Showing papers on "Blackout published in 1994"

Fuzzy inference application to planning of distribution network switching

Abstract: Optimal switching pattern planning is the main subject of distribution network reconfiguration to recover from a blackout or to avoid a blackout due to maintenance and construction. This is a combinatorial optimization problem, and an enumerative check of every pattern is necessary to obtain the optimal solution. In practice, successive heuristic search methods are adopted to obtain the quasi-optimal solution within a limited computation time. However, a very long computing time is still required when the problem size becomes slightly larger. The step-by-step nature of the methods results in many iterations, although it ensures satisfaction of the constraints. Reduction of the iterations is considered to be necessary to enhance processing speed. In this paper, “supply adequacy” is introduced as a new criteria index to guess the solution, which is obtained by fuzzy inference for each possible pair of source and load zone. The reconfiguration pattern is obtained at once or in a few processing steps by assigning to each zone the source with the highest adequacy. Numerical examples show that the proposed method can obtain the solution faster than the ordinary method, more remarkably with the increase of problem size.

Automatic landing device at time of power failure of multi-unit elevators

Abstract: PURPOSE:To secure an automatic landing device at the time of power failure in multi-unit elevators, capable of landing these elevators to the nearest floor automatically at the blackout with this automatic blackout landing device equipped with a built-in one-set battery. CONSTITUTION:Each one-set of automatic blackout landing devices 5 equipped with a built-in battery each is set up in plural units of elevators, and simultaneously this landing device 5 is made up of providing three emergency power circuits 9a, 9b and 9c which supplies three control panels 4a, 4b and 4c of each elevator in order of inputting each signal out of three blackout emergency pushbuttons 7a, 7b and 7c installed in respective elevator cages in time of a power failure, with power out of the built-in battery of the automatic landing devices 5 successively.

Data memory controller

Abstract: PURPOSE:To enable exactly grasping the time relation and perform data analysis efficiently by suspending writing in a data memory at immediately before a blackout during measurement and writing dummy data in the memory in the blackout time in connection to the measured data immediately before the restart of the measurement during recovery. CONSTITUTION:In case of blackout, the writing of measured data in a data memory 8 is suspended and a blackout detection signal is output from a power source monitor part 3 to each part. After recovery of time blackout, a blackout recovery signal is output from the power source monitor part 3 to each part. A blackout time detection part 5 detects the blackout time based on the time signal output from a timer circuit 4 and outputs the detected results through a microprocessor 6 to a data writing controller 11. The data writing controller 11 calculates the data number to be written during the blackout time following the blackout time and writing period by the time the blackout is recovered and the measurement operation is restarted. A specified number of dummy measurement after the measured data before the blackout in the data memory 8 based on the writing position data in the pointer memory 9.

Expert System for Dispatch Control in Restoration of EHV Power System after Complete Blackout

Abstract: Present-day power systems operate with high reliability, and it is rare that a blackout will extend over an entire system swiftly and securely. This paper considers automatic power supply to loads after a complete blackout of a system. First, taking into account characteristics of generators, loads, and initial power sources, a method is proposed of allocating several generators to each load in parallel to the system and supplying power to the load sequentially. Second, to remove the imbalance between supply and demand of power, a method is proposed of adjusting the amount of supply and generation according to a present imbalance and the sum of past ones. Third, to automatically issue orders for start-up, parallel, follow-up, stand-by, and stoppage of generators, several rules for each power station are set and an expert system is made based on them. Finally, the expert system is applied to a model power system, and it is verified that it can restore loads without any trouble for a complete blackout which occur at any time of a day and in any restoration pattern.