In a famous scene written by Paddy Chayefsky for the movie Network, Howard Beale is summoned by Arthur Jenson who explains to the crazed newsman that when he clings to his outmoded notions of how the world works, he is messing with the primal forces of nature. In transactive energy, the transactions are the only primal force, and notions of specific controls, and detailed manipulations of devices are out of date. Systems communicate only by the transactions, by prices to devices. To be consistence, future guidance to autonomous energy systems must be based on financial communications about energy transfers and energy resilience.
Transactive microgrids can balance energy supply and use over time with transactive energy. Internal prices adjust over time in response to supply and demand. No system needs to know anything about any other system, only what the market tells them. A transactive microgrid acts as a sealed system.
A microgrid manages energy resilience over time. An entire microgrid can act as a single system participating in in a larger microgrid, or interacting with a peer microgrid. A single node in the smaller microgrid also interacts with the larger microgrid. In each microgrid it interacts with, such a node is merely another peer. It buys and sells power in the smaller grid as it does in the bigger grid. The smaller microgrid may appear to be a power source to the larger. The smaller microgrid may always buy from the larger. In either microgrid, it acts precisely as do all others. No node knows that another node has a microgrid “within it”.
A proper transactive energy microgrid is essentially autonomous, creating the best balance with the information it has, making the decisions on the edge. Transactive energy markets are a proxy for management and control decisions. Internal system needs are projected into the market through the activation of bidding strategies. Budgets for each system determine priority, but unless a microgrid is badly under-sourced, systems can find some time to run. Within a microgrid, one can increase how frequently, or for how long a system can run by boosting its budget.
In fractal microgrids, one can identify “bridge” nodes, i.e., a node with a connection into the micromarkets that run each microgrid. In each microgrid it participates in, this bridge node uses only the market communications as does any other node. A bridge node likely has some internal “special” logic, just as a storage node has internal knowledge of its own battery chemistry, but this logic is of no concern to the microgrid markets. If the bridge is bringing ISO power and prices to the microgrid, it may compute a markup based on locational pricing, or based on transmission loss. There is no expectation that a node that interacts with two microgrids pass information from one to the other, unchanged.
The transactive energy markets in the two microgrids do not even need to use the same currency. One could use a fiat national currency, such as a US dollar. The other could be using some sort of cryptocurrency, or even a nominal currency defined only within the microgrid.
Direct policy directives can change the behavior of individual systems. Before the hurricane, I may want the power storage system to be fully charged. Because a storage system both buys and sells, it can be reluctant to sell, and eager to buy, until it is fully charged. Because a microgrid may also be able to buy and to sell power, the bridge node may be able to respond to a directive similar to the one that the storage system receives. These need not be the same at all levels. I may want to “starve” a microgrid even as I tell the same microgrid’s storage systems to charge up. How the overall system of systems responds is an emergent behavior.
Social policy, or command intent, can likely be implemented by a small range of directives issued only to the bridge nodes. In an industrial park, I may issue a directive to make all bridge nodes other than, say, the node representing a hospital microgrid to prefer exporting, just a little. The hospital may then be able to buy all it needs—even while all other microgrids find their new equilibria with somewhat less power.
Because fractal microgrids are self-similar, a directive may have effects several microgrids away. A “downstream” microgrid which is represented by a node in a hungry microgrid, may find itself on a diet as well, as the node is less able to acquire power to sell to that microgrid.
The basic market interactions needed by microgrids are well understood and few. They are being standardized this year in the OASIS Energy Interoperation TC. The directives to alter power flows between and across microgrids are not as well defined in standards. I think I have convinced myself, while writing this, that they can be accomplished solely with directives on preparing for resilience through financial information, just as they are for directives to storage systems.