1. In The Name of GOD SIMULTANEOUS VOLTAGE CONTROL OF SEVERAL LOADS ON FEEDERS OF A DISTRIBUTION SUB-STATION USING FUZZY MODELING AND FUZZY OPTIMIZATION A. Ebrahimi A. Zolfaghari S.Mohseni Electrical and Comp. Eng. Department Isfahan University of Technology, IRAN Barcelona 12-15 May 2003 A.Ebrahimi_ir_Session3_block1_slide1

2. Scope of this paper A new algorithm for simultaneous voltage control of several loads located on various feeders of a distribution sub-station Using Fuzzy Modeling and Fuzzy Optimization According to actual limitations Barcelona 12-15 May 2003 A.Ebrahimi_ir_Session3_block1_slide2

3. Usual Methods for Load Voltage Regulation Using Automatic switched shunt capacitors. Using Dynamic voltage regulators. Using A.V.R. & Tap Changer Systems at Distribution Substations. A.Ebrahimi_ir_Session3_block1_slide3 Barcelona 12-15 May 2003

4. Limitations: Variation of loads and their power factor The loads are distributed along the feeder High voltage drop during peak and over voltage during off-peak hours Different behaviors of various loads Different sensitivity of loads to voltage deviations ِِAt last but not least : No Remote Controlled Switch and no Monitoring Systems are usually available A.Ebrahimi_ir_Session3_block1_slide4 Barcelona 12-15 May 2003

5. There is an Optimization Problem! Max :  D = Min [  i1 (V i ),  i2 (V i )] S.T. : V A = V i + R i I i COS Ø i + X i I i SIN Ø i V A min  V A  V A max For all i =1, 2,…, n  D is the decision fuzzy set defined as the intersection of fuzzy sets  i A.Ebrahimi_ir_Session3_block1_slide5 Barcelona 12-15 May 2003

6. Why Fuzzy Modeling & Optimization? Fuzzy nature of loads and voltage variations Approximate data and rare of information No measurement and monitoring systems are available at most load points A.Ebrahimi_ir_Session3_block1_slide6 Barcelona 12-15 May 2003

7. The Proposed Algorithm By FLP and some approximations: V A = V i + R i I i COS Ø i + X i I i SIN Ø i V A is the magnitude of low voltage side of transformer at sub-station V i is the voltage of load i A.Ebrahimi_ir_Session3_block1_slide7 Barcelona 12-15 May 2003

8. Triangular Membership Function A.Ebrahimi_ir_Session3_block1_slide8 Barcelona 12-15 May 2003

9. Why Trapezoidal membership functions? Representing a more realistic modeling for flexible constraints. A.Ebrahimi_ir_Session3_block1_slide9 Barcelona 12-15 May 2003

10. Especial loads & Their Priority in Voltage Regulation By priority factors (  i ) multiplied to membership functions Decreasing acceptable bound of membership function A.Ebrahimi_ir_Session3_block1_slide10 Barcelona 12-15 May 2003

11. Case Study A distribution sub station with 4 radial feeders Loads assumed constant and at the end of feeders Using triangular and trapezoidal membership functions for voltage fuzzy sets Using several priority factors A.Ebrahimi_ir_Session3_block1_slide11 Barcelona 12-15 May 2003

12. A symbolic view of the test system A.Ebrahimi_ir_Session3_block1_slide12 Barcelona 12-15 May 2003

13. CONCLUSIONS Simultaneous voltage control of loads located at several distribution feeders Priorities for especial loads considered Useful and applicable in systems without remote controlled switches and monitoring system A.Ebrahimi_ir_Session3_block1_slide13 Barcelona 12-15 May 2003

14. Thanks For Your Attention A.Ebrahimi_ir_author_ALPHA3_Block1A.Ebrahimi_ir_author_ALPHA3_Block1 A.Ebrahimi_ir_Session3_block1_slide14 Barcelona 12-15 May 2003 33Bridge-Isfahan-Iran