SCADA technology has been in existence for several decades. It was initially developed for large utilities as an information gathering and control system tool to manage their generation and distribution assets. A significant investment, it provided the utility with the means to proactively manage their extensive physical plant. Initial system offerings and technologies were crude. The challenges were many. Communications alternatives were limited and the term “microprocessor technology” was familiar only to the “propeller head” segment of research firms. Images of dinosaur technology come to mind, with no offense intended to the dinosaur population. There were RTUs the size of switchgear sections with miles of wire and rack mounted modems. Needless to say, the phrases “elegant design and SCADA hardware” were rarely used in the same sentence, or paragraph for that matter. Fortunately, advances in microprocessor technology produced quantum leaps in functionality and design of SCADA systems throughout the 80’s and 90’s. Nonetheless, the core RTU based SCADA architecture has remained relatively unchanged albeit quite expensive over the past 25 years. Thus, its use has been limited to the larger utilities.
The base design of a conventional SCADA system consists of a network of RTUs (remote terminal units) located in the utility substations that are connected 24/7 to a central computer. RTUs are nothing more than “dumb panels” that serve as wiring termination points for the myriad of metering and control connection in the substation. The functionality of the RTU based SCADA system is dependent entirely on the communication link between the host computer and the remote terminal units. All logic and control decisions are monitored and performed by the host computer and /or operator. If the communication link between the RTUs and host is lost, the traditional SCADA system is rendered inoperative.
Conventional RTU based technology has been cost prohibitive for a large percentage of small to mid sized co-ops and municipal utilities for a host of reasons. First of all, the traditional SCADA architecture requires complete RTU implementation in all substations to derive the full benefit of the system. RTUs cannot function as stand alone panels and are dependent on their connection to the host computer. The labor costs associated with wiring the outputs of the various panel meters to RTUs are onerous. Also, the installed and operating costs to furnish substations with lease phone lines actually contributed to the market need to develop alternative communication technologies.
The central processing equipment of a conventional SCADA system typically consists of a mini-computer platform that simultaneously monitors and manages all of the remote SCADA locations. It is quite sophisticated and complex, requiring a significant investment of resources and personnel to effectively implement, manage and maintain. The cost of the central computer system can range from $100,000 to $250,000 depending on the functional requirements and size of the installation. Annual software maintenance contracts and training costs are usually in excess of $10,000.
Fundamentally, the traditional SCADA design was developed for large utilities. The utility has to make a complete commitment to the SCADA vendor and solution or not. The design does not allow for the utility to “sample the technology” and determine if it matches the needs of their business. You cannot simply absorb the installed cost of a six-figure host computer system and outfit one substation with RTUs. There is far too much risk involved with that type of purchase. Unfortunately, many small to medium utilities that have purchased traditional systems over the past 25 years have become the victims of obsolete technology or lack of a reasonable migration path to next generation technology. In other cases, the vendor exited the industry. This has resulted in a noticeable shift of potential SCADA users from the “early majority” segment of the utility market to the “late majority and laggards” of technology adopters. Independent research conducted during 2Q 2001 of electrical co-op utilities in the U.S. indicated a surprising number of these utilities that have either an inoperative SCADA system or no SCADA system.
As previously mentioned, the general architecture of RTU based SCADA technology is virtually the same today as it was decades ago. The primary reason for this is the computing power requirements to manage large SCADA applications. The majority of the major SCADA vendors were not willing to abandon the mini computer platform that has been their mainstay for decades. While there have been enhancements over the past 25 years, conventional SCADA systems still require a comprehensive and costly implementation to realize their full value. The combined host and application software package remains north of $100,000. These facts do not bode well for the municipal or co-op utility. There has not been much of a reasonable choice for the small utility to implement SCADA technology. That is, until recently.
The emergence of microprocessor-based technologies over the past twenty-five years has vastly improved the efficiency and productivity of many automation and information system architectures. The computing capabilities of PCs and networking technologies have bridged the large data processing gap that once existed between mini computers and the desktop PC workstation. The evolution of microprocessor based power meters over the past ten years has been equally impressive. These next generation power meters are equipped high-speed digital sampling processors that can compute and update hundreds of highly precise power values every second, replacing and outperforming the functions of dozens of conventional meters. Power meter options include: on board memory for data logging tasks, multiple communications ports and a wide selection of digital/analog inputs and outputs. Great strides in communication technologies have also provided the user with the choice of RF wireless, cellular and satellite mediums.
The result of these technological advances over the past two decades is the first viable system alternative to traditional SCADA technology. For the sake of discussion, we will refer to this innovative solution as SmartSCADA. The objective of SmartSCADA is to provide small utilities with a cost effective choice to traditional SCADA technology. SmartSCADA addresses the unique needs of the small utility. It is modular in design and deploys a distributed intelligence architecture. SmartSCADA relies on a network of intelligent power meters that replace the functionality of hundreds of conventional meters. These meters are equipped with on board memory to log a wide range of power information and pre-defined alarms and power quality events. They also feature programmable logic to respond to abnormal events at the substation via user-defined responses and control schemes. What this means to the user is a SCADA system that is not totally reliant on the connection between the central host computer to monitor and control their substations.
With SmartSCADA, all control logic is contained and implemented at the substation level by the power meters. If communications between the substations and host computer is interrupted, the SmartSCADA system will continue to function. This provides the user with redundant monitoring and control. The power meters can also be equipped with optional inputs and outputs that provide for monitoring equipment status, transformer temperatures and for controlling breakers and other substation devices. One of the key differentiators of SmartSCADA power meters vs. traditional RTU technology is the ability to monitor and record voltage transients and other power quality events in the substation. This capability provides the utility with a valuable information tool to monitor the quality of power delivered to the distribution substation and subsequently to their customers.
SmartSCADA provides the user with the choice of relying on the central workstation and system operator or the automatic control capabilities of the power meters to execute control functions. These situational control decisions, pre-programmed by the utility engineer, can be made at the substation by the power meters. The meters, equipped with programmable logic, are capable of monitoring and weighing multiple values and variables. The meters will automatically implement the desired control response as if the utility engineer were personally monitoring the substation power conditions. They can be modified over time to optimize the performance of the SmartSCADA system.
SmartSCADA also provides the user with the choice of multiple protocols and communications options to transport data from the substation to the host PC. These include: RS232/485 serial output for wireless and satellite communications, Modbus, DNP 3.0, Ethernet, cellular and traditional telephone modems. Hybrid solutions can also be implemented.
SmartSCADA utilizes a PC based architecture and Windows operating system. It is user friendly and much less expensive to maintain than traditional SCADA application software. Given the flexibility of SmartSCADA protocols and communications options, integration with third party products such as protective relays and transformer monitoring systems are feasible. Functional updates to both the SmartSCADA power meters and host PC can be downloaded without interruption to the system. This extends the obsolescence period of the technology for many years.
Perhaps the most encouraging aspect of SmartSCADA is the total installed cost. A typical turnkey SmartSCADA substation installation is less than half of a conventional SCADA system. The keys to the savings are the computing power and value of the intelligent power meters vs. RTUs and the labor savings derived from the elimination of panel meter wiring runs and integrating the functionality of numerous meters into one self contained device. These power meters are stand alone, mini power management systems that monitor, record and control a wide range of information. They replace the functionality of the entire network of panel meters and RTUs.
The SmartSCADA host PC and application software package ranges from $15,000 to $20,000 depending on the computer hardware options. There will be a relative amount of application engineering required on any SCADA system to provide the user with the unique information screens and programs that are tailored to their needs. Estimates for SmartSCADA application engineering and integration for a five breaker substation that is “SCADA ready” are in the $10,000 range. The integration costs for the host PC and SmartSCADA software will range from $10,000 to $20,000 depending on the size and scope of the project. This is a far cry from the $100,000+ cost for most RTU based central computer systems.
The deliverables of a fully implemented SmartSCADA system rival and in most cases, exceed the functionality of much more expensive and elaborate RTU based offerings. They include, but are not limited to:
- reduction of downtime via full time monitoring of all substation devices and critical parameters
- labor savings derived from ability to troubleshoot, identify and correct problems
- ability to record the history of substation operations and fine tune the efficiency of breakers and relays
- real time power and energy monitoring and recording provided the user with comprehensive load profiles and future energy purchases and growth planning
- monitor deviation of voltages and other critical values such as hours of operation, number of closures and transformer temperatures to extend useful life of physical plant
- provide real time stamping and recording of all power quality events at the substation
- monitor and control feeder loading and continual balancing of loads
- remote switching of feeder breakers and electronic tagging of protective relays
- adjustment of regulator controls
- automatic capacitor control
- increased degree of safety for line crews responsible for identifying fault locations and restoring service power
In practical terms, SmartSCADA offers the small utility with the first cost effective alternative to traditional SCADA. The system can be implemented one substation and one breaker at a time. If the utility wishes to monitor only first and not control, that option is available as well. A “SmartSCADA starter kit” is available for less than $10,000. It includes the application software, a microprocessor based power meter and system start up. This affords the user with a low risk opportunity to evaluate a specially configured, yet fully functional version of the SmartSCADA software and the ability to interface with a remote power meter. The small utility user can then evaluate the technology at their own pace and determine if the architecture meets the information gathering and control needs of their business. Hopefully, those former members of the "early majority" technology adopters who have been spurned by an unsuccessful initial SCADA experience will migrate back to try a new approach to an old problem. Finally, a SCADA system designed and developed with the little guy in mind.
