Simple TE Use Cases fueled the development of EML-CTS

I have written here before about NIST-CTS, an open source implementation of a transactive energy market, designed to support TE (Transactive Energy) market modelling within the NIST Cyberphysical Systems modelling tool. While most TE research has been dependent upon double auction-based markets, NIST CTS, the initial release of the EML-CTS system, was developed to model transactive energy using a financial-style order book.

Original NIST Use Case

The predominant supplier was a hypothetical bulk market providing 24 hourly prices. All purchases were committed, that is the purchaser owned the power whether or not it was consumed, but could opt to sell any portion thereof back to the market, offering any price the consumer chose. Of course, there was no guarantee that the consumer could sell back this power at any price.

Assume the operator of the wholesale market decides at what price it wants to sell at each hour of the next day. A module external to the market, herein called the External Market Adapter (EMA), computed any additional transmission fees, congestion fees, and distribution operator charges to compute 24 prices for use inside the microgrid. For purposes of discussion, discussion, assume these prices arrive at the market by 9:00 AM and are good until 3 PM.

These local market as 24 unbounded tenders to sell power, each for its own price. The combination of a product (power) and a discrete time (10 AM to 11 AM) defines an instrument, and each instrument is traded separately in the market. The Local Market notifies each participant in the microgrid of the tenders that create the 24 new instruments. Each of the nodes considers decides how much power to buy during each hour, if any, and submits tenders to buy each instrument to the market. As the tenders to buy and sell match, contracts are awarded, and each participant is notified.

The Local Market records the position, that is the net quantity of each instrument bought or sold for each party.

At 3:PM, each of the unbounded tenders from the EMA expires and is purged from the market for each instrument. The EMA knows its position for each hour and can firm up its commitments in the bulk market.

At any time, any party may submit a tender, an offer to either buy or to sell any instrument. Any participating node, including the EMA, may submit an offer to buy at a price of tis choosing. Any participating node, including the EMA, may submit an offer to sell power at a price of tis choosing, including to sell the power it previously made a commitment to buy.

Participants can trade any instrument only until it reaches maturity. For instruments in a microgrid market, maturity occurs when the begin time of the instrument interval is past—one cannot tender power from 1 PM to 2 PM at 2:25. Periodically, the system purges post-maturity instruments from the market.

Settlement

Settlement occurs after the market interval is complete, to align market operations with actual consumption. They system design assumes that there is some “spot price” for each interval.

The EMA is able to read the meters as well as the request the position for each party for each interval. If the meter for an interval is greater than the position, the difference is made up through imputing purchase of the difference at the spot price. No adjustment is made a position greater than the spot price.

While settlement mechanism were discussed, and the capability of position management was designed in, settlement was out of scope for the NIST-CTS implementation.

Temporal Refinements to the Original Use Case

The initial use case posited hourly intervals only. No provision was made to for an instrument to power for 15 minutes during the 3^rd quarter of an hour.

Any market participant can create a new instrument at any time by submitting a tender to the market for a legal interval. Legal intervals are those that conform to market rules. For example, a market may not permit a 7-minute interval that straddles an hour. All participants are notified when a new instrument is created. Intervals that are unusual may never be able to find a market.

It is interesting to speculate who would use, say, 5-minute intervals in a 1-hour market. Does the external market submit tenders for 12 short intervals in an hour ahead market? Does a local market participant acting as an arbitrageur, buying power for an hour and submitting tenders to resell it in smaller time slices? Would a battery system fall naturally into this arbitrageur role? Does a distribution grid operator make tenders at the beginning and end of an hour to smooth out sudden changes in power consumption associated with big price deltas on the hour? The EML-CTS system makes no assumptions and the area one of many ripe for research and trial.

When a participating node is itself internally managed by a TE nanomarket operating a nanogrid, there is no requirement that it make the same decisions as to temporal granularity as does the containing grid. Smaller discrete systems may naturally consume power for shorter intervals than do larger aggregate systems.

Future Market Research

There are many issues to settle to enable wide deployment of Transactive Energy and Fractal Microgrids. The architecture of EML-CTS was developed with a goal of enabling long-lived deployments even as our understanding changes with further research.

We need a wider understanding of how TE supports current evolution of traditional distribution grid operation. For example, Laminar Coordination and Laminar Control name the strategy of maturing the top-down grid to support DER. Under this model the grid is defined a layers of control, or laminae. Each layer informs nodes in a lower layer to establish goals and guidelines. Each node, which may itself represent a layer containing nodes, determines how it is able to respond. Each node abstracts and passes up situation awareness to the higher layer. These nodes could well be implemented as microgrids, using the micromarket for internal coordination.

There are ongoing discussions of correct market design. Many researchers are attempting to fine-tune the double auction markets that they consider the best method to establish initial pricing for and time interval. Others see financial-style markets as best able to respond to small changes in local power consumption and availability over time. In the EML-CTS architecture, a microgrid integrator can choose one market engine or another, or even use both, replaced without changing any of the software in the participating nodes.

None of the current TE engines handle well what Dr. David Chassin has termed the “airline ticket problem”. If a long-running power-consuming process can be delayed until the best economic time, how should a node probe the market to determine that time? How should noted manage their internal base loads and shiftable consumption?

Longstanding policy manipulates today’s power markets to support equitable access to power. Today these policies masquerade as tiers of power consumption. One can imagine market policies ranging from “first crack” at the market to after-market rebates on purchases. We make no judgements on which path is best; wide use of TE using the EML-CTS architecture enables new strategies even as it disables reliance on formal tiers.

The EML-CTS architecture relies on simple standard messages on a networked service bus to operate each micromarket. The message definitions, the Common Transactive Services, are being developed into open unencumbered standard specifications. Communication services for those standard messages are being developed into common open source libraries. Any experimental agent today, and any real-world device or system tomorrow developed to use the CTS standards should be able to participate in EML-CTS-based markets without change.

Back to basics: Some Definitions

Today I am restating some definitions of terms, reflecting how my own understanding has changed over time.

Transactive Energy

Transactive Energy (TE) is the term for an energy balancing approach using economic techniques for dynamic balance of supply and demand within energy and power grids.

TE is a particular case of Transactive Resource Management which uses markets to allocate any commodity (resource) whose value is determined solely by its time of delivery. Transactive Resource Management was first described at the Xerox Palo Alto Research Center. The GridWise Olympic Peninsula Testbed Demonstration Project was the first transactive active energy field experiment in 2008.Transactive Energy was described by Edward Cazalet in a number of papers and talks culminating in the reference book “Transactive Energy: A Sustainable Business and Regulatory Model for Electricity” (Barrager & Cazalet, 2014).

Transactive techniques allow dynamic balance of supply and demand where energy is in surplus or shortage, in contrast to traditional techniques which address surplus less effectively. Transactive Energy (TE) is seen as a fundamental organizing principle of future smart grids.

Microgrids & Micromarkets

Microgrids are independent systems that manage the distribution of power. Microgrid components may supply, consume, or store electric power. TE can be paired with microgrids to make decisions about power management and distribution without constraining technology choice or technology evolution inside each microgrid component.Micro-markets require physical delivery of the product or service. Micro-grids allow (and in fact are defined by) the ability to shift energy and power within them. There is a useful symmetry of managing the balance of supply and demand in a micro-grid by means of a co-extensive micro-market.

Participants in more than one micro-grid must be able to deliver and receive the products bought and sold. North American markets typically distinguish between transmission (longer distances) and distribution (shorter distances, more end points) with different regulatory regimes. Micro-grids (composed or standalone) can be structured to allow avoidance of complex regulations designed for much larger scale enterprises.

Common Transactive Services

The interactions of Transactive Energy were defined in the Energy Interoperation Specification (OASIS, 2012). The Common Transactive Services (CTS) refers to a minimal set of standardized services originally developed as part of the NIST Transactive Energy Challenge.

The Market Code resource uses CTS-defined messages for all interactions between components. CTS defines a restricted profile of Energy Interoperation that can interoperate with each of the transactive systems within a microgrid. CTS includes minimal extensions and is at an architectural level appropriate to the semantics of all transactive systems minimized for local micromarkets, and able to enable decoupled evolution. A recent project of NIST and the Energy Mashup Lab made the first use of CTS. The Energy Mashup Lab (http://www.theenergymashuplab.org/) (EML). The Lab is a non-profit (501C3) whose purpose is the development and promulgation of microgrids through promoting open source software for TE based microgrids.

Cyber-Physical Systems

Cyber-physical systems (CPS) are systems built around co-engineered interacting networks of physical and computational (IT) components. The term CPS includes the overlapping technologies referred to as the Internet of Things (IoT), the Industrial Internet, and Operational Technology (OT). CPS applications in specific economic sectors are referred to with the terms smart manufacturing, smart transportation (including autonomous vehicles), smart healthcare, and smart energy. (NIST Cyber-Physical Systems Public Working Group , 2017).

Many CPS applications are inherently distributed and equipped with wire-bound or wireless communication facilities. When their components are largely autonomous, the organizing principle is coordination rather than control. A CPS providing critical services such as dynamic and prospective traffic safety, factory and process control, or healthcare needs to be highly dependable requiring the availability of reliability performance, availability, safety, and security.

Any consideration of CPS always includes the physical. Whatever software they run, their physical actions are constrained by physics: mass, momentum, chemistry, biology, and, for TE, electricity. When CPS are deployed in infrastructure, they will likely operate in place longer than typical IT systems. With long-life comes diversity; even if one built a CPS monoculture, with common ownership and a single vendor, the evolution of products and technology over time would lead to diversity of components.

This inevitable necessary internal diversity of components within a CPS rewards an abstract or service-oriented model for CPS integration. Service-Oriented Architectures (SOA) coordinate systems not by orchestrating processes, but by coordinating effects. For TE, one can understand this not as “turn off pump #3” but instead “use less power for 10 minutes”, not as “charge battery” but as “power is currently available”. This consideration points to the desirability of integrating CPS using abstract coordination such as CTS.

Many CPS are social systems. Autonomous cars drive to human chosen destinations. Autonomous domotic power systems must balance domestic services while they balance power and price. Even factory systems may respond to labor shifts and human-provided maintenance schedules. The social component means that few CPS can be “set-and-forget” after install, but instead must respond to and provide services to humans.

Energy Mashup Labs unveils its CTS System for Transactive Energy

For the last two semesters, The Energy Mashup Lab (The Lab) Lab has worked with graduating students in the master’s program at the New Jersey Institute of Technology (NJIT) to develop fully open source software for transactive energy (TE) applications. This students work with The Lab through the Capstone Project (https://centers.njit.edu/uri/programs/capstone.php)  

The architecture is fully modular, designed to enable widely different technologies to interoperate in a highly scalable Actor-to-Actor system of systems.

All agents, whether buy or selling power, interact with the Local Market through a Transactive Energy User Agent (TEUA). A  Supervisory Controller (SC) directs each TEUA in what to buy or sell and when. The architecture defines an External Market Adaptor (EMA) to connect the local microgrid to a larger microgrid or to a traditional power distribution market. Because the interface between the EMA and the Local Market is just another TEUA, any microgrid can have connection to more than one external market, or to none at all.

The Local Market consists of Local Market Agent (LMA) and a Local Market Engine (LME). The LMA manages all conversations with the TEU Agents, accepting tenders and recording contracts. The Local Market Engine matches orders, efficiently finding actionable contracts in response to notifications from the LMA. All data logging is performed by the LMA.

The Lab uses the Parity Trading engine to connect buyers and sellers (https://github.com/paritytrading/parity) . The Parity Trading engine is a mature open source project that is used in some NASDAQ markets. Parity provides high speed trading and provides reliability features such as data mirroring, order-book cloning, and support of high-speed ticker-tape functions. The Parity Trading engine supports information exchange with FIX (Financial Information Exchange) reporting.

Every module has defined simple interfaces that enable making technology changes to support local business needs without changing other systems. For example, if a TE Market preferred a double auction to financial trading, using an existing market platform, that platform would be wrapped completely inside the LME, and no other modules would change.

All inter-module communication is based on simple REST messaging.

The NIST Common Transactive Services Project can be found at https://github.com/EnergyMashupLab/NIST-CTS-Agents

This blog was cross-posted at the Energy Mashup Lab at http://www.theenergymashuplab.org/blog

Defining OpenC2 Cybersecurity for OT: Microgrids

OpenC2 is an open cybersecurity command language for the Internet of Things, also known as Operational Technology (OT). Traditional cybersecurity concerns are focused on the traditional networks of file servers, database servers, web servers, and desktop computers. Cybersecurity commands from firewall directives to interdiction of malware in documents have as their goal the protection of those administrative and data services. The communications requirements and systems architectures of OT are quite different than those of administrative systems, and the services provided by OT are far more diverse. The security directives for each type of OT system are just now being defined.

The services provided by OT may be critical to the performance of other systems. A cyber-threat to a power distribution system may create risks to every mission supported by that system. OpenC2 on OT systems may be able to provide critical situation awareness on threats to other missions.

Microgrids are a type of OT whose purpose is to supply local power to a system, facility, campus, or base. New microgrids autonomously match the supply and demand of electrical power in real time. Many microgrids incorporate some level of internal power storage. A microgrid may incorporate proprietary controls for managing unique set of distributed energy resources such as solar or wind. Many microgrids incorporate some level of internal power storage. A good cyber-defense profile for microgrids should be common to all microgrids while allowing for diversity of technology within any particular microgrid.

OpenC2 commands are directed to discrete sets of functions grouped as a cyber-defense service, termed an Actuator Profile. A given system may offer multiple actuators. For example, a network gateway might offer three actuator profiles: a stateless packet filter service, a stateful packet filter service, and a malware-blocking service.

So, too, an OT system may support multiple actuator profiles. An OT system may support the Stateless Packet Filter Profile as well as OT specific services.

Part of developing the OpenC2 profile for Microgrids will be discovering the separable OpenC2 cyber-defense services. An autonomous microgrid that interacts with other microgrids may support an actuator profile for that. A microgrid may support a profile for situational awareness of operational risks to power-dependent systems. An actuator profile for power storage may be broken out of the overall microgrid profile, enabling technology agnostic commands to prepare for widespread threat to power availability (“Charge Up!”) as well to be ready to provide extra power to another microgrid to support a fast-developing operational need. This last service may be one of several profiles on a microgrid, but the sole profile on a battery.

Microgrid deployments, especially of autonomous microgrids, are poised for accelerated deployment across DoD facilities. Deployed Microgrids are foundational to other services on bases. Microgrid functionality is tied to many key vulnerabilities of expeditionary or mobile basing. The required profiles should be a priority so that the cyber-defense of these new assets can be managed within a common operational and training framework with other cyber command and control functions.

While microgrids are first on the list, traditional building automations systems, such as HVAC, access control, and intrusion detection will soon get their own profiles. These profiles are already being discussed, but without significant input from the building automation industry or from commercial owners. As each profile arrives, it will begin to drive the market.