Shunt compensation in EHV line is resorted to
Right Answer is:
Improve power factor
Shunt Compensation: In this type of compensation, either shunt inductors or shunt capacitors are used. They are connected between each line and neutral to reduce the effect of shunt susceptance of the line.
Shunt inductors are also known as shunt reactors. It absorbs the reactive power from the lines and controls the voltage of the line when the line is at no load or is lightly loaded. They are connected at both the ends of transmission lines.
Advantages of Shunt Reactor
- With the help of shunt capacitor banks, reactive power is injected into the line to maintain the voltage within the limits at heavy loads. The shunt capacitors are connected near the load terminals.
- Shunt compensation at no-load also keeps the receiving end voltage within limits which would otherwise be quite high because of the Ferranti Effect. Thus reactors should be introduced as the load is removed for proper voltage control.
- The shunt capacitors are used across an inductive load so as to provide part of the reactive VARs required by the load to keep the voltage within desirable limits.
- The shunt reactors are kept across capacitive loads or in light load conditions, to absorb some of the leading VARs for achieving voltage control. Capacitors are connected either directly to a bus or through the tertiary winding of the main transformer and are placed along the line to minimize losses and the voltage drop.
- For the same voltage boost, the reactive power capacity of a shunt capacitor is greater than that of a series capacitor. The shunt capacitor improves the pf of the load while the series capacitor has hardly any impact on the pf. Series capacitors are more effective for long lines for the improvement of system stability.
- A shunt reactor is an absorber of reactive power, thus improve the voltage profile and hence energy efficiency of the system.
Thus, we see that in both series and shunt compensation of long transmission lines it is possible to transmit large amounts of power efficiently with a flat voltage profile. The proper types of compensation should be provided in proper quantity at appropriate places to achieve the desired voltage control.