A Practical Current Source Inverter-Based High-Power Medium-Voltage PV System

The power converters currently used in high-power (a few megawatts) medium-voltage PV systems require the use of a line-frequency transformer (LFT), which is bulky and costly. To solve this issue, cascaded H-bridge converter and modular multilevel converter based converters were proposed and investigated in the literature. They can eliminate the LFT but suffer several technical challenges, one of which, for example, is a power imbalance. To address these challenges, extra efforts, such as modified converters, modulations, and controls, are needed. Such extras burden the original converters and introduce new challenges. Therefore, a new power converter is proposed in this work. It eliminates the LFT without these challenges faced by the existing solutions. In addition, it features reliable short-circuit protection, high scalability, simple, and well-proven converters. The operation principle is introduced, and the control scheme is developed. The performance is investigated and verified based on both simulations and lab-scaled experiments.

Automated summary

The current power converters used in high-power medium-voltage PV systems require the use of a bulky and costly line-frequency transformer. To address this issue, cascaded H-bridge converter and modular multilevel converter based converters have been proposed. However, they face technical challenges, such as power imbalance, which require additional efforts for modifications and controls. In this work, a new power converter is proposed that eliminates the need for a line-frequency transformer and overcomes these challenges. It features reliable short-circuit protection, high scalability, and well-proven converters. The operation principle and control scheme are introduced and performance is verified through simulations and lab-scaled experiments.