Preface Disclaimer, acronyms, and change log Ancillary Services Services necessary to support the transmission of electric power. Area Control Error ACE. The instantaneous difference between net actual and scheduled interchange. Automatic Generation Control AGC. Automatic regulation of the power output of generators Balancing Authoritiy The responsible entity within a Balancing Authority Area. Bilateral Transaction A direct contract between a seller and buyer outside of a centralized market. black-start Establishing the voltage from around zero Bulk Electric System BES. Transmission Elements and Power resources 100 kV or higher. Bulk Power System BPS. Facilities and control systems for an transmission network. Capacity Markets A market for trading capacity credits. Co-Located Load Load connected to the an existing or planned facility. Contingency Reserve Capacity deployed by the Balancing Authority to meet the Disturbance Control Standard. Control Performance Standard 1 CPS1. A standard that measures impact on frequency error Control Performance Standard 2 CPS2. A standard intended to limit unscheduled flows Critical Inertia Minimum level of system inertia necessary to ensure deployment of frequency responsive reserves. Day-ahead Markets Forward markets for electricity to be supplied the following day. DER Distributed Energy Resources Distribution Provider Provides and operates the “wires” between the transmission system and the end-use customer. Distribution The act of distributing gas or electric power to customers. Economic Dispatch Allocation of generating units for economical production. Electrical Resonance The behavior of power systems with conventional turbine-generators and variable speed induction generators. Fast Frequency Response FFR. Power in response to frequency changes during the arresting phase Financial Markets Trading financially settled products. Financial Transmission Right FTR. Compensation contract for transmission charges due to grid congestion. Flowgate Portion of the transmission system used to analyze power flow impact. Frequency Deviation A change in Interconnection frequency. Frequency Regulation The ability of a Balancing Authority to help maintain Scheduled Frequency. Frequency Response Measure The median of all Frequency Response observations reported annually. Frequency Stability The ability of a power system to maintain steady frequency following a severe system upset. Frequency Response The ability of a system to react to a change in system frequency. Futures Market For contracts for future delivery of a commodity or security. Generator Shift Factor GSF. Factor applied to a generator’s output change to determine flow contribution. Interchange Energy transfers that cross Balancing Authority boundaries. Interconnection Reliability Operating Limit A System Operating Limit that, if violated, could lead to instability or cascading outages. Interconnection A geographic area where BPS components are synchronized. IBR Inverter-based Resources Marginal Unit The unit providing the next increment or decrement of energy. Market Power The ability to control or affect price by a large market participant. Market Structure The rules, mechanisms, and processes under which a market operates. Market A venue where participants buy and sell products or services. Non-Spinning Reserve Unconnected to the system but capable of serving demand within a specified time. NYISO Markets Interdependent markets facilitating different pieces of the reliability puzzle. Operating Reserve – Spinning Generation synchronized to the system and fully available to serve load within the Disturbance Recovery Period. Operating Reserve – Supplemental Generation or load available to serve load within the Disturbance Recovery Period. Operating Reserve Capability above firm system demand required for regulation, load forecasting error, and outages. Primary Control A.k.a. Frequency Response. Primary Frequency Response PFR. Immediate proportional response to system Frequency Deviations. Ramp A.k.a. Ramp Rate. The rate at which the interchange schedule or generator output is attained. Regulating Reserve Reserve for AGC to provide normal regulating margin. Reliability The probability of satisfactory operation of a power system over the long run. Resonance Stability The behavior of power systems under oscillatory energy exchange conditions. Response Rate The Ramp Rate that a generating unit can achieve under normal conditions. Ride-through Ability to withstand voltage or frequency disturbances and continue operating. Rotor Angle Stability The ability to remain in synchronism under normal and disturbed conditions. Secondary Control Balancing services deployed in the “minutes” time frame. Security The degree of risk in a power system's ability to survive imminent disturbances. Spinning Reserve Synchronized generation and ready to serve additional demand. Spot Market For short-term contractual commitments. Stability Limit The maximum power flow possible while maintaining system stability. Stability The ability to maintain equilibrium during normal and abnormal conditions. Subsynchronous Resonance SSR. An condition involving energy exchange at natural frequencies below the synchronous frequency. synchronization Aligning a device's terminal voltage with another voltage source Synchronous Machine SM. An AC electrical machine operated with a constant electromagnetic field. Tertiary Control Actions taken to handle current and future contingencies. Torsional Resonance The SSR due to torsional interactions between series compensated lines and turbine-generator mechanical shafts. Virtual Synchronous Machine VSM. Equipment that includes a DC/AC converter controlled to mimic a conventional synchronous machine. Voltage Stability The ability of a power system to maintain steady voltages close to nominal value. Wholesale Markets The purchase and sale from generators to resellers. Zonal Price A pricing mechanism for a specific zone within a control area.