A method which is suitable for a system having a frequency converter and a generator, both of which are connected to a power grid, includes obtaining sub-synchronous components of the grid voltage and determining damping current set points according to the sub-synchronous components to compensate for sub-synchronous resonances of the grid. Damping current set points are determined by receiving the sub-synchronous components of the grid voltage and returning damping current set points as outputs. A variable damping gain is adjusted according to the sub-synchronous frequency of the grid, such that the required compensation level can be adapted to the frequency converter for damping sub-synchronous resonance of the grid.

A method for controlling an inverter-based resource (IBR) having a power converter and a generator connected to an electrical grid includes determining an available active power of the electrical grid. The method also includes determining an available active power of the IBR based on an effect of a speed and a rating of the generator. Further, the method includes determining a minimum available active power based on the available active power of the electrical grid and the available active power of the IBR. Moreover, the method includes determining an active power limit change for the IBR based on one or more thermal margins of the IBR. In addition, the method includes determining an active power estimation as a function of the minimum available active power and the active power limit change. The method further includes providing the active power estimation to a supervisory controller for controlling the IBR.

This application discloses a photovoltaic device, a photovoltaic inverter, a system, and a power limit control method. The device includes a DC-DC converter circuit, an inverter circuit, and a controller. An input end of the DC-DC converter circuit is connected to a photovoltaic array, and an output end of the DC-DC converter circuit is connected to an input end of the inverter circuit. The controller is configured to: receive a power scheduling instruction, where the power scheduling instruction carries a power reference value; and when the power reference value is less than a power at a maximum power point, reduce an input current of the DC-DC converter circuit; or when an input voltage of the DC-DC converter circuit is greater than or equal to a preset voltage, increase an input current of the DC-DC converter circuit until an output power of an inverter becomes consistent with the power reference value.

Disclosed is a power network system etc. which can safely detach a power router whose communication with a control apparatus becomes interrupted, from other power routers and power cells, the power network system including a second control apparatus controlling one of or plural of the power cells, when the second control apparatus detects abnormality in communication between the apparatus itself and the power router, the second control apparatus performs control so as to stop transmission/reception between the power router in which the abnormality is detected and another power router which is connected to the power router, and when the first control apparatus included in the power router detects abnormality in communication between the power router and the second control apparatus, the first control apparatus performs control so as to stop transmission/reception of the power conversion leg connected to the another power router.

Disclosed is a power network system etc. which can safely detach a power router whose communication with a control apparatus becomes interrupted, from other power routers and power cells, the power network system including a second control apparatus controlling one of or plural of the power cells, when the second control apparatus detects abnormality in communication between the apparatus itself and the power router, the second control apparatus performs control so as to stop transmission/reception between the power router in which the abnormality is detected and another power router which is connected to the power router, and when the first control apparatus included in the power router detects abnormality in communication between the power router and the second control apparatus, the first control apparatus performs control so as to stop transmission/reception of the power conversion leg connected to the another power router.

An inverter current equalization method includes separately comparing a reactive current of a first inverter and a reactive current of a second inverter with a reactive current reference value, to obtain a reactive current difference of the first inverter and a reactive current difference of the second inverter, separately comparing an active current of the first inverter and an active current of the second inverter with an active current reference value, to obtain an active current difference of the first inverter and an active current difference of the second inverter, and adjusting an input voltage amplitude of the first inverter and an input voltage amplitude of the second inverter based on the reactive current difference of the first inverter and the reactive current difference of the second inverter.

There is provided a power supply arbitration device that makes it possible for side of a power consumer to take initiative to stabilize a power grid and suppress peak power for the power consumer. The power supply arbitration device including a control unit, a communication unit that communicates with another device through a communication network, and a storage unit that stores information, in which, in a case where a power request received by the communication unit is requested from a power consumption device registered in the storage unit, the control unit specifies a power supply device registered in the storage unit as a power feeding device that supplies power requested by the registered power consumption device on a basis of a power consumption profile associated with the registered power consumption device.

There is provided a power supply arbitration device that makes it possible for side of a power consumer to take initiative to stabilize a power grid and suppress peak power for the power consumer. The power supply arbitration device including a control unit, a communication unit that communicates with another device through a communication network, and a storage unit that stores information, in which, in a case where a power request received by the communication unit is requested from a power consumption device registered in the storage unit, the control unit specifies a power supply device registered in the storage unit as a power feeding device that supplies power requested by the registered power consumption device on a basis of a power consumption profile associated with the registered power consumption device.

A method can be used to control a voltage source converter of a power supporting arrangement to act as a virtual synchronous machine. The method includes obtaining a measured power level of the converter, processing the measured power level using a differential equation of an angular velocity of the virtual synchronous machine in order to obtain a control contribution, providing a phase angle of a physical quantity used to control the converter based on the control contribution, monitoring the ability of the converter to act as a virtual synchronous machine, determining that the ability of the converter to act as a virtual synchronous machine is deemed insufficient, and adjusting the control contribution by increasing the damping term and/or decreasing the moment of inertia term in response to determining that the ability of the converter to act as a virtual synchronous machine is deemed insufficient.

A method can be used to control a voltage source converter of a power supporting arrangement to act as a virtual synchronous machine. The method includes obtaining a measured power level of the converter, processing the measured power level using a differential equation of an angular velocity of the virtual synchronous machine in order to obtain a control contribution, providing a phase angle of a physical quantity used to control the converter based on the control contribution, monitoring the ability of the converter to act as a virtual synchronous machine, determining that the ability of the converter to act as a virtual synchronous machine is deemed insufficient, and adjusting the control contribution by increasing the damping term and/or decreasing the moment of inertia term in response to determining that the ability of the converter to act as a virtual synchronous machine is deemed insufficient.