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For several years there has been a clear line of demarcation between a utility's "Smart Meter" and distribution organizations (e.g., SCADA), especially when it comes to their communications network and how the data gets back to control central. There are several advantages to leveraging an AMI network to perform additional and/or layered applications, where SCADA can easily be leveraged. Let's first take a look at some of the advantages that can be achieved with a ubiquitous IP- based solution focused on Distribution Automation (DA).
Making the move forward
The performance criteria for DA are high: DA circuits are very latency sensitive and there is often not enough bandwidth; the typical speeds (9600baud) are not fast enough, and to date have had to rely on devices in the field that communicate status of the grid via proprietary protocols or solutions that have been crafted in the field that don't quite meet all of the requirements of SCADA unless there is a lot of lit fiber. With existing non-IP DA solutions, there are challenges with respect to driving solicited or unsolicited messages back to SCADA central including latency, proprietary low bandwidth, older technology, not to mention command and control of these devices becomes more trustworthy (because of the defensibly secure links). Utilizing an IP-based network that provides enough bandwidth and a robust routing protocol enables the messages to traverse the network very fast, resulting in greater control and sound results. IP-based DA solutions with at least 100kbps could indeed revolutionize the way DA networks will be deployed in the future.
As earlier stated, one of the prime issues with existing DA networks is that most are proprietary in nature. Several companies provide DA networking solutions; however, native IP and open standards are few and far between. Most existing DA networks provide transport capable products, but are challenged to deliver timely and useful information when a fault occurs. Requirements for data delivery when a fault occurs is often measured in seconds and deploying a system that truly supports this in a reliable fashion takes significant engineering effort and craftsmanship on the part of the utility. Unreliable performance of the DA networks today results in practices that burden the utility overall. Moving away from these older solutions and towards a technologically sound transport option enables the SCADA operators to take greater advantage of the information that can be provided in ways that will benefit the utility.
Far too often, due to the lack of confidence that SCADA has in the communications network, utilities employ mechanisms to verify that links to the line devices are still reachable. Polling these end devices is one mechanism that is used today. Varying polling rates, from every five minutes to every 15 minutes, is not uncommon and is even more aggressive for some utilities. For most communications networks this presents a data flow problem that gets bottlenecked through the transport. Employing an IP-based network affords a utility the opportunity to think of doing business differently and taking advantage of data and statistics in a way that they have not been able to in the past. Exception-based reporting becomes more realistic; polling at a less frequent rate becomes a more palatable option because there is confidence that the communications network is available. Making the move to deploy an IP-based DA network will take time and further education, but will add far greater value than expected.
There are many important criteria evaluating an IP-based DA solution:
- Will the solution reduced the number of truck rolls to manage devices?
- Is the solution true two-way communications that supports command and control?
- Does the solution offer a feature rich routing protocol and full redundancy?
- Is the solution capable of responding to outages faster with greater reliability than the existing system?
- Does the solution as deployed offer improved SAIDI and CAIFI numbers?
An IP-based DA solution with at least 100kbps and dynamic routing satisfies all of the above.
What are the base level requirements?
- The network needs to have enough bandwidth and speed to manage the latency requirements of DA, and if it is to be used along with AMI, must scale as applications are added.
- Naturally the network needs to support open standards (DNP3, MODBUS, IEC61850) predicated on native IP.
Where is the opportunity?
The initial opportunity lies in supporting the future and the streamlining of networks that help manage the grid:
- Removal of the legacy technologies that do not accommodate future growth or change by the utility. An IP-based communications network affords the SCADA operators the advantage of adding devices or move devices without having to spend unnecessary funds due to supplier lock in and proprietary protocols.
- By employing an open, standards-based communications network, there is uniformity throughout the network. The ability to manage command and control remotely is truly enhanced through reduced service requests to physically visit the devices in the field and trusted delivery of statistics and data from the end device (Capacitor Bank Controllers and Switch reclosers for example).
By using IP and tunneling the respective protocols, there is an added advantage to the utility since security can be wrapped around the transport without modifying the legacy hardware currently deployed. Naturally, this includes all legacy protocols.
Making the Smart Grid Real -- DA+AMI
The first thing to consider is cost benefit. This presents itself in the overall opportunity to use a common network infrastructure (one network running for multiple applications) that allows plug and play of various applications from multiple suppliers. The key ingredients are open standards and IP. There has been a history of segregated networks between SCADA and AMR, so an inherent paradigm shift is needed to enable true two-way communications, cost effectively and with the ability to accommodate future services and applications.
Where are the savings?
- The utility pays for an infrastructure once, thereby garnering the advantage of adding additional applications.
- For the added applications, there is a single network and user interface for the network operators to learn as well as a single BOS.
- Where the utility chooses to drive their DA traffic across the AMI network, they now have the option of selecting any number of OEM devices to integrate because the network is based on open standards and IP.
- Legacy devices that are unable to report by exception can be enabled with an intelligent IP-based solution.
All in all, supporting open standards within an IP-based network creates the potential for a multitude of applications to be managed and data to be presented, on one network. This is an opportunity to build out ubiquitous, high-speed, low-latency solutions that are the foundation for the Smart Grid.
