A power system includes: a self-commutated power converter including a first arm and a second arm, each including switching elements; a first circuit breaker configured to interrupt a current flowing through a power transmission line provided between a first bus and a second bus; a first circuit breaker control unit configured to control the first circuit breaker; a converter control unit configured to stop the switching elements based on a first arm current value and a second arm current value; and a setting unit configured to set a voltage value of an AC voltage output from the power converter such that when a fault occurs in the power transmission line, the first circuit breaker is opened while the switching elements are not stopped. The converter control unit is configured to operate the switching elements such that an AC voltage with the set voltage value is output.

There is disclosed a method for identifying one or more faulted conductors in a power transmission system having at least two power-transmitting conductors and a method for determining fault location. Both methods include steps of monitoring current signals which are representative of currents in the conductors at a generally common location within the power transmission system; filtering the current signals; determining a maximum rate of change of each filtered current signal within a predetermined time interval after the fault event has commenced; and calculating a ratio of a pair of the maximum rates of change of the filtered current signals. For fault classification, the ratio is compared against a discrimination factor to identify the one or more faulted conductors. For fault location, the calculated ratio is compared against the calibration data to determine the distance from the connection terminal of the faulted conductor to the fault location.

A distribution network management system includes a power generation device including a renewable energy power generation source, and is connected to a distribution network through a first node; a first distributed device including a first distributed resource, connected to the distribution network through a second node, and configured to receive first node information and power generation information from the power generation device and attempt to control the first distributed resource so that an overvoltage for the first node is resolved; and a second distributed device including a second distributed resource, connected to the distribution network through a third node which is located farther away from the first node than the second node, and configured to, when the first node information and the power generation information are received from the first distributed device, attempt to control the second distributed resource so that the overvoltage for the first node is resolved.

Evaluating expected performance of a wind farm during a voltage event of a power grid, using a simulation tool. The tool initiates a simulated voltage event, at time, t.sub.0; initiates simulation of a subsequent response to the voltage event by the farm; retrieves information regarding an initial voltage state of a model of the farm, at t.sub.0, and predicts a final voltage state of the model of the wind farm, based on the retrieved information regarding the initial voltage state. At t.sub.0, a simulated output current, I, of the farm is lowered, based on the retrieved information and the predicted final voltage state, and a simulated output voltage, V, of the model of the farm, is monitored. The simulated output current, I, of the farm is subsequently adjusted, based on V, while monitoring V, I, and/or simulated output power of the model. Expected performance of the farm is then evaluated.

A method and a device for on-grid and off-grid dispatch, and an energy storage air-conditioning system are provided. The method for on-grid and off-grid dispatch includes: causing a load to be off-grid and causing an energy storage converter to supply power to the load after determining that grid is down; determining a given power and a given voltage according to a voltage and a current of the load obtained for the last time before the grid is down; and obtaining an actual voltage and an actual current outputted by the energy storage converter; and adjusting an output parameter of the energy storage converter according to the given power and the given voltage, as well as the actual voltage and the actual current outputted by the energy storage converter. It is possible to realize seamless shifting from an on-grid state to an off-grid state, thereby avoiding electric energy quality fluctuation during the shifting process and improving the stability.

One example includes a power generator protection system. The system includes a circuit breaker configured, when triggered, to provide an open circuit in a power line configured to conduct a current between a power grid point-of-interconnect (POI) and a power generator system. The system also includes a programmable controller configured to monitor the current and to generate a dynamic current threshold based on the current. The programmable controller can further be configured to compare the current with the dynamic current threshold and to trigger the circuit breaker based on a difference of the current relative to the dynamic current threshold to set an arc flash incident energy level of the power generator system at or below a predetermined safety level.

Described are systems and techniques for extracting frequency and voltage harmonic transients corresponding to individual load events. Such systems and techniques can be used to make electrical loads aware of the operation of other loads in an electric grid. Thus, awareness is achieved using information derived only from a utility voltage waveform at a load. Also described are systems and techniques for incorporating such awareness into load controllers which allows loads to autonomously meet system level objectives in addition to their individual requirements.

An impedance injection unit (IIU) system is coupled to a high-voltage (HV) transmission line. The IIUs are activated in sequences of activation in successive time periods. This injects an impedance waveform onto the HV transmission line. The ordering of IIUs in the sequences of activation is repeatedly changed in successive time periods. This equalizes electrical stress across the IIUs used, leading to overall improvement in IIU system lifetimes.

A method includes detecting a fault in a grid coupled to a distribution power network, the distribution power network comprising a distribution feeder, a plurality of distributed energy resources (DERs) coupled to the distribution feeder and a reference point of applicability (RPA) associated with the plurality of DERs, and in response to detecting the fault, determining an error voltage at the RPA, converting the error voltage into an error signal, broadcasting the error signal to the plurality of DERs, and based on the error signal, reducing the error voltage at the RPA by injecting a plurality of currents from the plurality of DERs to the distribution feeder.

A method for controlling the rebuilding of an electrical supply network, wherein the electrical supply network has a first network section and at least one further network section, at least one wind farm is connected to the first network section, the wind farm can be controlled via a wind farm control room, the first network section is coupled to the at least one further network section via at least one switching device in order to transmit electrical energy between the network sections, the at least one switching device is set up to disconnect the first network section from the at least one further network section in the event of a fault, a network control station is provided for the purpose of controlling the at least one switching device, wherein, in the event of a fault during which a network fault acting on the first network section occurs, the first network section is disconnected from the at least one further network section by the at least one switching device, the wind farm control room interchanges data with the network control station via a control room connection, wherein the control room connection is a failsafe communication connection between the wind farm control room and the network control station and can be operated independently of the electrical supply network, in particular can be operated even in the case of the fault in the first network section, and the wind farm receives data from the network control station via a wind farm connection, wherein the wind farm connection is a failsafe communication connection between the wind farm and the network control station and can be operated independently of the electrical supply network, in particular can be operated even in the case of the fault in the first network section, and further data which are not transmitted via the control room connection and are not transmitted via the wind farm connection are transmitted via a further data connection provided that the latter has not failed.