Abstract: A method for single-phase islanding detection in a three-phase electricity network, can include supplying power into a three-phase electricity network (EN) by a power supply assembly (PSA), the electricity network (EN) having a network voltage, and providing a stimulus signal into a positive sequence electric quantity of the electricity network, the positive sequence electric quantity being current, power or a derived quantity thereof. A magnitude and/or a rate of change of an indicative element of a negative sequence component of the network voltage is monitored, a frequency domain of the indicative element including a frequency corresponding to the stimulus signal. A single phase islanding condition is detected in the electricity network (EN) if the magnitude and/or rate of change of the indicative element exceeds a predetermined limit value.

Abstract: An exemplary method for detecting a three-phase islanding state in a three-phase electricity network includes supplying power to a three-phase electricity network via a power supply assembly, controlling an output frequency of the power supply assembly with a frequency reference signal adapted to deviate the output frequency of the power supply assembly from a grid frequency representing a frequency of a common electricity network whose portion of the three-phase electricity network is in normal operating conditions. The method also includes detecting a three-phase islanding state in the electricity network if the output frequency of the power supply assembly is outside an allowable value range. During a normal operating state of the electricity network, the frequency reference signal depends on an active output current of the power supply assembly.

Abstract: An exemplary method for detecting a three-phase islanding state in a three-phase electricity network includes supplying power to a three-phase electricity network via a power supply assembly, controlling an output frequency of the power supply assembly with a frequency reference signal adapted to deviate the output frequency of the power supply assembly from a grid frequency representing a frequency of a common electricity network whose portion of the three-phase electricity network is in normal operating conditions. The method also includes detecting a three-phase islanding state in the electricity network if the output frequency of the power supply assembly is outside an allowable value range. During a normal operating state of the electricity network, the frequency reference signal depends on an active output current of the power supply assembly.

Abstract: A method for single-phase islanding detection in a three-phase electricity network, can include supplying power into a three-phase electricity network (EN) by a power supply assembly (PSA), the electricity network (EN) having a network voltage, and providing a stimulus signal into a positive sequence electric quantity of the electricity network, the positive sequence electric quantity being current, power or a derived quantity thereof. A magnitude and/or a rate of change of an indicative element of a negative sequence component of the network voltage is monitored, a frequency domain of the indicative element including a frequency corresponding to the stimulus signal. A single phase islanding condition is detected in the electricity network (EN) if the magnitude and/or rate of change of the indicative element exceeds a predetermined limit value.