The Department of Energy’s (DOE) Smart Grid Task Force brought together some of the leading thought and research groups in the Smart Grid arena in early 2008. Together, they agreed upon seven characteristics of a “Smart Grid,” defining a future power delivery grid that meets the needs of the next generation of Americans.
- Enable active participation by consumers.
- Accommodate all generation and storage options.
- Enable new products, services and markets.
- Provide power quality for the range of needs in a digital economy.
- Optimize asset utilization and operating efficiency.
- Anticipate and respond to system disturbances in a self-healing manner.
- Operate resiliently against physical and cyber attacks, and natural disasters.
Advanced metering infrastructure (AMI), also commonly referred to as smart meters or simply advanced metering, is one of the key technologies required to enable several of the Smart Grid characteristics, and it plays some role in all of them. For this reason, AMI must be viewed as a foundation enabling technology for the Smart Grid.
The following describes the way in which AMI contributes to the realization of each of the seven characteristics of the Smart Grid:
Enable Active Participation by Consumers
Historically, consumers typically received a bill for one month of electricity usage, with little or no explanation of how their habits and behavior influenced their monthly cost of power. Since the future supply-demand balance requires that we address both sides of the equation, the Smart Grid must provide the mechanism for active participation by consumers. In order for consumers to begin to understand their usage of electricity, the meter must be able to track not just the total amount of electricity consumed in a billing period, but precisely when that electricity was used.
This is a core capability of an AMI system, and is referred to as interval data, or load profiling. The other key enabler provided by a proper AMI system is the AMI home area network (HAN), which allows real-time usage information, as well as pricing and control signals, to be transmitted wirelessly from the meter to devices in the home. Having the ability to monitor their usage in real time, using a device like an in-home display, gives the consumer meaningful feedback on how their habits or behavior ultimately impact their electricity bill, and provide them the opportunity to make more informed decisions about how and when they consume electricity.
Once the utility has implemented AMI and begun collecting interval data for all of their customers, they can then fundamentally change the way they charge for usage of electricity. Instead of charging a flat rate for usage, regardless of when it is consumed, they have the ability to link the time of consumption with an appropriate price for that time period that accurately reflects the wholesale power market conditions and relative scarcity of electricity at that time. Whether this is accomplished via simple time-of-use rates, or more complex dynamic rate structures like real time pricing or critical peak pricing, it effectively makes the consumer of electricity an active participant in the energy market.
Accommodate All Generation and Storage Options
At the residential level, supporting the connection and use of distributed generation and/or energy storage, collectively referred to as distributed energy resources (DER), requires the accurate measurement of the actual energy supplied by these DER. A properly designed AMI system enables full bi-directional energy measurement at the billing meter, as well as allowing for retrieval of measurement data from the device itself or an associated sub-meter, via the HAN. Collecting actual energy generated by each specific device will allow the utility to understand exactly how much customer generated power is being used to offset load, and exactly when that power is being produced.
This also encompasses distributed storage devices, which at the residential level will appear first in the form of electric vehicles. Here again, the AMI system can play the role of enabler by collecting data on the energy being used specifically for charging an electric vehicle, and also for transmitting pricing signals to the vehicle to help coordinate when charging takes place.
Enable New Products, Services and Markets
Once end-users of electricity, and potentially even end-use devices themselves, such as smart thermostats, have the ability to participate in energy markets, an environment will be created that fosters the evolution of an entire new class of products and services related to energy use and efficiency. As these new products and services evolve, it can be anticipated that markets will evolve alongside them to take advantage of the value created by improving the efficiency of energy usage.
Provide Power Quality for the Range of Needs in a Digital Economy
Specific to the residential customer, voltage is a key determinant of power quality. Utilities are supposed to deliver electricity to residential consumers within a specified voltage band of 120 volts +/- 5 percent during normal operating conditions, and when designing distribution systems, this is one of many design criteria. However, voltage at any given point on the distribution system is not a constant, as it varies according to the amount of cumulative load on the circuit. Therefore, the voltage delivered to any given customer at any given time will vary significantly, and historically the utility had no way of monitoring delivered voltage without installing special equipment in response to customer complaints. As a result, residential consumers have been relegated to living with whatever voltage levels they received from the utility, which may or may not be within the appropriate operating band. Abnormally high or low voltage can be highly problematic for certain types of devices or electrical equipment, adversely impacting operation and sometimes dramatically shortening operating lifespan.
Because of the enhanced capabilities of the electric meters that make up AMI, the technology will, for the first time, enable utilities to monitor voltage at the point of electricity delivery to every customer on their system. In doing so, they will be able to take a proactive position in identifying areas of their distribution systems where voltage levels are chronically out of tolerance, and address those problem areas before their customers suffer from equipment malfunction or failure.
Optimize Asset Utilization and Operating Efficiency
Improving the electrical efficiency of the Grid, from the point where electricity is generated all the way to where it is consumed, is one of the objectives of the Smart Grid. Approximately 9 percent of electrical energy is lost as “system losses” in the transmission and distribution systems. One of the keys to reducing system losses on the distribution system is accurate measurement of operating parameters at as many points on the system as reasonably possible, such that system analysts can better understand exactly where losses are occurring, and can then determine which losses can be economically reduced. Not only does AMI, by virtue of its “smart meters,” provide a high accuracy sensor at every delivery point on the distribution network, but the communication system used for AMI data retrieval also allows data collection from other non-meter data sensors. The AMI system is one of the keys to generating the data that can ultimately be used by advanced analytical software tools to help reduce technical losses in the Grid.
Anticipate and Respond to System Disturbances in a Self-healing Manner
The ability of portions of the distribution system to analyze operational parameters in real-time, and proactively take actions (switch re-configurations, etc...) to isolate faults and recover undamaged sections has the potential to greatly reduce average outage times. These types of applications require very low latency data communications capabilities which would typically be outside the scope of applicability for an AMI communications network. However, AMI systems do have some capabilities that are highly complementary to these applications.
One example would be the use of AMI system-generated outage and restoration messages to perform post-event analysis after an automated system reconfiguration in order to verify the status of the distribution system. Additionally, the ability to view actual delivered voltage for any individual meter point would give system operators greater insight into the operating state of a specific part of a circuit during post-event troubleshooting.
Operate Resiliently Against Physical and Cyber Attacks, and Natural Disasters
Since the entire concept of the Smart Grid relies on interconnected devices with high levels of automation, cyber security becomes one of, if not the most, important issues relative to Smart Grid. Resiliency against cyber attacks is a core competency of AMI. With the deployment of highly secure AMI networks, utilities will have the ability to extend automation out to all levels of their system without compromising system reliability. AMI is one of the primary drivers of security practices for the distribution network level of the Grid.
AMI changes the utility landscape by creating a secure network between advanced meters and utility business systems. For the first time, this allows the collection and distribution of information to customers and other parties such as competitive retail suppliers, in addition to the utility itself. In this way, AMI and the Smart Grid will deliver a new level of excellence in utility operations and customer service, securing a smart and efficient energy future for all.