Ivanovo State Power University

The main problem with implementing selective stator ground fault protection of multiple high-impedance grounded generators sharing a common bus is the low magnitude of the ground fault current and, often, the impossibility of installing a zero-sequence current transformer.

In 6- to 10-kV distribution networks operating with an isolated neutral, current protection based on monitoring the fundamental frequency component of the zero-sequence current is mainly used for protection against single-phase ground faults. The selectivity and stability of such protection are significantly affected by intense transient processes during intermittent arcing single-phase ground faults. One promising area for improving current protection against single-phase ground faults is to increase the selectivity and stability of their operation based on recognizing the types of ground faults using a multiparameter approach to implementing relay protection. To develop and study the methods and algorithms for recognizing the types of ground faults in 6- to 10-kV networks with an isolated neutral and to assess the effectiveness of their application in order to increase the selectivity and stability of current protection against single-phase ground faults, simulation modeling in MATLAB, SimPowerSystems, and Simulink was used. The configuration and parameters of the simulation models were selected taking into account the main features of 6- to 10-kV distribution cable and overhead networks of industrial, urban, and agricultural power-supply systems, determining the characteristics of steady-state and transient modes during single-phase ground faults. The principles of implementation and a diagram of multiparameter current protection against single-phase ground faults for 6- to 10-kV networks with an isolated neutral were developed, ensuring the recognition of all considered types of ground faults (stable, intermittent arc, and nonhazardous arc intermittent for the network) and the ability to automatically select on this basis the most effective method of its action (signal or shutdown). The results of functional tests on simulation models confirmed the efficiency of the developed algorithms for the operation of multiparameter current protection for all considered types of single-phase ground faults in 6- to 10-kV networks with an isolated neutral. The developed technical solution implements multiparameter current protection against single-phase earth faults, providing increased selectivity and stability of operation for all types of earth faults compared to traditional designs of current protection against this type of damage, continuity of operation not only for stable, but also for the most dangerous arc intermittent earth faults, as well as the ability to select the method of operation of protection for these types of earth faults.

Linear generators, used, among other things, as autonomous power sources and electromechanical shock absorbers, convert the energy of oscillations into electrical energy with a linear reciprocating motion of the inductor. The EMF of the generator has a nonsinusoidal shape due to higher spatial and temporal harmonics. The change in the speed of the inductor is determined by the nature of the acting forces, but in the analysis it is usually assumed to be harmonic with a sinusoidal distribution of magnetic induction. Reduction of EMF harmonics is possible in an electrical system containing a linear generator and a magnetic-fluid damper, due to the improvement of designs based on a refined analysis. Reduction of spatial harmonics of EMF is carried out by improving the tooth zone and the armature winding, using magnetic fluid, and reducing temporal harmonics due to the provision of the electrical system of the necessary change in the linear speed of the inductor. The analysis was performed in the ANSYS Electronics Desktop, ANSYS MAXWELL, and Elcut packages. An electrical engineering system for converting oscillation energy based on a linear generator and a magnetic-fluid damper was developed, its functions, features, and operating modes were described. Combined device designs, a three-phase combined winding with an EMF increased by 2% and a sinusoidal distortion coefficient reduced by 20% were developed. Mathematical analytical and numerical methods for calculating characteristics based on finite-element modeling were proposed. The developed electrical-engineering system allows for efficient redistribution of oscillation energy between a linear generator and a magnetic-fluid damper, and ensures a reduction in higher harmonics in the EMF. The use of magnetic fluid controlled by a magnetic field allows regulating the resistance force to the inductor movement, carrying out controlled viscous energy dissipation in the layers of the fluid, dampening oscillations, increasing the magnetic conductivity of the gap, to increase the magnetic flux, reducing the pulsations of the tooth harmonics of magnetic induction, increasing heat removal from magnets and windings, and providing effective lubrication.

The article is devoted to the development of new fault location algorithms based on emergency mode parameters at instantaneous values on overhead power transmission lines of 110 kV and above. Increasing the accuracy of fault location algorithms is an important and urgent task. The methodological and simulation errors of fault location are directly related to the configuration of the power transmission line. The presence of parallel power transmission lines, mutual induction or branch substations affects the accuracy of fault location. In this work, the authors modernize their own previously developed fault location algorithms based on instantaneous values for complex power transmission line configurations. The developed fault location algorithms do not require additional corrections or means for processing primary signals and can be successfully applied when using data from digital in-strumental transformers. The studies of the algorithms were carried out on the simulation models of the overhead power lines in the Simulink/MATLAB software package. The remote fault location of the damage was carried out according to the parameters of the emergency mode. The assignment of parameters for the simulation modeling is carried out using the Monte Carlo method with subsequent statistical processing of the results and the construction of a justified inspection zone.

This paper investigates the impact of seasonal temperature fluctuations on the operation of industrial compressors working under strictly defined pressure and flow rate parameters. Analysis shows that changes in air density significantly affect compressor performance. Modeling of a K-5500-42-1 centrifugal compressor (two versions) using the SimInTech environment allowed for a comparison of two control methods: air discharge (with energy losses) and the connection of an additional compressor. Modeling results indicate the need for control system optimization to improve energy efficiency and ensure stable compressor operation under various climatic conditions, considering the strict pressure and flow rate requirements. The work highlights the importance of considering the thermodynamic properties of air in the design and operation of industrial compressors.

Verifying parameters of the equivalent circuits of various power network components, such as synchronous generators, is one of the important applications of synchronized phasor measurements. Accurate “on-the-fly” measurements of stator current and voltage quantities under steady-state and transient conditions allows estimating generator model parameters without disconnecting the machine from the bulk power system and subsequent specialized testing procedures. A standard generator model represented by the well-known Park-Gorev equations has quite a few parameters that are rather hard to determine all at once. With this in mind, it would be beneficial to break up the estimation problem into several stages. First, synchronous reactances could be determined through a set of measurements pertaining to different steady-state conditions. After that, transient parameters and the inertia constant are to be identified by applying a set of measurements captured under transients. This study is devoted to the development and testing of various approaches to estimating the machine transient parameters along with the inertia constant through a set of data collected from a phasor measurement unit throughout power system transients. A general step-by-step procedure is described, and related numerical results obtained through computer-aided simulations are summarized.

The article deals with Arthur Schnitzler’s one act drama “Der grüne Kakadu”. Numerous questions were raised in this small in volume play thanks to the genre of one act play in which the dialogue is the leading ground of dramatic action as well as theatre within a theatre structure. The structural dramatic element is the story lines parallelism, the most important problems of Arthur Schnitzler’s work such as love and death, reality and illusion, truth and lie, play and actuality are covered from various perspectives. It has been proved that the confusion of reality and illusion helps to bring the features of characters to light – they represent only the theatrical discourse and are not able to realise their potential in real life. The aesthetic enjoyment of playing gets the negative connotation and makes for self-delusion and inability to find the place in real life. Thanks to translocation of real and theatrical the distance between the stage and audience are also reduced resulting in the reception problem proceeded by the offstage spectator as the main subject. The following approach to the creation of a dramatic work has become more and more relevant in the literature of the 20th century.

The problems of the microclimate in the production premises lead to an increase in energy costs for the station's own needs and a deterioration in the well-being of the maintenance staff. To avoid this, it is first necessary to analyze the variations of the main parameters. Therefore, the main building (boiler and turbine shop) was chosen for the study Ivanovo CHPP-2. The pilot study was conducted twice a month between 2020 and 2023. As a result of the research, experimental data on the main indicators of the microclimate of the main building of thermal power plants were obtained. The microclimate parameters were measured at the main operating levels in the turbine and boiler rooms during warm and cold periods of the year. The analysis of the obtained data on the microclimate revealed deviations of a number of parameters from the normal values such as temperature, humidity and concentration of volatile substances. The total temperature deviation from the norm in the boiler turbine shop was 15 °C in the warm period, and 7.2 °C in the cold period. Humidity differed by 7.12% in the warm period and by 12.26 °C in the cold period. The maximum deviation of the concentration of volatile organic substances in the air was 6.87 mg/m3.

Digital measuring current and voltage transformers (DCVT), which incorporate various current and voltage sensors are the key sources of information about processes at modern digital substations. Classic small-sized current transformers, Rogowski coils, magnetotransistor sensors, Hall effect sensors, fiber-optic Faraday effect sensors, as well as shunts can be used as current sensors in DCVTs. For redundancy purposes, current channels are performed in several copies and on different sensors. Sensors that are different in nature have their own set of advantages, which together makes it possible to obtain the effect of eliminating the shortcomings of specific sensors. For example, they may not have a saturation effect or transmit the direct current component quite accurately, which is a significant advantage over classic current transformers. At the mains frequency, the behavior of these sensors is predictable, but their behavior is not well studied at higher and lower frequencies. Thus, it is decided to study the frequency response and phase response of these sensors in a wide frequency range. To solve the problems within the framework of this study, physical experiment, analytical and empirical solution methods have been used. As a result of the study, the frequency response and phase response of current sensors of DCVT in a wide frequency range have been obtained. Analog filter has been designed to correct the signal of the magnetotransistor sensor. The results obtained coincide with theoretical data and can be considered when developing digital relay protection and automation algorithms.