U 5 / d o ^ / ss-/01 DESIGNING AND IMPLIMENTATION OF AN IMPROVED REMOTE SUPERVISORY CONTROL AND VOLTAGE REGULATION SYSTEM AT WIMALASURENDRA POWER STATION A dissertation submitted to the Department of Electrical Engineering, University of Moratuwa In partial fulfillment of the requirements for the Degree of Master of Science By S.W. KUMARAWADU LIBRARY UNIVERSITY OF MORATUWA, SRI LANKA MORATUWA Supervised by Dr. Trishantha Nanayakkara Department of Electrical Engineering Univetsity of Moratuwa I - 5 University of Moratuwa 89422 December 2006 8 9 4 2 2 DECLARATION I certify that this dissertation does not incorporate without acknowledgement any material previously submitted for a degree or diploma in any University to the best of my knowledge and believe it does not contain any material previously published, written or orally communicated by another person or myself except where due reference is made in the text. I also hereby give consent for my dissertation if accepted, to be made available for photocopying and for interlibrary loans, and for the title and summary tobe made available to outside organizations. Date: a* ^ ( We/I endorse the declaration by the candidate. Dr. DP. Trishantha Nanayakkara Supervisor CONTENTS PAGE DECLARATION ii CONTENTS ABSTRACT 111 v ACKNOWLEDGEMENT vi LIST OF FIGURES vii LIST OF TABLES viii CHAPTER - 1 1 Introduction 01 1.1 Background and motivation 02 1.1.1. Wimalasurendra power station (WPS) 02 1.1.2. Present status of WPS 03 1.2 Excitation system of WPS 03 1.3 Governing system of WPS 04 1.4 Evolution of supervisory and control technologies 05 1.5 Scope of work 06 CHAPTER - 2 2 Designing and implementation of Remote Supervisory & Control System 07 2.1 Remote Terminal Unit (RTU) 07 2.1.1 ADAM-4000 series 07 2.1.1.1 Remotely Programmable Input Ranges 07 2.1.1.2 Watchdog Timer 07 2.1.1.3 Ready for the Industrial Environment 08 2.1.1.4 Communication 08 2.1.1.5 RS-485 protocol 08 2.1.2 Analog Signal Inputs (4-20mA current loops) 08 2.1.3. Drawing Survey 09 2.1.3.1 Digital (Status) Inputs 09 2.1.3.2. Digital Relay Outputs ( Control Commands) 09 2.1.3.3 Drawings of the Modified Circuits 10 2.1.4 Relay Circuits for interfacing old system 10 2.1.5 Digital Input Module ( ADAM-4051) 15 2.2.6 Analog Input Module (ADAM-4017) 16 2.1.7 Digital Output Module ( ADAM-4068) 16 2.2. Control Station 18 2.2.1. Converter module (ADAM-4520) 18 2.2.1.1 Built-in Intelligence 18 iii 2.2.1.2 RS-485 network with Automatic Data Flow Control 18 2.2.1.3 Features of AD AM-4520 18 2.2.2 HMI (Human Machine Interface) 19 2.3. Basic Configuration 21 CHAPTER - 3 3 Improving the voltage regulation system of WPS 22 using new supervisory & control system. 3.1 Back-ground 22 3.2. Voltage Regulation 22 3.2.1 Duties of the automatic voltage regulator 22 3.2.2 Operational behaviour of synchronous machines 24 3.2.3 The principle of cross-current compensation 26 3.2.4 Special sequences in undisturbed operation 27 3.2.5 The transient behaviour generator - network 28 3.2.6 Excitation systems for synchronous machines 28 3.3. Existing voltage regulating system in WPS 29 3.3.1 BJ-30 regulator 29 3.3.2 Operation principle of existing system 30 3.3.3 Present condition 32 3.4. Testing of the existing system, for the new design 32 3.4.1 Voltage variation During a normal operation 32 3.4.2 Behaviour of the voltage variation during a system instability 33 3.4.3 Analysis for voltage feed back, generator current sensing 34 and field current Sensing 3.4.3.1 Analysis of Gen. Voltage feedback 34 3.4.3.2 Generator current sensing 36 3.4.4. Voltage variation for normal & quick response contacts 38 QR and QL 3.5. Modification of the excitation system for the design of new AVR 39 3.5.1 Description of the Circuit (AVR CCT 1) 39 3.6. PLC based new voltage regulation system 41 3.6.1 Vision 230 PLC unit 41 3.6.2. Description of the AVR CCT 2 42 3.6.3. Ladder programming and limit calculations for 44 voltage feed-back control 3.7 Performance analysis 45 3.7.1. Voltage variation during a normal operation 45 3.7.2. Voltage variation during a load rejection 45 iv ACKNOWLEDGEMENT First of all, I would like to thank Dr. D.P. Thrishantha Nanayakkara, who guided me through the entire project as the supervisor, with my appreciation and profound indebtedness for his help and advice. Also I particularly want to thank Prof. Ranjith Perera and Dr. Sisil Kumarawadu for their guidance for the completion of the project. I extend my sincere thank to Mr. C.P.W. Akarawita, DGM (L/C), CEB, for granting approval to purchase necessary equipment and implement the project at Wimalasurendra Power Station, Mr. S.S.B. Karuanaratne, CE(I & C) and Mr. W.M.T. Wijayananda, EE(I & C) of Laxapana complex for helping me during the project design and implementation and Mr. Vass Gunawardana, ES(m) and the maintenance staff of WPS, for helping me numerous ways. Further, I would like to extend my sincere thank to My wife Dinusha, daughter Malmudu, loving mother and mother in-law for bearing my absence which they felt badly during the busy period I had while working on this project. vi LIST OF FIGURES Figure Description Page • Fig. 1-1. Wimalasurendra Power Station 02 Fig. 1-2 Excitation System of WPS 04 Fig. 1 -3 The evolution of supervisory and control technologies 05 Fig. 2-1. Basic Configuration of Analog Circuits 08 Fig. 2-2. 12VDC intermediate Auxiliary relays 10 Fig. 2-3. 48VDC relays used for control commands 10 Fig. 2-4. Status inputs 11 Fig. 2-5. Control commands 12 Fig. 2-6. Excitation control 13 Fig. 2-7. Governor control 14 Fig. 2-8 Digital input, digital output and analog input modules with 17 temporary connections Fig. 2-9 Control station with ADAM4520 converter module, power 19 supply and the visual interface Fig. 2-10 Old panel base HMI 20 Fig. 2-11 New HMI at remote PC 20 Fig. 2-12. Basic Configuration 21 Fig. 3-1. Network structure and substitution diagram 23 Fig. 3-2. Analogy between governor speed control and AVR voltage control 25 Fig. 3-3. Principle of current compensation 27 Fig. 3.4. BJ30 Regulator 29 Fig. 3-5. Contactor panel 30 Fig. 3-6. Schematic wiring diagram of DC exciter generator excitation 31 System with type BJ 30 generator voltage regulator Fig. 3-7. Generator voltage waveform with manual excitation control during 32 normal operation Fig. 3-8. Voltage waveform during the load rejection of 3.1MW, 3MVAr 33 Fig. 3-9. Graph_ Voltage of feed-back analysis 34 Fig. 3-10. Graph_ Voltage of feed-back analysis 35 Fig. 3-11. Graph_ Voltage of feed-back analysis 36 Fig. 3-12. Graph_ Gen. current feed-back analysis 37 Fig. 3-13. Graph_ Field current feed-back analysis 38 Fig. 3-14 Voltage variation for quick response contacts QR and QL 38 vii Fig. 3-15 Schematic wiring diagram of the excitation system 39 with new voltage regulating system Fig. 3-16. Gen. T/F combination in parallel operation 40 Fig. 3-17 PLC based new circuit (AVR CCT 2) 42 Fig. 3-18. Temporary connected AVR circuitry 43 Fig. 3-19 Integer of transducer for voltage Vs Actual voltage 44 Fig. 3-20 Voltage variation during a normal operation 45 Fig. 3-21. Active and reactive power at load rejection 46 Fig. 3-22. Voltage prior to and after the load rejection status II 46 Fig. 3-23. Voltage prior to and after the load rejection status III 47 Fig. 4-2. Schematic diagram of the AVR with PID controller to prevent 49 Relay hunting LIST OF TABLES Table Description Page Table 2-1. Digital Status inputs 09 Table 2-2. Digital relay outputs 09 Table 2-3. Digital input channels 15 Table 2-4. Analog input channels 16 Table 2-5. Digital o/p channels 17 Table 3-1. Feed backs Vs Output voltage 34 Table 3-2 Vol across the fb coil Vs R m u (resistive element) 35 Table 3-3. Current feed back 37 Table 3-4. Field current feed back 37 viii