A statistical method is described to interpret partial discharge (PD) measurement data from rotating machines for the maintenance personnel. Cumulative damage to the electrical insulation caused by PD during an observation time window is estimated using multiple PD sensors strategically distributed along the entire length of the machine winding. The damage thus estimated is compared against a reference value based on the annual averages of similar machines to determine if maintenance action is needed and how soon, if required. A method is also described to track the electrical insulation's overall condition and generate real-time health status alerts continuously and reliably.

Overvoltage protection device for a variable-speed and constant-frequency electrical energy generation system includes at least one DC current generator connected, via a DC current bus to the input terminals of at least one inverter and to at least one regulation module for regulating the output voltage of the at least one inverter. The device includes a circuit including at least one switch in series with a resistor, the circuit being connected between the input terminals of the at least one inverter, at least one measurement sensor for measuring the DC voltage across the input terminals of the at least one inverter, a control circuit connected to the at least one measurement sensor and able to receive a voltage measured by the at least one measurement sensor, compare the measured voltage against a threshold and command the closure of the at least one switch if the measured voltage is greater than the threshold, and command opening thereof if not.

Overvoltage protection device for a variable-speed and constant-frequency electrical energy generation system includes at least one DC current generator connected, via a DC current bus to the input terminals of at least one inverter and to at least one regulation module for regulating the output voltage of the at least one inverter. The device includes a circuit including at least one switch in series with a resistor, the circuit being connected between the input terminals of the at least one inverter, at least one measurement sensor for measuring the DC voltage across the input terminals of the at least one inverter, a control circuit connected to the at least one measurement sensor and able to receive a voltage measured by the at least one measurement sensor, compare the measured voltage against a threshold and command the closure of the at least one switch if the measured voltage is greater than the threshold, and command opening thereof if not.

A method includes detecting an initial fault in a system and opening a contactor to isolate a load bus from the system for a window of time. During the window of time, the method includes detecting whether current flows from a generator of the system. If current flows from the generator of the system during the window of time, the method includes isolating the load bus from the generator. If current does not flow from the generator to the system during the window of time, the method includes isolating the load bus from all sources including the generator.

A method includes detecting an initial fault in a system and opening a contactor to isolate a load bus from the system for a window of time. During the window of time, the method includes detecting whether current flows from a generator of the system. If current flows from the generator of the system during the window of time, the method includes isolating the load bus from the generator. If current does not flow from the generator to the system during the window of time, the method includes isolating the load bus from all sources including the generator.

A fault handling method and apparatus for a wind power generator set, and a computer readable storage medium. The fault handling method comprises: dividing faults of a wind power generator set into groups according to a target protection object, each group of faults including a plurality of process faults associated with the target protection object and a target fault of the target protection object (101); if any one of the plurality of process faults in the same group as the target fault satisfies a corresponding process fault trigger condition and the target fault does not satisfy the corresponding target fault trigger condition, performing a fault-tolerant operation on the wind power generator set (102); if the target fault satisfies the corresponding target fault trigger condition, selecting, from the triggered process faults in the same group as the target fault, the process fault having the highest degree of association as a real fault that has caused shut-down of the wind power generator set (202). Thus, the invention can improve the reliability of a fault protection mechanism for a wind power generator set, and improve the accuracy of fault identification for a wind power generator set.

A system and method for detecting current overload and leakage in a transport refrigeration unit. The method comprises measuring, by a microcontroller of an active fault detection circuit, a line current for each of one or more phases supplying power to a GP load of a refrigerant vapor compression system of the transport refrigeration unit; measuring, by the microcontroller, a voltage received by the active fault detection circuit from a battery of the transport refrigeration unit and transmitted via a conductor of the active fault detection circuit to a microprocessor of the refrigerant vapor compression system; controlling, by the microcontroller, a switch along the conductor of the active fault detection circuit to control transmission of the voltage, via the conductor to the microprocessor, Controlling the switch comprises (i) closing the switch upon a determination that the voltage level is greater than or equal to an operational threshold voltage level, (ii) closing the switch upon a determination that the voltage level is less than the operational threshold voltage level, and (iii) opening the switch upon a determination that any of the one or more line currents exceeds a threshold. Other embodiments are described herein.

A system and method for detecting current overload and leakage in a transport refrigeration unit. The method comprises measuring, by a microcontroller of an active fault detection circuit, a line current for each of one or more phases supplying power to a GP load of a refrigerant vapor compression system of the transport refrigeration unit; measuring, by the microcontroller, a voltage received by the active fault detection circuit from a battery of the transport refrigeration unit and transmitted via a conductor of the active fault detection circuit to a microprocessor of the refrigerant vapor compression system; controlling, by the microcontroller, a switch along the conductor of the active fault detection circuit to control transmission of the voltage, via the conductor to the microprocessor, Controlling the switch comprises (i) closing the switch upon a determination that the voltage level is greater than or equal to an operational threshold voltage level, (ii) closing the switch upon a determination that the voltage level is less than the operational threshold voltage level, and (iii) opening the switch upon a determination that any of the one or more line currents exceeds a threshold. Other embodiments are described herein.

A power supply system includes: a synchronous generator connected to a three-phase power distribution system that is connected to a consumer load; an inverter that is connected to the power distribution system, supplies power to the consumer load, and compensates for unbalanced current of the synchronous generator; and a control device that generates a gate command for controlling the inverter. The control device: generates, based on a three-phase voltage and current output from the inverter, a target output voltage which is an amplitude of a vector in a complex plane combining voltages of three phases, and a target output phase which is a phase of the vector in the complex plane combining the voltages of three phases; generates a first compensation voltage, based on a current negative-phase-sequence component relating to the synchronous generator; and generates a gate command from the generated values.

A method for detection of a sub-synchronous oscillation in a power system includes measuring a three-phase measurement signal of an electric system value, analyzing the measurement signal to detect an oscillation component of the measurement signal having an oscillation frequency lower than a system frequency of the power system, deciding whether the detected oscillation component at the oscillation frequency qualifies as a sub-synchronous oscillation, and disconnecting a generator from the power system that might be affected by the sub-synchronous oscillation. To detect sub-synchronous oscillations with low computational effort and good accuracy, an amplitude of each phase of the oscillation component is calculated and compared against a threshold, a sub-synchronous oscillation is detected upon exceeding the threshold during a given time delay, and a fault signal is generated upon detecting a sub-synchronous oscillation. A device having a processing unit is also provided.