Last week I attended an Elster User’s Group Meeting in Pinehurst, NC, and co-presented on the topic of the convergence of distribution automation and AMI (Advanced Metering Infrastructure). Elster Group is a leading provider to electric, water, and gas utilities of communications, networking, and software solutions. They supply AMI meters and systems. It’s a good time to reflect upon the growing integration, and in some cases the convergence, of distribution operations and AMI in three different areas:
1. Communications between the control center and feeder devices
2. Outage detection, prediction, and restoration
3. Electrical analysis of the network
1. Communications between the control center and feeder devices
Last year, Elster launched its IP AxisLink platform, for AMI and DA convergence. The platform consists of the IP AxisLink Router/Gatekeeper/Gateway and the IP AxisLink secure tunnel server. The concept is that this platform enables a utility to use much of the same infrastructure that it uses for AMI for distribution automation and distribution operations purposes. The AxisLink Router, which is installed in the field, provides parallel paths for AMI and SCADA operations. The router can contain an Elster gateway, which is used to provide the path between the meshed network of revenue meters and the WAN communicating back to the Elster head end. At the same time, the router can provide access to distribution IED’s using IP-based protocols (such as DNP) over the EnergyAxis communications network. The IP AxisLink secure tunnel server, located at the control center, provides VPN tunneling of the SCADA communications between the SCADA front-end and the router.
The value provided is that at particular locations, a single box can be installed that will communicate both AMI and SCADA messages over the utility’s WAN. This avoids the need to install separate hardware for these two purposes, while utilizing the same WAN connection. In this way, controllers for reclosers, switched capacitors, voltage regulators, and switches can communicate with the SCADA/DMS leveraging the AMI infrastructure. Elster is not the only AMI supplier with solutions for using AMI for distribution automation. It is an alternative to traditional SCADA communications that bears evaluation from feeder device communications.
2. Outage detection, prediction, and restoration
Interfaces between AMI/meter data management (MDM) and the outage management system (OMS) are becoming more common. Efforts continue to enhance the functionality, but already there are several ways AMI data can improve the outage management process.First, if the AMI meters and communications contain the capability, the OMS can receive a last-gasp or outage notification message from the meter when it loses voltage, indicating a customer outage event has occurred. Customer outages are automatically reported to the OMS, even if the customer doesn’t call its supplier. Receiving outage notification messages is in addition to phone calls from customers reporting outages. These outage notification messages are particularly useful when no one is at a property where an outage occurred or when people there are asleep. The outage notification message can reduce customer interruption times and result in a more efficient dispatch of repair crews.
Second, with the proper interface between the OMS and AMI system and the right communications infrastructure and meter, a message can be sent from the OMS to query if a meter is in service. This is often referred to as “pinging the meter.” The meter can be pinged directly, assuming the AMI communications permits it, or the MDM can be pinged to determine the status of a meter. The meter can be pinged either by a customer service representative or an operator.
The value in pinging is that many customer outage reports are results of problems on customer sides of meters. Utilities commonly report that 50 to 67 percent of single-customer-call outages are results of problems on the customer side of meters and not the responsibility of distribution organizations. If a meter can pinged to determine it has voltage, despite a customer’s reports of service issues, responding troubleshooters and crews can save labor costs and vehicle miles.
Another value in meter query is in the ability to potentially perform intelligent outage scoping, or define the outage area by pinging select meters. This can lead to a faster definition of the outage area.
A third area in which interfaces between OMSs and AMI systems can provide value is through restoration notifications. They provide confirmation to distribution operators that customers have been restored downstream of a particular protective device. Restoration notification can be done through a restoration notification message transmitted from the restored meter to the OMS or through pinging of meters that presumably have been restored. The value of restoration notifications is that when all customers have not been restored because of a nested outage within the larger outage area, field personnel can be notified of additional problems before they leave the area.
3. Electrical analysis of the network
The widespread use of AMI data to improve electric operations is frequently discussed, but actual implementations are not yet widespread. One example is the use of load profile data from individual revenue meters to create distribution transformer load profiles for use in DMS applications. Instead of having generic customer class type profiles for the loads, each distribution transformer has a set of load profiles that are reflective of the actual customer demands based on the AMI-reported demands. Having load profiles for each individual distribution transformer provides more accurate calculation of the state of the network, including a better understanding of loading throughout the system. This improves the accuracy of DMS load flow calculations, allows operators to load equipment closer to its limits, and results in more accurate calculations used in FLISR (fault location, isolation, and service restoration) and volt/VAR applications.
More experience is being gained with the creation of individual load profiles for each distribution transformer using AMI data. Some distribution organizations are using funds from their ARRA stimulus grants to implement the interface to the meter data management (MDM) and the DMS. In one case, an XML interface using middleware messaging is being used to extract data from the MDM and consolidate the data into each distribution transformer load profile. The load profile will then be used in the DMS applications.
Increasingly often, real-time or near-real-time electrical data from AMI infrastructure will be used in the operation of the network. This includes both data from both revenue meters and data from feeder IED’s. While the timeliness of the data from revenue meters must be considered, due to the latency of some AMI networks, an interface between an AMI head-end system and the DMS can be constructed, using web services or messaging. The data from feeder IED’s can use the AMI communications infrastructure, as described in the first topic, in communications to the control center. Examples of electrical data that can be transmitted over the AMI communications infrastructure are voltage limit alarms or voltage magnitude analogs. Such data permits more precise control of the voltage in the network, permitting an organization to more effectively implement voltage conservation reduction.
