Inverter secondary-frequency-regulation control circuit based on virtual synchronous generator

Abstract

The invention discloses an inverter secondary-frequency-regulation control circuit based on a virtual synchronous generator. The inverter secondary-frequency-regulation control circuit comprises an inverter, an LC filter and a power measurement module, and also comprises a voltage loop and a VSG controller. The input end of the VSG controller is connected with the output end of the power measurement module, the output end of the VSG controller is connected with the input end of the voltage loop, and the output end of the voltage loop is connected with the inverter; the VSG controller comprises a power frequency controller and an excitation controller, the power frequency controller is used for simulating a rotor motion equation of the synchronous generator, the excitation controller is used for reactive-voltage droop control, the amplitude information of command voltage generated by the excitation controller and the phase information of command voltage generated by the power frequency controller are synthesized, and an input command signal em of the voltage loop cam be obtained. According to the inverter secondary-frequency-regulation control circuit, the VSG control strategy can automatically track load fluctuation and change output force of inverter secondary-frequency-regulation control circuit under the island model, and frequency support is provided for a micro grid.

Description

technical field [0001] The invention relates to the secondary frequency control of an inverter of a distributed power source in a microgrid, in particular to an inverter secondary frequency modulation control circuit based on a virtual synchronous generator. Background technique [0002] At present, in order to introduce the "synchronization" mechanism of the synchronous generator into the inverter, scholars have proposed a new control scheme, which enables the inverter to have the ability to damp power oscillation by simulating the rotor motion equation of the synchronous generator. , so as to help improve the stability of the system, the virtual synchronous generator control strategy (VSG, Virtual SynchronousGenerator), but most of the schemes in the current research can only realize the function of synchronous generator frequency regulation, that is, the VSG can adjust its own output in real time to provide power for the grid. Frequency support, however, the primary frequ...

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Problems solved by technology

[0004] Both the centralized and semi-distributed schemes require interconnection of communication lines, which has low reliability, and the low communication bandwidth will also cause delays in system response; the VF scheme in the decentralized control scheme essentially controls the voltage of the three-phase AC And frequency, the phase of the voltage is not controlled, which leads to the fact that in the transient process such as load mutation, the speed of the motor load will be slowed down by the impact, but the power supply frequency of the motor, that is, the synchronous angular velocity, remains unchanged, so Motor loads will produce instantaneous out-of-step, which will cause torque and speed oscillation. Due to the lack of control of the voltage phase, this transient process will last for a long time, which is why the response of constant voltage and frequency control is slow and the control accuracy is not high. At the same time, in order to meet the needs of load power changes, the inverter using VF control can only be an intermittent micro-source or a large-capacity non-intermittent micro-source containing a large-capacity energy storage device in the micro-grid

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