UTILITIES OPERATE IN AN ENVIRONMENT WHERE CUSTOMERS AND REGULATORY AGENCIES DEMAND IMPROVEMENTS IN RELIABILITY. Having set goals to improve its Customer Average Interruption Duration Index (CAIDI) and System Average Interruption Frequency Index (SAIFI), Oklahoma Gas & Electric (OG&E; Oklahoma City, Oklahoma, U.S.) identified distribution automation (DA) as a possible pathway to achieving these goals, using both advanced technology and its current manpower.

With the introduction of microprocessor-based equipment such as intelligent electronic devices (IEDs) and communication systems on distribution circuits, OG&E realized a method for testing the programming and training the various staff responsible for the operation and maintenance of this equipment would be necessary. It also recognized the fact that testing and training were not only needed during the system development and deployment, the capability to continue testing and training would be needed after the systems were in operation.

THE BEGINNING

OG&E's first permanent DA system went into operation in early 2006, serving a high-profile business and entertainment district on the east edge of downtown Oklahoma City. The system consisted of two three-phase trip/three-phase lockout reclosers (leftovers from a previous pilot project) on two 35-kV circuits, using a substation-based controller and radio communications. Testing and training on this system were conducted with reclosers and a DA controller wired and configured exactly like the equipment used in the field. This mock-up system worked well because the reclosers and required space were available. However, the configuration was limited in scope because the system could not be connected to the supervisory control and data acquisition (SCADA) system, which would have enabled more realistic training for the control center operators.

THE EXPANSION

In the fall of 2006, an expanded, more high-tech DA system, capable of closed-loop operation, was put into service on two 35-kV circuits in far-northwest Oklahoma City, serving a mixture of residential, commercial and industrial customers. In addition to two reclosers identical to those used in the first system (installed on a parallel line of one circuit with radio communications), the second system has five single-phase trip/three-phase lockout reclosers in a peer-to-peer configuration with fiber-optic communications. Also, instead of having one substation-based DA controller (the same controller type used in the first system), it uses a second DA controller installed in the other substation that controls the reclosers on the parallel line.

The testing and training configuration for the second system required some improvisation because purchasing five additional reclosers was cost prohibitive; therefore, five additional controllers were acquired to serve as spare parts. In order to simulate the operational state of the reclosers, the engineer in charge of the project built recloser simulators that operated identically to the actual device and provided all the required status points and bits. These additional controllers with the recloser simulators were wired and configured with the elements of the first DA system, along with an additional substation DA controller. Fiber-optic communications was also used in this configuration, as it was in the field with basic communication cables used for the radio-signal paths.

Although this testing and training system fulfilled the requirements, it had the same shortcoming as the first system in that it could not be connected to the SCADA system and used to train the control center operators.

THE CHANGE

With the addition of the third DA system in the spring of 2008, different reclosers and a different substation-based controller were introduced. This 15-kV system on the south side of Oklahoma City, serving residential and commercial customers, was the result of a revamped DA pilot project. This DA system involves three circuits from two substations and uses two existing reclosers (three-phase trip/three-phase lockout), two of the same 35-kV reclosers used in the previous two DA systems, a substation-based controller with built-in fault-detection isolation and restoration (FDIR), and radio communications.

The ability to configure a testing and training system for this DA system did not exist. The recloser simulators used for the second DA system would not work with the controllers used in the existing reclosers, and no extra reclosers or controllers were available. The testing and training for this system was conducted as a factory-acceptance test at the DA controller vendor's headquarters with a limited number of OG&E staff in attendance. On-site training using simulations was conducted with other staff after the system was put into service.

OG&E now has three DA systems in operation on two different primary voltages, consisting of 13 new and old reclosers from three different manufacturers (each with their own controller) with four substation-based DA controllers from two different manufacturers using both radios and fiber optics for communications. The utility also had to deal with losing the capability to test system programming and conduct training when its testing and training area was converted to office space.

THE NEED, THE SOLUTION

During the development and implementation of the three DA systems, the recognized need for having the capability to test the system programming was reinforced by operational events, circuit changes and relay setting changes. Any change in the programming should be tested before being uploaded to the device in operation. The need for continuous training was also reinforced because of personnel changes and the limited opportunity for hands-on experience. This limited opportunity is due to the fact that once the systems were in operation and debugged, the need to visit these sites did not occur often. Having a testing and training facility would provide the means for staff to practice and perfect their skills, better preparing them to perform their duties when required.

The testing and training configurations used in the first two DA systems had to be dismantled; therefore, using spare parts, OG&E opted to build a DA test lab in another location that could be configured for any of the systems currently in operation, could be adaptable for future systems and could cover the needs of various departments. Other design criteria for the test facility was to use all recloser simulators that could operate as both three-phase trip/three-phase lockout and single-phase trip/three-phase lockout, adapt to most recloser controllers, and have the ability to channel voltages and currents to any combination of devices.

The utility also wanted the facility to be connected to the SCADA system so the control center could have operational control and view the status of any active devices, have the capability to display a one-line diagram (from a SCADA test file) of the configured system on a big-screen monitor and view changes of the various devices, and have remote communication capability to any controller. To sum up, the utility decided if equipment is in the field, it needs to be in the lab.

THE TEST LAB

For the base of the DA test lab, OG&E decided to use four standard test benches, placed end to end, with risers under which the recloser controllers could be placed, in order to open up the front edge of the benches. Tall panels (10 ft [3 m]) were fabricated and attached to the back of each bench, which consists of three panels each to hold the recloser simulators and a communication panel containing both fiber optics and communication cables to simulate the radios.

On each of the recloser simulator panels are two sets of knife blade switches for current, three red and three green lights to indicate open/closed position, and a binding post panel for power and phase voltages, currents, 52 A-B points and open/close signals. Strips of insulated binding posts are mounted on panels across the top for the wiring and knife blade switches to channel the current to the different simulator panels used in the various configurations. A relay rack is positioned at each end to hold substation equipment such as the DA controller, breaker relay, and breaker simulator, as well as modems and remote terminal units (RTUs). A voltage/current distribution panel is mounted in one of the relay racks to provide a single connection point for the voltage/current supply instrument.

The recloser simulator panels used in the earlier configuration needed to be modified to allow operation as both single- or three-phase trip with three-phase lockout. This was accomplished by feeding the trip and close signals from the controller, through two separate three-element relays controlled by a toggle switch mounted on the front edge of each bench, below each recloser panel. Panel lights indicate the operational mode of each panel. Along with the mode relay-toggle switch are two other toggle switches per panel. One switch controls the 120-V panel power, indicated by a panel light. The remaining switch controls another three-element relay that channels the current to a common return cable at a point between any two recloser panels, indicated by a lightbulb mounted on the top edge of the main panel and between each recloser panel. This position, between any two active panels, is the location of the simulated fault for system operation.

THE RESULTS AND BENEFITS

The DA test lab was built by the technicians responsible for maintaining OG&E's DA systems with the assistance of staff in other departments. The test lab became operational in early 2009. There were many aspects about the reclosers and their controllers, as well as DA in general, that were learned and beneficial to OG&E technicians during the design, construction and testing of the DA test lab.

Here is some of what they learned:

• The various information transmitted between the recloser and controller and how that was accomplished

• The communication process between the reclosers, DA controller, SCADA and the control center

• The advantage that all the SCADA points required for the field devices and control center could be configured, loaded and tested for proper operation before being uploaded to the various devices

• ACKNOWLEDGMENTS

  Some recloser controllers could not be wired directly to the simulator panels because of certain information that is stored in the recloser itself instead of the controller. The manufacturers' of these reclosers have provided assistance to find solutions. Testing will begin soon on the possibility these simulator panels could represent capacitor banks in addition to reclosers.

Since the DA test lab became operational, it has been used to identify various issues and test solutions related to programming, SCADA points and remote control of field devices. It also has been used for several training and practice sessions with technicians, and training is being planned for other field personnel such as troubleshooters and linemen; the test lab will be configured for the specific DA system in their district.

Personnel changes will continue because of retirements or transfers, and the DA systems will evolve. The intelligent, automated grid is the future, expanding and incorporating the use of DA systems. Having the capability to conduct testing and training will remain essential.

The author thanks OG&E management and members of various departments who were involved in the development and construction of the DA test lab. Also, the following companies and their representatives provided valuable input during the development of the test lab: S&C Electric (Chicago, Illinois, U.S.), Nu-Lec Industries (Queensland, Australia), G&W Electric (Blue Island, Illinois), NovaTech, LLC (Quakertown, Pennsylvania, U.S.), Schweitzer Engineering Labs (Pullman, Washington, U.S.) and Advanced Control Systems (Norcross, Georgia, U.S.).

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Robert Williamson (williaro@oge.com) has been supervisor of the System Meters & Lab section of System Integrity - Operations Support for Oklahoma Gas & Electric (Oklahoma City, Oklahoma, U.S.) since November 2006. He began his career with the utility in December 1973 and has worked in warehousing, line construction, troubleshooting, testing and repair of instruments, and URD. He joined the Measurements section of the System Lab in 1987. Williamson holds an associate's degree in electronic engineering technology from Oklahoma State University.