Abstract: A method for transferring power between medium voltage feeders via a direct current link in a power distribution network includes setting an iteration step value for each of a set of power reference quantities of the link, setting an initial value of each reference quantity, iteratively changing values of each reference quantity, and selecting one changed value of the set by: changing a present value of each reference quantity with the set iteration step value into a new value, measuring a total active power at a substation of the power distribution network for each new value, and selecting the new value that provides the lowest measured total active power at the substation. A next iteration is performed with the selected new value as present value for the one of the set of power reference quantities and with the present value for the other of the set of power reference quantities.

Abstract: A method for restoration of a fault isolation in a medium voltage, MV, network having a plurality of feeders and a plurality of normally open, NO, switches possibly in parallel with MV direct current, DC, links is presented. The method is performed in a control device of the MV network. The method includes closing at least two NO switches in parallel with MVDC links of the plurality of NO switches, being connected to a fault isolated feeder of the plurality of feeders of the MV network, and opening the closed at least two NO switches in parallel with MVDC links except one. A control device, a computer program and a computer program product for restoration of a fault isolation in a MV network are also presented.

Abstract: A power distribution arrangement for distributing AC power to loads requiring AC power is disclosed. The power distribution arrangement comprises a power distribution substation comprising transformers, switches, buses, and feeders, a DC transmission line, and at least one control unit. The control unit may control operation of the switches to selectively connect or disconnect one or more feeders to or from at least one transformer via one or more buses and to selectively connect or disconnect the DC transmission line to or from one or more feeders via at least one bus, whereby AC power is distributed to the loads via the feeders. The control unit may control operation of the switches based on: loading in and a power transfer rating of respective feeders and transformers, and any power transfer via the DC transmission line from the other power distribution substation to the at least one bus.

Abstract: A power distribution arrangement for distributing AC power to loads requiring AC power is disclosed. The power distribution arrangement comprises a power distribution substation comprising transformers, switches, buses, and feeders, a DC transmission line, and at least one control unit. The control unit may control operation of the switches to selectively connect or disconnect one or more feeders to or from at least one transformer via one or more buses and to selectively connect or disconnect the DC transmission line to or from one or more feeders via at least one bus, whereby AC power is distributed to the loads via the feeders. The control unit may control operation of the switches based on: loading in and a power transfer rating of respective feeders and transformers, and any power transfer via the DC transmission line from the other power distribution substation to the at least one bus.

Abstract: A method for transfer of power between medium voltage, MV, feeders via a MV direct current, MVDC, link in a power distribution network is presented.

Abstract: One embodiment is a system comprising a medium voltage direct current (MVDC) link electrically coupling a first AC-DC converter and a second AC-DC converter. The first AC-DC converter is electrically coupled with a first alternating current (AC) feeder. The second AC-DC converter electrically coupled with a second AC feeder. A battery charger electrically coupled with the MVDC link via a converterless connection. A first electronic controller is operatively coupled with the first AC-DC converter. A second electronic controller is operatively coupled with the second AC-DC converter. During operation of the battery charger to charge a battery the first electronic controller is configured to control power flow between the first AC feeder and the second AC feeder and the second electronic controller is configured to control the voltage of the MVDC link.

Abstract: A method for restoration of a fault isolation in a medium voltage, MV, network having a plurality of feeders and a plurality of normally open, NO, switches possibly in parallel with MV direct current, DC, links is presented. The method is performed in a control device of the MV network. The method includes closing at least two NO switches in parallel with MVDC links of the plurality of NO switches, being connected to a fault isolated feeder of the plurality of feeders of the MV network, and opening the closed at least two NO switches in parallel with MVDC links except one. A control device, a computer program and a computer program product for restoration of a fault isolation in a MV network are also presented.

Abstract: Method (300) of controlling a distribution network (1) and a microgrid controller (8) adapted for the method. The distribution network (1) comprises assets (3-7) in a first part (1a) and a second part (1b). which parts (1a, 1b) are selectively connected to each other into an interconnected state at a connection point (PCC). The method comprises monitoring (301, 306) and controlling (310) the assets (3-7) of the distribution network (1). In a first control mode (310A), the first part (1a) is controlled by a distribution network controller (9) and the second part is controlled by the microgrid controller (8).

Abstract: A method of controlling a microgrid arrangement including a microgrid having a plurality of switches, and a plurality of Distributed Generators arranged for being connected to the microgrid. The method includes obtaining information about the microgrid arrangement. The method also includes, based on the obtained information, dynamically linking a first group of switches, of the plurality of switches, to each other. The method also includes detecting an event in the microgrid, and in response to the detection, automatically opening closed switches in the first group, whereby a first segment of the microgrid is disconnected from a second segment of the microgrid.

Abstract: A method performed by a network controller of an electrical microgrid having a plurality of energy storages. Each of the energy storages is associated with a respective storage controller. The method includes receiving information about a measurement made at a remote location in the microgrid. The method also includes obtaining respective participation factors in respect of the remote location for each of at least a first energy storage and a second energy storage of the plurality of energy storages. The method also includes obtaining respective states of charge for each of the at least first and second energy storages. The method also includes, for each of the at least first and second energy storages, calculating a reference value for the energy storage, and sending the reference value to the storage controller with which the energy storage is associated. The calculating includes calculating the reference value based on the obtained participation factors and the obtained states of charge.

Abstract: A method can be used for determining resiliency in a microgrid that includes a number of assets. The method includes obtaining status data about devices used to control the assets as well as about communication resources of this control, determining, based on the status data, the health and availability of each asset to assist each of a plurality of functions for handling disruptive events in the microgrid, determining a resiliency index of the microgrid in performing the plurality of functions, providing the resiliency index to a control system of the microgrid, comparing, in the control system, the resiliency index with a least one threshold, and changing the control of the microgrid if any of the thresholds is crossed.

Abstract: Unique systems, methods, techniques and apparatuses of fault mitigation are disclosed. One exemplary embodiment is a fault mitigation system for a medium voltage alternating current (MVAC) distribution network including a direct current (DC) link and a control system. The DC link is coupled to a first feeder line and a second feeder line. The control system is structured to determine a first feeder line is deenergized, operate the DC link so as to receive MVAC from a second feeder line and output low voltage alternating current (LVAC) to the first feeder line, operate a plurality of isolation devices, measure the LVAC in response to operating the plurality of isolation devices, determine a fault is isolated from a healthy portion of the first feeder line using the received LVAC measurements, and reenergize the healthy portion of the first feeder line.

Abstract: A method can be used for determining resiliency in a microgrid that includes a number of assets. The method includes obtaining status data about devices used to control the assets as well as about communication resources of this control, determining, based on the status data, the health and availability of each asset to assist each of a plurality of functions for handling disruptive events in the microgrid, determining a resiliency index of the microgrid in performing the plurality of functions, providing the resiliency index to a control system of the microgrid, comparing, in the control system, the resiliency index with a least one threshold, and changing the control of the microgrid if any of the thresholds is crossed.

Abstract: A microgrid arrangement includes a decentralized microgrid control system, a first microgrid and a second microgrid separated by a microgrid breaker. The first and second microgrids each include a number of assets, each asset being associated with a respective microgrid controller (MGC) of the microgrid control system. The control system can be operated by determining that the microgrid breaker is open, assigning a first MGC in the first microgrid to a first group of MGCs in the first microgrid, broadcasting information from the first MGC to other MGCs in the first group, determining that the microgrid breaker is closed, assigning the first MGC to a second group of MGCs in both the first microgrid and the second microgrid, and broadcasting information from the first MGC to MGCs in the second group.

Abstract: Unique systems, methods, techniques and apparatuses of a distribution system are disclosed. One exemplary embodiment is an alternating current (AC) distribution system including a first substation including a first transformer and a protective device; a first distribution network portion coupled to the first transformer; a second substation; a second distribution network portion; a DC interconnection system coupled between the first distribution network portion and the second distribution network portion; and a control system. The control system is structured to detect a fault in the first transformer or the transmission network, isolate the first distribution network from the fault, determine a set point of the DC interconnection system, and operate the DC interconnection system using the set point so as to transfer a portion of the MVAC from the second distribution network portion to the first distribution network portion.

Abstract: Systems, methods, techniques, and apparatuses of a medium voltage alternating current (MVAC) network are disclosed. One exemplary embodiment is a direct current (DC) interconnection system for an MVAC distribution network including an AC/AC power converter including a first AC terminal and a second AC terminal; a plurality of switching devices structured to selectively couple a first AC terminal to a plurality of feeder line points in the MVAC network; and a control system structured to receive a set of measurements, calculate a headroom value for each feeder line point using the set of measurements, select a first feeder line point using the calculated headroom values, operate the plurality of switching devices so as to couple the first AC terminal to the first feeder line point, and operate the AC/AC power converter so as to transmit MVAC power from the first AC terminal to the first feeder line point.

Abstract: A method for controlling a microgrid including a plurality of assets connected in the microgrid, including loads and Distributed Generators, of which DGs at least a plurality are resources capable of being controlled in a grid forming mode for controlling the voltage and frequency in the microgrid. The method includes selecting a set of resources of the plurality of resources based on the respective location within the microgrid of each of the resources in the selected set, and activating a grid forming control mode for the resources in the selected set.

Abstract: One embodiment is a system comprising a medium voltage direct current (MVDC) link electrically coupling a first AC-DC converter and a second AC-DC converter. The first AC-DC converter is electrically coupled with a first alternating current (AC) feeder. The second AC-DC converter electrically coupled with a second AC feeder. A battery charger electrically coupled with the MVDC link via a converterless connection. A first electronic controller is operatively coupled with the first AC-DC converter. A second electronic controller is operatively coupled with the second AC-DC converter. During operation of the battery charger to charge a battery the first electronic controller is configured to control power flow between the first AC feeder and the second AC feeder and the second electronic controller is configured to control the voltage of the MVDC link.

Abstract: A method for synchronization of first and second microgrids, having respective first and second voltages and frequencies. The method includes determining a possible voltage and frequency range, determining an overlapping voltage range, determining an overlapping frequency range, selecting a third voltage within the overlapping voltage range. The method also includes selecting a third frequency within the overlapping frequency range. The method also includes controlling the first microgrid to change from the first voltage and frequency to the third voltage and frequency. The method also includes controlling the second microgrid to change from the second voltage and frequency to the third voltage and frequency. The method also includes connecting the first and second microgrids to each other by closing a switch there between.

Abstract: Systems, methods, techniques and apparatuses of feeder line fault response are disclosed. One exemplary embodiment is a method for operating an alternating current (AC) distribution network including a first feeder line, a second feeder line, and a third feeder line. The method includes isolating a faulted portion of the first feeder line from a healthy portion of the first feeder line; closing a tie switch coupled between the healthy portion and the second feeder line in response to isolating the faulted portion from the healthy portion; determining the second feeder line is experiencing an overload condition after closing the tie switch; and transferring AC power including transferring AC power using a direct current (DC) interconnection system coupled to the third feeder line effective to remove the overload condition from the second feeder line.