HomeGlossary

Glossary - H

For your convenience, this page contains an alphabetically organized list of terms, definitions and common acronyms used in the electric utility industry.

A B C D E F G H I J K L M
N O P Q R S T U V W X Y Z

Term/Acronym Definition
HASL High Ancillary Service Limit
HDL High Dispatch Limit
HE Hour Ending
HEL High Emergency Limit

HIO

High Impact Outage

HITE

High Impact Transmission Element

HRL High Reasonability Limit
HRUC Hourly Reliability Unit Commitment
HSL High Sustainable Limit
HWR High Winter Ratio
HZ Hertz

High Ancillary Service Limit (HASL)

A dynamically calculated MW upper limit on a Resource to reserve the part of the Resource’s capacity committed for Ancillary Service, calculated as described in Section 6.5.7.2, Resource Limit Calculator.  HASL is also included in Section 5.7.4.1.1, Capacity Shortfall Ratio Share, and in the Reliability Unit Commitment (RUC) optimization but is not adjusted for Non-Frequency Responsive Capacity (NFRC) as in Section 6.5.7.2.

High Emergency Limit (HEL) The limit established by the QSE describing the maximum temporary unsustainable energy production capability of a Resource. This limit must be achievable for a time stated by the QSE, but not less than 30 minutes.

High Impact Outage (HIO)

A Planned Outage or Rescheduled Outage that interrupts flow on a High Impact Transmission Element (HITE).

High Impact Transmission Element (HITE)

A Transmission Element that may, in certain conditions, result in high congestion risk when taken out-of-service and that is identified as further described in Section 3.1.8, High Impact Transmission Element (HITE) Identification.

High Sustained Limit (HSL) High Sustained Limit (HSL) for a Generation Resource

The limit established by the QSE, continuously updated in Real-Time, that describes the maximum sustained energy production capability of the Resource.

High Sustained Limit (HSL) for a Load Resource

The limit calculated by ERCOT, using the QSE-established Maximum Power Consumption (MPC).

Hourly Reliability Unit Commitment (HRUC) Any RUC executed after the DRUC.
Hub A designated Settlement Point consisting of a Hub Bus or group of Hub Buses and the associated Settlement price calculation methodology prescribed in the definition of the Hub in Section 3.5.2, Hub Definitions. Hubs may only be created by an amendment to Section 3.5.2. The list of Hub Buses and the Settlement price calculation methodology that define a Hub can never be modified, and a Hub, once defined, exists in perpetuity.
Hub Bus An energized Electrical Bus or group of energized Electrical Buses defined as a single element in the Hub definition. The Locational Marginal Price (LMP) of the Hub Bus is the simple average of the LMPs assigned to each energized Electrical Bus in the Hub Bus. If all Electrical Buses within a Hub Bus are de-energized, the LMP of the Hub does not include the de-energized Hub Bus. This is used solely for calculating the prices of existing Hub Buses defined in Section 3.5.2, Hub Definitions.
Hub LMP See Locational Marginal Price