Voltage Control

WHY VOLTAGE CONTROL ?

Electrical energy is generated at power station ( Hydro-electric power plant, Steam Power plant, Nuclear power plant, Solar Electric power plant, others.. ) far away from where consumer located. Energy delivered to the consumer through Transmission and Distribution network.

For operation of motor, light, TV, AC and other loads it is desirable that the voltage at consumer terminal should be constant. Too many wide Variation of voltage may causes erratic operation.  The main reason behind voltage variation is that the variation in load on the supply system. With the increase in load on the supply system the voltage at the consumer premises falls down due to increase in voltage drop in alternator impedance,  transmission lines, transformer impedance, feeders and distributors. The reverse also happen should the load on the power system falls.

Such voltage variations are undesirable and the supplier is required to maintain the voltage at the consumer terminal.

HOW TO CONTROL VOLTAGE? 

This is achieved by installing voltage control equipment at generating station, transformer station supplying to feeder and at the feeder end. If the drop exceeds the permissible limit  (  ± 6% of declared voltage) the voltage regulating instrument start their work its provided at more the one point in the power system because of extensive transmission and distribution network and different load characteristics of different load circuit in the power system.

VOLTAGE CONTROL FOR DC SUPPLY SYSTEM:

In case of DC supply system voltage can controlled by using over- compound generators in case of feeder of equal lengths fed from it, in case of feeder of different lengths being fed by one series wound DC generator the voltage at the end of each feeder is kept constant by mean of feeder booster.

VOLTAGE CONTROL FOR AC SUPPLY SYSTEM:

In AC supply system voltage can be controlled by below methods:

1. Use of booster Transformer.
2. Use of induction regulator.
3. Use of series capacitor in long EHV transmission line and HVDC Transmission line.
4. Use of synchronous condenser.
5. Excitation control in power generation station.
6. Voltage regulator in power generation station.
7. Use tap changing Transformer at sending end and receiving end of the Transmission line, substations, in factories.
8. Switching in shunt capacitor during high load and low power factor.
9. Switching in Shunt reactor during low load and high power factor.
10. Use of static shunt compensation having shunt capacitors and thyristorized control for step-less control of reactive power and voltage.