Integrated SCADA Drives Muni’s Efficiency and Effectiveness

By John Bagwell

A visit to any utility these days is dominated by discussions, meetings and activities on how the utility can be more efficient, more effective and ultimately more competitive. When the utility is a municipal utility that provides all four major utility services-electric, gas, water and wastewater-the potential for inefficiencies expands significantly.

The Orangeburg (South Carolina) Department of Public Utilities (DPU) is a four-utility provider serving a population of approximately 50,000 in Orangeburg and the surrounding unincorporated county. The electric utility has 20 MW of generating capacity, used primarily for peak shaving, and purchases most of its power from South Carolina Electric & Gas. The utility also has 23 transmission and distribution substations, with 80 miles of transmission lines and 700 miles of distribution lines.

The DPU is faced with a multitude of competitive challenges. On the electric side of the business, how power is bought and sold changes everyday, and this situation is not likely to settle down until well after deregulation (or “re-regulation” as this phenomenon is known locally) officially hits South Carolina. Similar changes are occurring in the gas business with recent changes in the Federal Energy Regulatory Commission’s regulations. On the water/wastewater side, the privatization movement is a very real competitive threat (or opportunity, depending on your outlook) for which the DPU is fully preparing.

One way the DPU is achieving a competitive advantage is with an integrated supervisory control and data acquisition (SCADA) system. All four utility services are controlled by one system. The DPU first installed the SCADA system, supplied by C3-ilex Systems, Milpitas, Calif., in 1989. Since that time the system has been upgraded twice, with the most recent upgrade being completed in December 1999, when the DPU migrated to C3-ilex’s Windows NT-based system. This allows the DPU to take advantage of the NT operating system’s stable, robust computing environment, networking capabilities and the simplicity of use provided by the Windows user interface.

The SCADA system uses a total of 38 remote terminal units (RTUs) from C3-ilex for remote monitoring and control at points throughout the service territory. This includes 19 RTUs at distribution substations; two at power generating stations, where automated generation control is employed; one at a transmission substation; three at the water treatment plant; three at remote pumping stations; four at the wastewater treatment plant; two at lift stations; two at gas delivery points; and three at gas regulator stations.

The city has invested extensively in a fiber optic network, which is the communications media for all of the RTUs, except for five. These five RTUs communicate via leased telephone lines, as fiber optics is not practical due to the facilities’ remote location.

The integrated system benefits are numerous-some generate cost savings, while others improve performance resulting in customer service improvements. Some of the benefits include:

  • Reduced training and maintenance. One system means that operations staffs across all four utility services require only one type of SCADA training. System maintenance requirements are also greatly reduced. For example, there is now only one set of documentation instead of four. There are also fewer spare parts to inventory and increased institutional system knowledge.
  • Faster, less expensive implementation. Acquiring the system and getting it on-line was streamlined by going through one relatively large implementation instead of four distinctly separate implementations. This approach also afforded the DPU with significant cost savings.
  • Electric distribution intelligence. The DPU now has knowledge of how well the distribution system is performing, which is particularly important since Orangeburg lies in the middle of a lightning belt. Outages are now identified faster, and service is returned to customers much faster.
  • Water purchasing improvements. With the ability to control when and how much water is pumped from the city’s source (the Edisto River) via the RTUs, the city is able to use the water pricing model to pump water when the electric rates are lowest. This saves Orangeburg thousands of dollars each month.
  • Water production/wastewater treatment improvements. By replacing aging pneumatic controls, the DPU is realizing additional maintenance savings. The RTUs in the water and wastewater plants also provide accurate operating information, enabling more accurate decision-making in plant operations.
  • Gas purchasing accuracy. With the RTUs at each gas delivery point (where the city’s gas purchases are made), accurate, real-time data is always available for gas purchases, facilitating better gas purchase and usage planning.
  • Load Forecasting for both electric and gas systems. Using C3-ilex’s weather matching load forecasting program known as “WOLF” (Weather Oriented Load Forecast), the DPU has the ability to accurately predict usage for both the electric and gas systems. This enables the DPU to make decisions on electric and gas purchases and sales. By predicting future usage, the DPU’s customers are allowed some of the lowest utility rates in the country. (Currently the DPU has the lowest electric rates in South Carolina.)

One of the more creative uses of the SCADA technology is a process being used at the city’s wastewater treatment plant. Here, sludge is dried by exhaust from two 5 MW gas turbine generators, which are remotely operated by an RTU. After processing, the sludge is an inert fertilizer that is then sold for agricultural uses, an added plus with many agricultural areas within the service territory.

Future plans for Orangeburg’s SCADA system call for more integration with other information systems. First will be integration with the customer information system and the geographic information system for improved outage management. This will result in still faster outage isolation, crew dispatch and service restoration. This will be increasingly critical as customer service becomes a more sensitive measure of performance in the deregulated environment.

The DPU will also use the real-time data generated from the SCADA system for fault analysis and distribution system planning, which will improve distribution system performance over the long term.

A third future enhancement is distribution automation and more advanced substation automation for improved fault isolation and power maintenance.

The rapidly changing business environment that is the reality for today’s utility managers, calls for new ways of doing business to accomplish strategic and customer-focused initiatives better, faster and cheaper. Leveraging open, integratable technology, particularly in the real-time environment made possible with SCADA, is one tool that will enable utility management to make better decisions, improving operations and customer service, and ultimately improving the utility’s competitive position.

John Bagwell is the city of Orangeburg’s electric division director. During his 13 years with the city, Mr. Bagwell has held a number of technical and management positions. He holds a bachelor’s degree in electrical engineering from Clemson University.

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