## 1 Introduction  
The modern power grid transforms into complex networked systems that combine high percentages of renewable energy sources with energy storage capabilities. The hybrid AC/DC microgrid architecture has received substantial interest because it enables the combination of different energy sources and loads while improving system flexibility and efficiency. The introduction of multi-frequency power transfer represents a new method to shape the voltage peak, which results in increased RMS voltage without violating the peak limits. This, in turn, leads to the power capacity increase without the need to update distribution system lines. Also, it reduces network congestion through the simultaneous utilization of various frequency components across AC lines. The approach involves adding specific harmonic frequencies to the 50 Hz fundamental waveform to establish additional power channels through intentional harmonic signal superposition. The method draws inspiration from communication systems that use frequency-division multiplexing, and researchers have applied it to the \"energy internet\" for enabling bidirectional energy packet transfer through existing power lines [1; 2; 3; 4; 5]. The use of low-voltage DC links has become more common for connecting different grid-tied converters, photovoltaic (PV) generators, and battery energy storage systems (BESS) to a single bus. A hybrid AC/DC system is formed by a bidirectional inverter that connects the DC-link to the AC grid and other converters that connect PV and battery units to the DC bus [3]. The DC-link functions as the central power exchange system between sources and loads to enhance renewable energy integration and storage capabilities [6]. The conventional power systems operate at a single fundamental frequency (50 or 60 Hz), and any harmonic components are usually mitigated to maintain power quality. However, researchers have recently started to explore multi-frequency power transfer as a paradigm shift, using specific harmonic frequencies to transfer power simultaneously with the fundamental. This idea was first inspired by waveform peak-shaping techniques that showed that adding harmonics does not increase peak voltage [4; 5]. Rather than filtering out harmonics, the multi-frequency approach treats them as independent channels for energy transfer. Ref. [4] showed one of the early demonstrations of a single-phase islanded multi-frequency grid, where a 50 Hz base waveform and its 3 rd, 5 th, and 7 th harmonics were superimposed to increase the RMS voltage while maintaining peak voltage. Thus, for the same amount of power, the current would be smaller, which reduces the losses in the system. The multi-frequency concept has moved past single-phase experiments during recent years. A thorough assessment implemented the \"orthogonal power transfer\" principle, allowing separate power distribution between different frequencies. The experimental findings showed that renewable and storage sources can utilize the same three-phase line without any form of interference, which leads to better line utilization [1]. Research has shown that multi-frequency power transfer systems can independently manage multiple frequency components. The first single-phase converter, which injected fundamental and 150 Hz harmonics, led to the development of a three-phase, two-frequency system. A three-phase, three-frequency system, which uses positive-sequence 50 Hz, zero-sequence 3 rd, and negative-sequence 5 th harmonics, has been proposed to create three parallel power channels from a single line. The added harmonic channels can be controlled such that they do not interfere with the fundamental component, thus partitioning the power flow by frequency. The system achieved increased RMS voltages through harmonic amplitude adjustments, which stayed below peak limits. The experimental results, together with simulation outcomes, showed that orthogonal decomposition simplified control while eliminating network congestion according to [2; 7; 8].