| Title |
Secondary Indirect Constant Voltage Control Technique for Hybrid Solid State Transformer using Primary Side Information |
| Authors |
Taeyeong Lee ; Chun-Gi Yun ; Younghoon Cho |
| DOI |
10.6113/TKPE.2020.25.5.420 |
| Keywords |
Hybrid solid state transformer; Indirect constant voltage control scheme; Insulation voltage; Voltage drop compensation |
| Abstract |
This study proposes an indirect constant voltage control algorithm for hybrid solid-state transformers (HSSTs) by using primary side information. Considering the structure of HSSTs, measuring voltage and current information on the primary side of a transformer is necessary to control the converter and inverter of the power converter. The secondary side output voltage is measured to apply the conventional secondary side constant voltage control algorithm, and thus, the digital control board requires the same rated insulation voltage as that of the transformer. To solve this problem, the secondary voltage of the transformer obtained from the tap voltage is used. Moreover, output voltage decreases as load increases because the proposed indirect constant voltage control scheme does not consider the cable impedance between the secondary output terminal and the load. This study also proposes a technique for compensating the secondary output voltage by using the primary current of the transformer and the resistance value of the cable. An experiment is conducted using a scale-down HSST prototype consisting of a 660 V/220 V tap transformer. The problem of the proposed indirect constant voltage control strategy and the improvement effect due to the application of the compensation method are compared using the derived experimental results. |