ppt1 presentation voltage control methhods.pptx
- 2. Methods of Voltage Control 1. Shunt compensation 2. Series capacitor 3. Synchronous condenser 4. Tap changing transformer 5. Auto transformer tap changing
- 3. 1. Shunt Compensation Shunt Reactor : Used to compensate effect line capacitance limit voltage rise on open circuit or light load increases effective ZC They are connected either: directly to the lines at the ends Tertiary windings easily switched as VAR vary. In long lines to overcome ferranti effect. Connected to bus bar without C.B for switching.
- 4. Shunt Capacitor : • Supply leading reactive power and boost the voltage as loading of current reduces. • Switching substation inductive load absorb inductive current of lower P.F. • They are connected either: • H.V. bus • Tertiary winding of transformers • Advantage : • low cost and flexibility of installation. • Disadvantage : • Q is proportional to (voltage)^2. So output reduces.
- 5. 2. Series Compensation Series capacitor : Connected in series with line. Used to reduce inductive reactance of line so reduction of I 2X loss characteristic impedance ZC Reactive power produced increases with increasing power transfer. Application : improve power transfer capacity. voltage regulation
- 6. Performance of Shunt and Series Capacitors :
- 7. 3. Synchronous Condenser A synchronous machine running without a prime mover or a mechanical load Depending on field excitation, it can either absorb or generate VARs With a voltage regulator, it can automatically adjust VAR to maintain constant voltage Started as an induction motor and then synchronized Normally connected to tertiary windings of transformers Unlike a SVC, a synchronous condenser has an internal voltage Speed of response not as fast as that of an SVC
- 8. 4. Tap Changing Transformer • Off load Tap changing transformer : • Position of tap number of turns output voltage. • Stud 1 : min value • Stud 5 : max value • Light load primary voltage = alternator voltages and movable arm is placed at stud 1. • Load drop so movement of stud.