A Control Method for Compound Virtual Synchronous Machine Applicable to Unbalanced Conditions

Abstract

The invention provides a compound virtual synchronous machine control method suitable for unbalanced conditions, and belongs to the technical field of virtual synchronous machine control. The method is as follows: Step 1, calculate the positive-sequence fundamental wave active power and positive-sequence fundamental wave reactive power output by the inverter; Step 2, use the virtual speed control loop to obtain the phase command of the inverter output voltage; Step 3, use The virtual excitation control loop obtains the amplitude command of the inverter output voltage, and combines the phase command to obtain the reference voltage; step 4, adding virtual impedance control to the voltage loop and using positive sequence virtual impedance control to decouple active power and reactive power; Step 5. Correct the reference current value of step 4, and set the coefficient N to coordinate the control of power fluctuation and current quality; Step 6, set the coefficient k to select the reference current to obtain the actual reference current value of the current loop; Step 7, sample the inductor current , using the current loop to perform quasi-PR control on the current reference value and the inductor current 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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