Electrical Power
Upgrading Communications
Fiber optics chosen as optimal
solution for L&O Power Cooperative
Project Owner:
L&O Power Cooperative
Key Experience:
- Specified and procured all the components for this project, including fiber optic cables, hand holes, equipment racks, patch panels, Ethernet switches, fiber test equipment, patch cables,
and more - Locating services using GIS
- Installation included all cable plowing, trenching, boring, and pulling required for each L&O site as well as the 4.5-mile underground project
- Tested the functionality of the fiber network, providing sufficient data to be utilized as a baseline for future troubleshooting
Key Features:
- Privately owned and secure high speed fiber optic data network
- Optical ground wire (OPGW) serves as both a communications path and bonds adjacent towers to earth ground to shield the high-voltage conductors from lightning strikes
- Detailed GIS mapping of transmission lines and underground facilities
Reliable data communications are a necessity to all industries, and the utility industry is no exception. In critical moments, dependable communications are imperative. A poor connection can be the difference between a 5-minute or an extended electrical outage. No one wants an extended outage, extra expense, or inconvenience of having to commit additional resources to what should have been a simple solution. In addition, certain scenarios can put first responders or the general public at risk.
Realizing the risks of a less-than-reliable communications network, a long-standing client of DGR Engineering (DGR), L&O Power Cooperative (L&O), was determined to improve communications on its electric transmission system. L&O has utilized wireless radios on its system since the 80s and unlicensed 900 MHz digital Ethernet wireless radios since 2005. The radio system performed well for years but was designed as a budget-friendly way to connect sites over long distances while sending limited amounts of data. The need for constant uptime, along with an exponential rise in data traffic over recent years is exceeding the technology’s limitations.
DGR engineers explored different solutions. Radio technology with more data throughput such as Wi-Fi or microwave could be deployed. Microwave radios proved econ-omically unfeasible. Standard Wi-Fi technology could not meet the distance requirements and would require additional repeater sites and devices to meet L&O’s needs. Cellular radio options were reviewed, but paying for data and exposing critical data to the outside world was seen as a last resort or backup plan. A private fiber optic network owned exclusively by L&O became the solution that met both current and future needs. Fiber is reliable, secure, and offered data capacity that exceeded L&O’s projected future needs.
DGR recommended utilizing L&O’s existing transmission lines as the backbone for their fiber network, replacing the static wire on most lines with an Optical Ground Wire (OPGW) design. OPGW is a stranded electrical conductor with a steel tube core. The steel tube is then filled with numerous fiber optic strands. L&O understood that pursuing this solution would take longer to deploy but would be in their best interest long-term. As this OPGW infrastructure is built out, L&O intends to utilize existing wireless radios for backup communication in the event the OPGW line is compromised.
As part of the capital improvements study that DGR recently performed for L&O, it was identified that many of their lines were at the end of their useful life and due for replacement. The timing of the line replacement lined up well with their need for communication infrastructure improvements. DGR was tasked by L&O to design a new transmission plant to include OPGW. The remaining lines, yet to be completed, will require existing static wires to be replaced with OPGW or installation of a new underground fiber line to connect remaining terminal sites. The OPGW will be the backbone of the L&O communications infrastructure for the foreseeable future.
With the OPGW plan in place, DGR proposed the installation of a new 4.5-mile underground fiber line to connect their headquarters building to the OPGW network.
DGR’s team determined the optimal routes, materials, and cable locating requirements. DGR also consulted with local utilities to optimally navigate rights-of-way where possible. DGR’s team acquired the necessary permits from the Iowa DOT and Lyon County. No DNR permits, encroachment agreements, or new easement acquisitions were necessary for this particular project. The route consisted of utility rights-of-way, existing utility easements, and private property owned by L&O.
Underground cable location processes are necessary for all utilities that own and operate underground facilities. After investigation of contracted locating services options, L&O ultimately decided to take on the locating responsibility themselves. With the help of precise Global Positioning System (GPS) equipment that integrated into GIS and some additional effort during installation, L&O could perform locating services, accurate to within a few inches. The Owner felt comfortable with this amount of accuracy and appreciated the simplicity of the idea. All the underground cable installed was either armored or included a tracer wire to accommodate traditional cable locating practices as well.
The team at DGR developed plans and specifications two separate contracts the construction of the underground project; one for underground cable installation and the other for fiber splicing. The scope of the installation included all rural area cable plowing, trenching, boring, and pulling required for each L&O station site as well as the 4.5-mile mainline project. The installation contractor was able to substantially complete their scope of work in approximately one week while encountering only minor issues during construction. The fiber splicing connected all the OPGW system to underground cables as well as interconnecting fiber patch panels. DGR specified and procured all the components for this project, including fiber optic cables, hand hole, pedestals, equipment racks, patch panels, Ethernet switches, test equipment, patch cables, and more.
Testing the fiber optic cable upon project completion is a key milestone for this project as well. DGR’s ability to test the functionality of the fiber network provides L&O with sufficient data to be utilized as a baseline for future troubleshooting.
The DGR team was able to perform the necessary project design, permitting, specifications and procurement, incorporation of GIS, and complete the construction on time. GIS was originally outside the scope of this project, but in the end, contributed much value in construction, mapping and locating efficiencies. The GIS team at DGR was able to quickly develop a GIS solution, and it has been an invaluable tool. Overall, the DGR team was able to complete this job on time, on budget, and overcome numerous unforeseen challenges in completing the project.
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Project Owner:
Redwood Falls Public Utilities
Key Experience:
- Responsibility and involvement throughout the project, from initial planning and design to construction administration and contract closeout
- Development of a multi-year plan for staged construction of the improvements
- Coordination with private communications utilities including joint use of excavations
Key Features:
- Replacement of old overhead infrastructure with new underground infrastructure, to increase reliability and improve aesthetics
- Eliminated public safety concern of old transformer platform structures
The electric distribution lines in the downtown alleys of Redwood Falls, MN consisted of large overhead structures which included transformers mounted on platforms. Due to concerns with the age and condition of the structures, along with safety clearances to energized equipment and conductors, a project was undertaken to replace the old infrastructure with new underground lines and associated padmount equipment. In addition, these improvements would improve the overall attractiveness of the area.
The project was split into two phases to allow for completion over two construction seasons. Phase 1 included four blocks of downtown area, and the second phase included seven blocks. In addition to burying the overhead primary circuitry, the project also converted most of the overhead secondary circuitry associated with the conversion area to underground.
DGR Engineering (DGR) developed a full design for the new underground circuitry, including equipment and cable sizing, equipment locations, line routes, and material lists. Bidding and contract documents for construction of the improvements were developed which included detailed design drawings, staking sheets, and technical specifications. DGR worked with utility staff to determine where new easements would be needed for placement of padmount equipment.
The project was designed to allow for directional boring of the cables wherever practical, and for trench excavation when needed, due to the quantity and/or location of underground cables and ducts. Sections of pavement were removed when required and subsequently replaced with new concrete after the installation of new raceways was finished.
Contractors completed the boring, excavation, and surface repair work; and the installation of raceways, primary and
secondary cables, box pads, ground sleeves, and secondary boxes and cabinets. The utility completed the installation of padmount transformers and switches, primary cabinets, cable terminations, and meters. The utility also performed all equipment cutovers and energization, and removed the existing overhead lines and related facilities. The completed project resulted in a safer and more aesthetically pleasing downtown area that was also up to current standards for infrastructure and reliability.
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Gets a Makeover
Project improves energy efficiency and aesthetics
Project Owner:
City of Hawarden, IA
Key Experience:
- New LED lighting pattern meets and exceeds the brightness of the existing lights
Appearance of the lighting on the roadway is much more uniform than the legacy lighting - Overall number of street lights was reduced
Key Features:
- Improved roadway visibility
- Reduced operating costs
- Enhanced appearance along Highway 10
The legacy street lights along Highway 10 in Hawarden, Iowa had reached the end of their useful life. Many of the mast structures were beginning to corrode and a few, which were too old for replacement parts, had been removed completely, resulting in poorly lit areas along the street.
The City wanted to replace the old lighting system with a modern LED based system to reduce operating cost. In addition, they preferred to use decorative style lighting units which would enhance the aesthetics of the downtown area, and match what had been utilized in other parts of the city.
For the residential area of the street, cobra head fixtures were desired. This type of fixture is used to reduce cost while also providing improved lighting levels.
To begin the process, existing emitted light patterns were modeled using VisualTM 2012, an Acuity Brands Lighting software package, to determine the photometric patterns of the existing lighting system. The City wished to maintain or exceed current lighting levels. Once existing levels were determined, the new street lighting system was designed based on the Illuminating Engineering Society’s (IES) RP-8 guidelines and to meet or exceed existing lighting intensity levels. After the layout was completed, construction plans were developed. Preparations were made to hire a contractor to install the system along with the related foundations, conduit, wiring, and grounding.
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and relaying - Modernization of customer assets to improve reliability
Key Features:
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- Upgrade from original electromechanical generator relaying to modern
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related equipment - New remote workstation in the MMU dispatch center allowing for full access to operate and monitor the turbine generator set
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The turbine generator set was originally installed in 1968, and in the mid-1990’s the original controls were upgraded to an early generation microprocessor-based system. The technology and parts for the existing control system were becoming obsolete, maintenance was proving to be more problematic, and it was difficult to find support for the aging system. As a result, MMU was interested in upgrading the control system to one with the latest technology in order to maintain and improve upon its reliability going into the future.
DGR Engineering (DGR) developed design specifications and drawings to allow for the system upgrades to be procured through a municipal bid process. The contract was awarded to HPI, LLC of Houston, Texas. Project meetings were held bi-weekly between HPI, MMU, and DGR to review decisions and progress concerning the new control panels, software, and hardware details.
The project included full removal and replacement of the existing control panels within the turbine building control room. A local HMI touchscreen was included in the turbine control panel along with a remote workstation in the MMU dispatch center, each of which provides operators with full access to the operating and monitoring parameters of the turbine. A new fuel control valve was installed to interface with the control system and provide precise control of fuel flow. Additionally, the original motor control center (MCC) was replaced with a new MCC panel which included interfaces to the new control system.
The existing electromechanical protective relaying was replaced with modern digital relaying to make it consistent with other MMU system protection equipment. This allowed for the protection to be seamlessly integrated to the existing MMU SCADA network.
The turbine generator set was removed from service for approximately two months to allow for removal of the old equipment and installation and wiring of the new equipment. DGR developed settings for the new protective relaying and was involved throughout the startup and commissioning of the new control system equipment.
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Substation Construction
bringing project planning, design
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Project Owner:
Stanhope Municipal Utilties
Key Experience:
- Responsibility and involvement in all phases of the project, from project feasibility to final testing and checkout
- High-level of coordination among multiple entities
Key Features:
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In 2015, Stanhope Municipal Utilities (SMU), located in the small central Iowa community of Stanhope, faced some difficult decisions. The regional electric transmission system operator in the area was planning to upgrade the voltage of its lines. This process would eliminate the distribution substation, which at that time was located on the outskirts of Stanhope. SMU received service at distribution voltage from the substation. DGR Engineering (DGR) was engaged to assist SMU with evaluation of alternatives, as well as to determine how any resulting facilities could be financed.
Following initial evaluation, the two most-promising options were recommended. Option 1 included taking service at distribution voltage from the regional transmission system via a radial line of approximately 10 miles in length. Option 2 involved SMU constructing its own substation in Stanhope, connecting to the recently-upgraded transmission system. In both cases, the operating voltage of the distribution system in the community would need to be changed from 7.2kV delta to 12.47/7.2kV grounded wye.
In addition to developing an initial electrical plan for each option, cost estimates for both were also developed. For Option 1, a monthly charge representing “rental” of the facilities would have been required. For Option 2, SMU would need to arrange for and ultimately re-pay the loan needed to finance the construction of the new substation and conversion of the distribution system.
To allow SMU staff and the City Council to make a detailed evaluation of the recommended alternatives, a financial model was developed for the electric utility. This model provided a multi-year review of the impact on electric rate revenue needed to support both alternatives. Throughout the process, DGR coordinated closely with SMU’s financial advisor, Michael Maloney with the D. A. Davidson Company, to ensure the most advantageous structure for payment of debt service.
After careful consideration of the alternatives and rate impacts on its customer base, SMU approved proceeding with Option 2: construction of its own substation and “wye-ing out” its distribution system.
Following the decision, a full cost-of-service rate study was completed for SMU’s customers. The study evaluated the best alternatives for defining customer rate classes and developed appropriate structures for the retail rates paid by all customers.
This study also allocated the costs of providing service to the proposed rate classes, with the goal of having each rate class pay its fair share of the costs of operating the electric system (including covering its share of the cost of the proposed facilities).
The proposed rate changes were adopted, which led to SMU successfully issuing electric revenue bonds, with an overall interest rate averaging less than 3%, covering maturities of up to 20 years.
The project construction process involved a high level of coordination among many parties. The Stanhope City Clerk, Jessica Murray, coordinated activities at the local level. Public bidding processes were used to acquire major materials and contractors to build the new substation and convert the distribution system. Adam Dickinson from the neighboring Webster City Municipal Utilities (SMU’s electric system operations & maintenance provider) directed much of the complicated process of cutting over to the new facilities, aided by DGR engineers and field technicians.
Not only was the project completed in time to coordinate with the regional transmission system voltage upgrade, but the overall cost of the project was significantly under the original project estimate. Costs were reduced due to some of the unique ways the materials acquisition and construction processes were executed.
Funds for the work were obtained at reasonable long-term cost to SMU, and the new retail rates necessary to support the debt service were implemented. Overall, DGR was able to assist SMU in all aspects of the project, from initial evaluation,to design and financing, through final construction.
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