Atsushi Denda

PV output smoothing using a battery and natural gas engine-generator

In some situations involving weak grids or high penetration scenarios, the variability of photovoltaic systems can affect the local electrical grid. In order to mitigate destabilizing effects of power fluctuations, an energy storage device or other controllable generation or load can be used. This paper describes the development of a controller for coordinated operation of a small gas engine-generator set (genset) and a battery for smoothing PV plant output. There are a number of benefits derived from using a traditional generation resource in combination with the battery: the variability of the photovoltaic system can be reduced to a specific level with a smaller battery and Power Conditioning System (PCS) and the lifetime of the battery can be extended. The controller was designed specifically for a PV/energy storage project (Prosperity) and a gas engine-generator (Mesa Del Sol) currently operating on the same feeder in Albuquerque, NM. A number of smoothing simulations of the Prosperity PV system were conducted using power data collected from the site. By adjusting the control parameters, tradeoffs between battery use and ramp rates could be tuned. A cost function was created to optimize the control in order to balance - in this example - the need to have low ramp rates with reducing battery size and operation.

Frequency Spectrum Based Coordinate Control Scheme for Several Types of Distributed Power Generation Systems in a Micro Grid

A power control method to compensate power fluctuation of the load in the micro grid systems is proposed and discussed. Active power responses of several kinds of distributed power generation systems (DGs) such as gas engine, micro gas turbine etc., energy storage system, and load fluctuation of a site have been measured. Based on the measurements, coordinate control system for several kinds of DGs has been constructed. Simulation and experiments have been carried out with small-scale micro grid model system. It is shown that the load fluctuation has been compensated by the proposed method

Utilization of underground spaces in urban areas: Urban geo-grid plan

Abstract Miyake, N. and Denda, A., 1993. Utilization of underground spaces in urban areas: Urban geo-grid plan. In: M. Langer, K. Hoshino and K. Aoki (Editors). Engineering Geology in the Utilization of Underground Space.Eng. Geol., 35: 175–181. The Urban Geo-grid Plan aims for a systematic and better coexistence of above-ground and underground areas through the utilization of underground space presently not in use, without interfering with existing urban functions. There would be “base points” supporting regional functions which are laid out in a grid connected by “lines”. Base points would consist of “grid points” and “grid stations”, which serve as control centers for grid points, the grid points and grid stations being interconnected by tunnels to form an “underground network”. Normally, a base point would be used for multiple purposes to supplement regional functions which are inadequate, as well as urban functions, and in emergencies, such as earthquake disasters, it would demonstrate information and evacuations functions.