Market Design for ESSs A recent report compiled by FTI Consulting for the ESB highlighted seven principles important to the design of effective procurement frameworks for ESSs (see Figure 2). These principles are fundamental in framing the design problem from a regulatory and market perspective. Alongside these Essential System Services (Continued) Service table S1. A summary of various ESSs in Australia and their implementations within the WEM and NEM. NEM Equivalent Description Bulk energy Regulation Primary frequency response Secondary frequency response Tertiary frequency response Inertia service Power to meet demand (scheduled and unscheduled) Maintains frequency within the normal operating band, operating within seconds Arrests and stabilizes frequency following an event that results in a sudden mismatch of demand and supply, operating within milliseconds Restores frequency to its normal operating band after an event, operating within seconds to minutes Reschedules/unloads facilities that provide primary and secondary frequency response so that they are available to respond to new events Physical inertia that reduces the rate of change of frequency (ROCOF) following a contingency event Operating reserve System restart Voltage support and system strength (discussed further in the text) Capacity Balances the supply and demand of energy across a minute-to-hours horizon Facility capability to restart a black system and to assist with reconstruction following a black system event Stabilizes voltage in a location of a network * Energy (5-m dispatch, 5-m settlement from 2021) * Regulation raise/lower * Droop response and fast raise/ lower (6 s) * Possible new fast-frequency response (<2 s) from 2022 * Slow raise/lower (60 s) and delayed raise/lower (5 m) * Possible combination of 6- and 60-s services from 2022 * Energy redispatch WEM Equivalent * Energy (30-min dispatch and settlement); moving to 5-min dispatch in 2022 and 5-min settlement in 2025 * Load-following ancillary service up/down market * Moving to co-optimized Regulation Service, 2022 * Droop response and spinning reserve * Moving to co-optimized contingency reserve real-time market in 2022 * Spinning reserve * Moving to co-optimized contingency reserve real-time market in 2022 * Energy redispatch and redispatch of governmentowned energy assets * Moving to co-optimized contingency reserve real-time market in 2022 * No existing service * Possible scheduling of synchronous resources through a unit commitment for security mechanism or synchronous services market * Possible future inertia spot market * Possible new market for operating reserves and ramping availability from 2025 * System restart ancillary service * Network support and control ancillary service * Possible scheduling of synchronous resources through a unit commitment for security mechanism or synchronous services market Procurement of capacity (generation and demand-side management) to meet forecast peak demand on the yearly time horizon WEM: wholesale electricity market. september/october 2021 ieee power & energy magazine 33 * No explicit service except for reliability and emergency reserve trader function * Possible new market for operating reserves or ramping availability in the NEM * No explicit service; managed by energy redispatch and selfcommitment * System restart service * Provided as part of noncooptimized essential systems services framework from 2022 * Network control service * Provided as part of noncooptimized essential systems services framework from 2022 * Reserve capacity mechanism * Annually administered price mechanism for certified capacity * No existing service * Moving to a co-optimized ROCOF control service in 2022 principles is the recognition that any design process necessarily involves a compromise between elements to achieve an overall workable design. In particular, there is a natural tension between the idealized theoretical design of markets with assumptions of economically rational behavior and the physical reality of operation, which is complex, uncertain,