The article deals with the principle of evaluation of technical condition, based on a comprehensive analysis of the motor parameters which is a main unit in mechanical engineering. Diagnostics system and residential life assessment of electromechanical equipment is presented based on the AC engine and algorithms of its work. The important challenge of diagnostics remains the well-timed faults detection and maintenance and repair organization. The solution of such challenge remains accuracy and reliability of diagnostic systems.

В работе рассматриваются вопросы использования активного выпрямителя в неполностью загруженном по мощности частотно-регулируемом приводе в качестве активного фильтра токов высших гармоник, а также компенсатора потерь напряжения, вызванных наличием в распределительной сети мощной нелинейной нагрузки. На основе математической модели трехуровневого инвертора, который подключается к сети 6-10 кВ без понижающего трансформатора, разработана система прямого управления мощностью активного выпрямителя, способная одновременно компенсировать токи нелинейных искажений при неполной загруженности выпрямителя по активной мощности, потребляемой нагрузкой, а также стабилизировать напряжение с помощью управления реактивной мощностью на входе установки. Эффективность работы активного выпрямителя в режиме компенсации искажений оценивалась на основе компьютерного моделирования участка распределительной сети как функция зависимости от соотношения между токами линейной и нелинейной нагрузки в сети, а также от загруженности силового преобразователя по активной мощности.

The paper refers to the development of computer model, which allows to iteratively calculate the maximum power capacity of the three-phase overhead or cable power line. The model considers two factors, which coexistence is known for complicating estimations of the power, consumed by the load, namely: impedance of the grid voltage source and static load characteristics (VI or VAR curves). The modelling of the load as current source, which current is a function of the voltage magnitude at the power line output, allowed to consider static (V-I) characteristics of the load. The model was implemented in the Simulink environment, which iterative nature of calculations allows to converge the grid output and load input voltages and currents after the transient, and therefore to consider parameters of the steady-state operation as sought-for solution.

The article considers the most modern and most informative methods for diagnosing faults in squirrel-cage induction motors with a short-circuited rotor. The methods are based on the evaluation of vibrations and electrical parameters, as well as coordinates during operation and are normalized when powered from a sinusoidal voltage with frequency of 50 Hz. The main advantages and disadvantages of these methods, as well as the main indicators characterizing the general technical condition of the electric motor, are described. The application of these methods when powered from a non-sinusoidal voltage is impossible due to the complex harmonic composition of current and voltage. The consequence of this composition are the ripple moment and additional power loss. The interaction of the harmonics of the inverter and subharmonics, caused by faults, leads to the occurrence of a resonance phenomenon, and therefore to a decrease in the stability of the electric drive.

The current paper is dedicated to the important problem of electrical energy quality. The development of power electronics manufacturing technologies leads to increase of nonlinear load and nominal power. Therefore, the quality problem becomes highly important. In this paper the problems of nonlinear load reduction and its operating modes modelling are considered. Influence of phase shift angle in the non-linear load modelling results is considered.

The paper addresses approaches to increasing the efficiency of wind turbines operating in autonomous mode in Arctic regions. Such type of wind turbine operation is related to fluctuations of the generated power, that negatively affects grid power quality. The increase of wind turbines efficiency is achieved by the utilization of current reserve of power converter, which is a necessary part of megawatts-sized wind energy generation unit. The developed Simulink model of the wind turbines, built according to two of the most suitable for megawatts-level power generation topologies, was used to determine their power output depending on the wind turbine’s rotor speed and the wind speed. Obtained power profile was then used to determine the amount of free current reserve depending on the wind speed, which has verified the ability of both wind turbine topologies to efficiently improve grid power quality, therefore leading to reduction or absence of the necessity to install additional power equipment for the compensation purpose.