Detecting Power Grid Synchronization Failure on Sensing Frequency or Voltage Beyond Acceptable

Detecting Power Grid Synchronization Failure on Sensing Frequency or Voltage Beyond Acceptable

Detecting Power Grid Synchro Synchronization nization Failure Introduction 

Synchronization means the minimization of difference in voltage, v oltage, frequency and phase angle between the corresponding phases of the generator output and grid supply. An alternating current generator must be synchronized with the grid prior to connection. It can’t deliver the power unless it is running at same frequency as the network.



Synchronization must occur before connecting the generator to a grid. Synchronization can be achieved manually or automatically. automatically. he purpose of synchronization is to monitor, access, access, enable, and automatically automatically take the control action to prevent the abnormalities of voltage and frequency.

http://www.edgefxkits.com/

Rules Must Be Followed for Power

Grid Synchronization Voltage Fluctuation: 

!hen a generator is synchronized with a power grid.



 here is a voltage fluctuation on the distribution line.



"uring synchronization the voltage fluctuation should not e#ceed $% at the at the point of common coupling.

http://www.edgefxkits.com/

Rules Must Be Followed for Power Grid Synchronization Synchronization Synchron ization Liits: 

he limits allowing for synchronization are.



&hase angle' ()'*+ degrees

 a#imum  a#imum



voltage difference difference - %

a#imum slip frequency - +.//%

http://www.edgefxkits.com/

Rules Must Be Followed for Power Grid Synchron Synchronization ization Relays: 

0or checking the synchronization 1synch check relay2 must be used.



he usage of relays r elays can’t apply for induction generators.



he use of synch check relay is to accept as a backup during synchronization.



It ensures a generator will not connect to a dead distribution line.

http://www.edgefxkits.com/

Synchronization Synchro nization of Induction Generators 

Standard motor controllers will be used to synchronization of induction generators.



urbine urbine shaft power will w ill be used to mechanically drive the generators up to synchronization speed.



he speed of the motors depends on supplied frequency and number of  poles on the generators. generators.

http://www.edgefxkits.com/

Synchronization of Synchronous Machines 

0or synchronous generators output waveform should be in phase with the grid voltage waveform.



he rate of change of phase angle between the grid and the machine 3generator4 must be within the specified limits.



Some other rules are variable speed drive arrangement to maintain a constant output frequency. frequency.

http://www.edgefxkits.com/

Failure of Synchronization



here are various reasons for failure of power grid synchronization.



Synchronization circuit may fail for responding to a received input pulse.



It happens when the received input pulse is shorted than the sampling s ampling period of the synchronizer.



hen no synchronized representation will take place.



Synchronization circuit may fail, when the pulse rate of the input signal is higher than the synchronization rate of the synchronizer.

http://www.edgefxkits.com/

Synchronization Failures and their Detections 

5enerators and some local loads have become disconnected from main distribution lines due to some issues.



"ue to this there is a reduction in quality q uality of supply.



It may prevent automatic reconnection of devices. his is called as islanding.



Islanding must be detected and producing produ cing power must be stopped immediately immediately..

http://www.edgefxkits.com/

Following !azards May "a#e Place Due to Islanding 

6ine voltages may e#cessive7 when distributing lines and generators are disconnected the line is not earthed.



"ue to Islanding synchronization can’t be maintained.



he fault level contribution from the grid to sub'station may be lost.



"ue to this sufficient current may not be generated.



he voltage levels may go outside o utside of normal operating limits, and the quality of supply may be reduced. http://www.edgefxkits.com/

Detection Methods of slanding 

"etection of islanding can be done through active and passive methods.



&assive methods look for transient events on the grid.



Active methods will probe the grid by sending se nding signals from the distribution point of grid.



6oss of ains &rotection 36o4 will be designed to sense the disconnection of generators.



he blind area is called cal led 8on "etection 9one 38"94.

http://www.edgefxkits.com/

$hich Microcontrollers %re &sed in "his Pro'ect( 

/+ pin :+;< icrocontrollers are used in this pro=ect.



he icrocontroller monitors the under)over voltage being derived from a set of comparators.

http://www.edgefxkits.com/

Applications of Power Grid Failure Detection



6ighting is one of the main causes for power system faults.



he ma=or advantage is detecting the synchronization failure between generators and power grid.



!hen there is an >nder)over voltage or under)over frequency. frequency.



he comparator will detect the difference the actual power and reactive.



If there is no failure of power grid synchronization then the detectors will give the zero values.

http://www.edgefxkits.com/

Bloc# Diagra

http://www.edgefxkits.com/

!ardware Re)uireents

•

:+;< series icrocontroller 

•

6?"

•

@p'Amps

•

;;; timer 

•

?rystal

•

esistors

•

?apacitors

•

"iodes

•

ransformer 

•

Boltage egula egulator  tor 

•

elay

•

ransistors

•

Slide Switch

•

6amp

http://www.edgefxkits.com/

http://www.edgefxkits.com/