Govt. Exams
Entrance Exams
Phase-shifting transformers control power flow by introducing a phase shift between primary and secondary voltages, enabling effective power flow management on parallel transmission corridors in Indian grid.
Selective coordination requires the fuse nearest to the fault to operate first, isolating only the faulted section while maintaining service to other areas.
PMUs measure voltage and current phasors synchronized via GPS, enabling real-time monitoring and control. India has deployed PMUs across POWERGRID network for situational awareness.
P-V curves show how voltage varies with increasing active power at a bus. The nose point indicates the maximum power that can be transmitted before voltage collapse.
Reactive power Q = P × tan(φ), where φ is the phase angle between voltage and current. This fundamental relationship determines VAR compensation requirements.
Economic dispatch optimally allocates power generation among committed units to minimize fuel costs while satisfying load demand and operational constraints.
Subtransient reactance (Xd'') is used immediately after fault occurrence. Fault current = V/Xd'' for a 3-phase symmetrical fault at the generator terminals.
Distance relays provide selective protection for transmission lines by measuring impedance from relay location to fault point, standard in Indian POWERGRID.
HVDC reduces I²R losses (proportional to current squared) and eliminates reactive power flow, making it ideal for long-distance bulk power transmission.
The convergence rate of Newton-Raphson method is determined by the Jacobian matrix's condition number and the initial guess proximity to solution.
