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Abstract-The purpose of this paper is to present two novel methods of improving low voltage ride-through (LVRT) capacity of doubly fed induction generator (DFIG) wind turbines. The first one, combining regular crowbar protection and three switches, enabled us not to consider the insulation of rotor inverter when choosing the value of crowbar resistance. The switches were connected in series with rotor windings between the crowbar and rotor inverter. In the second one, a series dynamic resistor (SDR) was put between DC capacitor and rotor inverter. This method made DFIG wind turbines have the ability to limit rotor currents without improving capacitor voltage and changing the controller algorithm or controller parameters. However, applying the second method, we needed to increase the voltage rating of rotor inverter to avoid the insulation being destroyed. The second method was justified by simulations in Matlab/Simulink.

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The Power Control Unit (PCU) in Micro-satellites program proposed to develop by NSPO, acts as the satellite power control and distribution center. One of the modules in the PCU, named the Power Distribution (PD), the main function provides the rated voltage and current of each power outlet for the satellite subsystem. When overload or short-circuit happens and persists for a time period, PD will limit the load current in a pre-designed value, and shut off the load to avoid damage on essential devices. In this paper, we will introduce the PCU EBB function and circuit design of PD.

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