Design and implementation of a distributed generation grid-connected converter testing device

This paper presents a fluctuating voltage generation equipment for distributed generation grid-connected converter testing, which solves the challenge of testing distributed generation grid-connected converter in real power grid. The equipment is based on cascaded H-bridge structure, the voltage level of which is expandable. It can provide precise fluctuating voltage with fluctuating frequency ranging from 0.5 Hz to 25 Hz and fluctuating amplitude ranging from 0% to 10% of the fundamental voltage amplitude, and can simulate unbalance-degree-adjustable three-phase unbalance power grid, and the unbalance degree ranges from 0 to 10%. The equipment can fulfill voltage amplitude and frequency deviation, fluctuating voltage and grid unbalance adaptability test of the grid-connected converter. This paper analyzes the operating principle of this testing equipment and takes the field experimental result of the "35 kV-6MW wind turbine converter low-frequency disturbance testing equipment", which is based on the equipment topology proposed, as an example, sufficiently verifies the feasibility and effectiveness of utilizing this fluctuating voltage generation equipment for distributed generation grid-connected converter.