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The layered permittivity graded material is achieved by making layered graded distribution of high permittivity fillers inside polymer matrix. In this study, we investigated the influence of the local electric field distortion by the high permittivity fillers on the surface field distribution of the layered permittivity graded material. In order to calculate the local field distortion of the high...
To achieve a lower permittivity solid insulator for HV power apparatus, we have developed a polymer composite filled with nanoporous silica particles. This paper investigated the influence of nanopore size of the nanoporous-silica particles on particle porosity and permittivity of nanoporous-silica/epoxy composite (NanoPC). NanoPC was prepared by mixing epoxy resin and four kinds of nanoporous-silica...
This paper investigated partial discharge characteristics in a closed void and void discharge deterioration characteristics of polypropylene (PP) films. It focused on the influence of film-surface structure (rough-surface and smooth-surface) on the deterioration characteristics. The partial discharge characteristic was evaluated by measuring PD patterns (phase-charge-number) under AC voltage application...
Mesoporous-silica/epoxy composites consist of epoxy resin and the mesoporous-silica particles which have the micrometric particle-diameter and the nanometric pore-size. Mesoporous-silica/epoxy composite material can actualize nanoporous composite insulator. This paper presents the measurement results of specific gravity and dielectric permittivity for the mesoporous-silica/epoxy composites (MPC)....
In order to improve the accuracy of degradation diagnosis for CV power cables, it is important to clarify the inception and propagation mechanisms of electrical tree degradation from water tree degradation. This paper presents the influence of AC voltage prestressing on the inception voltage of AC electrical-tree in the deteriorated LDPE with dried water-tree. The experiment was carried out with a...
This paper presents an attempt to show the effectiveness of nanoporous-silica composite in epoxy matrix for voltage-endurance and lower permittivity by numerical analysis. By finite element analysis of the static electric field, we estimated the permittivity of the nanoporous-silica composite insulator required to reduce the electric field enhancement around the GIS solid spacer. In order to achieve...
An electric power system containing high penetration photovoltaic power generation system (PVS) should employ a highly accurate day-ahead forecast method of aggregated power output of PVS in the generation scheduling so as to realize the economic load dispatching. Considering the load-following capability of utility generators, however, small forecast error is not so influential, while large forecast...
We investigated the influence of AC voltage prestressing on the electrical-tree inception voltage in LDPE. When AC voltage prestress was not imposed, the impulse-tree inception voltage increased with the size of water tree due to the electrical field relaxation. On the other hand, when AC voltage prestress was imposed, the impulse-tree inception voltage did not change with the water-tree size and...
High penetration photovoltaic power generation system (PVS) would cause some negative impacts on the stable operation of electric power system. On the other hand, when PVSs are widely dispersed, the total power output fluctuation would be smoothed. In order to evaluate the spatial average insolation fluctuation by using the insolation data observed at the limited number of points, we have developed...
This study proposes a method to estimate the standard deviation (STD) of total power output fluctuation of high penetration photovoltaic power generation system (HP-PVS) dispersed in large area, so that the impact of HP-PVS on the load frequency control is discussed. First, by using the data of horizontal global insolation observed at 5 points in 25 km × 25 km area, the practical usefulness of STD...
Inundation maps of coastal marshes in western Louisiana were created with multitemporal Envisat Advanced Synthetic Aperture (ASAR) scenes collected before and during the three months after Hurricane Rita landfall in September 2005. Corroborated by inland water-levels, 7 days after landfall, 48% of coastal estuarine and palustrine marshes remained inundated by storm-surge waters. Forty-five days after...
Power output fluctuation of photovoltaic power generation systems (PVSs) may cause negative impact on the load frequency control of existing electric power system when the penetration of PVSs is quite large. For the cost-effective mitigation, the proper evaluation of apparent electricity load fluctuation property is very important, taking PVSs power output into account as negative load. Considering...
On constructing a microgrid, it is essential to balance capacity of photovoltaic power generation (PV) systems and storage batteries in accordance with a control target. In the present study, we constructed a simulation model of energy control system in the microgrid. By using this model, we investigated the acceptable capacity of PV systems according the capacity of NaS battery for keeping the target...
The large-scale penetration of photovoltaic power generation systems (PVSs) may cause both the positive and negative impact on the existing electric power system. For the detail impact assessment, the prediction of the future electricity load pattern as well as the power output pattern of PVSs is very important, while it would be very challenging issue. As a first step of the impact assessment, this...
Power output fluctuation of photovoltaic power generation systems (PVSs) may cause negative impact on the existing electric power system when the penetration of PVSs is quite large. A micro-grid consisting of clustered PVSs and a battery system would be one of the promising measures to the negative impact of clustered PVSs, while the maximum power and storage capacity of battery system should be reduced...
In order to clarify the mechanism of electrical-tree inception from water-tree degradation which often determines the remaining life of power cables, we have been investigating electrical tree inception and propagation from water-tree degradation in polyethylene. Some of the results suggested that at higher temperatures the extent of water-tree degradation was much higher than that of water-tree degradation...
This study proposes a numerical model to assess the usability of asset management of electric power apparatuses. A Monte-Carlo technique is employed, so that the various factors, i.e. the wide variety of degradation extent and failure probability among the electric power apparatuses, and the various replacement policy and constraints, etc, can be taken into account. As an example of electric power...
In order to clarify the mechanism of electrical-tree inception which often determines the remaining life of power cables, we have been investigating electrical tree inception and propagation from water-tree degradation in polyethylene. Some of the results suggested that at 363 K, the continuous permissible temperature of XLPE cables, the extent of water-tree degradation was much higher than that of...
Partial discharge (PD) in a void reflects degradation of insulating material and, therefore, is utilized for insulation diagnosis. Although it is well known that PD pattern changes with voltage application, it is not clear how the pattern change is related to material degradation or how it is related to final breakdown. We simultaneously observed PD characteristics and light emission from partial...
Periodic packet formation in an oxidized cross-linked polyethylene (XLPE) was discussed through a computer simulation, where negative space-charge packet is assumed to be due to deficiency in mobile holes. Under high field, a positive carrier (hole) is generated from the acceptor (impurity) site to a hopping site and trapped there once. It is detrapped by hopping or recombines with the parent ion...
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