Protection devices prevent damage to synchronous generators during loss-of-field events. In various embodiments, a first protective element is associated with a first protection zone to protect a generator from a loss-of-field event at full load. A second protective element is associated with a second protection zone to prevent thermal overload during underexcited operation of the generator and to protect from loss-of-filed at light load. A third protective element associated with a third protection zone limits operation of the generator within the generator's specific steady-state stability limits. A fourth protective element is associated with a fourth protection zone to provide an alarm prior to operation of the second protective element. In various embodiments, characteristics and limits of each of the protective elements are defined in the same plane (specifically, the P-Q plane) to simplify settings and allow for visualization of the element characteristics and the generator capability curve at one or more temperatures or cooling capacities.

The invention relates to a system and method for protecting against faults between turns in excitation windings of synchronous machines with static excitation, which is based on comparison between the excitation intensity measured and the theoretical excitation current calculated for that operating point using the voltage and current measurements in the armature.

A computer-implemented method is provided for detecting broken bar faults of an induction motor during operations. The method includes steps of injecting a frequency modulation continuous wave (FMCW) voltage signal to the voltage source to power the motor, acquiring, in a time domain, a signal of a stator current powering the induction motor via an interface, performing Fourier Transform (FT) on the stator current and the injected FMCW signal to get spectra of the stator current and the injected signal, computing cross correlation between the spectrum of injected signal and the spectrum of stator current, extracting a fault signature at frequency f=±2(1−s)f.sub.0 in the cross-correlation function, and detecting a broken-bar fault in the induction motor if the fault signature magnitude is greater than a threshold.

A method and apparatus for operating an overvoltage response for an electric machine includes opening a first switching element and a second switching element in response to an overvoltage condition. In the instance that the overvoltage condition persists, the method and apparatus can further open a third switchable element to cease the overvoltage condition.

The present disclosure relates to an over-voltage prevention apparatus and method of a distribution line connected with a distributed generator, which sets a range of a dispatched voltage based on a current voltage of a Pole Mounted Automatic Voltage Regulator (PVR) and a voltage at a connection point of a distributed generator to control so that the dispatched voltage is output within the corresponding range.

Described is a method including monitoring a point of regulation voltage input to a generator control unit and monitoring a generator output voltage as a backup point of regulation voltage input. The method also includes detecting an overvoltage fault at the point of regulation voltage input, the backup point of regulation voltage input, or both. Additionally, the method includes opening a first solid-state switch (110) in response to detecting the overvoltage fault. Opening the first solid-state switch (110) prevents provision of an input signal (104) to a generator excitation field (102). Further, the method includes opening a generator excitation field relay (112) in response to detecting the overvoltage fault. Opening the excitation field relay (112) also prevents provision of the input signal (104) to the generator excitation field (102).

The invention relates to a system and method for protecting against faults between turns in excitation windings of synchronous machines with static excitation, which is based on comparison between the excitation intensity measured and the theoretical excitation current calculated for that operating point using the voltage and current measurements in the armature.

A method and apparatus for operating an overvoltage response for an electric machine includes opening a first switching element and a second switching element in response to an overvoltage condition. In the instance that the overvoltage condition persists, the method and apparatus can further open a third switchable element to cease the overvoltage condition.

A method for enhancing an over-voltage protection by an over-voltage protection device for a generator is provided. The device includes a high voltage excitation off (HEO) circuit lowering an over-voltage level by an over-voltage lockout control value and a voltage-dependent Ki-Kp (VoKiKp) circuit 30 decreasing an over-voltage generation time by a voltage difference value of a battery voltage. A generator setting voltage is provided to operate the over-voltage and the voltage difference value of the generator 1. The over-voltage level is lowered and the over-voltage generation time is minimized, thereby enhancing the over-voltage protection of the regulator of the generator.

The present disclosure relates to an over-voltage prevention apparatus and method of a distribution line connected with a distributed generator, which sets a range of a dispatched voltage based on a current voltage of a Pole Mounted Automatic Voltage Regulator (PVR) and a voltage at a connection point of a distributed generator to control so that the dispatched voltage is output within the corresponding range.