Section 9 Market Software Metrics

Market performance can be confounded by software issues, which vary in importance levels, however amongst these various measures the failure of a market run is the most obvious failure.

Market Disruption

A market disruption is an action or event that causes a failure of an ISO market, related to system operation issues or system emergencies. Pursuant to section 7.7.15 of the ISO tariff, the ISO can take one or more of a number of specified actions in the event of a market disruption, to prevent a market disruption, or to minimize the extent of a market disruption. Figure 9.1 shows the frequency of HASP, RTUC, and RTD failures in the current month.

Figure 9.1: Frequency of Market Disruption

System Parameter Excursion

The power balance constraint is one of the requirements that is enforced in the market all the time to ensure the balance between electricity generation and demand. The tendency for 5-minute real-time prices to exceed hour-ahead prices is driven in large part by extreme price spikes in the real-time market when the market software meets the system-wide power balance constraint with small and temporary amounts of regulation resources rather than with energy resources. When this relaxation occurs, the system imposes a penalty price, which then affects the energy prices in the pricing run.

This constraint can occur in two different ways:

When the market software dispatches regulation up as supply to meet projected demand, this represents a “shortage” constraint that causes prices to spike upwards to the $1000/MWh bid cap.

When the market software dispatches regulation down to balance supply with projected demand, this represents an “excess” constraint that causes prices to spike downwards to the -$30/MWh bid floor.

Figures 9.2 and 9.3 present how often the power balance constraint is relaxed by day and by class of shortage during the real-time dispatch. Figures 9.4 and 9.5 present how often the power balance constraint is relaxed by day and by class of excess during the real-time dispatch.

Figure 9.2: Frequency of Shortage

Figure 9.3: Average MW of Shortage

Figure 9.4: Frequency of Excess

Figure 9.5: Average MW of Excess

Analysis of Minimum Online Capacity

The ISO utilizes the minimum online capacity (MOC) constraint to address the operational needs of certain operating procedures that require a minimum quantity of committed online resources in order to maintain reliability. MOC was deployed into the software systems with the expectation that it would commit an appropriate set of resources that were previously satisfied by either exceptional dispatch or nomogram enforcement in RUC, thus reducing the potential for overcommitment in RUC. This section studies the unit commitments driven by MOC constraint in IFM for the reporting period. Figure 9.6 below shows total Pmin and cleared value of the MOC units in the market. Figure 9.7 summarizes the number of MOC units.

Figure 9.6: MOC Unit Commitment and Dispatch

Figure 9.7: Daily Count of MOC Units