According to Merriam Webster dictionary: the ability of something to return to its original size and shape after being compressed or deformed. Resilience is an ability to recover from or adjust easily to adversity or change.
There are several aspects to resilience of the grid, including resilience to:
All routine management of the grid and recovery from extreme conditions require (almost) real-time connectivity, process capability, and extreme amounts of data to be transmitted quickly and reliably. Maintaining resilience of the grid in the face of factors like these requires capabilities that are now available and have been validated in cost-effective technologies but are only beginning to be deployed in commercial grids:
All routine management of the grid and recovery from extreme conditions require (almost) real-time connectivity, process capability, and extreme amounts of data to be transmitted quickly and reliably. Maintaining resilience of the grid in the face of factors like these requires capabilities that are now available and have been validated in cost-effective technologies but are only beginning to be deployed in commercial grids:
Due to the requirements to collect and transmit massive amounts of data, telecommunication services are fundamental for the resilience of the grid-- resilience of telecommunication networks becomes a fundamental feature of the grid solution, providing connectivity as required in the different conditions. Utilities that rely, totally or partially, on telecommunications services providers, are accepting that their grid resilience depends on the resilience of a third party’s networks. The traditional way to gain the needed independence from such third parties is to establish and operate private telecommunications networks using technologies like wireless (always dependent on the use and control of the radio spectrum) and wired technologies like fiber optics and Power Line Communications, using the utilities’ own power lines.
Due to decarbonization, we can expect a continuation of the immense increase in the number of generation plants, storage devices, and large additional consumers at the lower voltage levels. These changes are increasingly leading to capacity bottlenecks in the distribution grids. This problem is exacerbated by very high volatility in both generation and consumption. Due to time constraints, this increase and the associated loads cannot be solved by expanding the grids, so that a controlling intervention in the low voltage portion of the grid is indispensable. However, central control, as practiced up to now in the upper voltage levels, is difficult to implement on the lower voltage levels because the number of units to be controlled is thousands of times greater. Central control throughout the low-voltage grid would mean an unacceptable need for human resources and an unacceptable increase in communication costs. One solution here is decentralized control with automated control units in the local network stations. However, this autonomous solution requires real-time, high-speed communication among the local consumption and generation units, as well as rapid and reliable communication with the control unit. This is exactly where the BPL technology shows its full potential. In addition to the economic advantages of a decentralized control solution, the autonomous control results in relevant improvements in stability and reduced susceptibility to cyber-attacks on the power grids. E.ON has been dealing with this problem for some time and has already developed solutions based on the BPL technology, which are currently being validated in field studies.
Due to decarbonization, we can expect a continuation of the immense increase in the number of generation plants, storage devices, and large additional consumers at the lower voltage levels. These changes are increasingly leading to capacity bottlenecks in the distribution grids. This problem is exacerbated by very high volatility in both generation and consumption. Due to time constraints, this increase and the associated loads cannot be solved by expanding the grids, so that a controlling intervention in the low voltage portion of the grid is indispensable. However, central control, as practiced up to now in the upper voltage levels, is difficult to implement on the lower voltage levels because the number of units to be controlled is thousands of times greater. Central control throughout the low-voltage grid would mean an unacceptable need for human resources and an unacceptable increase in communication costs. One solution here is decentralized control with automated control units in the local network stations. However, this autonomous solution requires real-time, high-speed communication among the local consumption and generation units, as well as rapid and reliable communication with the control unit. This is exactly where the BPL technology shows its full potential. In addition to the economic advantages of a decentralized control solution, the autonomous control results in relevant improvements in stability and reduced susceptibility to cyber-attacks on the power grids. E.ON has been dealing with this problem for some time and has already developed solutions based on the BPL technology, which are currently being validated in field studies.
Some European utilities standardized and have begun commercial rollout of broadband over power lines technologies that can meet these demands, especially looking at the future needs of telecommunications capabilities. BPL chips combine communication and computational capabilities that enable cybersecurity and other functionalities that cannot be matched by common solutions like wireless communications and narrowband power line communications.
The following sections will explain in more detail the technological requirement of the new energy grid using an analogy to the financial system. Due to the centrality of the electric grid in the economy and society, and considering the transformational changes the grid is undergoing—integration of renewables and EVs, as well as the implementation of the highest security requirements—grid systems must become at least as resilient as financial systems.
First of all, it should be realized that requirements for the operation of electrical networks must address since the beginning the fundamental request in any electrical power system: it must be controlled in real time because the stability of the system depends on the matching of supply and demand, which must happen in real time. This fact is always an inherent requirement for real time data and communications. This is not happening in the financial system which allows for delayed reaction, different than real time. (Not all functions in the electricity system need to be done in real time, as in the case of metering-- no more than two decades ago, meter reading was done manually). As explained above, however, future services and needs are presenting an urgent requirement to approach real time (“near real-time”).
For residential customer data, electricity distribution systems, just as financial systems, must be resilient. Comparing the number of bytes required for a credit card transaction and an electricity metering profile reading we obtain the following:
Credit card communication data between the payment terminal and a server on average is less than 1 kilobyte, but there are a lot of differences between countries, so the standard is not exact. Typical data include the card holder info (credit card number, expiration date, cvv number), the terminal (the terminal number, merchant), specific information about the transaction (the amount of the transaction, transaction type (purchase, withdrawal, deposit, refund, reversal, balance inquiry, payments and inter-account transfers, transaction items), CP/IP header and TLS security information.
The metering profile is collected typically every 15 minutes per meter. A typical load profile with 20 registers (which could be up to 80) is about 300 - 500 bytes. It includes meter info, meter id (16 bytes), utility id (32 bytes), timestamp (22 bytes), communication module id (17 bytes), profile id (4 bytes), registers info, and registers list is for each register (OBIS code: 6 bytes, value: 4 bytes).
Today energy meters’ data collection is done every 15 minutes which represents 96 profiles every 24 hours, many times more data than is typical for credit card transactions. Digitalization will lead to a further increase in energy network data requirements due to:
All end-user data must be encrypted, in the financial system by TLS protocol and by corresponding protocols in energy networks. In addition, access to systems is protected by PKI infrastructure. Requirements on security of energy systems are developing rapidly and in resilient systems exceed those of financial systems. For example, during a credit card transaction, it is the PIN code or CVS number, which is authenticated using PKI infrastructure; however, only unidirectionally, from credit card to the server. In the energy sector, for example, E.ON’s authentication is bidirectional. In other words, complex energy networks, such as E.ON’s BPL network, use two-way (mutual) TLS authentication to secure end-to-end communication so that not only the server can authenticate the end BPL device, but also the applications on end BPL devices can authenticate the Server to make sure the server is the one that applications really want to communicate with.
Therefore, a PKI solution built into BPL devices provides extra security to allow applications running on BPL to safely renew the secret information used for encryption, authentication, and authorization.
From the above requirements under the current situation, the amount of only metering data does not represent a significant challenge to the grid communication. However, the increasing amount of data with growing integration of DERMs and requirements on security in normal operation, even without sudden critical events, already represent a challenge for existing communication options for smart metering and related customer services provision: narrow band PLC and LTE.
The critical non-predictable situations in the financial system caused by end customers are very rare. In addition, customers are insured by the Federal Deposit Insurance Corporation (FDIC), which today insures depositors up to $250,000 per banking institution. In spite of that, the 2008-09 financial crisis was again met with some notable bank runs. On September 25, 2008, Washington Mutual (WaMu), the sixth-largest American financial institution at the time, was shut down by the U.S. Office of Thrift Supervision. Over the preceding days, depositors had withdrawn more than $16.7 billion in deposits, causing the bank to run out of short-term cash reserves.
Despite the different regulations at the country level where normally they penalize poor quality of service levels, customers of energy systems do not have governmental insurance for electricity supply. Sudden, non predictable bursts of data and the need to provide a reliable highly-secure environment represent a key challenge for design of the grid and its telecommunications services. For smart metering and related customer services, the commonly used communication networks today, narrow band PLC and broadband wireless, do not meet them. They are facing transformational change which results in much higher data rates than those in financial systems. In the process of digitalization, the amount of data will increase dramatically. In addition, security, including TLS tunneling, authentication, and authorization, have to be implemented, with security at least as good as that in financial systems. The massive creation and upgrade of the grid networks are needed to increase reliability and response time.
Both broadband over power lines technology and narrowband powerline technology are shared media technologies, which means all meters share the bandwidth within the same network domain (often one domain is one secondary transformer station).
Broadband over power lines technology provides the reliability and response time to meet the security needs of a modern smart meter network. To protect the billing data and ensure the privacy of metering data, and more importantly guard the safe operation of the energy distribution network, modern smart meter networks are protected with a series of security frameworks, such as encrypted data tunneling, Public Key Infrastructure (PKI) based mutual authentication, digital signatures, and many other security protection services. These security frameworks require short response times and reliable bandwidth to support their security message interactions. Traditional narrower-band networking technology is slow in response time. That results in extreme jitters in connection which prevents the application of these modern security protocols. To enable end-to-end security, a persistent TLS tunneling is often engaged between smart meters and central data hubs. This means for modern security protocols to be in operation the central service will establish a connection to all meters in parallel and maintain such a link 24/7. Multiple connections are persistent.
However, a narrow band network is designed to maintain a single connection at a time. When a certain large number of meters are engaged in connection at the same time (periodic meter swiping at intervals like 15 minutes, one hour, or one day), the network results in continual dropping and re-establishment of network sessions. The traditional narrowband network supports only post-power quality monitoring, where it gathers all power quality events hours or days later, and then conducts its analysis and makes responses. It does not support multi-cast commands to be sent to a large number of meters during a short period of time to perform commands such as shed peak energy demands, synchronize meter readings, etc.
Another reason for broadband technology to be used in a smart metering network is message bursts. To support real-time response in power quality monitoring and operational control, this results in message bursts when an energy distribution network generates alerts and events or massive operation control commands when trying to shed energy to reduce peak demands. A broadband over power lines network has extra capacity to transfer unpredictable large amounts of data.
Finally, the loading of maintenance operations to the meters, like software enhancements, can require significant time that could be reduced for more efficient operations, and this reinforces the advantage of broad band.
Cellular data technologies such as LTE suffer from insufficient network coverage in rural areas and congested networks in urban city centers. Even in urban and suburban areas, especially in Europe with many underground grid facilities, the coverage is quite insufficient.
Cellular technology is designed as a shared bandwidth amount for all users under one base station (cell tower). In an urban setting, a high number of users actively enter and exit each base station’s coverage daily. Normally cellular users require data exchange only several times an hour. To optimize the cost, cellular operators provide a network backhaul capability at a fraction of volumes required if all cellular users made simultaneous demands on the network. This often results in cell phone users experiencing congested networks when moving from one cell tower to another.
Modern smart meters, on the other hand, require persistent encryption tunnels from each meter point to the data center in order to ensure end-to-end security. This is similar to adding hundreds or thousands of users to each cell tower and each user is using the internet 24/7 concurrently. Such increase in communication, without a doubt, will force cellular network backhaul to suffer with frequent service interruptions. When cellular technology is used in rural areas, providing coverage in high-speed network service to all rural geographic regions is noneconomical. Some cellular providers started to roll out 5G services with enhanced backhaul bandwidth to urban cellular towers to ease the rising concern of network congestions already experienced by cellular users without deploying the smart meter. However, 5G uses several magnitude higher frequencies than 4G (LTE), which will result in even smaller coverages for each cell tower and worsen the already insufficient 4G coverage.
Public cellular technology which is designed to enable operation to a limited number of users with certain probability completely underserve the needs for the grid operators who need priority usage during force majeure events. When a flood or tornado causes damage to a region, public cellular services are either interrupted or heavily demanded by the public for rescue efforts or just to update families, and these sudden dramatic increases in cellular usage often result in network congestion. That happens at the time when utilities have a critical need to communicate large amounts of data. The utility’s first priority during a force majeure event is to restore power by relying on the smart grid’s feedback to understand all energy-related events and sensors’ feedback. The utility will therefore also have a dramatic increase in data demands. These two types of demand will race each other and eventually render the entire service unavailable.
The utility owns dedicated wires that can provide communications during the recovery operation. The utility asset which is to be protected is also the asset that provides broadband powerline communication. Broadband powerline PLC technology with performance of 100 Mbps, high reliability and low jitter utilizes the power distribution lines for dedicated communication of utility data only. It collects all grid characteristics during such communication for evaluation and control.
