Line impedance compensation control strategy for multiple interlinking converters in hybrid AC/DC microgrid

In a hybrid AC/DC microgrid (MG), the interlinking converter (IC) plays an important role in power flow regulation between subgrids. However, line impedance will cause deviations in the power transmitted by the IC if a communication device is not used. To realize accurate power delivery between subgrids without communication, an IC control method based on line impedance compensation is proposed. A harmonic signal is injected into the IC in this method using converters of distributed generation, which are connected to an AC bus. The specified frequency of the signal indicating the voltage of the AC bus can be acquired by an IC using a filter and phase-locked-loop (PLL) so that the IC can obtain line impedance by local information and then compensate for voltage drop to realize accurate power transmission. The entire implementation of this method uses no communication. Moreover, when multiple ICs run in parallel, this method can also be conducted easily and effectively to realize accurate power flow between subgrids and power sharing among ICs in proportion to the ICs' rated capacity. This strategy is verified by simulation and hardware-in-the-loop tests.

Automated summary

In a hybrid AC/DC microgrid, the interlinking converter (IC) is crucial for power flow regulation between subgrids. To compensate for deviations caused by line impedance, a control method based on line impedance compensation is proposed, which injects a harmonic signal into the IC using distributed generation converters connected to an AC bus. By using a filter and phase-locked-loop (PLL), the IC can acquire the voltage information of the AC bus and determine the line impedance, enabling accurate power transmission without communication. This method can also be easily implemented for power sharing among ICs in parallel operation.