Composite virtual synchronous machine control method suitable for unbalanced condition

Abstract

The invention provides a composite virtual synchronous machine control method suitable for an unbalanced condition, and belongs to the technical field of virtual synchronous machine control. The method comprises the steps of 1, calculating positive sequence fundamental wave active power and positive sequence fundamental wave reactive power output by an inverter; 2, obtaining the phase instructionof the output voltage of the inverter by using a virtual speed regulation control loop; 3, obtaining the amplitude instruction of the output voltage of the inverter by using a virtual excitation control loop, and obtaining a reference voltage in combination with the phase instruction; 4, adding virtual impedance control into the voltage loop, and adopting positive sequence virtual impedance control to decouple the active power and the reactive power; 5, correcting the reference current value in the step 4, and setting a coefficient N to coordinate and control power fluctuation and current quality; 6, setting a coefficient k for selecting a reference current to obtain an actual reference current value of the current loop; and 7, sampling the inductive current, and performing quasi-PR control on the current reference value and the inductive current by using a current loop to obtain a modulation signal.

Description

technical field [0001] The invention relates to a compound virtual synchronous machine control method suitable for unbalanced conditions, and belongs to the technical field of virtual synchronous machine control. Background technique [0002] With the increase of the penetration rate of Distributed Generators (DG) in the power grid, the characteristics of low inertia and under-damping of the interface between DG power generation and power electronic devices make the power grid more susceptible to interference from the external environment than traditional power grids. It is conducive to the safe and stable operation of the power grid. In order to solve the stability problem caused by the large-scale access of distributed power to the grid, relevant scholars proposed a control method of virtual synchronous generator (VSG). By simulating the working principle of the synchronous generator, the VSG control makes the inverter have the external characteristics of frequency modula...

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Problems solved by technology

[0004] Aiming at the problem that the existing inverter VSG control method suitable for unbalanced conditions cannot provide voltage and frequency support for the system, the present invention proposes a composite VSG control method suitable for unbalanced conditions. The operating performance of the inverter under the condition of unbalanced grid voltage can ensure that the basic properties of VSG voltage source control are not changed, and provide voltage and frequency support for the system

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