Modeling of Interconnected Converter System with Coupled LCL and LC Filters

In some applications, voltage source converters with LC filters and current source converters with LCL filters might be connected together, forming a more complicated impedance network. This paper proposes a mathematical model for the interconnected converter system with coupled LCL and LC filters, which is a commonly seen configuration in micro-grid system or some testing benches for power converters with large capacity. It is found that different converters with interconnected filters are strongly coupled, and in this system both the voltage and current on the coupling point will be affected by the impedances of LCL and LC filters, as well as the control strategies on both sides. Therefore, the filter parameters and controllers for both converter sides need to be designed coordinately to ensure the stability of the system.