Real-time comprehensive simulation of electric power systems for the task of overvoltages value determination

For a correct determining of the overvoltage limiters characteristics, as well as the optimal location of its installation is required to use reliable information about the primary electrical quantities, especially voltage level, in different operation modes of electric power systems (EPS). This problem is highly complex, due to the danger of the experiments in real EPS. Methods and tools for calculation and researches of quasi-stationary and switching overvoltages which are applied to solve this problem not always allow to obtain satisfactory results. The developed tools of comprehensive real-time simulation of electric power systems, providing adequate reproduction of processes associated with overvoltages in EPS, are presented in the article. Fragments of the researches of switching overvoltage in the electrical network of the real power system are given

Reusable Reentry Satellite (RRS) system design study

The Reusable Reentry Satellite (RRS) is intended to provide investigators in several biological disciplines with a relatively inexpensive method to access space for up to 60 days with eventual recovery on Earth. The RRS will permit totally intact, relatively soft, recovery of the vehicle, system refurbishment, and reflight with new and varied payloads. The RRS is to be capable of three reflights per year over a 10-year program lifetime. The RRS vehicle will have a large and readily accessible volume near the vehicle center of gravity for the Payload Module (PM) containing the experiment hardware. The vehicle is configured to permit the experimenter late access to the PM prior to launch and rapid access following recovery. The RRS will operate in one of two modes: (1) as a free-flying spacecraft in orbit, and will be allowed to drift in attitude to provide an acceleration environment of less than 10(exp -5) g. the acceleration environment during orbital trim maneuvers will be less than 10(exp -3) g; and (2) as an artificial gravity system which spins at controlled rates to provide an artificial gravity of up to 1.5 Earth g. The RRS system will be designed to be rugged, easily maintained, and economically refurbishable for the next flight. Some systems may be designed to be replaced rather than refurbished, if cost effective and capable of meeting the specified turnaround time. The minimum time between recovery and reflight will be approximately 60 days. The PMs will be designed to be relatively autonomous, with experiments that require few commands and limited telemetry. Mass data storage will be accommodated in the PM. The hardware development and implementation phase is currently expected to start in 1991 with a first launch in late 1993