Power SystemProtection
S.A.Soman
Power SystemDynamicsOverview
SystemProtectionRelaysExample System
Underfrequency andRate of Change ofFrequency Relays
Undervoltage andReverse Power Relay
LightningProtectionLightningOvervoltages
Lightning ProtectionDevices
Summary
Power System Protection
S.A.Soman
Department of Electrical EngineeringIIT Bombay
Protection Paradigms - System Protection
Power SystemProtection
S.A.Soman
Power SystemDynamicsOverview
SystemProtectionRelaysExample System
Underfrequency andRate of Change ofFrequency Relays
Undervoltage andReverse Power Relay
LightningProtectionLightningOvervoltages
Lightning ProtectionDevices
Summary
Protection Paradigms - System Protection
1 Power System DynamicsOverview
2 System Protection RelaysExample SystemUnderfrequency and Rate of Change of FrequencyRelaysUndervoltage and Reverse Power Relay
3 Lightning ProtectionLightning OvervoltagesLightning Protection Devices
4 Summary
Power SystemProtection
S.A.Soman
Power SystemDynamicsOverview
SystemProtectionRelaysExample System
Underfrequency andRate of Change ofFrequency Relays
Undervoltage andReverse Power Relay
LightningProtectionLightningOvervoltages
Lightning ProtectionDevices
Summary
Protection Paradigms - System Protection
1 Power System DynamicsOverview
2 System Protection RelaysExample SystemUnderfrequency and Rate of Change of FrequencyRelaysUndervoltage and Reverse Power Relay
3 Lightning ProtectionLightning OvervoltagesLightning Protection Devices
4 Summary
Power SystemProtection
S.A.Soman
Power SystemDynamicsOverview
SystemProtectionRelaysExample System
Underfrequency andRate of Change ofFrequency Relays
Undervoltage andReverse Power Relay
LightningProtectionLightningOvervoltages
Lightning ProtectionDevices
Summary
Protection Paradigms - System Protection
Overview of Power System DynamicsSystem protection requires study of system dynamics andcontrol. Power system dynamics
Can be described in terms of a set of differential andalgebraic equations.
Analysis is done by EMTP.
Post fault system stability is determined by transientstability studies.
Power SystemProtection
S.A.Soman
Power SystemDynamicsOverview
SystemProtectionRelaysExample System
Underfrequency andRate of Change ofFrequency Relays
Undervoltage andReverse Power Relay
LightningProtectionLightningOvervoltages
Lightning ProtectionDevices
Summary
Protection Paradigms - System Protection
Power SystemProtection
S.A.Soman
Power SystemDynamicsOverview
SystemProtectionRelaysExample System
Underfrequency andRate of Change ofFrequency Relays
Undervoltage andReverse Power Relay
LightningProtectionLightningOvervoltages
Lightning ProtectionDevices
Summary
Protection Paradigms - System Protection
System Protection RelaysFollowing relays are used to detect system disturbancesand for enhancing system stability.
Under frequency and over frequency relays.
Rate of change of frequency relays.
Under voltage relays.
Reverse power flow relays.
Vector shift relays.
For example, consider a voltage distribution system withlocal generation which is synchronized with the grid. Duringgrid disturbances, the local plant generators have to beisolated from the grid.
Power SystemProtection
S.A.Soman
Power SystemDynamicsOverview
SystemProtectionRelaysExample System
Underfrequency andRate of Change ofFrequency Relays
Undervoltage andReverse Power Relay
LightningProtectionLightningOvervoltages
Lightning ProtectionDevices
Summary
Protection Paradigms - System Protection
1 Power System DynamicsOverview
2 System Protection RelaysExample SystemUnderfrequency and Rate of Change of FrequencyRelaysUndervoltage and Reverse Power Relay
3 Lightning ProtectionLightning OvervoltagesLightning Protection Devices
4 Summary
Power SystemProtection
S.A.Soman
Power SystemDynamicsOverview
SystemProtectionRelaysExample System
Underfrequency andRate of Change ofFrequency Relays
Undervoltage andReverse Power Relay
LightningProtectionLightningOvervoltages
Lightning ProtectionDevices
Summary
Protection Paradigms - System Protection
Example System with Local Generation
Power SystemProtection
S.A.Soman
Power SystemDynamicsOverview
SystemProtectionRelaysExample System
Underfrequency andRate of Change ofFrequency Relays
Undervoltage andReverse Power Relay
LightningProtectionLightningOvervoltages
Lightning ProtectionDevices
Summary
Protection Paradigms - System Protection
Loss of Utility in the Example System
Power SystemProtection
S.A.Soman
Power SystemDynamicsOverview
SystemProtectionRelaysExample System
Underfrequency andRate of Change ofFrequency Relays
Undervoltage andReverse Power Relay
LightningProtectionLightningOvervoltages
Lightning ProtectionDevices
Summary
Protection Paradigms - System Protection
1 Power System DynamicsOverview
2 System Protection RelaysExample SystemUnderfrequency and Rate of Change of FrequencyRelaysUndervoltage and Reverse Power Relay
3 Lightning ProtectionLightning OvervoltagesLightning Protection Devices
4 Summary
Power SystemProtection
S.A.Soman
Power SystemDynamicsOverview
SystemProtectionRelaysExample System
Underfrequency andRate of Change ofFrequency Relays
Undervoltage andReverse Power Relay
LightningProtectionLightningOvervoltages
Lightning ProtectionDevices
Summary
Protection Paradigms - System Protection
Underfrequency and Rate of Change of Frequency Relays
Load-generation imbalance in a system leads to fall infrequency.
Underfrequency relay detects this drop and isolateslocal generation from the grid.
Load-generation balance has to be maintained in theislanded system.
In order to speed up the islanding decision, rate ofchange of frequency relay is used.
Power SystemProtection
S.A.Soman
Power SystemDynamicsOverview
SystemProtectionRelaysExample System
Underfrequency andRate of Change ofFrequency Relays
Undervoltage andReverse Power Relay
LightningProtectionLightningOvervoltages
Lightning ProtectionDevices
Summary
Protection Paradigms - System Protection
1 Power System DynamicsOverview
2 System Protection RelaysExample SystemUnderfrequency and Rate of Change of FrequencyRelaysUndervoltage and Reverse Power Relay
3 Lightning ProtectionLightning OvervoltagesLightning Protection Devices
4 Summary
Power SystemProtection
S.A.Soman
Power SystemDynamicsOverview
SystemProtectionRelaysExample System
Underfrequency andRate of Change ofFrequency Relays
Undervoltage andReverse Power Relay
LightningProtectionLightningOvervoltages
Lightning ProtectionDevices
Summary
Protection Paradigms - System Protection
Undervoltage Relay
If the fault on the grid is close to the plant, voltage atthe supply point of plant generator drops.
This drop in voltage is used as a signal in undervoltagerelay.
Reverse Power Relay
During prefault state, power was being fed to the plant.
During fault in the utility system, the plant will beisolated from the grid and it may be connected to thedownstream loads.
Then, power will flow in reverse direction from plantgenerator to feed the downstream loads.
This reversal of power flow can be used to island theplant generator.
Power SystemProtection
S.A.Soman
Power SystemDynamicsOverview
SystemProtectionRelaysExample System
Underfrequency andRate of Change ofFrequency Relays
Undervoltage andReverse Power Relay
LightningProtectionLightningOvervoltages
Lightning ProtectionDevices
Summary
Protection Paradigms - System Protection
Undervoltage Relay
If the fault on the grid is close to the plant, voltage atthe supply point of plant generator drops.
This drop in voltage is used as a signal in undervoltagerelay.
Reverse Power Relay
During prefault state, power was being fed to the plant.
During fault in the utility system, the plant will beisolated from the grid and it may be connected to thedownstream loads.
Then, power will flow in reverse direction from plantgenerator to feed the downstream loads.
This reversal of power flow can be used to island theplant generator.
Power SystemProtection
S.A.Soman
Power SystemDynamicsOverview
SystemProtectionRelaysExample System
Underfrequency andRate of Change ofFrequency Relays
Undervoltage andReverse Power Relay
LightningProtectionLightningOvervoltages
Lightning ProtectionDevices
Summary
Protection Paradigms - System Protection
Undervoltage Relay
If the fault on the grid is close to the plant, voltage atthe supply point of plant generator drops.
This drop in voltage is used as a signal in undervoltagerelay.
Reverse Power Relay
During prefault state, power was being fed to the plant.
During fault in the utility system, the plant will beisolated from the grid and it may be connected to thedownstream loads.
Then, power will flow in reverse direction from plantgenerator to feed the downstream loads.
This reversal of power flow can be used to island theplant generator.
Power SystemProtection
S.A.Soman
Power SystemDynamicsOverview
SystemProtectionRelaysExample System
Underfrequency andRate of Change ofFrequency Relays
Undervoltage andReverse Power Relay
LightningProtectionLightningOvervoltages
Lightning ProtectionDevices
Summary
Protection Paradigms - System Protection
Undervoltage Relay
If the fault on the grid is close to the plant, voltage atthe supply point of plant generator drops.
This drop in voltage is used as a signal in undervoltagerelay.
Reverse Power Relay
During prefault state, power was being fed to the plant.
During fault in the utility system, the plant will beisolated from the grid and it may be connected to thedownstream loads.
Then, power will flow in reverse direction from plantgenerator to feed the downstream loads.
This reversal of power flow can be used to island theplant generator.
Power SystemProtection
S.A.Soman
Power SystemDynamicsOverview
SystemProtectionRelaysExample System
Underfrequency andRate of Change ofFrequency Relays
Undervoltage andReverse Power Relay
LightningProtectionLightningOvervoltages
Lightning ProtectionDevices
Summary
Protection Paradigms - System Protection
Operation of Reverse Power Flow Pelay
Power SystemProtection
S.A.Soman
Power SystemDynamicsOverview
SystemProtectionRelaysExample System
Underfrequency andRate of Change ofFrequency Relays
Undervoltage andReverse Power Relay
LightningProtectionLightningOvervoltages
Lightning ProtectionDevices
Summary
Protection Paradigms - System Protection
Operation of Reverse Power Relay
Power SystemProtection
S.A.Soman
Power SystemDynamicsOverview
SystemProtectionRelaysExample System
Underfrequency andRate of Change ofFrequency Relays
Undervoltage andReverse Power Relay
LightningProtectionLightningOvervoltages
Lightning ProtectionDevices
Summary
Protection Paradigms - System Protection
1 Power System DynamicsOverview
2 System Protection RelaysExample SystemUnderfrequency and Rate of Change of FrequencyRelaysUndervoltage and Reverse Power Relay
3 Lightning ProtectionLightning OvervoltagesLightning Protection Devices
4 Summary
Power SystemProtection
S.A.Soman
Power SystemDynamicsOverview
SystemProtectionRelaysExample System
Underfrequency andRate of Change ofFrequency Relays
Undervoltage andReverse Power Relay
LightningProtectionLightningOvervoltages
Lightning ProtectionDevices
Summary
Protection Paradigms - System Protection
Lightning OvervoltagesLightning discharges produce overvoltage surges and theyare extremely harmful. Lightning overvoltages can beclassified as
Induced overvoltages.Overvoltages due to shielding failures.Overvoltages by back flashovers.
Power SystemProtection
S.A.Soman
Power SystemDynamicsOverview
SystemProtectionRelaysExample System
Underfrequency andRate of Change ofFrequency Relays
Undervoltage andReverse Power Relay
LightningProtectionLightningOvervoltages
Lightning ProtectionDevices
Summary
Protection Paradigms - System Protection
1 Power System DynamicsOverview
2 System Protection RelaysExample SystemUnderfrequency and Rate of Change of FrequencyRelaysUndervoltage and Reverse Power Relay
3 Lightning ProtectionLightning OvervoltagesLightning Protection Devices
4 Summary
Power SystemProtection
S.A.Soman
Power SystemDynamicsOverview
SystemProtectionRelaysExample System
Underfrequency andRate of Change ofFrequency Relays
Undervoltage andReverse Power Relay
LightningProtectionLightningOvervoltages
Lightning ProtectionDevices
Summary
Protection Paradigms - System Protection
Lightning Protection DevicesThe most commonly used devices for protection againstlightning are:
Shielding by earth wires.
Proper earthing of transmission towers.
Surge Arrestors like ZnO varistor.
Power SystemProtection
S.A.Soman
Power SystemDynamicsOverview
SystemProtectionRelaysExample System
Underfrequency andRate of Change ofFrequency Relays
Undervoltage andReverse Power Relay
LightningProtectionLightningOvervoltages
Lightning ProtectionDevices
Summary
Protection Paradigms - System Protection
Summary
Power System Dynamics.
Various System Protection Relays.
Lightning Protection.