Research on Control Strategy of Non-isolated Low voltage Flexible Interconnected Converter

Under the background of the construction of new power systems, flexible interconnection technology has been widely applied. In order to suppress the circulating current after the closure of the substation, isolated flexible interconnected inverters are often used. Therefore, there are problems such as large device size, low efficiency, and high cost, which are not conducive to promotion. In order to solve the above problems. To solve the problems of large volume, low efficiency, and high cost of low-voltage flexible interconnection devices, this paper proposes a non-isolated transformer topology. And based on this topology, a zero sequence circulating current control method is proposed to suppress the zero sequence circulating current after canceling the isolation transformer. Finally, through simulation verification, the topology and zero sequence circulating current suppression strategy proposed in this paper can effectively suppress the zero sequence circulating current, reduce equipment volume, improve equipment efficiency, and reduce equipment costs.