Introduction
Golden Spread Electric Co-operative members supply electricity to most of the rural Texas and Oklahoma Panhandle.
Organized in 1984 to provide electric service for its 11 rural distribution co-operative members, Golden Spread historically purchased power for its members from Southwestern Public Service Company, from West Texas Utilities Company, and the 486-megawatt gas-fueled combined cycle Mustang Station. Golden Spread owns 50% of the Mustang Station.
Electric utility merger and acquisition activity and the pending Texas deregulation caused uncertainty as to where Golden Spread would purchase its power for its members in the future. Complicating this dilemma is the volatile irrigation load requirements of the Golden Spread member users. With antiquated reporting techniques, the trending of the load was performed much later than the actual required load was known. Golden Spread needed immediate reporting of metering information in order to adequately operate in the changing electric industry.
Taking action:
All of this required Golden Spread to take action to obtain immediate metering information. Golden Spread worked with C.H. Guernsey & Co., their consulting engineer, to evaluate and formulate a plan to resolve the issues and problems of this situation. The problem was solved with a SCADA system.
The challenges seemed overwhelming for a project of this scope, technical complexity, and short timeframe required for implementation.
To summarize, Golden Spread and C.H. Guernsey & Co. sought a SCADA supplier to meet the following requirements:
The Solution:
Golden Spread and C.H. Guernsey & Co. teamed with a SCADA supplier to formulate a solution that was both unique, and flexible.
The SCADA supplier provided a dualredundant SCADA master station that will use DNP 3.0 protocol to communicate between the field devices and the master station. The field devices used were XPPB RTU’s. These RTU’s are located at the 76 POD metering points and collect the required voltage, amps, and other required parameters and report the information back to the master station located in the Guernsey office in Oklahoma City, OK.
In addition, this system is designed to be able to communicate directly with IED’s without the aid of an RTU.
The most difficult portion of the system was the communications system. The flexible part of the solution is that it does not matter what communication system is used. Leased line, spread spectrum radio, microwave, or fiber, the RTU’s and master station will perform in any communications environment. The unique part of the solution is the communication system selected to be used – the public Internet.
Note that the Internet was selected because of the economics and time restraints of the project. The system could very easily be implemented using spread spectrum radio, CDPD, microwave, etc., or a combination of any of these.
System description:
The XPPB RTU’s were placed at each of the 76 POD metering locations to monitor the POD’s for each member co-op. The number of RTU’s per each co-op ranged from 3 to 15. These are noted on the diagram in Fig 1. Each RTU group sent its information to the individual co-op headquarters via 900MHz spread spectrum radios.
At the individual co-op headquarters is the master radio that is connected to the co-op’s LAN. The signal is then routed to the Internet via a Cisco 1601 router. The router acts as a firewall. Each individual co-operative is set up similarly.
The master station in Oklahoma City is connected to the Internet to the Golden Spread LAN via a Cisco 2514 router (again, acting as a firewall). The master station at Amarillo is utilizing the DNP 3.0 over TCP/IP to communicate to the RTU’s in the field.
Furthermore, there are four (4) existing master stations in the Golden Spread membership that need to report information from their master stations to the master station at Amarillo. At one of these 4 co-op headquarters, the connection to the Internet will be similar as at the other co-op headquarters. The only difference is that ICCP over TCP/IP will be utilized instead of DNP 3.0. ICCP will be utilized to facilitate master station to master station communications. Originally, these 4 co-ops were to be connected over a dedicated line. During implementation of the project, it was determined that these communications were to be over the Internet.
It was recommended that a quality high speed ISP service over DSL, ADSL, or cable be utilized. For redundancy, it is recommended that two connections from the master station to the Internet be made. However, as the project expands in its implementation and use, the redundant connection can be implemented as desired.
With this system installed by Golden Spread, who only needed to gather information, Golden Spread offered each member co-operative the flexibility to implement control through SCADA on their own systems, while maintaining the Golden Spread portion of the system. This can be added at little additional cost.
Issues and concerns
This approach brings up issues and concerns that have historically prevented its use. With today’s technology, the risks associated with this approach are mitigated and have to be reevaluated. Briefly mentioned here are the risks considered and the conclusions or alternatives reached.
Risks
Note that what has been discussed here has been Internet SCADA. This is very different than “web-based” SCADA solutions and IED SCADA solutions. "Web-based" SCADA solutions use standard web-based applications (java, etc.) that are more “visible” to those looking at them. Most Internet connected IED SCADA solutions have a similar danger associated with them – they are web-browser based.
The Internet SCADA application presented here uses the Internet as a communications medium, passing only certain information through the Internet, not any of the application.
Benefits of the approach
The benefits of using this approach are:
About the Author
Steve Mueller, President and Chief Executive Officer of Survalent Technology Corporation, Mississauga, Ontario, Canada, has more than 9 years experience with SCADA systems. The last three and a half-years were spent directing the efforts of Quindar Products Ltd. (previous name of the company now known as Survalent Technology). He can be reached at Smueller@survalent.com. The web site is at www.survalent.com.
Golden Spread Electric Co-operative members supply electricity to most of the rural Texas and Oklahoma Panhandle.
Organized in 1984 to provide electric service for its 11 rural distribution co-operative members, Golden Spread historically purchased power for its members from Southwestern Public Service Company, from West Texas Utilities Company, and the 486-megawatt gas-fueled combined cycle Mustang Station. Golden Spread owns 50% of the Mustang Station.
Electric utility merger and acquisition activity and the pending Texas deregulation caused uncertainty as to where Golden Spread would purchase its power for its members in the future. Complicating this dilemma is the volatile irrigation load requirements of the Golden Spread member users. With antiquated reporting techniques, the trending of the load was performed much later than the actual required load was known. Golden Spread needed immediate reporting of metering information in order to adequately operate in the changing electric industry.
Taking action:
All of this required Golden Spread to take action to obtain immediate metering information. Golden Spread worked with C.H. Guernsey & Co., their consulting engineer, to evaluate and formulate a plan to resolve the issues and problems of this situation. The problem was solved with a SCADA system.
The challenges seemed overwhelming for a project of this scope, technical complexity, and short timeframe required for implementation.
To summarize, Golden Spread and C.H. Guernsey & Co. sought a SCADA supplier to meet the following requirements:
- Obtain metering information from Points of Delivery from 9 member co-op locations (76 Points of Delivery, with no field devices yet installed).
- Obtain information from 3 member co-ops that have existing SCADA master stations.
- Send all information to Golden Spread SCADA master station in Amarillo, TX. Member co-op locations are from 10 to 250 miles from Amarillo, TX.
- No existing communications infrastructure was in place.
- Provide the means and capability for Golden Spread to place a backup master station anywhere in the Golden Spread system.
- Publish desired SCADA information on Golden Spread’s website for the member cooperatives to view.
- Send required SCADA information to ACES Power Marketing, Golden Spread’s selected power marketer.
The Solution:
Golden Spread and C.H. Guernsey & Co. teamed with a SCADA supplier to formulate a solution that was both unique, and flexible.
The SCADA supplier provided a dualredundant SCADA master station that will use DNP 3.0 protocol to communicate between the field devices and the master station. The field devices used were XPPB RTU’s. These RTU’s are located at the 76 POD metering points and collect the required voltage, amps, and other required parameters and report the information back to the master station located in the Guernsey office in Oklahoma City, OK.
In addition, this system is designed to be able to communicate directly with IED’s without the aid of an RTU.
The most difficult portion of the system was the communications system. The flexible part of the solution is that it does not matter what communication system is used. Leased line, spread spectrum radio, microwave, or fiber, the RTU’s and master station will perform in any communications environment. The unique part of the solution is the communication system selected to be used – the public Internet.
Note that the Internet was selected because of the economics and time restraints of the project. The system could very easily be implemented using spread spectrum radio, CDPD, microwave, etc., or a combination of any of these.
System description:
The XPPB RTU’s were placed at each of the 76 POD metering locations to monitor the POD’s for each member co-op. The number of RTU’s per each co-op ranged from 3 to 15. These are noted on the diagram in Fig 1. Each RTU group sent its information to the individual co-op headquarters via 900MHz spread spectrum radios.
At the individual co-op headquarters is the master radio that is connected to the co-op’s LAN. The signal is then routed to the Internet via a Cisco 1601 router. The router acts as a firewall. Each individual co-operative is set up similarly.
The master station in Oklahoma City is connected to the Internet to the Golden Spread LAN via a Cisco 2514 router (again, acting as a firewall). The master station at Amarillo is utilizing the DNP 3.0 over TCP/IP to communicate to the RTU’s in the field.
Furthermore, there are four (4) existing master stations in the Golden Spread membership that need to report information from their master stations to the master station at Amarillo. At one of these 4 co-op headquarters, the connection to the Internet will be similar as at the other co-op headquarters. The only difference is that ICCP over TCP/IP will be utilized instead of DNP 3.0. ICCP will be utilized to facilitate master station to master station communications. Originally, these 4 co-ops were to be connected over a dedicated line. During implementation of the project, it was determined that these communications were to be over the Internet.
It was recommended that a quality high speed ISP service over DSL, ADSL, or cable be utilized. For redundancy, it is recommended that two connections from the master station to the Internet be made. However, as the project expands in its implementation and use, the redundant connection can be implemented as desired.
With this system installed by Golden Spread, who only needed to gather information, Golden Spread offered each member co-operative the flexibility to implement control through SCADA on their own systems, while maintaining the Golden Spread portion of the system. This can be added at little additional cost.
Issues and concerns
This approach brings up issues and concerns that have historically prevented its use. With today’s technology, the risks associated with this approach are mitigated and have to be reevaluated. Briefly mentioned here are the risks considered and the conclusions or alternatives reached.
Risks
- Speed and delays
The approach is sending only the changing SCADA data through the Internet, not the entire graphics screen, so speed is not really an issue. - Reliability and stability
Simply compare using the Internet to using phone lines or radios. The Internet is no worse, and may be even better considering that you may have an alternative path if one path is inoperable. Also, a major part of the Internet is phone line. - Security
Security is the main concern of utilizing a SCADA system operating on a public Internet. Most security hacker and virus attacks are thru e-mail and the WWW. What we all keep forgetting, however, is that the Internet is not the WWW. - Passwords and permissions
- You can tighten the Security Zone (firewalls, routers, intranet)
- Obscurity – You are addressing an IP address (such as 202.321.55.106), not a domain name.
- Encryption can be deployed to heighten security.
- Viruses
Viruses typically attack Windows-based operating systems. In addition, they find their way to many applications through e-mail and web based applications. Reduce the vulnerability of your system to viruses by using non-Windows based op systems. If a Windows-based system is used, reduce vulnerability by NOT running Microsoft IIS and by NOT installing Microsoft Web server.
Also, consider these Security protections:
Note that what has been discussed here has been Internet SCADA. This is very different than “web-based” SCADA solutions and IED SCADA solutions. "Web-based" SCADA solutions use standard web-based applications (java, etc.) that are more “visible” to those looking at them. Most Internet connected IED SCADA solutions have a similar danger associated with them – they are web-browser based.
The Internet SCADA application presented here uses the Internet as a communications medium, passing only certain information through the Internet, not any of the application.
Benefits of the approach
The benefits of using this approach are:
- It is an economical approach considering the complexity and enormity of the project.
- Using the Internet communications is an economic alternative to other communications (leased line, radio, CDPD, etc.). However, as mentioned previously, this solution can use any communication medium, or a mixture of mediums.
- You can use the Internet as a backup if your main communications go down.
- This approach is one way to communicate to a remote station that may be 100 miles away, but you do not have a dedicated infrastructure in place.
- With this approach, it does not matter where the master station is located. In Amarillo, TX, Richmond, VA, or Toronto, Canada, the master can be placed at any site.
- This can be used for a redundant “system” for emergency restoration.
About the Author
Steve Mueller, President and Chief Executive Officer of Survalent Technology Corporation, Mississauga, Ontario, Canada, has more than 9 years experience with SCADA systems. The last three and a half-years were spent directing the efforts of Quindar Products Ltd. (previous name of the company now known as Survalent Technology). He can be reached at Smueller@survalent.com. The web site is at www.survalent.com.
