Research on the dynamic windproof and antiskid ability guarantee of port crane

This paper introduces the windproof and antiskid safety, types and working principles of dynamic windproof and antiskid devices in normal working conditions, analyzes the dynamic braking capacity and points out the deficiencies in the design, and puts forward relevant suggestion to provide basis for the subsequent evaluation of windproof and antiskid performance of port cranes.

EXPERIMENTAL STUDY OF STATIC CHARACTERISTICS ASYNCHRONOUS MACHINE IN DYNAMIC BRAKING MODE WITH INDUCTION RESISTANCE IN THE ROTOR WINDING

The article discusses the results of a study of the static electromechanical characteristics of an asynchronous machine (AM) when prototypes of induction resistances (IR) with improved parameters are included in its rotor circuits. The dynamic braking (DB) of asynchronous machines, which is widespread in practice, provides for the dissipation of the kinetic energy of the rotating parts in the resistance boxes included in the rotor winding. In the process of stopping, to maintain a constant average braking torque AM, a bulky relay-contactor circuit for shunting rotor resistances is used. However, it is not possible to eliminate significant fluctuations in the electromagnetic torque in this way. To optimize the DB AM process, it is proposed to include a three-phase IR in the rotor winding instead of resistance boxes, the value of which automatically decreases along with the rotor current frequency. This approach allows you to abandon contact equipment and ensure smooth braking of the machine with fluctuations in the electromagnetic moment in narrower limits. The known IR designs are designed for starting modes of induction motors with a wound rotor, but they cannot ensure the constancy of the torque on the AM shaft in the DB mode. Therefore, the purpose of the study is to develop and experimentally confirm the effectiveness of simple control circuits of an induction machine in the specified mode with improved contactless induction rheostats in the rotor. The paper presents a diagram of a pilot plant and a figure explaining the design features of the IR. The studies were carried out for an asynchronous machine of the MTB-412-8 type, equipped with a thyristor exciter and a tachogenerator. The three phases of the AM rotor included ICs connected by a "star". The experiments were carried out in the direction of obtaining the necessary braking characteristics of the AM by varying the switching circuit of the stator phases and the value of the current supplying them. The figures show the mechanical characteristics of AM, obtained in the process of studying the influence on them of three typical circuits for switching on the phases of the stator winding and two values ​​of the fixed supply current. The research results show that the desired form of the mentioned AM characteristics is achieved only when using the stator phase switching in a function of the rotor speed and a constant supply current value.

EXPERIMENTAL STUDY OF THE STATIC CHARACTERISTICS OF THE SYNCHRONOUS MACHINE IN THE MODE OF DYNAMIC BRAKING WITH INDUCTION RESISTANCE IN THE WINDING OF THE STATOR

The article discusses the results of a study of the static electromechanical characteristics of a synchronous machine (SM) when prototypes of induction resistances (IR) with improved parameters are included in its stator circuits. Widespread in practice, dynamic braking (DB) of synchronous machines provides for the dissipation of the kinetic energy of the rotor in the resistance boxes included in the stator winding. In the process of stopping, to maintain the constancy of the average braking torque of the SM, a bulky relay-contactor shunt circuit for stator resistances is used. At low speeds, regulation of the excitation current of the SM or its forcing can also be applied. However, it is not possible to eliminate significant fluctuations in the electromagnetic moment in this way. To optimize the SM DB process, instead of resistance boxes, it was proposed to include a three-phase induction resistance in the stator winding, the value of which automatically decreases along with the stator current frequency. This approach allows you to drastically reduce the number of contact equipment and ensure smooth braking of the machine with electromagnetic moment fluctuations within narrow limits. Known IR designs are designed for asynchronous motors with a phase rotor and satisfy the requirements of the given quality factor of their starting characteristics, but cannot ensure the constancy of the torque on the SM shaft in the DB mode. Therefore, the objective of the work is to improve the design of the IR and obtain the necessary inhibitory mechanical characteristics of the SM using experimental studies. The work provides a pilot plant diagram and a drawing explaining the design features of the IR. The studies were performed for a synchronous machine, type МСА-72 / 4А, equipped with a thyristor exciter and a speed sensor. In three phases of the SM stator, IRs connected by a "star" were turned on. The experiments were carried out in the direction of obtaining the necessary braking characteristics of the SM by varying the design of the internal elements of the IR. The figures show the mechanical characteristics of the SM obtained in the process of studying the effect on them of the thickness of the inner steel rings and massive ferromagnetic disks at three values of the fixed excitation current. The research results show that the desired form of the mentioned characteristics of the SM is achieved only when using massive internal elements in the design of the IR. A separate figure shows the curves of changes in some values of the SM load, which will facilitate the development of methods for calculating the DB mode of the machine for the optimal design of the IR.

Research on Dynamic Braking Torque Test Method of Brake Motor

Through the brief introduction of the working principle of the brake motor, combined with the theoretical analysis of the brake motor dynamic brake torque test method (directtest method and indirect test method), it is concluded that the selection of the test method is closely related. According to the sensor type, installation position, test range and accuracy requirements. The differences between direct measurement method and indirect measurement method are compared, their respective measurement methods are introduced, and their advantages and disadvantages are summarized. According to the test requirements, the appropriate test method can be selected, and the direct test method and indirect test method can be selected at the same time, to ensure the safety and stability of product

Torsional Oscillations Mitigation via Interval Type-2 Fuzzy Logic Brake Control

Turbine-generator shaft torsional oscillations is an interdisciplinary power system dynamic problem because it encompasses mechanical and electrical sectors of power grids. They give rise to a premature expenditure of fatigue life of the turbine-generator shaft metal which could lead to shaft cracks. This paper introduces an interval type-2 fuzzy logic controller to regularize the dynamic braking interventions of a novel braking resistor model for mitigation of torsional oscillations resulting from unsuccessful autoreclosure procedures near generation stations. The effectiveness of proposed scheme is elucidated by considering the unsuccessful autoreclosure of three-phase-to-ground fault in a single machine infinite bus power system via MATLAB/Simulink-based modeling and simulation environment with the help of interval type-2 fuzzy logic controller toolbox. The comparative simulation results with and without the suggested mitigation regime show that the proposed scheme is effective in the mitigation of torsional torque oscillations