The present invention provides an AC power supply capable of programming output impedance and a method for simulating output impedance. The method comprises the following steps. The simulating command, selectively provided by a control circuit, is associated with a voltage adjustment value and a phase adjustment value of a test circuit. The control circuit calculates the voltage adjustment value and a preset voltage value to form a voltage command, and calculates the phase adjustment value and a preset phase value to form a phase command. A power supply circuit generates a simulated output voltage according to the voltage command and the phase command. The preset voltage value and the preset phase value are related to a preset output voltage provided by the power supply circuit, and the simulated output voltage is a simulation of the preset output voltage, provided by the power supply circuit, passed through the test circuit.

An electrical consumer of an aircraft comprises an electric motor and an inverter for producing an alternating voltage for the electric motor. A method for controlling the electrical consumer comprises determining a rotational frequency for the electric motor. The method also includes establishing whether the rotational frequency leads to oscillations in the input current of the inverter which are below a predefined threshold, the oscillations being produced by the inverter when producing a supply voltage for the electric motor, and changing the rotational frequency if it has been established that the rotational frequency leads to oscillations below the predefined threshold.

A control server according to an embodiment sorts a plurality of notebook PCs into a plurality of groups so that the total value of the remaining energy is a value similar to the total value of the remaining energy of the rechargeable batteries of a plurality of notebook PCs included in a different group. The control server according to the embodiment performs local search individually on the sorted groups, and generates a control plan for the individual notebook PCs.

Voltage fluctuations in a supply network are intended to be reduced efficiently and cost-effectively. According to the method, a current flowing into a load is measured and a corresponding current measurement signal is obtained. The voltage fluctuations are reduced with the aid of a TCR, which constitutes a thyristor-controlled reactance, and a VSC, which constitutes a voltage source converter. The current measurement signal or a corresponding variable is divided into a first portion and a second portion depending on a predefined absolute limit value. The TCR is controlled on the basis of the first portion and the VSC is controlled on the basis of the second portion. Alternatively, the TCR can be controlled with the load current measurement signal and the VSC can be controlled with a sum of the load current measurement signal and a TCR current measurement signal.

A predictive control method of a grid-connected converter based on a structurally adaptive extended state observer (ESO) is provided. The method includes: obtaining data of a grid current and a grid voltage and converting the data to data in a dq coordinate system; calculating a selected voltage vector based on a voltage in the dq coordinate system; adaptively inputting the current in the dq coordinate system to a parallel ESO, a cascade ESO, or a hybrid cascade-parallel ESO, so as to obtain a current predicted current value and estimated total disturbance; carrying out a two-step grid current prediction based on the current predicted current value, the estimated total disturbance and the selected voltage vector; and taking minimizing a cost function as a control target, so as to obtain an optimal voltage vector based on a two-step grid current prediction result, and carrying out switching control of the grid-connected converter.

An interface circuit to interface an energy source to a power bus of a microgrid includes a switching inverter circuit, an output filter circuit coupled between an output of the three-phase inverter circuit and the power bus, and a control circuit loop to control switching of the switching inverter circuit. The control circuit loop is coupled to the output filter circuit and the switching inverter and includes a proportional-integral oscillator-based repetitive (PIOR) controller.

An apparatus is configured to supply power to a load or absorb power from the load, the load being connected or connectable to a load conductor. The apparatus comprises a power supplying and/or absorbing device, configured for selectively supplying power to the load conductor or absorbing power from the load conductor, and a control unit configured to control the power supplying and/or absorbing device. The control unit is configured to determine, based on at least one value indicative of voltage of the load conductor and a virtual impedance of the power supplying and/or absorbing device, a voltage reference value for the power supplying and/or absorbing device, and control the power supplying and/or absorbing device to supply power to the load conductor, and thereby supply power to the load, or absorb power from the load conductor, and thereby absorb power from the load, based on the determined voltage reference value.

An interface circuit to interface an energy source to a power bus of a microgrid includes a switching inverter circuit, an output filter circuit coupled between an output of the three-phase inverter circuit and the power bus, and a control circuit loop to control switching of the switching inverter circuit. The control circuit loop is coupled to the output filter circuit and the switching inverter and includes a proportional-integral oscillator-based repetitive (PIOR) controller.

A grid connection inverter system includes a converter, an additional damping controller, a sampling circuit, and a controller. The converter is configured to output a grid connection voltage, a grid connection current, and power to the power grid. The sampling circuit is configured to detect the grid connection voltage, the grid connection current, and a power grid frequency of the power grid. The additional damping controller is configured to output a power additional value to the controller based on the grid connection voltage and the power grid frequency when the power grid is in a low-frequency oscillation state, where the power additional value includes an active power additional value and a reactive power additional value. The controller is configured to adjust, based on the power additional value, reactive power and active power that are output by the converter.

A dynamic stability control method for power systems with renewable energy, in which a non-linear system of a grid-forming inverter corresponding to a renewable energy power system is created. An external subsystem corresponding to the grid-forming inverter is constructed based on a Lie derivative. According to the external subsystem, a linear sliding surface corresponding to the external subsystem is constructed, and a dynamic stability control unit corresponding to the external subsystem is generated based on sliding mode control. A first instruction data corresponding to the dynamic stability control unit is generated to control dynamic stability of the renewable energy power system in real time. The voltage instruction value of the grid-forming inverter is modified to improve the dynamic stability of the renewable energy power system. A system for implementing such method is also provided.