss the structural analysis of a 90-degree self-supporting steel monopole from a 115kV transmission line and one from a 345kV line. This analysis will compare the base reactions for these structures for each of the 43 overlapping load regions between NESC 250B and NESC 250D. The ratio of the base reactions, (NESC 250B with load factors)/(NESC 250D with load factor = 1.0) will be calculated and mapped. This structural analysis will show that certain regions of the country are designed with probabilistically "High" design loads while many other regions are designed with probabilistically "Low" design loads. Recommendations will be made on how to design structures with probabilistically appropriate design loads.

   Erik Ruggeri 

Cigre B2 (OH Transmission) Updates from the latest Colloquium, Hakodate, Japan, April 25, 2019

Engineering process and performance of installing LC spiral rods on OH lines at highway crossings in Canada.

To mitigate dangers associated with ice shedding at highway crossings, Hydro Quebec analyzed and implemented the installation of LC spiral rods. The material in these rods is a Low Curie metal alloy (Fe-Ni in this case). This material has a unique property of losing magnetic properties above a certain temperature (0°F for the material chosen). This prevents the rods from heating the wire in warmer conditions. The installation had its unique challenges but was successful in preventing ice accretion in these spans. Corrosion Evaluation of ASCR with ACM (Atmospheric Corrosion Monitoring) in coastal and acid fog environments.

Research has been performed on collection and evaluation of corrosion potentials in environments subjected to heavy (sea) salt and sulfate (pollution). The studies highlight the difference in strand corrosion associated with these two environments and discusses methods to measure the amount of aluminum or steel left after the onset of corrosion (eddy current flaw detection method). Finally, field measurements are collected and used to determine line inspection intervals.

Spacer dampers for EHV transmission lines: control of aeolian vibration and sub-span oscillations.

Researchers at Hydro Quebec have a mile test span in which they are testing the behavior of a hex-bundle phase with respect to minimizing both aeolian vibrations and sub-span oscillations. The wind data collected has been plotted against swing angle of the bundle as well as the amplitude of the sub-span oscillations (oscillations occurring between the spacer dampers). The effects or perceived benefits of armor rods at the spacer damper locations are also analyzed in this study.

New tools and procedures for Live Line Maintenance (LLM)

Techniques used by Brazil TSPs (Transmission Service Providers) to evaluate Safe Approach Distances (SAD) for 800 kV DC lines. There are over 4500 km (2700 miles) of these high voltage DC lines. This equates to almost a million glass bells to monitor and maintain. New methods for insulator change-out, as well as the impact of broken bells on SADs and procedures to replace insulators with lines energized.

In Hungary, researchers are creating LLM chairs and carts for the purpose of replacing insulators and navigating the cart past the suspension insulator at the 400 kV DC voltage level.

   Farshid Salehi, Ph.D. 

  Mike Tabrizi, Ph.D. 

Sub-Synchronous Control Interaction: Overview of Modeling, Risk Assessment and Countermeasures

Power electronic-based devices such as renewable resources, battery storage and FACTs devices have been widely used in the modern power grids. Complex and multi-layer controllers associated with these elements have presented new challenges in transmission and distribution networks. Some of these challenges such as Sub-Synchronous Control Interaction (SSCI), weak grid interconnection, middle frequency resonance (MFR) and high frequency resonance have received more attention and, recent investigations have highlighted the strong tie between the nature and extent of these phenomena and the control systems and strategies utilized to parameterize the controllers of the power electronic-based devices.

Sub-synchronous control interaction is relatively new phenomena and results from the energy exchange between control system of power electronic-based devices and nearby series-compensated line within the sun-synchronous frequency range. SSCI has electrical and fast-growing nature and can cause severe damages to the grid's elements. Therefore, expeditious mitigation and detection solutions in, addition to effective and comprehensive modeling and risk assessment approaches are required to avoid the negative impact of the SSCI.

This presentation will cover the basic understanding of the SSCI, modeling and vulnerability assessment of power grids to SSCI, and propose some mitigation and detection solutions for this harmful phenomenon.

   Nate Schrein 

  Travis Layton 

Concrete Supply Options In Remote Locations For Transmission Lines And Substations

Regions of the United States that are favorable to renewable generation growth generally have sustained winds and sunny skies year around. However, the areas favorable to renewable generation are often found in remote locations with low population densities and little infrastructure in place. Transmission providers tasked with connecting these generators to the grid often deal with the logistical challenges of constructing transmission lines and substations in remote locations. When a transmission line is constructed, engineers and constructors may find that the line traverses sparsely populated areas, sometimes hours away from concrete suppliers. This paper will focus on concrete supply in remote locations as it can be a significant logistical hurdle that needs to be overcome. On the design and planning side, there are measures that can be taken to help mitigate these logistical challenges. For construction, there are several concrete supply options that can be considered. Upfront planning and concrete supply options will be discussed within this paper. Additionally, advantages and disadvantages for each concrete supply option will be reviewed.

   Joshua Wright, P.E.  

  Christopher Fornataro, P.E. 

Meeting Modern Resiliency Goals Through Cascade Failure Analysis

On August 25th, 2017, Category 4 hurricane Harvey made landfall in the Coastal Bend area of American Electric Power’s (AEP’s) Texas service territory causing significant damage to both distribution and transmission facilities. In total, over 766 transmission line structures and 5,726 distribution poles were left downed or damaged resulting in roughly 220,000 outages. One of AEP’s transmission lines significantly impacted by the storm was the Whitepoint - STP 345kV Circuit. Built by Central Power and Light in 1972 and later acquired by AEP, the Whitepoint – STP 345kV circuit stretches from outside of Corpus Christi (San Patricio County) to near Danevang (Wharton County). During hurricane Harvey, a cascading failure occurred on a more than 30-mile section of the 130-mile line leaving approximately 128 structures either downed or damaged. The cascaded section of the line consisted of a single horizontal circuit supported by steel lattice mast H-frame tangent structures and three-mast lattice guyed angle structures. The cascaded section of the line was replaced and put back in service by May of 2018 using tubular H-frame tangent and strain structures and three-pole tubular dead-end structures. In early 2018, AEP’s Transmission Engineering Services group tasked DiGioia Gray and Associates (DiGioia Gray) to study the Whitepoint – STP 345kV cascade event. In conjunction with The Electrical Power Research Institute (EPRI), DiGioia Gray developed a software tool to implement EPRI’s algorithm for evaluating the potential for line cascading failures. EPRI’s method, Cascading fAilure riSk assEssment (CASE), defines unbalanced forces on electric transmission structures and assesses the risk of progressive structure failures, or cascades, along the alignment of an overhead transmission line. The intent of DiGioia Gray’s study was to use the CASE software (CASE TOOL) to analyze the original cascade failure and the remaining uneffected100-mile sections, compare the resiliency of the replacement line to the failed line section, and provide an assessment of AEP’s current design practices regarding cascade failures. The analysis considered three weather conditions and four failure events that typically initiate cascading failures on overhead line systems. The findings revealed that the failed portion of the line did not meet current recommended industry standards and was unable to contain a cascade failure under the majority of the load conditions considered. The findings also revealed that the replacement line met all current minimum standards for cascading as specified by ASCE Manual 74. In summary, the study showed the value in using the CASE analysis and the CASE TOOL to assess resiliency levels of old and new transmission lines. The study validated that AEP’s design practices meet current industry standards, and outlined the importance of those standards to ensure safety, reliability, and resiliency are met in the design of future transmission facilities.