Research on fault current limitation and active control for power electronic transformer in direct current grid

Abstract

Due to the low impedance of DC (Direct Current) power transmission line, short‐circuit current has a very high increment speed, which causes problems as difficulty in current limitation method. This paper proposes a new method to realize the current‐limiting control of short‐circuit current by using active control of power electronic transformer. The method improves the topology of dual active bridge modules that contribute the DC transformer, and installs an IGBT (Insulated Gate Bipolar Transistor) switch in reverse direction on supporting capacitor branch of each module to control the capacitor on or off, which can guarantee the storage energy within the capacitor will not release in initial stage in case of DC short circuit fault happen. Therefore, there is no large inrush current flow out. Furthermore, combined with the requirements of current tracking control during low‐voltage ride‐through, the transformer output current under short‐circuit condition is actively controlled in order to meet the needs of renewable energy power generation equipment. Finally, the simulation and hardware‐in‐the‐loop experiments verify the correctness of this method.

Optical DC Transformers Incorporating Improved Sensing Cell Materials and Signal Processing

“…Zhuo et al proposed a power electronic transformerbased control method to improve the structure of the dual active bridge module of the contributing DC transformer in order to deal with the difficulty of current limitation in the DC power grid. The results show that the method is capable of actively controlling the current output from the transformer to meet the requirements of renewable energy power generation equipment [5]. Wang et al proposed a multi-short flexible DC distribution protection system based on transient current curvature in response to the problem of the DC distribution system's short time for identifying the fault transient cycle.…”

“…In Equation ( 4), ε denotes the specific difference of the DC transformer. In this study, room temperature 293 K was used as the standard temperature, so at the standard temperature, the initial specific difference is shown in Equation (5).…”

Study of the IPOS DC/DC Converter for DC Offshore Wind Farm

“…Reference [11] analyzes the causes and suppression methods of DAB fault current DC bias, but it still cannot effectively limit the magnitude of the fault current. Reference [12] achieved the purpose of limiting the short-circuit current by improving the control strategy during the fault. However, the control method makes the secondary side H-bridge of the DAB blocked.…”

Analysis of Losses in a Three-Port High-Frequency Transformer Under Different Frequencies and Load Conditions

“…The cables are elaborately intertwined to maintain a consistent distribution of electric current, thereby reducing the impact of the proximity effect. Using stranded cable improves the effectiveness of high-frequency transformers, requiring the design to be optimised to meet the unique needs of power electronics applications [19,21]. This work focuses on providing the results of identifying an optimal design for a high-frequency transformer in a TAB arrangement.…”