In its effort to provide a secure and reliable distribution network, Dairyland Power Cooperative (DPC) recognized the need to streamline its power delivery by deploying a more advanced metering system.
DPC supplies electrical energy to more than 600,000 customers in a service area that extends 45,000 sq miles (116,550 sq km). Formed in 1941, the cooperative is regarded as a pioneer in rural electrification to the homes and farms in “America’s Dairyland.” DPC bids its native load and generation capacity into the energy market to provide wholesale electricity to 25 member distribution cooperatives and 16 municipal utilities in four U.S. states: Wisconsin, Minnesota, Iowa and Illinois.
Specifically supplying distributed rural communities, DPC strives to provide reliable service to its customers at prices designed to exceed members’ expectations. The cooperative’s earliest distribution substations were not equipped with real-time data acquisition. Instead, the metering data was recorded on magnetic tapes, which were translated monthly by employing a field technician to drive to each substation and manually gather the data.
Later, solid-state recorders were installed, and the data was collected using analog cell phones with a modem interface, but this was still collected on a monthly basis. In 2000, DPC began searching for a communications system that would optimize operations and help to monitor critical data in the field. Specifically, it wanted a system that could monitor and collect real-time data on the distribution network.
State of Practice
In 2000, wireless communications technology for data transmission in utilities was still a relatively new concept. While it had come a long way from its manual beginning, DPC’s existing infrastructure was complicated and becoming increasingly expensive. It was using a combination of analog cellular technology to collect interval data, a variety of radio types for real-time monitoring and leased circuits from a combination of about 30 different technology providers.
The communications network was impacted by variances in weather, the circuits were becoming increasingly expensive and the repair process was difficult to coordinate. With all of these various technologies in place, there was no overall integration solution to simplify the communications network and optimize communications. Additionally, much of the equipment in use was low in both speed and capacity.
Staff at DPC realized a higher throughput was required for the system. A more robust communications network would reduce interference and latency, increase mitigation and deliver data within a congested communications network.
The communications solution required also would need to effectively communicate, despite the challenging landscape. In the rural areas served by DPC, there are hills and steep terrain, creating line-of-sight challenges. Additionally, the Midwest experiences harsh winters and extreme temperature ranges. These challenges, combined with remote areas of coverage, all contributed to the cooperative’s need for technology that had effective throughput and long-range capabilities.
In Search of a Solution
The utility identified key applications where up-to-date data communications technology was needed most:
- Real-time metering data for DPC and member cooperatives
- Distribution automation data to DPC and member cooperatives
- Communications to load profile metering data for billing
- Communications link to load management radio transmitters
- Engineering access to equipment
- Automated meter reading (AMR) data from the substation to the cooperative members’ offices.
After identifying the specific applications required to satisfy the communications needs within the distribution system, DPC prepared a specification and began researching vendors.
A distribution automation study was conducted that compared various communications technologies able to withstand harsh weather conditions and line-of-sight challenges from the hilly terrain. As a result of the study, DPC awarded the contract to the vendor whose communications system completely satisfied the cooperative’s specification. The decision on the selected vendor, FreeWave Technologies — a provider of wireless data radios — was based on feedback obtained from other service providers as well as close negotiations and discussions with the vendor’s technical team. During the study, DPC found that equipment with similar characteristics to FreeWave was reliable but failed to provide the internal system performance the cooperative was seeking.
From Pilot to Deployment
Initially, DPC implemented FreeWave radios on a pilot scheme basis, installing the FGR series radios. FreeWave, which offered free path studies and network configuration, also gave the utility the opportunity to try a small sample of its devices before purchasing the entire communications system.
Following the deployment, the product performance satisfied all expectations and FreeWave radios eventually replaced the majority of the pre-existing technology (such as leased circuits and analog cell phones), allowing for real-time data collection across the network. In some areas of the network, there was no prior technology, which created a fully integrated solution across DPC’s entire communications network.
The FGR series offers real-time remote diagnostics and setup — transparent to network communications — as well as versatility. A single radio can operate simultaneously as a master, slave and repeater. The quality and versatility of the FGR series, which is used for many government and defense applications, has also led to its use in locations ranging from Mount Everest and Antarctica to the Amazon rainforest. DPC has been especially pleased with the FGR series radio link performance, single-system integration and overall reliability.
The FreeWave HTPlus Ethernet radio is ideal when there is a need for industrial-grade, high-speed Ethernet communications that can operate in harsh environments and noisy radio-frequency conditions. It delivers data at a rate of up to 867 kbps and is an ideal radio for supervisory control and data acquisition (SCADA) backhaul networks.
DPC is using the wireless data radios for a variety of distribution automation applications within its data communications network, including advanced metering infrastructure backhaul, transmission capacitor bank control, transmission line sectionalizing, and fault detection and isolation. Frequency hopping spread spectrum (FHSS) wireless solutions are resilient when faced with impairments such as interference and jamming.
One of the key features of FHSS radios is they only require a small sector of the radio spectrum, continually moving rapidly between various frequencies. The spread-spectrum radios use an advanced encryption protocol to ensure additional security. The cooperative also uses HTPlus radios for applications that require more effective throughput. The radio network features a single-system design that is easily maintained, and the majority of the maintenance is credited to the Tool Suite diagnostic software and 24/7 technical support.
As a member of the Midcontinent Independent System Operator, DPC participates in the energy market by bidding its generation and load into the market. It now uses the SCADA data provided by its real-time communications networks to accurately calculate these values. Therefore, reliability of the communications network is crucial for ensuring accuracy of the calculations. If data is inaccurate, there can be significant cost penalties to purchase power on the real-time market. Having an internal communications network comprising these wireless data radio solutions helps to control costs, provide system reliability and ensure network security.
The success of this project has led to more integration projects for DPC and its member cooperatives, in line with the philosophy of build it and they will come.
The Communications Underpinning
Overall, DPC has achieved single-system integration, link performance and overall reliability by implementing a wireless data communications network. The organization has found a partner in FreeWave with whom it has established a business relationship. Identifying the best fit for DPC’s communications network was a challenge, especially with most of the cooperative’s customers living in rural communities. Not only have the radios provided effective throughput, link performance and noise immunity, but they were easily integrated into the utility’s existing network.
Seven years ago, there was no visibility of the distribution substations. Today, DPC has real-time data (20 sec) for revenue metering and revenue billing data (MV-90), and engineering remote access using a single-integrated communications solution.
The organization is satisfied with the performance of the radios it has deployed and is considering FreeWave for future wireless data communications needs. While the current network is nearly complete as far as communications needs, ongoing growth is expected, which will, in turn, require additional communications needs. DPC will continue to consider using wireless data radio solutions within its communications network infrastructure.
The author wishes to thank Curt Goldman and FreeWave Technologies for their assistance in this project and continued support of Dairyland Power Cooperative’s private radio communications network.
Ken Graves ([email protected]) has been employed in the communications industry for 43 years with the last 33 years at Dairyland Power Cooperative. He manages the telecommunications services group at DPC, providing engineering and technical support to the coop and its member coops for microwave, fiber, mobile radio, telephony, network services, load management, and transmission and distribution substation SCADA.
Dairyland Power Cooperative | www.dairynet.com
FreeWave Technologies | www.freewave.com