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Enhancement of system resilience of microgrid is important when the system is operated in the islanded mode. The commonly used clean energy in microgrid is the intermittent renewable energy which would deteriorate the system resilience of microgrid. To solve this problem, the residual energy pre-served in the energy storage system is introduced in this paper to extend the time duration of fundamental load demand when the power outage is present. The experiment is implemented in the demo system in the campus of National Central University to verify the performance of proposed management strategy.

Applications of solid-state converters for adjustable speed drives (ASDs) are popular in industrial systems. The ac/dc/ac conversion system, frequently used to provide ac voltages with adjustable frequency/magnitude in the ASDs, consists of a voltage source inverter (VSI) fed by a three-phase diode-bridge rectifier, which generates significant amount of line harmonic and interharmonic currents into the supply system and may cause undesired effects on other power system components. This paper presents an analytical approach for characterizing the current harmonics and interharmonics of the VSI-fed ASD injected into the supply system in steady state, where the circuit models for the rectifier, the dc link, the PWM inverter, and the ac motor are considered in the analysis. The accuracy of the results obtained by the proposed model is demonstrated by comparing with those obtained by using the time-domain simulation tool, Simulink of Matlab, and by laboratory tests. It is shown that the proposed approach is effective to characterize current harmonics and interharmonics generated by the ASD, while the solution accuracy and the computational efficiency are still maintained. Index Terms--Adjustable speed drive, double Fourier series, harmonics, interharmonics, voltage source inverter.

This paper presents a study for modeling harmonic currents injected by three-level pulse-width-modulated (PWM) converters of the high-speed railway traction drive in steady-state motoring mode. An analytical solution for converter harmonics based on the double Fourier series theory is described. The time-domain simulation results obtained by the use of PSpice are then compared with those obtained by the proposed model. It is shown that the harmonic currents determined according to the proposed model agree well with those results obtained by using the time-domain simulation tool. Index Terms--Double Fourier series, harmonic model, three-level PWM converter, traction drive.