Join 60,000+ competitive exam aspirants
or with email
Your Cart
SubtotalтВ╣0
TotalтВ╣0
Examoogle тАв User тАв info@examoogle.com тАв EE-2024-8821
Chapter 1 of 12 тАв Page 1 of 248ЁЯФТ Protected PDF тАв Watermarked
Join 60,000+ competitive exam aspirants
Which equipment is used for EHV lines to improve power transferability?
Shunt capacitor
Shunt reactor
Series capacitor
All of these
Series capacitor
Series capacitors are connected in series with EHV transmission lines to compensate for the inductive reactance of the line. By reducing the effective line impedance, they significantly enhance the power transfer capability and improve the steady-state stability of the system.
Series capacitors are connected in series with EHV transmission lines to compensate for the inductive reactance of the line. By reducing the effective line impedance, they significantly enhance the power transfer capability and improve the steady-state stability of the system.
P=XLтАЛтИТXCтАЛV1тАЛV2тАЛтАЛsin(╬┤) тАФ Maximum power transfer equation with compensation
k=XLтАЛXCтАЛтАЛ├Ч100% тАФ Percentage of series compensation
Transmission lines possess inductive reactance (XLтАЛ=2╧АfL), which limits the maximum power flow according to the power angle equation. A series capacitor provides capacitive reactance (XCтАЛ=2╧АfC1тАЛ), which subtracts from the inductive reactance, resulting in a reduced net impedance (XnetтАЛ=XLтАЛтИТXCтАЛ). This increases the power flow P=XLтАЛтИТXCтАЛV1тАЛV2тАЛтАЛsin(╬┤), allowing for higher transferability over long distances.
Series capacitors are used for lines exceeding 300-400 km in length.
They reduce the voltage drop across the line for a given power flow.
The degree of compensation typically ranges between 25% to 70%.
Proper protection (spark gaps/varistors) is required to prevent overvoltages during faults.
Increases the power transfer capability of long lines
Improves transient stability by increasing the synchronizing power
Provides inherent voltage regulation
Reduces transmission losses for a given power transfer
Risk of sub-synchronous resonance (SSR) with turbine-generator sets
Requires complex protection schemes against overvoltages
Potential for voltage instability under specific load conditions
Long-distance EHV and UHV transmission lines
Inter-regional power grid interconnections
Improving stability in heavily loaded networks
Shunt capacitors are used for reactive power compensation to maintain voltage profiles, not directly to increase power transfer capacity in the steady-state power equation.
Shunt reactors are used for compensation of the line capacitance (Ferranti effect) in light load conditions, which actually serves to limit overvoltages rather than boost power transfer.
C is correct тАФ Series capacitors directly reduce the inductive reactance of the line, which inversely increases the maximum power transfer capacity.
Always remember that Series devices affect the line impedance (impedance modification), while Shunt devices affect the voltage profile (voltage control).