A method for evaluating resonance stability of a flexible direct current (DC) transmission system in an offshore wind farm includes: establishing an s-domain equivalent circuit of a flexible DC transmission system in an offshore wind farm, constructing an s-domain node admittance matrix of the flexible DC transmission system in the offshore wind farm, determining a resonant mode of the system based on a zero root of a determinant of the node admittance matrix, and determining stability of the system. In the method, an s-domain impedance model is used to describe dynamic characteristics of a wind turbine, a flexible DC converter, and other power devices, avoiding coupling between device modeling and an operation mode of the system. In addition, the node admittance matrix is used for analysis so as to fully consider a plurality of power electronic devices and a grid structure of the offshore wind farm, realizing comprehensive analysis.

The application relates to an oscillation active damping control method and system for grid-tied type-4 wind turbine generator. The method comprises: based on an interconnection model of multiple subsystems, constructing a stored energy function and a dissipated energy function of a current inner loop control subsystem, and interaction energy functions between the current inner loop control subsystem and other subsystems are constructed, then establishing an energy feedback model of Type-4 wind turbine generator; when the oscillation occurs, obtaining instantaneous angular frequency of the PLL, and then based on the energy feedback model, adjusting the current reference value of the q-axis current inner loop generated by the reactive power outer loop control subsystem, to make the stored energy function decrease with time, so as to suppress the oscillation.

A distributed energy conversion system may include one or more DC power sources and two or more inverters to convert DC power from the power sources to AC power. The AC power from the two or more inverters may be combined to provide a single AC output. A module may include one or more photovoltaic cells and two or more inverters. An integrated circuit may include power electronics to convert DC input power to AC output power and processing circuitry to control the power electronics. The AC output power may be synchronized with an AC power distribution system.

Regulating a power ramp rate of a wind park at a point of common coupling (PCC) between the wind park and a utility grid. The method comprises receiving a power reference for the wind park; determining the power ramp rate of the wind park as a function of the power output of each individual wind turbine in the park, wherein the power ramp rate of the wind park is based on the power ramp rates of the individual wind turbines and determining a corresponding plurality of power set-points for each wind turbine based on the power ramp rates and power reference. The corresponding plurality of power set-points is dispatched to the plurality of wind turbines for regulating the power ramp rate of the wind park in dependency of the power ramp rates of the plurality of wind turbines.

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.

The present disclosure discloses an offshore wind farm low-frequency alternating-current uncontrolled rectification electric power transmission system, comprising an onshore converter station and an offshore alternating-current system. The offshore alternating-current system comprises wind turbine generators, alternating-current submarine cables, a confluence bus, and offshore booster stations; the onshore converter station comprises a wind field side alternating-current bus, an alternating-current system side alternating-current bus, an alternating-current filter, an energy dissipation device, a rectifier, and a converter; the rectifier is composed of a three-phase six-pulse uncontrolled rectifier bridge, and the converter may be an MMC or an LCC; the rated frequency of the offshore alternating-current system is selected to be close to 10 Hz.

A method of controlling a wind power plant including an energy storage device, the wind power plant being connected to a power grid and comprising one or more wind turbine generators that produce electrical power for delivery to the power grid, the method comprising: processing input data related to one or more inputs to the wind power plant to determine a probability forecast for each input; and controlling charging and discharging of the energy storage device in accordance with each probability forecast and a prescribed probability of violating one or more grid requirements.

According to embodiments described herein control of the auxiliary power system in a hybrid power plant is provided by determining a grid-draw threshold from an external power grid; monitoring power consumption for powered systems of the hybrid power plant; monitoring power generation of the hybrid power plant; discharging an alternative power source of one or more of an Energy Storage System (ESS) and an auxiliary generator in response to the power consumption exceeding the grid-draw threshold; and implementing prediction algorithms for power generation of the hybrid power plant and the power consumption. Accordingly, a source of power is managed between several alternative sources and the external power grid to meet plant operator defined criteria when maintaining power in various wind speed conditions.

Disclosed are various embodiments for optimizing energy management. A quantity of renewable power that will be generated by renewable energy generation sources can be forecasted. The energy demand for a building or a cluster of buildings can be forecasted. A pricing model for buying energy from a grid can be determined. A quantity of energy to import from the grid or export to the grid can be scheduled based on the quantity of renewable energy forecasted and the state of charge or health of battery energy storage system, current and future operations of building HVAC, lighting and plug loads system, the forecasted energy demand for the building, and the pricing of the energy from the grid.