A Grid Simulator with Accurate Harmonic Voltage and Virtual Impedance Control

Abstract

The invention proposes a power grid simulator having accurate harmonic voltage and virtual impedance control. The power grid simulator comprises a reactor, a rectification unit, a main inversion unit and an auxiliary inversion unit, wherein the rectification unit comprises a three-phase PWM rectifier and a PWM rectification controller, the main inversion unit comprises a main inverter and a main inversion controller, the auxiliary inversion unit comprises an auxiliary inverter and an auxiliary inversion controller, an input end of the three-phase PWM rectifier is accessed to a power grid through the reactor, an output end of the three-phase PWM rectifier is connected with the main inverter and the auxiliary inverter respectively, and an output end of the auxiliary inverter is connected with an output end of the main inverter. Compared with the prior art, the power grid simulator having accurate harmonic voltage and virtual impedance control, provided by the invention, has the advantages that a standard power grid output voltage, a power grid voltage fault working condition and a power grid harmonic component can be simulated, the power grid impedance change can also be simulated, and the demand of distributed power generation test research can be met very well.

Description

technical field [0001] The invention relates to the technical field of new energy power transmission, in particular to a grid simulator with precise harmonic voltage and virtual impedance control. Background technique [0002] As the penetration rate of renewable energy grid-connected power generation systems in the power system continues to increase, new energy power generation has an increasing impact on grid operation. In order to evaluate the performance index of the grid-connected converter, it is generally necessary to use electrical equipment that can simulate various grid operating characteristics to test the converter. Among them, a power electronic device that can simulate various grid characteristics is the grid simulator. On the one hand, the grid simulator needs to simulate the abnormal working conditions of the grid (such as voltage drop, frequency deviation, harmonic pollution, etc.) to assess the fault ride-through capability of the grid-connected converter; ...

AI Technical Summary

Problems solved by technology

The cut-off frequency of the output filter of the grid simulator is limited by the switching frequency and equipment power, so that the high-frequency harmonics output by the grid simulator are greatly attenuated, and the simulation accuracy cannot be guaranteed

The performance of the grid-connected inverter in the distributed grid is closely related to the grid impedance, especially in a weak grid, the grid impedance will cause the resonance point of the output filter in the distributed grid-connected inverter to move down, which may lead to distributed grid-connected system instability

However, none of the existing grid simulator solutions can effectively simulate grid impedance, so it is necessary to provide a grid simulator that can not only simulate grid output voltage but also simulate grid impedance changes

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