Method and system for disconnecting a generator from a power system

1. A method for disconnecting a generator from a power system when the generator and the power system connected thereto are non-synchronized, the method comprises the steps of:

measuring an electrical parameter of a stator of the generator with a voltage and current measuring device;

transmitting an output signal from the voltage and current measuring device to a processing unit, the processing unit:

determining a loss of synchronization between the generator and the power system by detecting an amplitude variation of the electrical parameter measured from the generator, wherein a frequency of the amplitude variation is proportional to a rotor angle variation of the generator, the rotor angle variation arising due to the loss of synchronization between the generator and the power system;

determining a slope or a frequency of the amplitude variation to determine when a minimum amplitude of the electrical parameter will occur;

transmitting a command signal to at least one circuit breaker electrically connected between the generator and the power system for disconnecting the generator from the power system, wherein the command signal is provided to the at least one circuit breaker prior to the minimum amplitude of the electrical parameter being attained; and

the at least one circuit breaker disconnecting the generator from the power system when the minimum amplitude of the electrical parameter occurs.

2. The method as claimed in claim 1 , wherein the electrical parameter is an impedance of the generator.

3. The method as claimed in claim 1 , wherein the amplitude variation of the electrical parameter is periodic.

4. The method as claimed in claim 1 , wherein the electrical parameter of the generator includes at least one of a stator current, a stator voltage, and an impedance.

5. A protection system for a generator connected to a power system, the protection system comprising:

a voltage and current measuring unit electrically connected to a stator of the generator and measuring an electrical parameter of the generator, said voltage and current measuring unit generating an output signal indicative of the measured electrical parameter;

a processing unit electrically connected to the measuring unit, said processing unit processing the output signal received from the measuring unit to determine whether there is a loss of synchronization between the generator and the power system; and

at least one circuit breaker electrically connected to said processing unit, said at least one circuit breaker electrically connecting the generator to the power system when said at least one circuit breaker is closed;

wherein said processing unit determines a loss of synchronization between the generator and the power system by detecting an amplitude variation of the electrical parameter from the output signal, and a frequency of the amplitude variation is proportional to a rotor angle variation of the generator, the rotor angle variation arising due to the loss of synchronization between the generator and power system;

said processing unit determines when a minimum amplitude of the electrical parameter will occur by determining a slope or a frequency of the amplitude variation; and

said processing unit transmits a command signal to said at least one circuit breaker, prior to the minimum amplitude being attained, to disconnect the generator from the power system by the at least one circuit breaker disconnecting the generator from the power system when the minimum amplitude occurs.

6. The protection system as claimed in claim 5 , wherein the electrical parameter of the generator includes at least one of a stator current, a stator voltage, and an impedance.