Load Frequency Control
CHAPTER 1
1.1 INTRODUCTION Load frequency control (LFC) or Automatic generation control (AGC) is an emerging issue in electric power systems. The objective is to maintain the system frequency and the power exchange between the areas within specified limits, irrespective of sudden change in load. The prime mover governing system provides a means of controlling power and frequency; and this function commonly called Load Frequency Control or Automatic Generation Control. The automatic load frequency control (ALFC) loop regulates the megawatt output and the frequency variations when a power plant is subjected to a unit step load disturbance.
The automatic frequency loop consists of 2 loops. The primary loop responds to a frequency signal which is a indirect measure of megawatt balance. By tending to maintain a megawatt balance, the primary loop performs indirectly a frequency control depending upon 2 to 3% of droop setting of the generator.
Secondary loop control is done by a PID controller, as it accounts 2% frequency drop. It is the role of secondary controller to eliminate the frequency deviation and the tie line power variation when subjected to unit step load disturbances.
There are several methods for tuning a PID controller. The most effective methods generally involves the development of some form of process model, and then choosing P,I and D based on dynamic model parameters. Classical Ziegler Nichols method, Pessen’s Ziegler Nichols method, Integral Squared Error (ISE) method, Integral Time Squared Error (ISTE) method, software tools or even manual tuning can be used for the design of PID controller.
Load frequency controllers implemented in real time power plants are usually proportional, integral and derivative controller (PID) type, and they have many drawbacks, such as long settling time and relatively large overshoots with sustained oscillations And proportional and integral gain of PID type beyond a value leads to sluggish behavior in
1.1 INTRODUCTION Load frequency control (LFC) or Automatic generation control (AGC) is an emerging issue in electric power systems. The objective is to maintain the system frequency and the power exchange between the areas within specified limits, irrespective of sudden change in load. The prime mover governing system provides a means of controlling power and frequency; and this function commonly called Load Frequency Control or Automatic Generation Control. The automatic load frequency control (ALFC) loop regulates the megawatt output and the frequency variations when a power plant is subjected to a unit step load disturbance.
The automatic frequency loop consists of 2 loops. The primary loop responds to a frequency signal which is a indirect measure of megawatt balance. By tending to maintain a megawatt balance, the primary loop performs indirectly a frequency control depending upon 2 to 3% of droop setting of the generator.
Secondary loop control is done by a PID controller, as it accounts 2% frequency drop. It is the role of secondary controller to eliminate the frequency deviation and the tie line power variation when subjected to unit step load disturbances.
There are several methods for tuning a PID controller. The most effective methods generally involves the development of some form of process model, and then choosing P,I and D based on dynamic model parameters. Classical Ziegler Nichols method, Pessen’s Ziegler Nichols method, Integral Squared Error (ISE) method, Integral Time Squared Error (ISTE) method, software tools or even manual tuning can be used for the design of PID controller.
Load frequency controllers implemented in real time power plants are usually proportional, integral and derivative controller (PID) type, and they have many drawbacks, such as long settling time and relatively large overshoots with sustained oscillations And proportional and integral gain of PID type beyond a value leads to sluggish behavior in