Zhibing Zhao

Risk Analysis for Distribution Systems in the Northeast U.S. Under Wind Storms

Summary form only given. With the growing trend of extreme weather events in the Northeast U.S., a region of dense vegetation, evaluating hazard effects of wind storms on power distribution systems becomes increasingly important for disaster preparedness and fast responses in utilities. In this paper, probabilistic wind storm models for the study region have been built by mining 160-year storm events recorded in the National Oceanic and Atmospheric Administrations Atlantic basin hurricane database (HURDAT). Further, wind storms are classified into six categories according to NOAA criteria and IEEE standard to facilitate the evaluation of distribution system responses under different levels of hazards. The impacts of wind storms in all categories are accurately evaluated through a Sequential Monte Carlo method enhanced by a temporal wind storm sampling strategy. Extensive studies for the selected typical distribution system indicate that our models and methods effectively reveal the hazardous effects of wind storms in the study region, leading to useful insights towards building better system hardening schemes.

Modeling and control strategy for cascade bi-directional DC/DC converter in Microgrid

In the energy storage system in Microgrid, the voltage of super capacitor drops quickly when the super capacitor is delivering power. In condition that the voltage of DC bus constant, we need to enhance the conversion ratio of DC/DC converter. To avoid the switching devices operating at extremely high or low duty ratios and satisfy the practical requirements of Microgrid, a bi-directional topology is adopted and a cascade connection is proposed. In this paper, modeling and control strategy for n-stage converter are given. Simulation results are presented to verify the control method.

Maximum Lifecycle Tracking for Tidal Energy Generation System

Abstract— The tidal energy conversion system has become a major facility for ocean energy harvesting. The intermittency of tidal currents and the resulting large cyclic stresses in the tidal generator, however, make the energy harvesting from tidal currents more challenging than from other renewable sources, such as wind and solar. This paper presents a concept of maximum life-cycle tracking, which minimizes, the torque stress on the shaft, therefore maximizing the life cycle of the tidal energy systems by tracking power-speed curves with a power electronic inverter. By implementing the new concept, the life cycle of a the tidal generator can be extended tens of times.

Low-voltage SPD coordination analysis

SPD is an important device to protect indoor electrical appliances from lightning surge. In practical application, multilevel SPD would be applied to obtain better protection effect. In this paper, effects of two-level SPD cooperation are simulated. Based on the results, patterns of SPD cooperation with or without load and influence of SPD characteristics and cable length on protection effect are concluded.