A survey report for the design technologies of hydropower generating equipment was issued in 1994 but it has not amended since then. After the issue, the development of hydropower generating equipment is remarkable together with many new technologies. Therefore, a new version is issued in this year. This article introduces the outline of the report.
Renewable energy sources such as photovoltaic generation (PV) have been promoted to be innovated. However, the output of PV is influenced by the weather condition and cause a steep fluctuation. So it is important to forecast the output of PV when an electric power company makes the power supply schedule for demand. In this paper, the authors proposed a forecasting method for amount of insolation closely related to the output of PV. In the proposed method, the amount of insolation is forecasted through the application of Genetic Algorithm which is one of the optimization method by using the past measured data. In addition, the correlation coefficients are analyzed with the weather data and measured insolation data. And, the correlation coefficients are used as the weight of observe value. The authors verify the validity and prediction accuracy of the proposed method. Moreover, we tried to improve the forecasting error by using the latest measured weather data and weather data of the other point.
Recent years, installation of PV system is active by the environmental problem and feed in tariff system. Due to PV's output fluctuation, the Static Var Compensator (SVC) made by power electronics technology is planning to install in distribution system. The SVC is expected for maintain the voltage. But SVC differs in a theory of operation of the existing voltage controller Load Ratio control Transformer (LRT) and Step Voltage Regulator (SVR). Because the SVC operation makes the system impedance changes, the existing voltage controller may not operate effectively. In this study, the intelligent-control method which used the RBF network is proposed. This method can reduce the effects of the SVC operation by including the performance characteristics of SVC in the conventional method. An advantage of unnecessary arrangement attention of the SVC setup node and easy cooperation with the existing equipment is obtained by applying this method.
When a large number of photovoltaic (PV) power generations are installed in the distribution system, it is expected that distribution line voltage will fluctuate by the PV output. Then, the large capacity of SVC may be required because the distribution line voltage cannot be controlled by only SVR operation. In this paper, a reactive power control method in proportion to the PV output change is proposed to reduce the capacity of SVC by complementing SVR operation. By the simulation analyses, it was shown that the capacity of the SVC was reduced by the proposed reactive power control. In addition the distribution line loss of the proposed method was smaller than that of the constant power factor control.
We evaluate performance of lithium-ion batteries on the small electric bus, conducting tests of cell and battery pack using discharge/charge machine. We suggest the test item on distinction between good or bad of a battery. In the discharge/charge cycle tests of cell at environmental temperature 25°C, the relative capacity was 60 percent at 10,000 cycles. In the discharge capacity test of battery packs on the small electric bus, the relative capacity maintained more than 90 percent in progress for approximately 900 days. Finally, based on these results, we analyzed about influence factor on a battery discharge capacity.
To establish effective countermeasures on power facilities against lightning damage, it is necessary to clarify the lightning characteristics such as current parameters at the area of interest. In order to collect lightning current parameters effectively, the authors have observed electric and magnetic field waveforms simultaneously at south Kyushu, where the lightning flash density in summer is high. Based on observed electric field waveforms, the lightning current parameters have been estimated by adopting the Diendorfer-Uman model (DU model) as the return stroke model. In this paper the accuracy of the estimated return-stroke current waveform is verified by comparison with directly measured return-stroke current waveform, along with the accuracy of the estimated charge transfer from the electric field waveform measured with a slow antenna.
In this technical note, fundamental concepts of six numerical electromagnetic computation methods, which have been used as of today in in the field of high voltage engineering, are explained with emphasis on the finite-difference time-domain (FDTD) method. Then, representative applications of the FDTD method to electromagnetic field and surge simulations are reviewed. They include lightning electromagnetic fields at close and far distances; lightning surges on overhead power transmission line conductors and towers; lightning surges on overhead distribution and telecommunication lines; surges on grounding electrodes; propagation characteristics of power-line-communication signals along power cables; step responses of impulse voltage measuring systems; lightning electromagnetic environment in power substations; lightning surges in wind-turbine-generator towers; lightning surges in photovoltaic arrays; lightning electromagnetic environment in electric vehicles; and lightning electromagnetic environment in airborne vehicles.