Join 60,000+ competitive exam aspirants
or with email
Your Cart
Subtotal₹0
Total₹0
Examoogle • User • info@examoogle.com • EE-2024-8821
Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
Join 60,000+ competitive exam aspirants
Economical dispatch controller has
Fast response
Slow response
Very Fast response
None of above
Slow response
Quick Summary: The Economical Dispatch Controller (EDC) operates on a time scale significantly slower than primary load-frequency controllers (LFC) or automatic generation control (AGC). While LFC acts in seconds to stabilize frequency, the EDC acts in minutes to optimize fuel costs based on the incremental cost characteristics of units.
The Economical Dispatch Controller (EDC) operates on a time scale significantly slower than primary load-frequency controllers (LFC) or automatic generation control (AGC). While LFC acts in seconds to stabilize frequency, the EDC acts in minutes to optimize fuel costs based on the incremental cost characteristics of units.
dPidCi=λ — The coordination equation for economic load dispatch where incremental cost equals system lambda.
FT=∑i=1nCi(Pi) — The objective function to minimize total fuel cost FT subject to load constraints.
The EDC calculates the optimal power output for each generator by setting the incremental fuel cost equal to a common system value known as the Lagrange multiplier (or Lambda, λ). Because fuel price updates, unit availability checks, and optimization computations involve processing large volumes of system data over intervals, the control action is deliberately kept slow to avoid interfering with transient frequency stability.
EDC is part of the tertiary control level in power systems.
It optimizes generation to minimize production costs.
Its operation period is typically 5 to 30 minutes.
It is slower than frequency control because it handles economic rather than stability constraints.
Reduces total fuel consumption and operational costs.
Ensures operation within thermal and technical constraints of power plants.
Cannot respond to rapid load fluctuations.
Requires high-quality real-time data from all generating units.
Real-time energy management systems (EMS).
Power system dispatch centers.
| Feature | LFC (Primary) | EDC (Tertiary) |
|---|---|---|
Response Time | Seconds | Minutes |
Primary control acts to balance load and generation instantly to maintain frequency.
Economic Dispatch must be 'slow' to prevent instability, as frequent adjustments to setpoints would cause mechanical stress and excessive fuel burning during transients.
B is correct — Economical dispatch controllers are designed for slow response (typically minutes) because they prioritize fuel cost optimization over transient stability.
In power system hierarchy, always remember: Primary = Frequency (Fast), Secondary = Tie-line Power (Medium), Tertiary = Economy (Slow).