Load Dispatching Flashcards
7 cards from real SOPD practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Load Dispatching flashcards as text
What is the purpose of 'tie-line bias control' in interconnected system operations?
Answer: Each control area adjusts generation proportional to both ACE and its frequency bias, preventing over-correction by any single area
Tie-line bias control ensures each control area absorbs its share of a disturbance based on its frequency bias setting, preventing inadvertent over- or under-correction.
A dispatcher notices that a heavily loaded 345 kV line is approaching its thermal rating. Which action directly relieves the thermal overload?
Answer: Rescheduling generation to redirect power flow away from the overloaded line
Re-dispatching generation changes the direction of power flow in the network, which is the primary tool for relieving thermal overloads on specific transmission elements.
Which metric best describes a control area's ability to follow NERC's CPS1 standard?
Answer: A statistical measure of how well ACE is controlled relative to a target bound over a rolling 12-month period
CPS1 (Control Performance Standard 1) measures the statistical correlation between a control area's ACE and system frequency error over a 12-month period.
What is the difference between 'regulation' and 'load following' as ancillary services?
Answer: Regulation handles fast, second-by-second frequency deviations via AGC; load following manages slower, predictable load trends over minutes
Regulation (via AGC) corrects short-term random frequency deviations, while load following accommodates the predictable, slower trend of load changing over 15-minute intervals.
A generating unit operating at its maximum economic output is asked to 'back down' despite high system demand. What is the most likely reason?
Answer: A transmission constraint requires reducing generation in that area to prevent a line overload
Transmission congestion often forces dispatchers to curtail generation in specific areas, even at high demand, to keep power flows within equipment thermal ratings.
What does 'N-1 security criterion' mean for a dispatcher planning load dispatch?
Answer: The system must be able to withstand the loss of any single element without violating reliability standards
The N-1 criterion requires that the system remain stable and within operating limits following the sudden loss of any single element such as a generator or transmission line.
When a dispatcher 'curtails' an energy transaction, what action is being taken?
Answer: Reducing or canceling a scheduled power transfer between parties due to reliability or congestion constraints
Curtailment of an energy transaction means reducing or eliminating a scheduled interchange to relieve a transmission constraint or address a reliability issue.