Design of the control circuit used in variable speed diesel generator set
The advanced circuit design of boost and inverter has created much interest in generator of variable speed diesel generating sets. The boost circuit and the topological structure of the three-phase half-bridge inverter were analyzed. The control strategy of Sinusoidal PWM (SPWM) was implemented. To reduce the noise in the control feedback, a low pass filter was in used. At the end of this paper, the authors performed a series of experiments to confirm the stability of the generator set. The experiment results verified that the boost circuit and the inverter designed in this paper are reasonable and can satisfy all the requirements of the diesel generator set.
Fuel saving variable speed generating set
The paper presents method and systems improving quality of power produced by renewable energy sources (RES). The power, delivered by RES, is not stable and not easy predictable. Therefore an additional controllable power sources is applied. There are considered three basic topologies of the controllable generating set used as conditioner. There are fixed speed system with synchronous generator, adjustable speed doubly fed induction generator (DFIG) and adjustable speed system using brushless permanent magnet generator. The simplest fixed speed system, using synchronous generator, operates usually in region of low efficiency of Diesel engine whereas the most efficient is adjustable speed system using permanent magnet generator. Laboratory tests of the adjustable speed generation system using permanent magnet confirm its ability to operate as adjustable speed system.
An Internet-based Real-time Heavy Rainfall Display System
A new storm warning system, which can be accessed through the Internet and by cellular phones is described. At the time of a heavy rainfall for disaster prevention, it is important that every resident understand how heavy is that rainfall. A real-time heavy rainfall display system designed for all of Japan provides such information (http://www.disaster-i.net/rain/). In that system values for 1-hour precipitation, 24-hour accumulated precipitation, etc. are displayed at every observatory. Advantages are that not only the latest observations but differences from the historical highest records can be seen. Almost all information is displayed by characters so that users have easy access to the system even when the communication network is crowded. Access date for the six months after the system opened shows that the average daily number of accesses of the top page was 306, and the largest number 3078. The maximum number for daily access to all the pages was about 21,500. This is about 2% of the number obtained on the same day for a similar system operated by the Ministry of Land, Infrastructure and Transport (http://www.river.go.jp/).