Single area load frequency control by using pi,fuzzy logic control1

Load Frequency control

1. Single area Load Frequency Control : a comparative study Based on PI and Fuzzy logic controllers By S.L.D.. Saisree

2. Contents Main Theme Of the paper Introduction Reasons for Maintaining constant frequency Load Frequency control Single Area System Automatic Generation Control (AGC) Block diagram representation AGC of Single Area System PI controller Fuzzy Logic Control Comparison Between PI and Fuzzy logic controllers

3. Main Theme of the paper This Paper is about the single area load frequency control of an Isolated powersystem . The automatic control over the generation by using controllers i.e., Proportional Integral Controller or Fuzzy Logic controller. The frequency get improved by using the controller when ever the load change occurs The comparison between the conventional ( PI controller) and the fuzzy logic controller(FLC).

4. Introduction Isolated power generating units leads in instability due to load variations and there by the frequency changes . Load Frequency Control (LFC) is a system to maintain reasonably uniform frequency, by balancing the generation and demand The Frequency sensor, electronic based controllers, Speed governor will operate when there is change in frequency. The integral controller is linear type controller, provides zero steady state error ( Δf =0) with less transient state performance. Fuzzy logic controller is robust, nonlinear type, less cost than conventional controllers and better transient performance. The performance of the PI controller is compared with Fuzzy logic controller.

5. Why to maintain the frequency constant? The Machines will operate at different speed. Steam turbine blades will damage. Transformer losses are depends on the frequency. protective and control equipment may operate case of under/over frequency. Electrical clocks used for the synchronous motors will lose operation. In continuous process industry it affects the process operation.

6. Load Frequency control LFC is used give sufficient amount of the active power demand when ever load change occurs & maintain the steady state frequency. If we use only Speed governor we cannot achieve the steady state frequency. It alone operate in other than steady state frequency. To obtain the steady state frequency we use the controllers. Control over the load is complex & that depends on the consumer requirement. Hence, generation is controller and maintained at constant frequency when load variations occur.

7. Single area A coherent area in which all generators supplying the sufficient generation to the load. Assume there is no tie line connection with any other area. No connection with the grid The generators are unison respond with the change in frequency.

8. Load frequency control of the Isolated power system is

9. Automatic Generation Control(AGC) The control of the generation automatically by using the controllers command power ( ΔPc ) is given there by generation will controlled. In AGC the speed governor ,controllers either conventional or fuzzy based controllers are used Where as in manual control there is only speed governor action is exists & no use of any controllers. (For smaller generating units manual actions is preferred) Under balanced condition the speed governor will not operate.

10. AGC of a single area:

11. PI controller PI controller is proportional + Integral controller. It is the electronic based PI controller combination of the Operational amplifier,Power ampilifier,inverter amplifier It increases the type by 1 thus the steady state error will be zero . The PI controller have poor transient performance (takes time to make Δf =0) All this conventional controllers are linear type i.e., the values will change based on the operating condition.

12. Fuzzy Logic control Fuzzy logic is one of the soft computing method. Fuzzy means “ vagueness“& It deals with imprecision, uncertainty. Transient performance is improved than PI controller

13. Comparison PI controller Transient state performance is more(settle down time is slow) Not robust linear type Simple in construction Cost is high So such data is required. Fuzzy Logic Controller(FLC) Transient state performance is less(settle down time is fast) Robust Non linear type Complex Cost is low Requires more data for different linguistic variables.

14. Thank you Presented by S.L.D.Saisree