SCADA by Satellite Helps AMP-Ohio Increase Data Reliability

By Phil Meier, American Municipal Power-Ohio

Electric power cooperatives and investor-owned utilities (IOUs) nationwide have used supervisory control and data acquisition (SCADA) systems for many years to track power-flow data and ensure economical use of resources. A growing number of these organizations are faced with an important challenge: recognizing the need to upgrade their aging SCADA infrastructure to maximize data accuracy and reliability, and reduce unnecessary costs.

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At American Municipal Power-Ohio (AMP-Ohio), our SCADA system’s functionality is especially critical as it affects the operations of more than 100 municipal electric communities in four states. After watching our data acquisition become less and less efficient, we recently completed a comprehensive upgrade of our SCADA system with the use of high-speed satellite connectivity and smart meters. We hope that CIOs at other utilities can benefit from the lessons we’ve learned during this upgrade-thereby helping them better serve their customers and make their jobs easier.

Accurate, Reliable Data is Key

Now in its 35th year, AMP-Ohio is a non-profit association representing 81 member municipal electric communities in Ohio, 24 in Pennsylvania, two in West Virginia and one in Michigan. We supply wholesale power and technical services to our members and also operate coal-fired facilities, hydroelectric plants and wind farms.

The power-flow data generated by our SCADA system helps us track every member’s load, hour-by hour-revealing if they are over-committing power (dumping) or under-committing power (peaking) relative to their contracts with IOUs. This data also allows us to economically allocate our generation resources, thereby preventing or reducing our members’ peaking and dumping charges.

Out With the Old

Until recently, our SCADA system consisted of electric meters in the field, connected to remote terminal units (RTUs) and leased analog phone lines. The phone lines were connected to our Columbus, Ohio, headquarters through a front-end processor. The processor collected the data and stored it inside the system, allowing for display and calculation of data.

Early in the decade, we concluded that leased phone lines, as a means of communicating with substations, were unreliable, expensive and moving toward obsolescence. These “landlines” had a 7 percent outage rate, which meant our technical staff was being called out far too frequently to resolve problems related to poor telephone service.

Also, when you consider our data gathering frequency and the granularity of the collected data, you can understand how these outages led to inaccurate reads.

The level of customer service we received from the telecom carriers was, in a word, terrible. The quality of our network, we learned, was only as good as the last-mile technology we deployed. We desperately wanted a dramatic increase in data speed and reliability.


VSAT terminal, uninterrupted power supply and communications equipment mounted and installed at an AMP-Ohio member substation.
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Today, three years later, we have nearly completed the deployment of our upgraded SCADA system with a solution that combines smart meters and a high-speed satellite network from Spacenet Inc. (www.spacenet.com) of McLean, Va.

The Evaluation Process

The AMP-Ohio SCADA Upgrade Task Force began its process by evaluating several different connectivity options, including Frame Relay, radio and high-speed satellite, which is commonly known as VSAT. Radio did not meet our performance requirements and Frame Relay was determined to be too expensive. Even without considering price, we determined Frame Relay would likely result in many of the same reliability issues as leased lines because it utilizes copper lines for its last-mile connection. Whether they were proposing leased lines or a Frame Relay network, telecom carriers were also requiring us to install expensive isolation equipment at all our substations to protect their equipment from transient voltage.

Our search for a highly reliable, economical solution ultimately led us to VSAT. We met with the nation’s three leading VSAT providers and compared their services in a trial test period at our headquarters and several remote locations. During the test, we evaluated data accuracy, speed, ease of data acquisition, and the ease of working with the vendor.


VSAT terminal installed at a wind turbine generator.
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After selecting Spacenet’s solution, we spoke with some of their customers. These conversations were extremely valuable, as they led us to add several specifications-such as heating the VSAT dish and enclosing the outdoor equipment in a weatherproof cabinet that we would eventually design.

The process of selecting our new smart meters was a bit easier. We evaluated and worked with several different Internet Protocol (IP)-based smart-meter manufacturers before selecting one with an Ethernet connection. The selection was driven by the ease of communications, the built-in web server and support for the Modbus master communication protocol, which enables communications with other equipment. These new smart meters allowed us to retire the old RTUs. Now, we can secure power quality data with the ability to control generation through the meter with greater programming ease.

Reaping the Benefits

Our SCADA-upgrade project began in October 2003 when the task force made its recommendation to AMP-Ohio’s Board of Trustees. The board approved the smart-meter/VSAT upgrade that same month.

In December 2004, we officially began the upgrade, with the mission of providing telemetry applications to allow more than 117 planned transmission substations and generation locations to carry vital data to our SCADA system. Due to rapid growth, we expect this new network will eventually serve a total of 150 sites.

The task force gave the board a projected cost of $1.9 million in capital costs, spread over five years, and a projected payback in 11 years. The payback calculation was based on cost avoidance. The actual payback for the investment is expected to be much shorter, likely five years, due to other savings that were initially much harder to quantify.

Operating costs for the VSAT network are lower than the terrestrial-based SCADA system that we replaced. This means we’ll benefit from hard savings before the payback period is completed. We expect to reduce our telecommunications costs by more than $120,000 in the first year of deployment, which more than covers what we are paying Spacenet in that same period.

There are also other hard cost savings, including those associated with resolving telecom system failures and reducing energy purchases associated with these failures. We also save time and aggravation in the deployment process: A VSAT data-point installation requires only two weeks, compared with up to two months for a landline.


Detail of the VSAT Indoor Unit, housed in a weatherproof container.
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In terms of sheer performance, our new VSAT-based SCADA network provides faster data transmission from the substation to the energy control center (ECC). We selected a satellite service that is eight times faster than our previous landline service. Data is now provided every 15 seconds instead of every two minutes. More frequent updates provide us with an advantage in our power-supply planning, which results in better decision-making.

The new VSAT equipment is a significant upgrade to our field units, provides better data for the ECC operators, and greatly increases communications reliability. Our uptime increased from 93 percent with the leased-line network to 99.99 percent with the Spacenet VSAT solution. This means we rarely miss data when polling sites.

Perhaps the biggest payoff has come in terms of avoiding network outages. With the leased-line network, an outage could last weeks-forcing us to estimate data from substation metering for a very long period. With our new VSAT network, occasional outages might only last a few minutes. The need to estimate data inputs for a period of two minutes does not compromise data quality nearly as much as the longer outages experienced with the leased-line network.

As a result of the increase in data reliability, our operations executives have requested that historically un-metered loads now be metered so the data acquired may be used directly in our billing of member municipalities. The collection of real-time meter data will enable us to bill and receive payment from our members in a more efficient manner, thus reducing interest costs.

For member communities, the advantages are also apparent. Superintendents for the member communities have said the new VSAT network lets them track their load more effectively and forecast their needs more precisely. That means lower costs for them.

Future Applications

With full deployment nearly completed, we are already looking ahead to other possible applications for our new VSAT network. We expect to use the network to improve demand response at the customer level. We’ll be able to turn on customer generation during peak periods or encourage customers to cut load during those same periods. We are already controlling generation to members through the VSAT network.

The network is also capable of checking the power quality of the electricity coming into the municipality. This is an important point, as power-quality issues assume greater importance due to the computer-controlled equipment many businesses now use. For example, in the first VSAT deployment, we were able to distinguish a 0.3 percent variance in a meter read that was caused by an errant potential ratio initially programmed in the meter.

Upgrading our SCADA system with a smart-meter/VSAT network has opened a world of advantages, enabling us to provide the best possible service to our members. The network’s high reliability also means our engineers and technicians rarely need to respond to after-hour emergencies. What a relief.௣à¯£

Phil Meier is chief information officer of American Municipal Power-Ohio, where he is responsible for all SCADA and IT systems. With the association since 1989, he has managed several critical software acquisitions and implementations, and also managed construction of a $163 million hydroelectric power plant on the Ohio River in 1995. He can be reached at (614) 337-6222 or pmeier@amp-ohio.org.

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