The results of a physical simulation using negatively charged artificial thunderstorm cells to test the spectrum of possible electromagnetic effects of upward streamer discharges on the model elements of transmission line monitoring systems (sensor or antennas) are presented. Rod and elongated model elements with different electric field amplification coefficients are investigated. A generalization is made about the parameters of upward streamer current impulse and its electromagnetic effect on both kinds of model elements. A wavelet analysis of the upward streamer corona current impulse and of the signal simultaneously induced in the neighboring model element is conducted. A generalization of the spectral characteristics of the upward streamer current and of the signals induced by the electromagnetic radiation of the nearby impulse streamer corona on model elements is made. The reasons for super-high and ultra-high frequency ranges in the wavelet spectrum of the induced electromagnetic effect are discussed. The characteristic spectral ranges of the possible electromagnetic effect of upward streamer flash on the elements of transmission line monitoring systems are considered.

Physical Simulation of the Spectrum of Possible Electromagnetic Effects of Upward Streamer Discharges on Model Elements of Transmission Line Monitoring Systems Using Artificial Thunderstorm Cell

The impact of space point definition on dynamic electro-geometrical model of lightning strike probability

The results of a study using an artificial thunderstorm cell of the possible influence of incomplete ascending discharges from concentrated model elements of overhead line monitoring systems on their functioning in the electric field of a thundercloud and/or lightning are presented. It is shown that ascending incomplete discharges (streamers and/or leaders) are formed from the model elements of the overhead line monitoring system (sensors, receiving and transmitting devices of a concentrated type), which can affect the functioning of such devices, including due to the fact that frequencies close to the operating frequencies of the elements of the overhead line monitoring system are present in the spectrum of their currents. It is established that the spectral characteristics of incomplete streamer and leader discharges formed from model elements of sensors and of receiving and transmitting devices of the monitoring system under the influence of an artificial lightning cell include frequency ranges close to the frequency ranges of analog-to-digital converters of sensors and data transmission devices over a high-frequency channel of concentrated monitoring systems. The essential role of the streamer corona on the formation of the ultrahigh-frequency component of the current pulse of incomplete discharges is revealed. The obtained results can help to ensure lightning protection of monitoring systems in a real thunderstorm situation.

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Application of Artificial Thunderstorm Cell for Investigation of Effect of Incomplete Upward Discharges on Functioning of Concentrated Model Elements of Overhead Transmission Line Monitoring Systems

The article represents results of a physical simulation of incomplete upward leader discharges induced on air transmission lines’ elements, using charged artificial thunderstorm cells of negative polarity. The influence of such discharges on closely located model sensors (both of rod and elongated types) of digital monitoring systems, as well as on the models of receiver-transmission systems of local data collection (antennas), was determined. Effect of heterogeneity of electromagnetic field caused by incomplete upward discharges on frequency specter of signals generated on sensors and antennas was estimated. Wavelet analysis was carried out to determine the basic frequency diapasons of such signals. Based on experimental data obtained, suppositions about the extent of influence of nearby incomplete leader discharges on the functioning of currently used systems of transmission lines’ monitoring were made.

Artificial Negative Polarity Thunderstorm Cell Modeling of Nearby Incomplete Upward Discharges’ Influence on Elements of Monitoring Systems for Air Transmission Lines

The paper provides the comparative analysis of energy consumption by the fans of forced-draft mechanisms. The mathematical description of an object was for this purpose developed, rated schemes of energy consumption of an object at the different control laws are given. The comparison of rated findings of energy consumption by the fan electric drive at throttle regulation and with the use of the directing devices showed that during the system work in the minimum points the control of the directing devices allows one to save up to 25% of energy. This effect significantly decreases during the work of a technology object with nominal pressures. Taking the aforementioned into account, the refusal of throttle regulation in favor of the directing devices is possible when a technology object works for an essential time with the lowered pressure.

Estimation of energy saving in electric drives of traction-blowing mechanisms

A computer-aided design system (CAD) for the protection from lightning of the unit substations and overhead power lines was developed. A software package containing a calculation model of areas protected from direct lightning strikes, backflashover of the primary and secondary insulation, induced pulse voltage in the secondary circuits, protection from lightning of the power lines, and protection of power substations against the lightning overvoltage along with the overhead power lines was developed. A database of the generic solutions for protection from lightning was developed, it being a structured collection of files containing the layout of buildings and equipment at the substation and the arresters’ layout plan with taking into account the electromagnetic compatibility. A database for earthing arrangement of arresters is the structured set of the typical arresters earthing. In order to find the required generic solution, the user selects the desired file by parameters using the standard tools for working with Windows files. On the basis of the regulatory documents on system and software engineering, the procedure for verification of the computer programs, to be applied as a part of the CAD for the protection from lightning of substations and overhead power lines, was developed. The verification procedure is based on testing of computer programs, as part of the developed system, using test sets containing the test cases. Test cases and test sets for testing the computer programs were developed. The computer-aided design system (CAD) allows significantly reducing the cost for designing of the protection from lightning and improving the quality of the projects.

A Computer-Aided Design System for Protecting Substations and Overhead Power Lines from Lightning

The idea of the system control and monitoring of a complete 35-kV switchgear with the shielded solid insulation is presented. The switchgear is constructed in the form of two cells. One of the cells, which has a three-position sulphur hexafluoride load break–disconnecting–grounding switch with a motor-spring drive is incorporated into the switch module and includes bus and cable modules, a cell cabinet, and a control and monitoring system. The other cell contains the same elements, plus a fuse and a high-speed grounding switch. The control and monitoring system is developed in two forms, one for standard and one for digital substations. Technical characteristics and the structure of the system, as well as the execution algorithms, are given. Monitoring of the electromagnetic fields and partial discharges with the use of the various indicators and sensors, monitoring of insulation, and its temperature, as well as residual life of the switching devices and drives, are of great significance. Modbus is usually used as the automation protocol for standard substations. It allows carrying out the dispatching control and data integration into the control system, but it does not allow real-time transmission of the instantaneous values of current and voltage, RPA discrete signals, etc. In accordance with the IEC 61850 standards, all real-time commutation processes are carried out by the Ethernet technology, which is described by the IEEE 802.3 protocol and provides digital data transfer in accordance with stringent RPA requirements. Structural implementation of two system modifications in the form of the nonstandard telecommunication equipment with a temperature–humidity control system located on the top of the switchgear cabinet with the arrangement of the control, indication, and alarm element is described.

M. A. Koshelev

Papers

A Computer-Aided Design System for Protecting Substations and Overhead Power Lines from Lightning

The idea of system control and monitoring of a complete medium-voltage switchgear with solid insulation