Tell you in three minutes! How smart is it to deploy smart meters on smart grids?

Traditional grids around the world are beginning to feel pressured by growing energy demand. The number of power outages is increasing. How can we improve these systems in a sustainable way? One possible solution we have all heard of is the integration of information technology into the grid. It will be a good start by integrating modern technologies, architectures and tools into the grids that are already in use and service, and integrating these approaches when planning new grids.

Tell you in three minutes! How smart is it to deploy smart meters on smart grids?

Traditional grids around the world are beginning to feel pressured by growing energy demand. The number of power outages is increasing. How can we improve these systems in a sustainable way?

One possible solution we have all heard of is the integration of information technology into the grid. It will be a good start by integrating modern technologies, architectures and tools into the grids that are already in use and service, and integrating these approaches when planning new grids.

Most traditional power grids are made up of many electromechanical systems; in these existing grids, in most cases communication is only sent to the user in one direction. We must have a two-way communication mechanism to share and use information to improve the service level and efficiency of transmission and distribution.

Most of the traditional grid architectures use centralized power generation. The main power generation center will actually send the total power to the transmission and distribution center for local distribution to users.

Smart grid

What we need is to deploy more distribution channels throughout the region to build a truly distributed energy architecture, such as deploying renewable energy – an important part of what we call smart grids.

In the case of smart grids, even consumers can now generate energy and distribute excess energy through various means such as solar and wind energy, even if the power company sees it as competing with itself. A smart grid is a suitable networked system with two-way communication capabilities.

Since traditional power grids do not implement monitoring using various modern sensor technologies deployed in a typical smart grid architecture, they are both "dumb" and "deaf". Sometimes power plants don't even know that there is a power outage or power shortage in an area until they receive a call from the consumer (the phone system has a backup battery). In a smart grid architecture, numerous sensors are deployed throughout the grid infrastructure for monitoring, testing, and communication. This can even achieve self-healing and recovery/removal and automatic reboot of power bypassing the point of failure.

As electric meters with communication capabilities enter many homes, power companies and energy regulators seek to use this technology to raise awareness of energy conservation. Utilizing this concept—sometimes called the smart grid—power companies are trying to take advantage of the network that enters the user's home so that they can actively manage the transmission load.

In Arizona, USA, and many other parts of the world, power companies can now provide real-time pricing information that allows users to adjust their power usage. For example, under peak load conditions (such as the typical heatwave weather in Arizona), utilities can send messages to users informing them that prices will rise in the next hour and encourage them to turn off appliances. Some home monitors can display this message. Even better, power companies can communicate with their home devices via smart meters, turn on thermostats or turn off pool pumps to prevent local power outages or even large power outages. The system requires a reliable communication protocol between the meter and the appliance, sometimes referred to as the home network (HAN). 900MHz wireless communication using the ZigBee protocol is a good choice here. An example of HAN is shown in Figure 1.

Tell you in three minutes! How smart is it to deploy smart meters on smart grids?

Figure 1: Example of a home network.

Automatic meter reading (AMR)

With solid-state electronic energy meters, we can now add communication links, so if the link is wireless, then the utility company can collect the data by simply driving it from the side.

Advanced Metering Infrastructure (AMI)

In this next phase of the show, the AMI can be networked with a range of other AMI meters; depending on location, satellite or low-cost RF links can be used. The two main RF communication protocols currently in use are Power Line Carrier (PLC) and license-free Industrial, Scientific, and Medical (ISM) bands. We can fully expect that 5G will be "infinite" in the next few years.

Smart meter

Electric energy meter evolution

I still remember the traditional electric meter installed in the basement of a six-bedroom apartment in Brooklyn, New York City. Once, I clearly remember that Edison United Electric Company cut off the power supply of my home because of the arrears/unpaid bills (my parents did their best, but in the 50s and 60s when I grew up, my family lived very tightly). The Edison United Electric Company’s buddy walked to the door of our small four-room apartment and said that I would break my home’s electricity and let me follow him to the basement of the meter. I just turned 9 years old and winter is coming.

When he came to the six electric meters that were lined up, he turned and said to me: "Now I have to take the electric meter from your apartment and take it away from the socket. I will cover the meter socket with a protective cover. In order to avoid the exposed wires to electricity." Because I already know that I will become an electrical engineer, so I listened and observed very carefully. "Before I cover these electrical contacts, I connect the wires through these contacts like this" (he shorts the contacts in series with the meter). "Now, before your father pays the bill, your family will have electricity. But don't say anything to anyone, I won't admit that I know this, understand?"

Ok, I was really taken a lesson in terms of humanity and electricity that day! I thank him, and learned that the meter was connected in series with the power supply that day, and there was an easy way to bypass the meter. That was 1959. After about two weeks, my family paid the bills and everything went smoothly, but the experience was clearly left in my memory, and it is still vivid today – remember where I came from and understand the era. Those old-fashioned electromechanical meters.

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Figure 2: Electromechanical energy meter used at the end of the 19th century.

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Figure 3: Next is the solid-state electronic energy meter. This meter measures instantaneous power, power factor and reactive power and stores these data.

Radio frequency communication link of smart meter

If your home is like my home, there are also a lot of wireless devices (wireless LAN, home security systems, smart phones, etc.), as well as other RF signals coming in from outside the house. This makes it very difficult to achieve reliable wireless data communication (it is not uncommon to receive a sub-microvolt level signal at the RF input) - even suppressing bad RF "interference" power levels higher). Since the meter may be placed anywhere in the house, outside the house, or in the basement, there must be a reliable RF connection between it and the utility pole or the utility company.

If the meter is operating in a license-free RF band, in order to comply with the radiation standards of each region or country, we must seriously consider the communication protocol. 900MHz, 2.4GHz and 5.8GHz are several frequency bands that are widely used. 900MHz is the preferred frequency band to connect the meter to and connect to the data acquisition destination. The 900MHz provides a longer communication range and is especially suitable for low power budget applications. Wireless M-Bus is a European standard for remote meter reading and is now part of the EN European NormaTIve Standard developed in EN 13757. Silicon Labs has a handy wireless M-Bus development kit and software.

Unused FM (frequency) broadcast band

Even though Ecuador has discussed the use of FM radio bands, the country's broadcast spectrum (88MHz to 108MHz) has not yet been effectively utilized; in fact, it has not been fully utilized due to the lack of useful information transmission during certain time periods. The possibility of using this unused spectrum time for smart grid data transmission is proposed in the reference "Support to Data Transmission on Smart Grids Using the FM Band Spectrum". The Neighborhood Network (NAN) topology will include smart meters that send user power and fault information to a Data Aggregation Point (DAP), which in turn forms a Metropolitan Area Network (MAN) to manage the collected data and Transfer to the organization responsible for power consumption. This article establishes a complete topology to support smart grid applications by using the “white space” in the FM band. The article also proposes a data measurement system architecture that develops a device that can transmit RF signals to send information to the DAP and then collect the data to a server located in the power company in the south-central region of Ecuador (Figure 4).

Tell you in three minutes! How smart is it to deploy smart meters on smart grids?

Figure 4: Topology for using white space bands in the smart grid in Ecuador.

This recommended topology requires the generation of a NAN, where each smart meter (SM) has a wireless transmitter that sends information to the DAP. Channels specifically selected within the unused white space (FM) will be used to transmit data. All DAPs in a particular area generate a MAN whose information is ultimately collected by servers in EERCS. Low-power data transmission prevents interference with other nearby networks and the available bandwidth is sufficient for this application.

Narrowband PLC/wireless communication

References "On the Diversity of Hybrid Narrowband-PLC/Wireless CommunicaTIons for Smart Grids" considers narrowband power line communication in the 3 kHz to 500 kHz band for two-way smart grid data communication (NB-PLC) and license-free wireless bands (902MHz to 928MHz in the United States, IEEE 802.15.4g and the emerging IEEE 802.11ah standard).

The system can operate with channel and noise statistics (which are often encountered with power lines and wireless data transmissions). This is because the channel and noise characteristics of the power line and wireless transmission are independent and have different properties. This article enhances the reliability of the entire system by simultaneously transmitting the diversity provided by the same information signal over the power line and the wireless link. They proposed an efficient technique that combines the NB-PLC with the signal received by the radio link for coherent and differential modulation schemes (Figure 5) while taking into account the randomness of noise on the two links.

Tell you in three minutes! How smart is it to deploy smart meters on smart grids?

Figure 5: Block diagram of the NB-PLC/Wireless Diversity System.

NB-PLC solves the last mile communication between the user's smart meter and the data concentrator, which is deployed by the local power department on medium or low voltage power lines.

License-free bands (such as 902MHz to 928MHz) can interfere with communication on the smart grid due to uncoordinated RF transmissions, and therefore have noise and interference problems. The NB-PLC has noise/interference that is different from the narrowband signal and the periodic impulse noise synchronized with the AC half wave. This is combined with the noise/interference of power management systems such as DC/DC converters, inverters and long-wave broadcast signals, coupled to the power line in the 3kHz to 500kHz spectral domain.

In this paper, three combined methods are studied, and their channel and noise statistical characteristics for processing power lines and wireless transmission methods on smart grids are summarized, which are different performance and complexity tradeoffs as a new alternative to traditional combination techniques.

Satellite communication (SATCOM)

Innovations such as SpaceX's Reusable Rocket Boosters reduce satellite communication costs and enable better communication efficiency design. Satellite communications may be another viable resource for deploying smart grids. In the past, satellite communications have been limited to monitoring and data acquisition (SCADA) due to their insufficiency and cost.

Smart meters and phasor measurement units (PMUs) will generate a large amount of new grid data. The PMU is able to measure and record grid conditions very accurately, providing insight into grid stability and pressure. The PMU is used to measure the so-called synchronized phasor, which is a time-synchronized number that represents the amplitude and phase angle of the power line sine wave.

The benefit of satellite communications is that it can provide a very wide range of services, especially in areas where terrestrial communications infrastructure is not available. Satellite communications can provide good services for applications such as machine-to-machine (M2M) communications. Keep in mind that electric vehicles (EVs) will soon play an important role in the smart grid because they can be either loads or power supplies for smart grids. Moreover, understanding the exact location of an electric car is an important set of data points for smart grid optimization – see The Tesla Model S, ultracapacitors, and large energy storage. "A text.

Traditionally, the primary use of satellite communications has been one-way media services. With the latest advances in satellite communication technology, two-way communication is now a reality. An example is providing IP services for M2M applications.

Some examples include:

• Inmarsat launched a broadband global network (BGAN) M2M satellite with a maximum data rate of 500 kb/s, a latency of less than 1 second and a service availability of 99.9%. Smart grids have stringent requirements in terms of availability, with 99.9% availability equivalent to less than 50 minutes of downtime per year. • • The 66 satellite networks covered by Iridium worldwide have low latency due to their low Earth Orbit (LEO) and are not affected by the weather due to the use of L-band frequencies. Low latency is very important in smart grid communication scenarios because in the case of severe power outages, ensuring real-time communication and always-on (eg, for substations) is essential. Low latency is also important for smart metering to optimize its management. • • The next generation of Iridium NEXT will provide services this year with data rates up to 1.4Mb/s. The bandwidth required for smart grids is increasing, so it is no longer possible to use older narrowband SCADA systems. Some new applications require a higher rate than 100kb/s. • In terms of communication security, satellite communications are believed to be more difficult to intervene and more secure than terrestrial communication systems. Some applications for satellite communications include customer premises and power plants. An example is an automatic meter reading (AMI) backhaul for billing and demand response (Figure 6).

Tell you in three minutes! How smart is it to deploy smart meters on smart grids?

Figure 6: Smart grid applications can utilize satellite communications to map them to areas where relevant devices are installed.

Another satellite communication application on the smart grid is video surveillance at remote sites. Many power companies have used satellite communications to monitor their remote assets, so high-throughput and low-latency communications applications will benefit from satellite communications.

Smart meter power consumption

Meter designers may choose a low-power meter design so they can use the design in battery-powered gas and water meters. A good power management IC (PMIC) I've found is Texas Instruments' TPS65290, which has good quiescent current; it also provides a universal power supply for battery-powered gas or water meter designs. design. Silicon Labs' Si10XX is a good low power wireless MCU.

Safety and tamper resistance

Non-technical causes have caused billions of dollars in revenue losses for power companies around the world as hackers attacked the meter to slow down or stop the accumulation of power statistics. This loss has made power companies strongly demand to strengthen the protection design architecture in new smart meters. Some of these tampering methods include the terminals of the reverse meter, bypass current, wires connected to the mobile meter, and magnetic tampering. This is a way of stealing electricity from power companies.

In the first line of defense against tampering, some precautions may include using an inductive switch or mechanical switch to detect if someone is trying to open the meter case and enter it. The switch is connected to a GPIO port - if the meter housing is opened, the status is changed and an alarm is issued to the MCU, which in turn sounds an alarm or sends a safety alert.

Magnetic tampering uses a magnet to slow down the speed of the meter's character wheel, making it look like the customer is using less power than it actually is. One of the countermeasures is to use a Hall sensor to detect the presence of a strong magnetic field generated by the magnet. You can also use the GPIO port to activate some alerts.

The meter can also be hardened by designing the shunt as a current sensor with an isolated sigma-delta ADC that is immune to strong magnets. There are other ways to use this tampering.

Patrick Le Fevre, chief marketing and communications officer at Powerbox, has conducted extensive research on protecting smart grids. He has a number of excellent technical insights on the company's website, such as his plan to the US federal government in the NaTIonal Electric Grid Security and Resilience Action Plan.

Smart meter reference design

Maxim Integrated offers some great solutions for smart meters, including a useful reference platform called "Newport." NXP also has some good design examples.

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