Wyniki 1-2 spośród 2 dla zapytania: authorDesc:"Mahmoud M.S. ALSUOD"

Development of the system of preemptive control over excitation of a synchronous generator to reduce voltage dips when starting-up asynchronous motors DOI:10.15199/48.2018.10.49

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One of indicators of quality of electric power in ship electric power systems are characteristics of voltage dips. The quality of electric power has a great influence on the course of technological processes: operation of electric motors of various mechanisms, microprocessor facilities, automated control systems of the production process and telecommunication systems in the event of significant voltage dips may be disturbed for a while. One of the reasons for occurrence of voltage dips is a change in loading of the ship electric power system (SEPS), among which the most significant effect is provided by asynchronous motors (AM). Since starting current of asynchronous squirrel-cage motor is inductive (power factor at starting up is 0.15 - 0.20) and exceeds the rated current by 5-7 times, it effects the synchronous generator performing demagnetizing action, which at high power of the motor is not always compensated by magnetizing force created by excitation winding of the synchronous generator. In order to reduce starting currents and, consequently, to reduce voltage fluctuations, special methods of starting of AM may be used. Such methods include starting with reactive and active resistance in stator circuit, starting with autotransformer, with star-delta transition of windings of the motor stator using a soft starter. It is also possible to connect AM to the network after providing a sufficient power reserve in the network by connecting additional diesel generator to the network or disconnecting the least essential consumers of electric power. Since the first variant of reduction of starting currents requires for special switching equipment and performance of additional installation work, the peculiarities of application of the second variant are considered in this paper. The use of software (SW) as a top-level subsystem of the automated control system for SEPS allows at each moment to determine the structure of the power [...]

Research on information channel characteristics of a ship electric power system DOI:10.15199/48.2018.06.04

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Modern automation systems are spatially distributed systems. They are created with the use of multi-task controllers and have network organization [1, 2]. Different parts of the system have different physical nature (continuous object and discrete control part), while the whole system can be described by a complex combination of differential equations, algebraic equations, inequalities, and logical conditions. The tasks in a microcontroller are overlapped and blocked out while waiting for shared resources. The time of tasks execution may vary. Network transmission takes place with delays, magnitude and stability of which depends both on the communication protocol and on channels utilization. To avoid the negative impact of such delay and make the best use of computing resources, which are available for control system, design engineering of control algorithms and software should be conducted with the consideration of these factors. Nonoptimal management of information flows without taking into account the inertia of facilities management and delays in time that occur when sending commands over the network will lead to degradation of quality control. Automatic control system and sub-system of electric power unit protection will not work adequate without providing them with timely and accurate information about technical condition of diesel generator sets and other components. Inasmuch as generating units start up and putting into operation requires relatively long time, the reliable information about damages should be acquired as soon as possible. Therefore, the tasks of information flows analyses and assessment of impact of autonomous power system on the information network are urgent. The most difficult step in the implementation of automated control system is the development of software that meets the appropriate quality standards [3-5]. The toplevel software task is remote monitoring and control of electric power system[...]

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