Nowadays, there is quite high demand for electromagnetic transient (EMT) analysis programs and real-time simulators for power systems. In addition to the conventional demand such as overvoltage, over-current and oscillation simulations, the new demand that includes simulations of power-electronics circuits and power quality is increasing. With this background, development groups of EMT programs and real-time simulators have made progress in terms of computational performance and user experience. In Japan, Central Research Institute of Electric Power Industry has newly developed an EMT analysis program called XTAP (eXpandable Transient Analysis Program). This article overviews these international and domestic development trends of EMT analysis programs and real-time simulators.

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AC filter design method for SVC and HVDC is commonly known in the relevant CIGRE technical brochure and IEC technical report. However the conventional method requires many iterative calculations of the harmonic voltages and currents until the calculation results become within the regulation levels by changing filter parameters based on the experience. In this respect, a new improved design method is proposed, which enables efficient evaluation on the complex impedance plane to confirm as to whether the proposed filter impedance is in the permissible range. In an actual project of Okuura SVC of Kyusyu Electric Power Co., Inc., the new method was applied to the AC filter design. This paper describes on the actual procedure of the AC filter design with the new method, the actual references of the harmonic performance calculation, and the field test measurement results on Okuura SVC. The calculation results and the filed measurement results are consistent with each other, thus the validity of the new design method is verified on its accuracy and effectiveness.

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A “Smart House” is a highly energy-optimized house equipped with photovoltaic systems (PV systems), electric battery systems, fuel cell cogeneration systems (FC systems), electric vehicles (EVs) and so on. Smart houses are attracting much attention recently thanks to their enhanced ability to save energy by making full use of renewable energy and by achieving power grid stability despite an increased power draw for installed PV systems. Yet running a smart house's power system, with its multiple power sources and power storages, is no simple task. In this paper, we consider the problem of power scheduling for a smart house with a PV system, an FC system and an EV. We formulate the problem as a mixed integer programming problem, and then extend it to a stochastic programming problem involving recourse costs to cope with uncertain electricity demand, heat demand and PV power generation. Using our method, we seek to achieve the optimal power schedule running at the minimum expected operation cost. We present some results of numerical experiments with data on real-life demands and PV power generation to show the effectiveness of our method.

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The voltage variation in the remote system is large when the system is connected by long distance AC cables due to the cable capacitance. In Japan, the longest 54km 66kV AC submarine cable interconnection between Kyushyu mainland and Goto-islands was commissioned in 2005. It is requested to mitigate the voltage variation caused by switching off and on of one circuit of AC cables out of two circuits when a fault occurs. Since the conventional voltage control methods such as transformer tap changer or shunt capacitor and reactor banks are not sufficient because of their slow response time, therefore an SVC (Static Var Compensator) was installed in Goto-islands. In such application, SVC control method should be developed not to override the existing voltage control systems. This paper describes the SVC control method developed for Goto-islands AC interconnection project, which can be applied to similar applications. The effectiveness of the control method was verified by effective-value-based simulation results and field test results of which implemented before SVC commissioning in 2007.

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To maintain the insulation reliability on gas insulated switchgear (GIS), several partial discharge (PD) monitoring techniques have been utilized. To estimate the risk of a defect, it is important to identify the kind of defects and its condition. In this paper, every PD pulse of various defect types was sequentially measured by using high-speed PD measuring system. The sequential PD measurement was proved to be useful to identify the defect condition, because the temporal change of PD characteristics could show the accumulation of the space charge around the defect in GIS.

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PV power output mainly depends on the solar irradiance which is affected by various meteorological factors. So, it is required to predict solar irradiance in the future for the efficient operation of PV systems. In this paper, we develop a novel approach for solar irradiance forecast, in which we introduce to combine the black-box model (JIT Modeling) with the physical model (GPV data). We investigate the predictive accuracy of solar irradiance over wide controlled-area of each electric power company by utilizing the measured data on the 44 observation points throughout Japan offered by JMA and the 64 points around Kanto by NEDO. Finally, we propose the application forecast method of solar irradiance to the point which is difficulty in compiling the database. And we consider the influence of different GPV default time on solar irradiance prediction.

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