FLEXIBLE ALTERNATING CURRENT TRANSMISSION SYSTEM …

1 EE 2036 FLEXIBLE ALTERNATING CURRENT TRANSMISSION SYSTEM (FACTS) SCE Page 1 of 73 DEPARTMENT OF EEE A Course Material on FLEXIBLE ALTERNATING CURRENT TRANSMISSION SYSTEM By ASSISTANT PROFESSOR DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING SASURIE COLLEGE OF ENGINEERING VIJAYAMANGALAM 638 056 EE 2036 FLEXIBLE ALTERNATING CURRENT TRANSMISSION SYSTEM (FACTS) SCE Page 2 of 73 DEPARTMENT OF EEE QUALITY CERTIFICATE This is to certify that the e-course material Subject Code : EE 2036 Scubject : FLEXIBLE ALTERNATING CURRENT TRANSMISSION SYSTEM Class : IV YEAR EEE being prepared by me and it meets the knowledge requirement of the university curriculum.

2 Signature of the Author Name: Designation: This is to certify that the course material being prepared by is of adequate quality. She has referred more than five books among them minimum one is from abroad author. Signature of HD Name: SEAL EE 2036 FLEXIBLE ALTERNATING CURRENT TRANSMISSION SYSTEM (FACTS) SCE Page 3 of 73 DEPARTMENT OF EEE CONTENTS TOPIC PAGE NO. UNIT I - introduction The concept of FLEXIBLE AC TRANSMISSION 6 Reactive Power Control in electrical power TRANSMISSION lines 6 Uncompensated TRANSMISSION line 6 introduction 7 Load compensation 7 SYSTEM compensation 8 Lossless distributed parameter lines 8 Symmetrical lines 8 Midpoint conditions of a symmetrical line 8 Passive components 8 Shunt compensation 9 Series compensation 10 Overview of FACTS devices 11 Static Var Compensator (SVC) 11 Thyristor Controlled Series Capacitor (TCSC) 13 Unified Power Flow Controller 13 Integral Power Flow Controller 14 UNIT II STATIC VAR COMPENSATOR (SVC)

3 AND APPLICATIONS Voltage control by SVC 15 Advantages of the slope in the SVC dynamic characteristics 16 Influence of SVC on the SYSTEM voltage 16 Coupling transformer Ignored 16 Coupling transformer considered 17 SVC applications 18 introduction 18 Enhancement of Transient Stability 18 Power angle curves 18 Synchronizing Torque 20 Steady state power transfer capacity 22 Enhancement of power SYSTEM damping 25 Prevention of voltage stability 26 Principle of SVC control 26 Configuration and design of the SVC controller 28 Rating of an SVC 29 UNIT III THYRISTOR CONTROLLED SERIES CAPACITOR (TCSC) AND APPLICATIONS Operation of TCSC 31 Basic Principle 31 Different modes of operation 32 Modelling of TCSC 35 Variable-Reactance model 35 Transient-Stability model 36 Long term-stability model 37 EE 2036 FLEXIBLE ALTERNATING CURRENT TRANSMISSION SYSTEM (FACTS) SCE Page 4 of 73 DEPARTMENT OF EEE Applications 38 introduction 38 Improvement of the SYSTEM -stability 38 Enhancement of SYSTEM damping 39 Voltage collapse prevention 43 UNIT IV - EMERGING FACTS CONTROLLERS Static Synchronous Compensator(STATCOM) 46 Principle of Operation 46 V-I characteristics of STATCOM 49 Unified Power Flow Controller(UPFC)

4 51 Principle of operation 51 Modes of operation 52 Applications 54 Modeling of UPFC for power flow studies 55 UNIT V - CO-ORDINATION OF FACTS CONTROLLERS introduction 56 FACTS controller interaction 56 Steady-State Interactions 56 Electromechanical-Oscillation Interactions 57 Control or Small-Signal oscillations 57 Sub Synchronous resonance Interactions 57 High-Frequency Interactions 58 SVC-SVC Interactions 58 The effect of electrical coupling and short circuit levels 58 Co-Ordination of multiple controllers using linear-control techniques 60 introduction 60 The basic procedure for controller design 60 Co-ordination of multiple controllers using Non-linear control tecniques 62 Question Bank 64 EE 2036 FLEXIBLE ALTERNATING CURRENT TRANSMISSION SYSTEM (FACTS) SCE Page 5 of 73 DEPARTMENT OF EEE EE2036 FLEXIBLE AC TRANSMISSION SYSTEMS L T P C3 0 0 3 AIM: To enhance the TRANSMISSION capability of TRANSMISSION SYSTEM by shunt and series compensation using static controllers.

5 OBJECTIVES: i. To understand the concept of FLEXIBLE AC TRANSMISSION and the associated problems. ii. To review the static devices for series and shunt control. iii. To study the operation of controllers for enhancing the TRANSMISSION capability. UNIT I introduction 9 The concept of FLEXIBLE AC TRANSMISSION - reactive power control in electrical power TRANSMISSION lines -uncompensated TRANSMISSION line series and shunt compensation. Overview of FACTS devices - Static Var Compensator (SVC) Thyristor Switched Series capacitor (TCSC) Unified Power Flow controller (UPFC) - Integrated Power Flow Controller (IPFC). UNIT II STATIC VAR COMPENSATOR (SVC) AND APPLICATIONS 9 Voltage control by SVC advantages of slope in dynamic characteristics influence of SVC on SYSTEM voltage.

6 Applications - enhancement of transient stability steady state power transfer enhancement of power SYSTEM damping prevention of voltage instability. UNIT III THYRISTOR CONTROLLED SERIES CAPACITOR(TCSC)AND APPLICATIONS 9 Operation of the TCSC - different modes of operation modeling of TCSC variable reactance model modeling for stability studies. Applications - improvement of the SYSTEM stability limit enhancement of SYSTEM damping voltage collapse prevention. UNIT IV EMERGING FACTS CONTROLLERS 9 Static Synchronous Compensator (STATCOM) operating principle V-I characteristics Unified Power Flow Controller (UPFC) Principle of operation - modes of operation applications modeling of UPFC for power flow studies.

7 UNIT V CO-ORDINATION OF FACTS CONTROLLERS 9 FACTs Controller interactions SVC SVC interaction - co-ordination of multiple controllers using linear control techniques Quantitative treatment of control coordination. TOTAL : 45 PERIODS TEXT BOOK: 1. Mohan Mathur, R., Rajiv. K. Varma, Thyristor Based Facts Controllers for Electrical TRANSMISSION Systems , IEEE press and John Wiley & Sons, Inc. REFERENCES: 1. , FLEXIBLE AC TRANSMISSION SYSTEM , Institution of Electrical and Electronic Engineers (IEEE), 1999. 2. Narain , Laszio. Gyugyl, Understanding FACTS Concepts and Technology of FLEXIBLE AC TRANSMISSION SYSTEM , Standard Publishers, Delhi 2001. EE 2036 FLEXIBLE ALTERNATING CURRENT TRANSMISSION SYSTEM (FACTS) SCE Page 6 of 73 DEPARTMENT OF EEE UNIT I introduction CONCEPT OF FACTS A FLEXIBLE ALTERNATING CURRENT TRANSMISSION SYSTEM (FACTS) is a SYSTEM composed of static equipment used for the AC TRANSMISSION of electrical energy and it is meant to enhance controllability and increase power transfer capability of the network and it is generally a power electronics-based SYSTEM .

8 FACTS is defined by the IEEE as a power electronics based SYSTEM other static equipment that provide control of one or more AC TRANSMISSION SYSTEM parameters to enhance controllability and increase power transfer capability . REACTIVE POWER CONTROL To make TRANSMISSION networks operate within desired voltage limits and methods of making up or taking away reactive power is called reactive-power control . The AC networks and the devices connected to them create associated time-varying electrical fields related to the applied voltage and as well as magnetic fields dependent on the CURRENT flow and they build up these fields store energy that is released when they collapse.

9 Apart from the energy dissipation in resistive components, all energy-coupling devices ( : motors and generators) operate based on their capacity to store and release energy. While the major means of control of reactive power and voltage is via the excitation systems of synchronous generators and devices may be deployed in a TRANSMISSION network to maintain a good voltage profile in the SYSTEM . The shunt connected devices like shunt capacitors or inductors or synchronous inductors may be fixed or switched (using circuit breaker). The Vernier or smooth control of reactive power is also possible by varying effective susceptance characteristics by use of power electronic devices.

10 Example: Static Var Componsator(SVC) and a Thyristor Controlled Reactor (TCR). EE 2036 FLEXIBLE ALTERNATING CURRENT TRANSMISSION SYSTEM (FACTS) SCE Page 7 of 73 DEPARTMENT OF EEE UNCOMPENSATED TRANSMISSION LINES introduction For simplicity let us consider only the inductive reactance From the above figure it is clear that between he sending and the receiving end voltages and magnitude variation as well as a phase difference is created and the most significant part of the voltage drop in the line reactance is due to the reactive component of the load CURRENT and to keep the voltages in the network nearly at the rated value. Two compensation methods are: 1. Load compensation 2. SYSTEM compensation Load Compensation It is possible to compensate for the reactive CURRENT of the load by adding a parallel capacitive load so that Ic = Ix and the effective power factor to become unity.