Rev 2 Protection.docx
Content
Loss of Prime Mover should be very hi compared to Direction relay used for over current application. Therefore, these can be protected by using Directional Relay.
Directional relay. During the normal condition generator stator supply full load current to the grid. During the loss of Prime Mover the magnitude of stator current is smaller than when it was generating and the stator current goes 180 deg. Phase shift. The magnitude of phase current is very small compared to
forward current, hence the degree sensitivity of Directional relay used for Loss of Prime Mover should be very hi compared to Direction relay used for over current application. Therefore, these can be protected by using Directional Relay. The Directional relay input are:Phase Voltage & Phase Current , Output:- Tripping to Generator CB Loss of Prime Mover : Generator Motoring(32)
Loss of prime mover is due to the loss of Steam supply to turbine.In case of loss of prime mover , ie loss of mechanical inputs, The generator continue to remainssynchronized with the grid. The generator now running as synchronous motor. Thegenerator now draws a small amount of active power from the grid in order to drivethe turbine. At the same time the generator supply reactive power to grid since itsexcitation is intact (AVR is supplying field voltage
& field current).Running in this mode is not harmful to generator but is definitely harmful to primemover (Steam Turbine). Loss of Steam supply to the Prime Mover (Steam Turbine)causes a churning of trapped steam in the turbine, which causes the temperaturerise and may damage the turbine blades.
2)GENERATOR REVERSE POWER PROTECTION (32) Reverse power can be occur when there is loss of Prime Mover as already discussed or when two or more generator are running in parallel. if one generator does not accept load usually because its unloaded running speed is less than the other generator (called speed droop) then the other generator will motorized the drooping generator. The generator are classified by their Prime Mover which determine the
amount of Reverse power they can motor
Directional relay. During the normal condition generator stator supply full load current to the grid. During the loss of Prime Mover the magnitude of stator current is smaller than when it was generating and the stator current goes 180 deg. Phase shift. The magnitude of phase current is very small compared to
forward current, hence the degree sensitivity of Directional relay used for Loss of Prime Mover should be very hi compared to Direction relay used for over current application. Therefore, these can be protected by using Directional Relay. The Directional relay input are:Phase Voltage & Phase Current , Output:- Tripping to Generator CB Loss of Prime Mover : Generator Motoring(32)
Loss of prime mover is due to the loss of Steam supply to turbine.In case of loss of prime mover , ie loss of mechanical inputs, The generator continue to remainssynchronized with the grid. The generator now running as synchronous motor. Thegenerator now draws a small amount of active power from the grid in order to drivethe turbine. At the same time the generator supply reactive power to grid since itsexcitation is intact (AVR is supplying field voltage
& field current).Running in this mode is not harmful to generator but is definitely harmful to primemover (Steam Turbine). Loss of Steam supply to the Prime Mover (Steam Turbine)causes a churning of trapped steam in the turbine, which causes the temperaturerise and may damage the turbine blades.
2)GENERATOR REVERSE POWER PROTECTION (32) Reverse power can be occur when there is loss of Prime Mover as already discussed or when two or more generator are running in parallel. if one generator does not accept load usually because its unloaded running speed is less than the other generator (called speed droop) then the other generator will motorized the drooping generator. The generator are classified by their Prime Mover which determine the
amount of Reverse power they can motor
