Affects Version/s: CTSPR01
Fix Version/s: ctsWD15
CTS is suited for representing the binary flexibility of individual supply or demand objects.
CTS is perfectly able to represent an offer from a conventional fueled generator, for example. The generator offers a quantity of supply at a strike price. The generator may become dispatched if the quantity is paired to willing demand via bilateral trading. Alternatively, the generator may become dispatched by a market if the market clears at a price greater than or equal to the strike price. It is irrelevant how the transactions proceed, but the CTS is suitable for either bilateral trades or real-time bilateral markets.
CTS can represent simple binary flexibility from an object. CTS could represent a bid from a residential water heater to consume a quantity of electricity, for example. The control action is binary. If the bid is accepted, the water heater heats water; if the bid is not accepted, it waits idle. CTS could have been used for PNNL’s Olympic Peninsula field study, for example, which created a real-time double auction and managed devices as described in this paragraph.
However, the applicability of such binary flexibility works only for relatively short time intervals. Many end-use devices must eventually operate and provide a utility to their owners, which is why applicability of CTS may be limited to short-term, real-time market intervals. Over long time intervals such devices cannot remain off. An unstated requirement of CTS is apparently that it requires a pre-existing market position or baseline, and a CTS-based offer or bid represents a diversion from that baseline. It does not seem that CTS can represent the baseline itself,however, although its parent EMIX is said to have this capability.
It is argued that CTS can represent aggregated supplies and demands. For example, a bid or offer could be made via CTS for an entire building or for the entities within an energy microgrid. But this works only if the aggregate flexibility remains binary and can be represented at a single strike price. This limits the communication of priorities, as would be possible using supply and demand curves, where quantity may be a rich function of price alternatives.
CTS can apparently flag a bid or offer to indicate that its quantity may be partially accepted, but all subquantities then possess the same strike price. CTS also may communicate multiple “Tender” offers to buy or sell, but it does not address the association of such alternatives into a cohesive supply or demand curve and the resulting mutual exclusivity of such alternatives.
The commonality between all binary flexibility is that it can be represented by the pairing of a single quantity and single strike price. Figure 1 shows three alternative graphical representations of a CTS bid (or, more generally, of a single object’s binary bid or offer). Panel (a) is a conventional way of showing supply and demand, as adopted from wholesale electricity practices. Both supply and demand are shown as positive quantities in the same quadrant. The
top, right corner of the supply block is the offered quantity and strike price. Panel (a) shows a single offer. Demand is typically shown as a line. Here an inflection occurs at the demand quantity and strike price. Panels (b) and (c) are alternative representations that use signed quantities and prices. The
only differences between the two panels is that (b) shows price as a function of signed quantity,and (c) shows signed quantity as a function of price. While these functional relationships could be mathematically represented in many ways, this white paper will use a piecewise linear approach, which provides a pathway for extension of CTS quite naturally to a broader set of TE applications. A CTS bid or offer requires a single pairing of price and quantity (i.e., a single “vertex”), but a second point is implied for the alternative binary action—the quantity zero at the strike price. This distinction is subtle, but it is important to the extensibility of CTS. Namely, CTS will be extensible if it explicitly includes what is now an implicit price/quantity pairing.
Incidentally, all bid and offer prices should be understood to, in effect, extend to positive and negative infinity as shown in panels (b) and (c).
See attachment (URI in environment) for graphics