Project Number: AEE Smart Recloser Circuit Breaker A Major Qualifying Project Report: Submitted to the Faculty Of the WORCESTER POLYTECHNIC INSTITUTE In partial fulfillment of the requirements for the Degree of Bachelor of Science By _________________________ Yusuf Ziya Aydin _________________________ Kerron Brown _________________________ Andre Campbell 4/28/2009 Approved: ______________________________ Professor Alexander Emanuel, Advisor Abstract This project explores a method for protecting electric power distribution systems against persistent faults. We designed and implemented a device that we called “Smart Recloser Breaker” to provide the necessary protection for a power distribution system. The “Smart Recloser Breaker” is to open when there is a fault on the main line and close only when the fault is removed or cleared. The device functionality was tested and demonstrated using theoretical and actual simulations. 2 Acknowledgements We would like to take this opportunity to show our gratitude to our Advisor, Prof. Alexander Emanuel for the help he administered to us during the course of this project. We would also like to thank the Professors of the ECE department for the advice they gave us. And last but not least we would like to thank our parents and friends for their love and support. Without the help of the people we have mentioned, this project would have never been possible. 3 Table of Contents Abstract ......................................................................................................................................................... 2 Acknowledgements ....................................................................................................................................... 3 Table of Contents .......................................................................................................................................... 4 Table of Figures ............................................................................................................................................. 5 1. Introduction .......................................................................................................................................... 7 2. Background ........................................................................................................................................... 8 2.1. Power Distribution System ........................................................................................................... 8 2.2. Distribution Lines ........................................................................................................................ 10 2.3. Fault and Fault Protection........................................................................................................... 11 2.4. Circuit Breakers and Reclosers .................................................................................................... 12 3. Problem Statement ............................................................................................................................. 13 4. Design Approach and Simulations ...................................................................................................... 14 4.1. Overall Design ............................................................................................................................. 14 4.1.1. Main Line ............................................................................................................................. 14 4.1.2. Circuit Breaker ..................................................................................................................... 15 4.1.3. 1st Control System ............................................................................................................... 15 4.1.4. 2nd Control System .............................................................................................................. 15 4.2. Detailed Circuit Design and Simulations ..................................................................................... 16 4.2.1. Main Line ............................................................................................................................. 16 4.2.2. Circuit Breaker ..................................................................................................................... 18 4.2.3. 1st Control Circuit ................................................................................................................ 31 4.2.4. 2nd Control Circuit................................................................................................................ 35 5. Results ................................................................................................................................................. 39 Appendix ..................................................................................................................................................... 49 PSPICE Simulation Codes ........................................................................................................................ 49 Multisim Simulation Circuits ................................................................................................................... 51 6. Works Cited……………………………………………………………………………………………………………………………………52 4 Table of Figures Figure 1 - Typical Layout of an Electrical Power System ............................................................................... 9 Figure 2 - A picture of single phased distribution lines............................................................................... 11 Figure 3 - Schematic .................................................................................................................................... 13 Figure 4 - Block Diagram ............................................................................................................................. 14 Figure 5 – Main Line .................................................................................................................................... 16 Figure 6 – Substation voltage V(1) and current through the main line I(V1) during normal operating conditions .................................................................................................................................................... 17 Figure 7 - Substation voltage V(1) and current through the main line I(V1) during fault .......................... 17 Figure 8 – Allegro ACS750SCA-100 ............................................................................................................. 18 Figure 9 - Current Sensor ............................................................................................................................ 19 Figure 10 - AC Coupling ............................................................................................................................... 20 Figure 11 - Simulation for AC Coupling ....................................................................................................... 21 Figure 12 – Amplifier ................................................................................................................................... 22 Figure 13 - Measuring current output simulation during regular operation .............................................. 23 Figure 14 - Measuring current output simulation during fault ................................................................... 23 Figure 15 - Measuring Current .................................................................................................................... 24 Figure 16 - AC-DC Conversion Circuit .......................................................................................................... 25 Figure 17 - AC-DC Conversion Output during regular operation ................................................................ 26 Figure 18 - AC-DC Conversion Output during fault ..................................................................................... 26 Figure 19 - Voltage Comparison Circuit ...................................................................................................... 27 Figure 20 - comparator output simulation during regular operation ......................................................... 28 Figure 21 - Comparator output simulation during fault ............................................................................. 28 Figure 22-Circuit Symbol for a SCR ............................................................................................................. 29 Figure 23 - Feedback to main line and second control system ................................................................... 30 Figure 24 - Current Comparison Circuit ...................................................................................................... 31 Figure 25 - AC-DC Conversion Circuit .......................................................................................................... 32 Figure 26 - AC-DC Conversion Output during fault ..................................................................................... 32 Figure 27 – Voltage Comparator of the First Control System ..................................................................... 33 Figure 28 – Feedback to Circuit Breaker Circuit .......................................................................................... 34 Figure 29 - First Control System .................................................................................................................