Tie-Line Control

Tie-line is used to control frequency for the power station and power transfer from one station to an another station in interconnected system. It is also to avoid overload in the system as a result from accidental power exchange.

Formula derivation
Lets look at this example,

Generation Control

Principles of Generation Control


  • In an interconnection system, power stations are connected synchronous and the frequency should be the same.
  • The load in power system always change, sometimes change rapidly.
  • The generator must able to increase its ouput from zero to full load quickly
  • It is impossible for the generator output equal to the load in the system.
  • When the generator output exceeds the demand load, the  generator speed and frequency will increase and vice versa.
  • The frequency for each station is not always fixed, but the change is very small.
  • To overcome the change of frequency, then it must be monitored based on the standard resources.
  • If any frequency changes, the generator's output control action should be taken.
Conditions for the two generators that can be operated in the interconnection system is:

  1. Same sequence.
  2. Same frequency.
  3. Same busbar voltage.
  4. Generator must be able to increase output from zero to full load quickly.
Generation Control System

  1. Tie-line control
  2. Automatic Generation Control
  3. Turbine speed control

Electronic Voltage regulator

Voltage regulator



Voltage regulator is designed to maintain constant voltage level. A voltage regulator may be a simple "feed-forward" design or may include negative feedback control loops. It may use an electromechanical mechanism, or electronic components. Depending on the design, it may be used to regulate one or more AC or DC voltages.


Electronic voltage regulators are found in devices such as:
  • Computer power supplies.
  • Automobile alternators
  • Central power station generator plants, 
  • Substation or along distribution lines