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Keywords

solid state transformer, distribution network, cascaded Hbridge, voltage balance, dual active bridge DCDC converter, power balance

Abstract

Solid State Transformer (SST) is the central equipment of distribution network in Energy Internet, which controls the power flow actively. In this paper, a novel voltage and power balance control strategy for Cascaded HBridge (CHB) type SST is proposed, and the design method and operation mechanism of the control strategy are analyzed. Firstly, in order to solve the problem of unbalanced voltage on the DC side of CHB in the input stage, a voltage and reactive power balance control strategy that utilizes both active and reactive duty cycle modification are proposed. This method not only eliminates the coupling effect between the balance controller and the system controller, but also balances the voltage and reactive power of CHB capacitors. Secondly, the activeduty component of the input stage is taken as the power balance control feedback of the isolationstage and the correction is made to solve the problem of unbalanced power transferring of the dual active bridge DCDC converters due to the parameter differences. In addition, the coordination control of the front and rear controller is analyzed to improve the system transient performance. Finally, the feasibility and effectiveness of the control strategy are verified by simulation.

DOI

10.19781/j.issn.16739140.2021.01.017

First Page

152

Last Page

159

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