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Examoogle • User • info@examoogle.com • EE-2024-8821
Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
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Optimum dispatch state is
Secure
Partially secure
Not secure
Not define properly
Secure
Quick Summary: In power system operation, the 'Optimum Dispatch' (Economic Load Dispatch) state is focused solely on minimizing the total cost of generation by adjusting the power output of generators, often at the expense of security margins. Because it prioritizes cost optimization over the static security constraints (N-1 criteria), it is inherently 'Not Secure' compared to a state that explicitly incorporates security constraints.
In power system operation, the 'Optimum Dispatch' (Economic Load Dispatch) state is focused solely on minimizing the total cost of generation by adjusting the power output of generators, often at the expense of security margins. Because it prioritizes cost optimization over the static security constraints (N-1 criteria), it is inherently 'Not Secure' compared to a state that explicitly incorporates security constraints.
FT=∑i=1n(aiPi2+biPi+ci) — Total generation cost function
dPidCi=λ — Coordination equation for optimum dispatch
The Economic Load Dispatch (ELD) problem involves solving minF=∑Ci(Pi) subject to ∑Pi=PD+Ploss. This optimization often pushes the system toward boundary constraints (e.g., thermal limits or bus voltage limits) to maximize efficiency, thereby leaving the system vulnerable to contingency events, which renders the state 'Not Secure' in terms of operational reliability.
Optimum dispatch focuses on economic efficiency (min cost).
Security-constrained dispatch incorporates system reliability margins.
The transition to optimum dispatch often utilizes the full capacity of generators.
System security and economic efficiency are typically inversely related in unconstrained models.
Minimal fuel expenditure
Maximized thermal efficiency of plant units
High vulnerability to contingency failure
Low operational reserve margins
Energy management system (EMS) optimization
Long-term generation scheduling
A state is considered secure if all equipment is within limits and no violation occurs under N-1 contingencies.
Option A is incorrect because optimum dispatch does not guarantee security.
Option B is vague; security is typically treated as a binary or probabilistic threshold.
C is correct — An optimum dispatch state prioritizes cost minimization, which often ignores the security margins required to handle contingencies, thus classifying it as 'Not secure'.
Always remember that in power systems, there is a fundamental trade-off between the 'Economic Dispatch' (cost-focused) and 'Security-Constrained Economic Dispatch' (SCED) (reliability-focused).