System, device and method for exporting power are provided including at least one AC optimizer with plurality of DC inputs each connecting with respective one of plurality of DC sources, and independent maximum power point tracking (MPPT) performed for each respective DC source to extract power from each DC source for output and coupling to AC grid. When multiple AC optimizers are employed, with each AC optimizer having multiple DC inputs, each DC input can be connected to PV module with independent MPPT function. Since, each AC optimizer can serve multiple PV modules, significant cost saving and efficiencies can be achieved. Optionally, on PV sub-module level, each of the multiple DC inputs can be used as an independent MPPT channel for a PV sub-module cell string.

Methods, systems, and computer readable mediums for protecting and controlling a microgrid with a dynamic boundary are disclosed. One method includes detecting a fault in a microgrid that includes a dynamic point-of-common-coupling (PCC), in response to determining that the microgrid is operating in a grid-connected mode, isolating the fault by tripping a microgrid side smart switch and a grid side smart switch that are located immediately adjacent to the fault, initiating the reclosing of the grid side smart switch, and initiating the reclosing for the microgrid side smart switch via resynchronization if the grid side smart switch is successfully reclosed, and in response to determining that the microgrid is operating in an islanded mode, isolating the fault by tripping a microgrid side smart switch that is located immediately adjacent to the fault, and initiating the reclosing of the microgrid side smart switch.

A nanogrid and a virtual inverter controller for the nanogrid are disclosed. The nanogrid includes at least one parallel branch, and at least one branch is equipped with a protector. At least one of the protectors is equipped with one virtual inverter controller. The virtual inverter controller includes a sensor component configured to detect at least one characteristic parameter on the branch, and a control component affecting the electrical connection state of the corresponding protector of the virtual inverter controller according to the characteristic parameter.

A method and apparatus for autonomous rapid shut-down of a power conditioner. In one embodiment, the method comprises determining an amount of active and reactive current generated by a power conditioner; determining whether the amount of active and reactive current satisfies an open circuit threshold; and initiating, when the amount of active and reactive current satisfies the open circuit threshold, deactivation of the power conditioner.

The present innovations control and improve operation of one or more microgrids optionally and/or intermittently coupled to an Electric Power System(s).

Embodiments herein describe operating wind turbines in an offshore park to provide auxiliary power to a local AC grid or to an onshore grid during a grid malfunction. In one embodiment, the offshore park is coupled via a HVDC link to an onshore grid. When the HVDC link is down, a substation in the park includes a backup generator for creating a weak grid for powering auxiliary systems in a pilot turbine. The wind turbines in the park can switch to an auxiliary control system help power the auxiliary systems in the substation and in other turbines. In another embodiment, the offshore park is AC coupled to an onshore grid using a transformer in the substation. The wind turbines can participate in a brown or black start following a grid fault by switching to operating using the auxiliary control system.

Aspects of the present invention relate to controlling a renewable energy power plant comprising a plurality of wind turbine generators (WTG)s and an energy storage system (ESS). A method includes: controlling the plurality of WTGs to stop generating power, and thereby to enter a non-exporting mode of operation of the renewable energy power plant, during which one or more auxiliary systems of the renewable energy power plant are powered to maintain at least one of the plurality of WTGs in a standby state, operable to start generating power upon demand; wherein the one or more auxiliary systems are powered during the non-exporting mode of operation.

A method for designing a distributed communication topology of a micro-grid based on network mirroring and global propagation rates includes the following steps: first, determining the communication connectivity of distributed directed networks in the micro-grid; next, obtaining, for connected directed communication networks, mirror networks thereof based on a mirroring operation, and selecting an optimal distributed directed communication topology corresponding to a maximum performance indicator based on algebraic connectivity and communication costs; solving, for the optimized distributed communication topology, pinned distributed generation sets corresponding to different pinning numbers based on global propagation rates and out-degrees; and finally, establishing a distributed secondary voltage control of the micro-grid based on the optimal distributed communication network and pinned nodes of the micro-grid, to achieve accurate reactive power sharing and average voltage restoration.

A fault isolating device for use in a microgrid disconnected from a main power grid includes a voltage meter for detecting a voltage anomaly indicative of an electrical fault, a timer for establishing a time window that begins and ends a predetermined time after a voltage anomaly is detected, a switch that is opened at the start of the time window, and a microcontroller that determines whether to leave the switch open to isolate a faulted portion of the microgrid or to close the switch. A plurality of fault isolating devices can be distributed throughout a microgrid to isolate a faulted branch or faulted branches of an islanded microgrid without interfering with normal fuse operation when the microgrid is connected to the main power grid.

A method for block loading an electrical grid with a combined cycle power plant (CCPP) includes operating a gas turbine system of the CCPP in an islanding mode with a steam turbine system of the CCPP off line with turning gear rotating only; loading the steam turbine system accordingly to temperature matching conditions of the steam turbine system, the loading of the steam turbine system includes controlling gas turbine exhaust fed to the steam turbine system and the gas turbine exhaust temperature heats the steam turbine system and to meet temperature matching conditions of the steam turbine system; wherein controlling gas turbine exhaust includes controlling fuel flow and air flow to the gas turbine system; and operating at least one of the gas turbine system and steam turbine system to block load the electrical grid from a load on at least one of gas turbine system and steam turbine system.