Power System Operation, Control, and Economic Load Dispatch (with GATE PYQs)

 Q251. The main objective of power system operation is:

A) Reliable and economical supply of electricity
B) Maximum generation
C) Frequency increase
D) None
Ans: A

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Q252. Economic load dispatch deals with:
A) Minimizing generation cost
B) Maximizing generation
C) Reducing losses only
D) None
Ans: A

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Q253. The incremental fuel cost curve represents:
A) dC/dP versus P
B) Cost versus voltage
C) Power factor versus P
D) None
Ans: A

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Q254. In economic load dispatch (ELD), all units operating optimally have:
A) Equal incremental cost
B) Equal power output
C) Equal losses
D) None
Ans: A

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Q255. The penalty factor accounts for:
A) Transmission losses
B) Generation cost
C) Frequency deviation
D) None
Ans: A

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Q256. The coordination equation for ELD with losses is:
A) $\frac{dC_i}{dP_i} = λ / P_{gi}$
B) $\frac{dC_i}{dP_i} = λ \times PF_i$
C) $\frac{dC_i}{dP_i} = λ × L_i$
D) $\frac{dC_i}{dP_i} = λ × P_{gi}$
Ans: C

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Q257. Lambda (λ) in ELD represents:
A) Incremental cost of power
B) Load demand
C) Loss factor
D) None
Ans: A

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Q258. The cost function of a generating unit is generally:
A) Quadratic
B) Linear
C) Exponential
D) None
Ans: A

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Q259. The general fuel cost equation is:
A) $C = a + bP + cP^2$
B) $C = aP^2 + bP + cP^3$
C) $C = bP$
D) None
Ans: A

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Q260. The incremental cost of generation is:
A) $\frac{dC}{dP} = b + 2cP$
B) $C/P$
C) $a + b + c$
D) None
Ans: A

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Q261. Transmission loss formula (approximate) is:
A) $P_L = \sum_i \sum_j P_i B_{ij} P_j$
B) $P_L = \sum_i P_i$
C) $P_L = B_i P_i$
D) None
Ans: A

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Q262. The B-coefficients represent:
A) Loss coefficients
B) Generation coefficients
C) Frequency factors
D) None
Ans: A

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Q263. The penalty factor for plant i is:
A) $PF_i = 1 / (1 - ∂P_L/∂P_i)$
B) $PF_i = (1 + ∂P_L/∂P_i)$
C) $PF_i = (1 - ∂P_L/∂P_i)$
D) None
Ans: A

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Q264. In an optimal dispatch with losses:
A) $λ = \frac{∂C_i/∂P_i}{PF_i}$
B) $λ = ∂C_i/∂P_i × PF_i$
C) $λ = C_i × PF_i$
D) None
Ans: A

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Q265. Economic dispatch neglects:
A) Transmission losses
B) Fuel cost
C) Generation limits
D) None
Ans: A

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Q266. Unit commitment problem involves:
A) Deciding which units to run and when
B) Cost curve optimization
C) Power factor correction
D) None
Ans: A

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Q267. Constraints in unit commitment include:
A) Minimum up/down time
B) Ramp rate limits
C) Spinning reserve
D) All
Ans: D

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Q268. Spinning reserve is:
A) Extra capacity available online
B) Offline capacity
C) Transmission backup
D) None
Ans: A

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Q269. The load-frequency control maintains:
A) System frequency constant
B) System voltage
C) Power factor
D) None
Ans: A

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Q270. The speed governor controls:
A) Turbine input
B) Field voltage
C) Excitation current
D) None
Ans: A

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Q271. The relation between frequency and load is:
A) Inversely proportional
B) Directly proportional
C) Independent
D) None
Ans: A

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Q272. The primary control in LFC is provided by:
A) Governor
B) AVR
C) Turbine
D) None
Ans: A

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Q273. The secondary control in LFC is:
A) Automatic generation control (AGC)
B) Speed governor
C) Exciter
D) None
Ans: A

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Q274. Area Control Error (ACE) =
A) $ΔP_{tie} + BΔf$
B) $ΔP + ΔV$
C) $Δf / ΔP$
D) None
Ans: A

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Q275. The frequency bias factor (B) is used to:
A) Stabilize tie-line frequency control
B) Control excitation
C) Measure loss
D) None
Ans: A

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Q276. Integral controller in AGC eliminates:
A) Steady-state frequency error
B) Transients
C) Voltage dips
D) None
Ans: A

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Q277. The governor droop characteristic defines:
A) Speed vs load change
B) Voltage vs reactive power
C) Current vs time
D) None
Ans: A

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Q278. In a two-area system, ACE of each area is controlled to:
A) Zero
B) One
C) Constant
D) None
Ans: A

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Q279. The load frequency characteristic of an area is also called:
A) Power-frequency characteristic
B) Power-voltage characteristic
C) Frequency-reactive curve
D) None
Ans: A

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Q280. The tie-line power deviation depends on:
A) Δδ (angular difference between areas)
B) Voltage difference
C) Frequency difference
D) None
Ans: A

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Q281. The tie-line power flow equation is:
A) $P_{12} = \frac{V_1V_2}{X} \sin(δ_1 - δ_2)$
B) $P = VI \cos φ$
C) $P = V^2 / X$
D) None
Ans: A

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Q282. A positive ACE indicates:
A) Area is over-generating
B) Area is under-generating
C) Both
D) None
Ans: A

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Q283. Automatic Generation Control (AGC) acts on:
A) Governor set point
B) Field current
C) Transformer tap
D) None
Ans: A

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Q284. The main objective of AGC is to maintain:
A) Frequency and tie-line power
B) Voltage
C) Reactive power
D) None
Ans: A

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Q285. Economic dispatch and AGC can be coordinated by:
A) λ–ΔP controller
B) Frequency controller
C) Speed governor
D) None
Ans: A

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Q286. The incremental rate of change of load with frequency is called:
A) Frequency sensitivity factor
B) Power factor
C) Regulation constant
D) None
Ans: A

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Q287. The composite frequency response characteristic =
A) $B = β_1 + β_2$
B) $B = Δf / ΔP$
C) $B = P / f$
D) None
Ans: A

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Q288. Load damping constant represents:
A) Change in load with frequency deviation
B) Speed deviation
C) Phase angle
D) None
Ans: A

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Q289. Voltage control in generators is done by:
A) Automatic Voltage Regulator (AVR)
B) Governor
C) Transformer tap
D) None
Ans: A

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Q290. The excitation system provides control over:
A) Terminal voltage and reactive power
B) Speed
C) Real power
D) None
Ans: A

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Q291. Over-excitation in AVR leads to:
A) High terminal voltage
B) Low terminal voltage
C) Constant voltage
D) None
Ans: A

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Q292. Exciter ceiling voltage defines:
A) Maximum voltage output
B) Minimum excitation
C) Normal voltage
D) None
Ans: A

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Q293. The steady-state frequency deviation is inversely proportional to:
A) Regulation constant (R)
B) Governor gain
C) Load
D) None
Ans: A

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Q294. High governor gain implies:
A) Faster response
B) Slower response
C) No effect
D) None
Ans: A

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Q295. The transient response of LFC is improved by:
A) Integral controller
B) Derivative controller
C) Both
D) None
Ans: C

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Q296. The tie-line bias control ensures:
A) Frequency restoration
B) Constant voltage
C) Power factor correction
D) None
Ans: A

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Q297. The steady-state tie-line power deviation after control =
A) Zero
B) 1 pu
C) Constant
D) None
Ans: A

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Q298. The droop of a governor is typically:
A) 4–5%
B) 10%
C) 1%
D) None
Ans: A

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Q299. The time constant of a turbine is typically:
A) 3–10 seconds
B) 0.1 seconds
C) 1 minute
D) None
Ans: A

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Q300. The primary and secondary control together maintain:
A) Frequency and tie-line interchange
B) Voltage
C) Power factor
D) None
Ans: A