±35 kV/500 kW DC Grid-Connected Medium Frequency Converter for PV Power Generation

The previous two chapters discussed the MVDC collection scheme of PV power generation based on high frequency conversion, which can realize high-efficiency power conversion at high-voltage level and reduce the size of the converter. However, due to the limitation of the current capacity of high-frequency and high-voltage transformer, it brings some challenges to ultra-high-power applications. Therefore, the DC converter based on medium frequency transformer has attracted more and more attention due to its advantages of large-capacity, high reliability, and low cost [1]. Based on this scheme, the DC collection can be realized by adopting the relatively mature technology of medium frequency high-voltage transformer insulation equipment and the control algorithm based on PWM inverter, which has low maintenance and high reliability. So this solution is relatively cost-effective in DC collection application.