Abstract:
A method and a microgrid controller (4) for controlling load shedding in a microgrid (1), which microgrid (1) comprises a plurality of loads (12:1-12:5, 13:1-13:5), a plurality of power sources (2, 2A), and a point of common coupling (3) for selectively connecting the microgrid (1) to a main grid (30). The microgrid controller is provided for performing the method, which includes: - monitoring (202, 302) the power balance in the microgrid (1); - determining (204, 302) a need for load shedding in view of the power balance; and - selecting (206, 306) at least one load to be disconnected, in view of the need for load shedding. Especially, the selecting (206, 306) is performed in view of the locations of the plurality of loads (12:1-12:5, 13:1-13:5) within the microgrid (1) in relation to at least one microgrid system voltage and microgrid system frequency controlling entity (2, 3, 30) of the microgrid (1), wherein the loads (12:1-12:3; 13:1-13:2) that are closest to the microgrid system voltage and microgrid system frequency controlling entity, or entities, (2, 30) are prioritized for disconnection, and subsequently disconnecting (208) the selected load, or loads (12:1-12:3; 13:1-13:2).
Abstract:
The present disclosure relates to a method of controlling a microgrid arrangement (1) comprising a microgrid (6), a plurality of Distributed Generators (DGs) (2a, 2b.2c) connected to the microgrid (6), and a switch (5) for, in a closed position, connecting the microgrid (6) to a power grid(4), and for, in an open position, disconnecting the microgrid(6) from said power grid (4). The method comprises detecting instability in the microgrid(6). The method also comprises, in response to the detection, switching operating mode of a first DG (2a) of the plurality of DGs from a grid following mode to a grid forming support mode and of a second DG (2b) the plurality of DGs to a grid forming mode. The method also comprises, when the first DG(2a) is in the grid forming support mode, controlling output to the microgrid (6) from the first DG (2a) based on a first voltage reference during a transient state of the microgrid and based on a power reference during a steady state of the microgrid, and controlling output to the microgrid from the second DG (2b) based on a second voltage reference during both the transient state and the steady state.
Abstract:
A method for controlling a microgrid (1) comprising a plurality of microgrid assets (2), comprising determining (200) an individual control mode for island operation for each microgrid asset (2), which determining of individual control modes for island operation is performed when the microgrid (1) is connected. The determining (200) comprises calculating (201) the capability of each microgrid asset (2) to contribute in each of the available control modes of the microgrid asset (2), and determining (203) a specific control mode for each microgrid asset (2) in case of islanding. The method further comprises determining (110) whether a disconnection from the main grid occur. In case the microgrid (1) continues to be connected to the main grid, the method includes repeating the steps of determining (200) an individual control mode for each microgrid asset (2) as a preparation for islanding operation. In case the microgrid (1) becomes disconnected from the main grid the method includes controlling (301 ) each microgrid asset (2) in accordance with the determined control mode for the microgrid asset. Microgrid controllers 21 for distributed control of the method are also provided.
Abstract:
The present invention relates to a method for enabling dynamic evaluation of performance of a battery energy store. The battery energy store comprises a plurality of batteries and the method comprises excitation of the battery energy store, including increasing (1) a current charge/discharge for one or more of the plurality of batteries, and decreasing (1) a current charge/discharge for one or more of the plurality of batteries, wherein a total current charge/discharge for the plurality of batteries is kept unchanged; measuring (2) real-time parameters (V, I, T) of the excited battery energy store (1), estimating (3) a state of charge (SOC) for the battery energy store, the estimation being based on the measured real-time parameters and offline data (4) of the energy store, identification (3) of R-C parameters for an equivalent circuit model (ECM) of the battery energy store, the identification being based on the measured real-time parameters, updating (5) a look-up table with the identified R-C parameters for different operating conditions; and simulating (5) performance of the battery energy store based on two or more operating conditions. A system, a marine vessel and a computer program product thereof are also presented.
Abstract:
A method (100) for controlling power in a microgrid (1) that comprises power sources (3), loads (5) and at least one connection to a main grid (2) where a transformer (4) is arranged to transfer electric power between the microgrid (1) and the main grid (2) is disclosed. The method comprises: monitoring (101 ) the power balance within the microgrid (1); monitoring (102) the transformer (4), including monitoring the transformer temperature; and detecting (103) a need for overloading the transformer (4) based on the power balance within the microgrid (1). Especially, the method comprises: determining (106) a load profile for the transformer (4) based on the power balance within the microgrid (1); determining a prognosis (107) of the transformer temperature based on the load profile; and determining (108) a schedule for power control of the microgrid (1), which determining of a schedule for power control includes analyzing (108A) the prognosis of the transformer temperature.
Abstract:
A photovoltaic power plant system (1) for power generation is provided, comprising one or more photovoltaic clusters (18a, 18b, 18c, 18d) and one or more modular multilevel converters (22). Each photovoltaic cluster (18a, 18b, 18c, 18d) comprises a number of photovoltaic strings (14) connected to one or more MPPT DC/DC, converters (17a) connected to a common LVDC, bus. Each photovoltaic cluster (18a, 18b, 18c, 18d) comprises a DC/DC converter (13a) comprising an input connected to the LVDC bus, and an output connected to a MVDC collection grid (29a, 29b). Each of the one or more modular multilevel converters (22) comprises an input connected to the one or more photovoltaic clusters (18a, 18b, 18c, 18d) via the MVDC collection grid (29a, 29b) and an output connected to a transmission grid (23).
Abstract:
The present disclosure relates to a method of controlling a microgrid arrangement (1) comprising a microgrid (6) comprising a plurality of switches (8), and a plurality of Distributed Generators (DGs) (2a,2b,2c) arranged for being connected to the microgrid (6). The method comprises obtaining information about the microgrid arrangement(1).The method also comprises, based on the obtained information, dynamically linking a first group of switches, of the plurality of switches (8), to each other. The method also comprises detecting an event in the microgrid (6), and in response to the detection, automatically opening closed switches in the first group, whereby a first segment (9a) of the microgrid (6) is disconnected from a second segment (9b) of the microgrid (6).
Abstract:
The present invention relates to a method for enabling dynamic evaluation of performance of a battery energy store. The method comprises measuring (2) real-time parameters (V, I, T) of a battery energy store (1), estimating (3) a state of charge (SOC) for the battery energy store, the estimation being based on the measured real-time parameters and off-line data (4) of the energy store, identification (3) of R-C parameters for an equivalent circuit model (ECM) of the battery energy store, the identification being based on the measured real-time parameters, updating (5) a look-up table with the identified R-C parameters for different operating conditions, and simulating (5) performance of the battery energy store based on two or more operating conditions. A system, a marine vessel and a computer program product thereof are also presented.
Abstract:
A photovoltaic power plant system (1) for power generation is provided, comprising one or more photovoltaic clusters (18a, 18b, 18c, 18d) and one or more modular multilevel converters (22). Each photovoltaic cluster (18a, 18b, 18c, 18d) comprises a number of photovoltaic strings (14) connected to one or more MPPT DC/DC, converters (17a) connected to a common LVDC, bus. Each photovoltaic cluster (18a, 18b, 18c, 18d) comprises a DC/DC converter (13a) comprising an input connected to the LVDC bus, and an output connected to a MVDC collection grid (29a, 29b). Each of the one or more modular multilevel converters (22) comprises an input connected to the one or more photovoltaic clusters (18a, 18b, 18c, 18d) via the MVDC collection grid (29a, 29b) and an output connected to a transmission grid (23).