A method for controlling a wind farm to damp low-frequency electrical oscillations, in particular subsynchronous resonances, in an electrical supply grid having a grid voltage with a nominal grid frequency is provided. The wind farm comprises at least one wind turbine connected to the electrical supply grid. The method includes sensing at least one low-frequency electrical oscillation of the electrical supply grid; determining an oscillation characteristic of each of the at least one sensed oscillation, the oscillation characteristic describing at least one property of the sensed oscillation; specifying an active-power damping signal and/or a reactive-power damping signal for damping the at least one low-frequency oscillation; feeding in an active power component in accordance with the active-power damping signal or a reactive power component in accordance with the reactive-power damping signal, the active-power damping signal and the reactive-power damping signal being specified in dependence on the determined oscillation characteristic.

Methods and apparatuses for controlling reactive power of a wind turbine, and a wind farm are provided. An exemplary method includes: obtaining operation data of single wind turbines in a wind turbine group at the current time point; determining the total maximum capacitive reactive capacity and total minimum inductive reactive capacity, satisfying a safety constraint condition at the next time point, of the wind turbine group; calculating a deviation value of a wind turbine group reactive instruction at the current time point; and updating the wind turbine group reactive instruction on the basis of the acquired, determined, and calculated data so as to perform reactive power control.

A method for assisting control of an electrical supply grid) or a portion thereof is provided. The method includes recording system states of the grid and/or influencing the grid, transmitting the states to a central evaluation and/or control unit and/or between other subscribers, including wind turbines and/or wind farms that supply the grid, for use in controlling their supply to the grid. The method includes controlling the grid on the basis of the transmitted states. Fundamentally identical states are simultaneously recorded at multiple recording locations associated with the grid and the recording of at least one of the states at a respective recording location is performed by a turbine and/or farm and the turbine or farm recording a state at one recording location and the turbine or farm recording a state at another recording location are independent at least such that they supply to the grid at different points.

A method for assisting control of an electrical supply grid) or a portion thereof is provided. The method includes recording system states of the grid and/or influencing the grid, transmitting the states to a central evaluation and/or control unit and/or between other subscribers, including wind turbines and/or wind farms that supply the grid, for use in controlling their supply to the grid. The method includes controlling the grid on the basis of the transmitted states. Fundamentally identical states are simultaneously recorded at multiple recording locations associated with the grid and the recording of at least one of the states at a respective recording location is performed by a turbine and/or farm and the turbine or farm recording a state at one recording location and the turbine or farm recording a state at another recording location are independent at least such that they supply to the grid at different points.

A method for feeding electric power into an electrical supply grid by means of a local feed unit. The feed unit is connected to a grid link point connected to a transformer point directly or via a supply connection. The transformer point is connected to a grid section via a transformer. The method includes feeding electrical real power into the electrical supply grid at the grid link point, feeding electrical reactive power into the electrical supply grid at the grid link point, detecting a change to be made in the real power to be fed in, and changing the fed-in real power in accordance with the detected change to be made. The method includes limiting a change in the fed-in reactive power over time when changing the fed-in real power and/or immediately thereafter or temporarily activating voltage control on the basis of the change in the fed-in real power.

A method for feeding electric power into an electrical supply grid by means of a local feed unit. The feed unit is connected to a grid link point connected to a transformer point directly or via a supply connection. The transformer point is connected to a grid section via a transformer. The method includes feeding electrical real power into the electrical supply grid at the grid link point, feeding electrical reactive power into the electrical supply grid at the grid link point, detecting a change to be made in the real power to be fed in, and changing the fed-in real power in accordance with the detected change to be made. The method includes limiting a change in the fed-in reactive power over time when changing the fed-in real power and/or immediately thereafter or temporarily activating voltage control on the basis of the change in the fed-in real power.

A control system for a power production facility is provided. The control system includes a plurality of power generating assets configured to supply power to a power grid. The control system further includes a controller coupled in communication with the plurality of power generating assets. The controller is configured to receive at least one feedback value corresponding to a feedback parameter. The at least one feedback value represents a measured value associated with the power grid. The control system is further configured to determine, based on the received at least one feedback value, to operate in one of a closed-loop mode or an open-loop mode of control.

An online voltage control method for coordinating multi-type reactive power resources is provided. First, a linearized power flow equation of branch reactive power is established, and an online voltage control model of multi-type reactive power resources including an objective function and constraint conditions is constructed. The constrain conditions includes generator reactive power constraints, reactive power compensator constraints, transformer tap position constraints, a nodal reactive power balance constraint, and slack contained nodal voltage constraints. Then, an optimization result of voltage control is obtained by solving the model. The method makes full use of reactive voltage operation characteristics of a power grid, constructs a practical online solution model for reactive voltage control of large power grid of coordinating multiple reactive power resources, and under a condition of acceptable accuracy loss, takes in account safety of power grid operation, economy of reactive power resource actions and high reliability of online operation.

A method and system for controlling voltage and reactive power for electrical grids includes monitoring the output of the energy generation facilities at the point of interconnection (POI) of each energy generation facility to the power transmission system of the electrical grid. In addition, the voltage at a point of utilization (POU) is monitored to determine when the output voltage of the energy generation facilities must be adjusted to maintain voltage at the POU. In addition, when it is determined that energy generation facilities are exchanging reactive power, the voltage set points of the energy generation facilities are adjusted to reduce the exchanged power.

Disclosed is an optimal power flow acquiring method for regional distribution network of small hydropower groups based on deep learning, which specifically includes the following steps: generating required data sets by adopting continuous power flow and power flow equation calculation methods; the data set is randomly divided into training data (80 percent) and test data (20 percent); training the built convolutional neural network model with training data to learn the mapping relationship between load and generator output power; inputting test data, and directly obtaining P.sub.G and Q.sub.G from the trained convolutional neural network; and solving residual variables V.sub.i and θ.sub.i with traditional power flow solver. The application can accelerate the solving speed of the optimal power flow problem with higher prediction accuracy.