The present application relates to a method for controlling a power system connected to a power grid, including: receiving a reactive power instruction and a measured reactive power from a generator; generating a reactive power error signal based on the difference between the reactive power instruction and the measured reactive power; receiving the reactive power error signal; generating a voltage instruction based on reactive power error signal; generating a voltage droop signal based on a reference reactance and a voltage at a point of common coupling; generating a voltage error signal according to at least one of the voltage instruction or the measured terminal voltage of the generator and the voltage droop signal; and producing a reactive current instruction for the converter power path based on the voltage error signal. The present application also discloses a control system for a power system connected to a power grid and a wind farm.

Systems and methods for managing reactive power during low voltage ride through are provided. Responsive to detecting a fault on a power grid, a controller may identify a power regulation mode of the generator system. The controller can switch the power regulation mode to an offset power regulation mode of the generator system responsive to identifying the power regulation mode. The controller may adjust a value of a parameter of the generator system from a normal value to an offset value, wherein the parameter is selected based on the offset power regulation mode. The controller can maintain the value of the parameter as the offset value for a period of time. After the period of time, the controller can modify the value of the parameter from the offset value to the normal value, and the power regulation mode from the offset power regulation mode to the identified power regulation mode.

Systems, methods, and frameworks for distribution grid optimal power flow (D-OPF) are provided, to find the optimal droop and mode settings of smart inverters (SIs). The droop and mode settings of SIs can be found as per the Institute of Electrical and Electronics Engineers (IEEE)-1547 in coordination with the operations of legacy voltage control devices for optimal Volt-VAR control performance. The D-OPF framework can utilize two timescale coordination of control of legacy grid voltage control devices, modes and droop settings of SIs, and active/reactive power dispatch of SIs.

Harmonics of a power output of a power plant at a point of common coupling between the power plant and a utility grid, wherein the power plant comprises a plurality of energy production units. The method comprises determining an electrical characteristic at the point of common coupling; determining the electrical characteristic at an output terminal of each of the energy production units and dispatching a control signal to at least one of the energy production units to control the electrical characteristic at an output terminal of the respective energy production units. The control signal is based on the measurement of the electrical characteristic at the point of common coupling and arranged for damping the harmonic of the power output of the power plant at the point of common coupling, wherein the control signal is determined on the basis of a predetermined prioritizing sequence of said electrical characteristic.

Harmonics of a power output of a power plant at a point of common coupling between the power plant and a utility grid, wherein the power plant comprises a plurality of energy production units. The method comprises determining an electrical characteristic at the point of common coupling; determining the electrical characteristic at an output terminal of each of the energy production units and dispatching a control signal to at least one of the energy production units to control the electrical characteristic at an output terminal of the respective energy production units. The control signal is based on the measurement of the electrical characteristic at the point of common coupling and arranged for damping the harmonic of the power output of the power plant at the point of common coupling, wherein the control signal is determined on the basis of a predetermined prioritizing sequence of said electrical characteristic.

A power supply system, a converter, and a circulating current suppression method of the converter. The power supply system includes at least two converters that are coupled between a direct current power supply and an alternating current grid. Each converter obtains target output reactive power when an output current of the converter starts to increase from an initial current, obtains a reactive power compensation parameter based on the three-phase output voltages. Further, each converter obtains compensated output reactive power of the converter based on the reactive power compensation parameter and adjusts actual output reactive power of the converter based on the target output reactive power and the compensated output reactive power, so that an absolute value of a difference between common-mode output voltages of any two of the at least two adjusted converters is less than a difference threshold.

A method includes receiving, via one or more turbine-level controllers, an indication of at least one of a communication loss between the one or more turbine-level controllers and a farm-level controller, a detection of an absence of reactive power regulation by the farm-level controller, or a reactive power command of the farm-level controller being equal to or above a saturation threshold during transitioning between a baseline operational mode and reactive power mode, the reactive power mode being characterized in that only reactive power is generate. Upon receipt of the indication, the method includes adjusting a reactive power response of one or more reactive power regulators of the one or more turbine-level controllers so as to avoid an overshoot reactive power event or an undershoot reactive power event at the point of interconnection.

Hybrid renewable energy source systems and methods are provided. A hybrid renewable energy source system can include a renewable energy source system (e.g., a photovoltaic (PV) system) in conjunction with an energy storage system (ESS), such as a battery energy storage system (BESS). The hybrid renewable energy source system can include at least one intelligent decentralized controller at the inverter/converter level, feeding a robust coordinated controller, thereby allowing the hybrid renewable energy source system to operate as a unified single power generation unit (PGU).

The invention relates to controlling a power generating unit. Aspects of the invention include determining a virtual impedance value (Zvir), determining a virtual grid power (Pvsm) based on the virtual resistance value (Rvir) and the grid current (Igrid), determining a virtual synchronous machine rotational speed (ωVSM) and/or a synchronous machine angle (θVSM) of a virtual synchronous generator, and determining a voltage reference (Vabc) for controlling a line side converter to generate the desired reactive power (Qgrid) based on the virtual synchronous machine rotational speed or angle (ωVSM, θVSM), a virtual voltage (ΔVαβ, ΔVdq) and the voltage magnitude reference (Vqref).

A system and method are provided for damping power system oscillations in a power system network having one or more local inverter-based generators within a plant, the plant connected to a grid at a point of intersection (POI). The system and method include a plant-level controller or local controller that receives one or more grid signals having a characteristic indicative of a power system oscillation. The plant-level controller or local controller generates an auxiliary signal from the grid signals that is used by the local controller of the inverter-based generators. At the local controller, the auxiliary signal is used to modulate reactive power output from the inverter-based generator to change a voltage at the POI, the voltage change damping the power system oscillations.