## 1 Introduction  
With the recent development of energy-based digitalization throughout society, dependence on electricity and demand for electricity are rapidly increasing. However, it is difficult to expand large-scale power plants such as fossil and nuclear power plants due to various issues such as the depletion of fossil energy, environmental problems, and social regulations [1; 2]. Therefore, that a new power grid that includes new and renewable energy sources rather than fossil fuels and nuclear power generation methods used previously and a micro-grid have been proposed as an alternative. The micro-grid can be classified into an AC (Alternating Current) and DC (Direct Current) distribution system. Recently, researches on DC distribution micro-grid with various advantages, such as improved efficiency by reducing the number of power conversions, have been actively conducted,compared to AC distribution systems. In particular, research on large-scale micro-grid systems is needed due to the recent surge in electricity consumption, dependence, and the need to increase the rate of renewable energy owing to environmental regulations. In order to operate micro-grid systems that can provide large-scale power, a power converter with a large capacity is required. However, there is a limit to configure them as a single power conversion stack. Therefore, parallel operation by a number of power converters is essential for the large capacity of micro-grid systems. Parallel operation of these power converters is generally performed by communication, and their performance is largely determined by the speed of communication [3; 4; 5; 6; 7]. In addition, parallel operation of power converters for parallel operation of a power converter to increase capacity is operated by various communication methods. The most common communication method is parallel operation using Modbus communication through R5485. In particular, according to [PERSON] [8], the Modbus protocol is widely adopted in power converters for renewable energy such that researches of linkage between the Modbus protocol and the IEC (International Electrotechnical Commission) 61850 protocol, used in a micro-grid, are steadily being conducted. However, Modbus communication has the limitation of half-duplex communication, which cannot be transmitted and received at the same time [9]. In the case of the half-duplex communication method, since the communication period increases proportionally as the communication object increases, there is a limitation to speed controlling. Decreased control speed not only reduces power quality, but can also cause critical troubleshooting where rapid protection cooperation is required in the event of a troubleshooting. Various methods are being studied to overcome the limitations of this communication speed, and the typical method for this is a four-line communication method. For the four-line communication method, the communication line will be longer as the system becomes larger, which increases the relative financial burden. Therefore, research is needed on what has the ability to do the full-duplex communication method, but also transmit and receive at the same time through two-wire communication. Theoretically, implementing a full-duplex communication approach in a two-wire communication method would allow data to be processed at more than twice the speed of half-duplex communication [10; 11]. Therefore, this paper suggests new communication hardware that enables full-duplex communication by the time division method while compensating the shortcomings of the existing serial communication system. The proposed hardware for communications can detect incoming signals at the same time as multiple devices transmit signals to the same communication line. If it is possible to send and receive signals simultaneously, it is possible to quickly control not only a number of power converters but also other devices, and to respond quickly to incident.