Don’t Forget about Radio: Leveraging One-Way Communications to Inform Devices and Users

Today, the “Smart” in “Smart Grid,” “Smart Meter,” or “Smart Home” is synonymous with two-way communications between devices and a centralized system, as opposed to the one-way “command and control” electric grid of the 20th century. This two-way communications capability is fundamental to data-driven automation, control, and optimization of the current and future electric grid. That said, utilities and solution providers should consider the capabilities and distinct benefits of one-way communication systems.

While a one-way system cannot directly replace Advanced Metering Infrastructure (AMI), the simple setup, inherent data security, low cost, and scalability of the network make it a tool still worthy of consideration for certain applications. One-way systems can effectively support emergency broadcasts and transactive energy, and may have the power to transform demand-side management as we know it today.

The One-Way Landscape

One-way communication networks take three forms:

• At its most simple, there are point-to-point (P2P) networks with just two nodes — the broadcaster and the receiver — via a dedicated communication path that can be wireless or hardwired.
• Point-to-multipoint (P2MP) systems, also sometimes referred to as “narrow cast”, wherein one broadcaster sends data to a specific list of receivers. This is best illustrated in the pre-internet cable TV model.
• The third type is broadcast communications, where a single broadcaster sends information to all receivers within an area, such as terrestrial and satellite radio and TV. For example, the data-carrying portion of radio signals communicates song and station information often seen in car and home radio displays. This article focuses specifically on radio broadcast communications, as satellite signals may not penetrate buildings to reach in-home devices such as water heaters or thermostats directly.

Broadcast Communications 101

Three characteristics are inherent to broadcast communication networks and provide unique value: scalability, simplistic system setup, and security.

First, broadcast communications networks are capable of reaching a very large number of devices simultaneously. As with a dedicated communication line, they avoid network congestion. Examples could include broadcasting price signals for a dynamic pricing program, sending command signals for a demand response program, or supporting utility emergency response management with reports and backup communications.

Second, system setup is simple. A very robust broadcast network of satellites and radio towers can be leveraged to access a portion of system bandwidth. Using this national network would require:

1. Negotiating bandwidth access with major networks or local radio stations.
2. Establishing a secure data path from the utility to the radio station.
3. Installing signal receivers to reach selected devices such as thermostats, electronic displays, or inverters.
4. Programming the receivers (can be done via radio).
5. Testing and optimizing transmitter and receiver settings.

Third, one-way communications are inherently secure. Data sent to FM broadcast towers from a utility is generally not internet accessible, nor is data sent from the broadcast tower to the end device. More importantly, no data is sent from the end-devices to the utility, meaning that the utility is only adding one “access point” regardless if the end-device has an internet connection. This also makes device setup and firmware updates much easier, avoiding the need for burdensome device-level registration and password protections. Finally, the reduced cyber risk greatly simplifies the leasing of FM bandwidth options.

Consider an electric vehicle smart charging program as an example. EV’s are increasingly smart and connected, traveling from port to port connecting to public bluetooth, wifi, and cellular networks. These EVs are not the type of asset a utility CTO wants exchanging data on their network without protection. Since each EV has an FM receiver, information such as price signals could be sent to the EV without exchanging data with the utilities’ network. This mechanism could reach thousands of vehicles with little additional effort and without exposing the utility to additional cybersecurity vulnerabilities.

Utility Examples of Broadcast Communications

In this capacity, a utility would use the broadcast communication network to supplement nonfunctioning microwave or cellular networks in the aftermath of a natural disaster otherwise limiting crews to short-range walkie-talkies. Vital information such as crew assignments, priority lists, status updates, and communication alerts could be encrypted and sent via radio. Crews would use USB FM receivers in laptops or cellphones. Messages could also be displayed through a service vehicle’s FM radio. Crews would receive a temporary access code, enabling them to receive broadcast data, including any necessary software.

USB FM receivers are the size of a thumbstick, cost as little as $5, and can be secured using rapidly deployed access codes and encryption. As such, broadcast communication networks represent a very safe method to coordinate and communicate with emergency crews without compromising utility systems.

Demand Response: For a demand response program, the utility needs to add a feedback mechanism. This would be achieved by leveraging devices already linked to a two-way network such as AMI or sensors in the Supervisory Control and Data Acquisition (SCADA) system.

Utilities would install FM receivers on customer grid edge devices such as water heaters, pumps, or HVAC systems. To retrofit older devices, the FM receiver could be coupled with a simple load switch. Utilities have been using this approach in DSM programs for over a decade. For modern, intelligent devices, the FM receiver could be connected directly to the device to capture commands and data points. In either case, the utility would reconcile the commands and the responses by measuring the data provided by the utility’s AMI or SCADA system.

Other potential applications for this technology include:

1. DR & Ancillary Services: Sending pricing information or command signals to DERs.
2. Transactive Energy: Sending real-time pricing signals to devices participating in a transactive market.
3. Asset Management: Providing basic system reports such as, “Primary communications line is down, do not respond” or delivering secure firmware/software updates.
4. Authenticated Messaging and Security: Sending reports and updates to crews or other service providers who should not have access to a utility’s network – such as crews and support staff from other utilities during a crisis.

Broadcast Communications Limitations

As seen in the DR example, the technology has limits. Primarily, direct feedback from specific devices or groups of devices requires a secondary communications channel such as SCADA, wifi, or cellular. Other issues include:

1. Bandwidth – FM broadcast technology uses Radio Data System 1.0 (RDS1.0) that can transmit 1kb per second (about a paragraph of text), enough for changing electronic signs, or sending commands and simple reports.
2. Range: Typical FM signals travel 60-120 miles, and can be blocked by physical obstacles, as experienced when driving through a tunnel or parking garage. Lower frequencies (100MHz for example) travel further and penetrate more deeply than higher frequencies.
3. Device targeting is possible, but only a finite number. Targeting single devices or groups of devices can be achieved by incorporating authentication codes or other signals. The current standard, RDS1.0, can target up to 64,000 unique addresses, but identifier codes consume valuable bandwidth.
4. Devices need a receiver installed with appropriate programming. Any device or appliance in one of these systems will need a receiver. The effort required to install these receivers can vary depending on the device. Devices with an ANSI/CTA-2045 port (similar to a USB port for demand response devices like HVAC) have plug and play options. Other devices have data ports that can accept an adapter. Also, FM receivers can access home networks to connect to multiple devices. Finally, a radio-controlled circuit switch can be installed in front of a device (like a light switch).

A new standard, RDS2.0, is currently in testing. It will be able to reach over 100,000 unique addresses and increases the data transmission capacity of 8-fold. A second standard, HD radio, increases the number of devices and data transmission rate another 10-fold. Some receivers will need to be replaced to take advantage of these new standards, while other radios could be upgraded to use the new standards.

A Vision for the Future: Bringing DSM to Toasters

Currently, DSM programs focus on expensive, high-energy consuming devices such as HVAC systems, water heaters, and EV chargers. This makes sense, as DSM programs cost money, and both users and program operators need to prioritize their time and efforts.

In a world where FM receivers cost less than a dollar, and integrate into most electronics, a new paradigm for DSM is possible. One where billions of small loads like cell phone chargers that constantly draw power, cable boxes that sleep instead of shutting off, TV’s constantly looking for a signal from a remote control, and coffee makers with standby clocks could all participate in a broad-based DSM program.

For example, cell phone chargers leak 0.25W when not charging. While not a big number in isolation, multiplied 300 million times equates to 75MW of unused, unmanaged load. An average TV in standby mode uses 45W of power, which in aggregate consumes 4,500MWs. In total, these passive loads account for an estimated 10% of all residential power consumption, a staggering number that is rising as consumers adopt more “always-on” electronics.

Fortunately, this vision is quite possible. A related technology, radio-frequency identification (RFID), has transformed much of manufacturing tracking and logistics. Beginning in the 1990’s tracking rail cars and toll booth EZ-Passes, RFID tags are today so ubiquitous they cost less than a penny. Devices to enable the DSM vision above are conceptually simpler, since RFID uses two-way communications.

Until such simple, low cost integrated devices exist, one-way broadcast communications technology can supplement the two-way networks that are the cornerstone of the modern grid. The simple setup, inherent security, and scalability provide new opportunities for this century-old technology to address today’s challenges.