Design and control of a medium and high voltage modular multilevel power grid simulator

Abstract

The rapid and large-scale renewable energy development poses new challenges for the traditional power grid, particularly with the increasing utilization of high-power electronic interfaces. To address this, a novel grid simulator topology and its control strategy are proposed, which can generate various required waveforms with high performance. The grid simulator adopts a modular multilevel structure, a three-phase PWM module, and an H-bridge module with a shared DC bus. Model predictive control (MPC) outputs high-quality, fast voltage waveforms for accurate voltage tracking. Additionally, the model reference adaptive control (MRAC) is integrated into the PWM converter in the pre-stage to estimate the network side inductance value, which is used to improve the system’s robustness. Moreover, a switching distribution method is proposed for feedforward control to enhance reliability. Through simulation and experiment, it is verified that the proposed power grid simulator and its control strategy can effectively and accurately generate various fault waveforms such as voltage drop, voltage abrupt change, and abrupt frequency change. As a result, it can be used as test equipment for renewable energy or power electronic equipment.

Keywords

• Medium and high voltage grid simulator
• Model predictive control
• Modular multilevel converter
• Grid fault
• Model reference adaptive control