This question was asked inGPSC Deputy Executive Engineer (Electrical) Class-2 Master Paper 2026Question 111 of 195 published · Gujarat Public Service CommissionOpen paper
Q111ModeratePower System Stability

પાવર સિસ્ટમની સ્થિરતા સુધારી શકાય છે
1. શ્રેણી વળતર (series compensation)નો ઉપયોગ કરીને
2. સમાંતર પારેષણ લાઇનોનો ઉપયોગ કરીને
3. પારેષણ વોલ્ટેજ ઘટાડીને
ઉપરોક્તમાંથી કયાં વિધાનો સાચાં છે?

જવાબ અને પગલાવાર ઉકેલ
સાચો જવાબ: D. ફક્ત 1 અને 2
ટૂંકી સમજૂતી

D — ફક્ત 1 અને 2. P ≈ (EV/X)sinδ; શ્રેણી વળતર અને સમાંતર લાઇનો અસરકારક X ઘટાડીને Pmax અને સ્થિરતા માર્જિન વધારે છે. વોલ્ટેજ ઘટાડવાથી Pmax ઘટે છે, તેથી સ્થિરતા બગડે છે.

વિગતવાર ઉકેલ (મૂળ ભાષામાં)

Statement-wise Verification

  • Statement 1 - Correct.
    Using series compensations
    Series compensation can increase transfer capability by reducing effective reactance, and parallel transmission paths can reduce transfer reactance.
  • Statement 2 - Correct.
    Using parallel transmission lines
    Series compensation can increase transfer capability by reducing effective reactance, and parallel transmission paths can reduce transfer reactance.
  • Statement 3 - Incorrect.
    Reducing voltage of transmission
    Lower transmission voltage generally worsens power-transfer capability/stability; higher voltage helps

Core Concept

Power-system stability concerns the ability of synchronous machines and network states to remain or return to acceptable operation after disturbances. Series compensation can increase transfer capability by reducing effective reactance, and parallel transmission paths can reduce transfer reactance. Stability studies focus strongly on rotor-angle/electromechanical dynamics rather than ordinary steady-state voltage calculation alone.

Formula / Key Relationship

Simplified transfer P≈(EV/X)sinδ; reducing effective X raises transfer capability.

Why the Other Options Are Wrong

Option A is incorrect because it omits correct statement(s) 2. Option B is incorrect because it includes incorrect statement(s) 3 and omits correct statement(s) 1. Option C is incorrect because it omits correct statement(s) 1.

Exam Shortcut / Approach

Lower transfer reactance generally improves synchronizing power margin.

Common Mistake

Do not confuse ordinary load flow with a dynamic stability study.

Quick Revision

Series Compensation and Parallel Lines is linked with Stability Improvement, Power System Stability and Power Systems. Lower transfer reactance generally improves synchronizing power margin.

Verified · SRO editorial desk Report
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