Girmanin Tashar Da Karamin Zabi: Dalilin Inganci Don Integirsi Masu Microgrids

Amfani da elektronika na kashi a tattalin arziki yana zama mafi yawa, daga ingantaccen hanyar aikin kuli da LED drivers, zuwa mafi yawan hanyoyi kamar PV systems da muhimmanci. Tushen, wani power system yana da uku waɗanda suka biye: power plants, transmission systems, da distribution systems. Traditionally, low-frequency transformers sun amfani a biyu: electrical isolation da voltage matching. Amma, 50-/60-Hz transformers sun fi tsawo da kayayyaki. Power converters sun amfani don in iya gudanar da sabon da kuma gaske power systems, ta haka sun yi amfani da concept of solid-state transformers (SST). Ta haka, tun da amfani da high- ko medium-frequency power conversion, SSTs sun ya kiyaye tsawo da transformer size da kuma sun bayar da mafi yawan power density da aka bincike da conventional transformers.

Abubuwan da suka faru a cikin magnetic materials—da high flux density, high power and frequency capability, da kuma low power losses—sun ba researchers su fadada in yi SSTs da mafi yawan power density da efficiency. A duk lokacin, research sun nuna shiga traditional dual-winding transformers. Amma, babban integration of distributed generation, da kuma development of smart grids da microgrids, ya ba da concept of multi-port solid-state transformers (MPSST).

A cikin port har zuwa converter, dual active bridge (DAB) converter an amfani, wanda yake amfani da leakage inductance na transformer a matsayin inductor na converter. Wannan ya kiyaye tsawo da kuma ya kiyaye loss. Leakage inductance yana da alaka da winding placement, core geometry, da kuma coupling coefficient, wanda yana haɓaka transformer design to be more complex. Phase shift control an amfani a DAB converters don in regulate power flow between ports. Amma, a MPSST, phase shift a cikin port wata yana haɓaka power flow a wasu port, wanda yana haɓaka control complexity with the number of ports. Saboda haka, most MPSST research focuses on three-port systems.

Wani paper yana nuna bayanai game da design of a solid-state transformer for microgrid applications. Transformer yana da uku port a cikin single magnetic core. Yana yi a switching frequency of 50 kHz, da kuka port rated for 25 kW. Port configuration yana nufin realistic microgrid model comprising the utility grid, energy storage system, photovoltaic system, da local load. Grid port yana yi a 4,160 VAC, while the other three ports operate at 400 V.

Four-Port SST

Transformer Design

Table 1 yana nuna abubuwan da ake amfani don manufacturing transformer cores, da kuma advantages da disadvantages. Ladda yana nuna in za a zaba material da zake iya support 25 kW per port a 50 kHz operating frequency. Commercially available transformer core materials include silicon steel, amorphous alloy, ferrite, and nanocrystalline. For the target application—a four-port transformer operating at 50 kHz with 25 kW per port—the most suitable core material must be identified. By analyzing the table, both nanocrystalline and ferrite are shortlisted as potential candidates. However, nanocrystalline exhibits higher power losses at switching frequencies above 20 kHz. Therefore, ferrite is ultimately selected as the core material for the transformer.

Different Core Materials and Their Characteristics

Transformer core design yana da muhimmanci, saboda yana haɓaka compactness, power density, da overall size—but most importantly, it influences the transformer’s leakage inductance. For a 330-kW, 50-Hz dual-port transformer, core shapes such as core-type and shell-type have been compared, demonstrating that the shell-type configuration offers lower leakage inductance and smoother power flow. Therefore, a shell-type configuration will be used, with all four windings stacked concentrically on the center limb of the transformer, thereby improving the coupling coefficient.

The shell-type core measures 186×152×30 mm, and the ferrite material used is 3C94 in a 4xU93×76×30 mm configuration. Litz wire is used for winding both the medium-voltage (MV) and high-current ports, rated at 3.42 A and 62.5 A, respectively. For the low-voltage (LV) ports, 16 AWG and 4 AWG wires are employed. Twisting the LV windings together further enhances magnetic coupling.

After completing the proposed MV MPSST design, Maxwell-3D/Simplorer simulations are performed. The port voltages for the medium-voltage grid, energy storage, load, and photovoltaic systems are set to 7.2 kVDC and 400 VDC, respectively. Simulations are conducted under full load, with the load port delivering 25 kW at a switching frequency of 50 kHz and a 50% duty cycle. Power control is achieved by adjusting the phase shift between converter cells. Results are presented in the table. Different models exhibit varying characteristics such as core shape, cross-sectional area, loss, and volume. As shown in the table, Model 7 demonstrates lower leakage inductance and higher efficiency.

Model and Simulation Results

Experimental Setup

The core is constructed using four U-shaped cores assembled into one layer. The complete core consists of three layers with windings placed on the center limb. The three low-voltage (LV) port windings are wound together to enhance coupling. A dual active bridge (DAB) converter is designed to test the proposed transformer. SiC MOSFETs are used in the converter design. For the medium-voltage (MV) port, a rectifier bridge is implemented using SiC diodes, which is also connected to a resistive load bank rated to handle 7.2 kV.

Conclusion

Wani paper yana nuna bayanai game da design of a four-port medium-voltage multi-port solid-state transformer (MV MPSST) that enables the integration of four different sources or loads in microgrid applications. One port of the transformer is a medium-voltage (MV) port rated for 4.16 kV AC. Various transformer models and core materials were reviewed. In addition to the transformer design, test setups were developed for both the MV and LV ports. An efficiency of 99% was achieved in the experimental validation.