Why LTE wireless brings power grid security, convenience, and convergence to the last mile

Many environmentally aware and cost-conscious consumers invest in solar panels at their homes. Previously, we just consumed energy. Now, we can potentially send energy back into the grid and track it in near real-time.

It’s thrilling to see your power consumption statistics confirm that your rooftop solar is worthwhile. You’re proud to be a Prosumer—Producer and Consumer at once! However, you may have a myriad of questions: What is that spike in my consumption that’s causing me to pay for power from the grid instead of earning credits? Who else can see the data shared by my smart meters and rooftop solar? Am I protected when my grid loses power?

The utility provider also has questions: How do we ensure that consumer-produced solar power does not overwhelm my power grid? How can I quickly expand into new neighborhoods? When we open up our grid to rooftop solar systems, how can we stop bad actors from hacking into the rest of the power grid?

Solving the Last Mile challenge

This blog post is about that last mile in the power grid. This is where power enters the consumer domain; it’s also where safety and security become paramount. We will address how LTE enables more real-time monitoring of power grid components when high power lines enter a neighborhood and how consumer power generation affects and enables the power grid. We will also explore how LTE provides power grid security that enables utilities to share wireless access across the consumer and operational domains.

Figure 1: The Last Mile is where prosumers demand safety and reliability from the power grid.

Through the previous three blog posts in this series, we gained a better understanding of how a private LTE network can be used to bring ubiquitous connectivity and reliability to multiple aspects of the power grid. LTE wireless networks are a welcome new tool for grid modernization. They achieve latencies comparable to fiber, but at a fraction of the scaling costs during expansions.

In the blog posts, we also traced how power generated by fossil fuels, gas, wind and distributed energy resources are balanced at transmission substations. These connect over short latency connections to distribution substations—the gateways to power delivery for enterprises, industries and homes. Having a common wireless network over the entire power grid allows converged access to utilities’ operational performance and employee communication.

The new Prosumer changes the landscape

With the rise of distributed energy resources like rooftop solar systems and the growth in sustainable consumer power, it’s increasingly important for utilities to have continually updated information on the demand variance of consumers in the power grid. What was traditionally unidirectional (power grid feeding homes) is now bidirectional (solar and electric vehicles returning some power to the grid, while still consuming power from the grid). The new reality of “producing-consumers,” or prosumers, requires real-time feedback to ensure the success of the balancing act between total power generation and demand.

With real-time information in the last mile, substations can isolate fossil fuel-sourced power when sustainable energy production is high and switch in fossil-fuel power on a cloudy or still day, when solar or wind power generation is low.

Real-time monitoring of neighborhood power lines:

Figure 2: Three-phase power carried over separate lines uses sensors and communication nodes to keep you safe. (source)

Three-phase power

Power of 4/11/33kV or more is stepped down at the distribution substation and neighborhood pole transformers and fed into communities. Figure 2 shows an example of a pole near your home. To keep neighborhoods safe from falling or malfunctional power lines, utilities must monitor performance of the power line in real-time. High-power devices like car chargers and washing machines use power derived from three phases of current (requiring three lines in Figure 2). Lower power devices including our refrigerators need only a single phase to operate.

Some of the aspects that need real-time monitoring include:

• Ambient Conductor temperature—Monitoring to ensure that the heat generated by the conductor in the ambient environment is within operating parameters. Power lines operating outside their temperature margins can cause instability in the grid.
• Inclination or the amount of line sagging—Using sensors to ensure that conductors carrying the three separate phases do not come too close together. Inclination in poles could be a cause for the sag. Fallen conductors can cause injury and fires.
• Wind movement—Detecting galloping conductors when wind and bad weather cause lines to come too close to each other and create grid instability by electromagnetic effects.
• Distribution of electricity—At points where transformers step down 4kV or higher voltages down to consumption at 240/120V, sensors are used for fault isolation. They detect incipient faults associated with the gradual intrusion of tree limbs as they grow into and toward the lines.
• Consumption of electricity—Using communication nodes on poles, connected by mesh networks, to collect information from smart meters and other devices. These collectors may be connected to public networks to share consumption information with the local utility provider. Replacing the public networks with private LTE provides more guaranteed, reliable performance over licensed spectrum and is an opportunity for optimization.

The real-time feedback from LTE wireless in the last mile enables utility companies to ensure power grid security and be more proactive in staying ahead of potential faults in the neighborhood grid in some of the following ways:

• Substations receive the information needed to isolate smaller parts of the neighborhood grid, avoiding instability and blackouts in the larger grid.
• Safety is enhanced by proactive monitoring of weather-stricken infrastructure.
• A real-time analysis of consumption and prosumer generation allows for more efficient onboarding of distribution energy resources across transmission and distribution substations in the power grid.

Ending the competition for bandwidth in the last mile

Performance in the last mile of power delivery:

Figure 3: The power grid has to compete for wireless resources on the public network.

The last mile is also where consumer traffic from smartphones and fixed wireless competes with connections to power grid devices. Because demand on internet access is at its maximum here, running critical devices for the power grid on the same network can be both unreliable and expensive.   Figure 3 represents how power grid traffic has to compete with FWA (Fixed Wireless) and MBB (smartphone) traffic.  A dedicated Private LTE network for the power grid is one way to address this.

Also, with the rapid migration of population to suburbia, utilities are racing to expand existing last miles of power infrastructure. The time-to-activation of internet connections for new power grid devices on the suburban grid is quickest with wireless, and is most reliable with licensed LTE wireless.

Device price points for LTE chipsets keep falling. That means smart meters and consumer devices placed in the last 100s of meters between the poles and the consumer can be served by the same licensed LTE network as the rest of the power grid. With guaranteed performance, licensed LTE networks will replace existing best-effort mesh networks.

Figure 4: Critical traffic can be prioritized and independent of prosumer traffic on an LTE private network.

Introducing private wireless in the last mile also ensures that power grid-specific priority and pre-emption are built into the traffic to address different levels of criticality. Figure 4 shows a representation of how power grid devices (green line) can have unfettered access on a private LTE network, as compared to the blue line where power grid devices compete with consumer smartphone traffic on a public LTE or unlicensed wireless network. The performance and SLAs needed for reliable grid operations are within the control of the power grid provider. Consistent performance becomes independent of the prosumers.

Security in the last mile and across the power grid

Figure 5: 3GPP-based LTE takes security seriously, and from an end-to-end perspective.

The LTE wireless network serving devices on the power grid needs to consider security from the device through utility head-end.  The SIM on the power grid device connects securely to the eNB radio base station.  Secure protocols connect the eNB to the Core Network (EPC) which is the gateway to the internet/head end. 

To address concerns that most utilities have on wireless network security on a critical power grid, LTE has three pillars of security:

• Authentication. The LTE network verifies the SIM’s identity by challenging it for the right keys and results. Devices can be blocked from the network to prevent rogue SIMs from accessing the network. Application-level authentication mechanisms ensure authentication from device to application.
• Integrity. Checksums are used to ensure that the received message is the same as that transmitted. This mitigates man-in-the-middle attacks. Denial of Service attacks are addressed with algorithms that use EPC keys to track sequential LTE message counts and avoid rogue network nodes from intercepting signaling in the network.
• Encryption. Encryption of data with a key known only to the LTE receiver guards against hackers listening to the data

For mission-critical networks for utilities, we must also consider the concept of micro-segmentation. Mission-critical and security-critical workloads should not share resources with workloads having a low-criticality rating. Micro-segmentation is a key defense for isolating many of the attack vectors in a multi-tenant cloud environment.

Recommended isolation mechanisms are:

• Tenant isolation, using dedicated host resources, such as memory, execution, storage and networks, for each tenant in a multi-tenant environment
• Physical isolation, using physically separated hosts to prevent the compromise of one physical node allowing an attacker to move laterally across the virtualized network
• Traffic separation, using traffic filtering and/or network slicing functionality for inbound and outbound traffic
• Container runtime environment mechanisms, using software-based isolation with namespaces, control groups and file system protections to separate different workgroups from each other. This applies especially to cloud-native container-based packet core deployments.

Micro-segmentation and isolation mechanisms prevent the consumer last mile from becoming an entry point for security risks into the larger power grid. The default security that comes with SIM-based authentication and access would also extend to other consumer-facing power devices such as solar inverters, electric charging stations and power storage solutions—all of which feed power back into the grid.

The security and protection used on the last-mile delivery grid are extensions of the high security enforced on the transmission and distribution grid, allowing for much quicker reactions and fixes. With mission-critical security moving quickly and efficiently to stay ahead of bad actors, smart meters and substations will be protected with the same ferocity as the rest of the grid.

Private LTE network for a secure, reliable last mile

So, let us return to those pressing questions utilities are asking today: How do we maintain that delicate two-way conversation between production and consumption in a prosumer world? How can we quickly and cost-effectively extend our infrastructure to serve new customers and better serve our current ones? And when we open up our grid to prosumers, how do we ensure the security of our mission-critical grid?

I and my fellow prosumers, with our solar panels, are just one facet of the complex shift in the operating landscape for power utilities. As we’ve seen, LTE wireless enables new technologies and improved efficiencies that answer many of the challenges facing utilities. As utilities continue to adopt grid modernization, the reliability and security introduced by LTE wireless will extend from power distribution to power delivery infrastructure.

Read the entire blog post series where we unpack the state of the digital power grid and show how private networks are enabling utilities to achieve their goals.

• Wireless: The smart network for the smart grid and grid modernization
• Wireless brings low latency, high performance to interconnect generation, distribution in the power grid
• The wireless power substation: transformation towards power grid sustainability

References:

• Yang, Yi (April 26, 2011), Power Line Sensor Networks for Enhancing Power Line Reliability and Utilization (PDF), Georgia Institute of Technology
• Electricity distributors warn excess solar power in network could cause blackouts, damage infrastructure

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