Power Supply Network Research Articles

Optimization of Ship Power Supply Network and Intelligent Energy Management Strategy Under Multiple Energy Modes

<p>Purpose: This article aims to address the issues of incomplete management models and slow convergence speed of optimization models in energy management in ship multi energy systems, and to construct a comprehensive dynamic optimization objective model. Method: Firstly, establish an optimization design model with the objective functions of energy storage system cost, grid power fluctuation smoothing, and energy supply and demand balance; Then, in the optimization process of the objective function, a bus voltage coordination control strategy is adopted, and for the parameter optimization problem in the strategy, a cuckoo search algorithm based on population feature feedback is used for optimization. Result: Through simulation experiments, the method proposed in this article provides effective guidance for capacity configuration and energy management of multi energy ship microgrids, improving quality and efficiency.</p> <p> </p>

Assessment Accuracy of Standard Point Positioning Enhanced by Observation and Position Domain Filtering Utilizing a Multi-Epoch Least-Squares Integration Method

To enhance the positioning accuracy of standalone GNSS receivers in environments unable to provide precise ephemeris and clock offset, such as undeveloped forest areas that lack network communication and power supply, this study employed the Time Difference Carrier Phase (TDCP) technology to improve the positioning accuracy of Standard Point Positioning (SPP), where the Least-Squares (LS) and the extended Multi-Epoch Least Squares (MELS) method were applied in the position domain filtering for a single GNSS receiver and compare its performance with the existing observation domain filtering method. Firstly, the simulated data sets with various positioning accuracies were used to verify the effectiveness and convergence of the LS filtering methods. The results indicate that the LS filtering method produces a lower root mean square (RMS) error than the original strategy. Secondly, this study uses two kinematic GNSS data sets to evaluate the performance of the observation and position domain filtering, with an emphasis on the MELS method. The numerical experiment results show that the position domain LS filtering method outperforms the other two methods. The open environment experiments result shows that the positioning domain filtering method achieved positioning accuracies of 0.202 m, 0.843 m, and 2.036 m in the E, N, and U directions, respectively, with improvements of 68.0%, 21.6%, and 24.0%, compared to the original algorithm which achieved positioning accuracies of 0.631 m, 1.076 m, and 2.680 m. It also achieved improvements of 24.0%, 4.0%, and 18.3%, respectively, compared to the observation domain filtering method with positioning accuracies of 0.353 m, 0.886 m, and 2.526 m. The forest scenes experiments result shows that the positioning domain filtering method achieved positioning accuracies of 1.308 m, 1.375 m, and 2.133 m in the E, N, and U directions, respectively, with improvements of 42.4%, 36.2%, and 27.6%, compared to original algorithm which achieved positioning accuracies of 1.863 m, 1.873 m, and 2.722 m, and also achieved improvements of 27.0%, 19.4% and 10.6%, respectively, comparing to observation domain filtering method with positioning accuracies of 1.661 m, 1.642 m and 2.359 m. Moreover, the examination of the LS method results based on different epochs reveals that the filtering accuracy increases as more epochs are incorporated into the position domain integration and the enhancement value reaches a few millimeters.

Patent Research of DC Electric Drive Power Supply Systems Based on Active Converters With Power Correction

Despite the fact that the AC electric drive has recently been increasingly “displacing” the DC drive, it is quite relevant, because completely satisfies the requirements of technological processes. Consideration of the problem of electromagnetic compatibility of DC converter installations with the supply electrical network occupies a large place. The article provides research and analysis of the influence of valve loads on the quality of the power supply network and ways to improve the quality of power supply by replacing existing converters with active DC-DC converters with power factor correction, as well as a patent study.

Electromagnetic Susceptibility Analysis of the Operational Amplifier to Conducted EMI Injected through the Power Supply Port.

Operational amplifiers (op-amps) are widely used in circuit systems. The increasing complexity of the power supply network has led to the susceptibility of the power supply port to electromagnetic interference (EMI) in circuit systems. Therefore, it is necessary to investigate the electromagnetic susceptibility (EMS) of op-amps at the power supply port. In this paper, we assessed the effect of EMI on the operational performance of op-amps through the power supply port by a bulk current injection (BCI) method. Firstly, we conducted the continuous sine wave into the power supply port by a current injection probe and measured the change in the offset voltage under EMI. Secondly, we proposed a new method of conducted susceptibility and obtained the susceptibility threshold regularities of the op-amps at the power supply port under the interference of different waveform signals. Our study provided conclusive evidence that EMI reduced the reliability of the op-amp by affecting the offset voltage of op-amps and demonstrated that the sensitivity type of op-amps was peak-sensitive at the power supply port. This study contributed to a deep understanding of the EMS mechanism and guided the design of electromagnetic compatibility (EMC) of op-amps.

Principle of predicting the reduction of insulation properties of electric motor windings

The simplicity of the design of the asynchronous electric motors (AM) allows them to be widely used in industry. The AM fleet sometimes reaches 80% of the total load of the enterprise. According to statistics, more than 60% of AM failures are observed due to damage to the insulation of the AM stator winding. The reason is premature dynamic and thermal aging of the insulation, which leads to the failure of the conductive and grooved parts of the AM winding. As a result of a decrease in the dielectric properties of the insulation, damage occurs in the stator windings of AM, such as turn, phase-to-phase short circuits, which tend to develop into a short circuit. Short circuits in the stator windings of the AM are emergency and lead to a sudden disconnection of the AM from the power supply network by existing relay protection means, for example, current cut-off or thermal protection. Sudden, non-sanctioned disconnection of the electric motor from the power supply leads to the shutdown of technological equipment, damage to equipment, raw materials and economic losses. The aim of the work is to develop the principles of timely monitoring and prediction of the state of housing and interphrase insulation of stator windings of AM using the energy of capacitors with local compensation of reactive power. To achieve this goal, research was carried out at a laboratory institution with AM, in which branches of turns were made. The transient processes of capacitor discharge are considered and new methods for monitoring and predicting the residual insulation life are proposed. The new method is based on monitoring the condition of the insulation after each disconnection of the AM from the power supply, while using the energy that remains in the capacitors. The use of a change in the velocity characteristic of the constant discharge time of the capacitor made it possible to predict the residual service life of the AM. The personality of the study is that under the conditions of local compensation of reactive power, it is possible to use the energy remaining in the capacitors to diagnose and predict the state of insulation, as well as the change in the velocity characteristic of the capacitor discharge time constant, which is a criterion parameter for predicting the residual service life of the AM. The carried out studies confirmed the development of test diagnostics in conditions of reactive voltage compensation, which is a new direction in systems non-poisonous diagnostics, which requires continued research and applications in industry.

SIMULATION MODELING OF MULTI-PORT DC-DC CONVERTER IN MPPT SOLAR BATTERY CONTROLLERS UNDER NEURAL NETWORK CONTROL

Photovoltaic generation system - energy system, designed to convert useful solar energy through photovoltaic systems. It can consist of several components, including a solar array, DC/DC and DC/AC semiconductor converter, battery, filter or transformer, control system (CS). Depending on the application, photovoltaic systems can be operated as part of a self-contained power plant or operate on a network. Thus, it is possible to distinguish several basic configurations of photovoltaic generation systems. The standalone generation system is the most common configuration of photovoltaic generation systems, which contains rechargeable batteries (AB). This system is completely independent of the centralized power supply networks and is suitable for comfortable energy supply to consumers. The use of AB makes it possible to increase the reliability of the photovoltaic system and to extend the possibilities of using e.g. battery power is used during insufficient light or when the load exceeds the generation of solar cells. The scope of such configurations are lighting systems of residential and non-residential objects, power supply of houses and buildings, security systems and emergency power supply, power supply of remote residential and non-residential objects, Power supply to spacecraft, etc. Autonomous generation systems typically contain two transducers. The DC/DC converter acts as a battery charge controller. The control system for such a transducer may include the function of tracking the maximum power point for the maximum use of solar energy. The excess energy will be stored in AB. The DC/AC converter converts the DC current energy into the AC energy of the required frequency and voltage. The advantage of such a system is the possibility of using solar energy, both during the day and at night, due to the power of AB and the possibility of using the system at remote sites where there is no grid power supply. The disadvantage of such a system is the loss of double conversion of solar energy and the high cost of batteries. Artificial Neural Network (ANN) provides an alternative way to solve complex problems. A neural network, with the right structure, can compute the values of any continuous function with some predetermined accuracy. The neural network requires no knowledge of the internal parameters of the solar module, learns quickly, has the ability to optimize and approximate. Therefore, the use of INS to track the maximum power point is relevant and of practical and scientific importance. Keywords: multi-port DC converter, artificial neural network (ANN), rechargeable batteries (AB), pulse width modulation (PWM), solar panels (SP), MOSFET power keys

A Model Predictive Control-Based Voltage Optimization Method for Highway Transportation Power Supply Networks With Soft Open Points

A Model Predictive Control-Based Voltage Optimization Method for Highway Transportation Power Supply Networks With Soft Open Points

Retracted: Adaptive Control Strategy of Multiemergency Power Supply Network System Connected to New Energy

Retracted: Adaptive Control Strategy of Multiemergency Power Supply Network System Connected to New Energy

ПЕРСПЕКТИВЫ ПРИМЕНЕНИЯ НАКОПИТЕЛЕЙ ЭЛЕКТРОЭНЕРГИИ В ЭНЕРГЕТИЧЕСКИХ СИСТЕМАХ

This paper explores the possibility of using different types of electric power storage devices in energy systems. A comparative analysis of such types of storage devices as: electrochemical, electrical, electromagnetic, mechanical. The properties of lead-acid, nickel-cadmium, sodium-sulfur, lithium-ion batteries, supercapacitors, superconducting magnets, kinetic storage devices are analyzed with the identification of advantages and disadvantages of their use; the fields of their application are considered. The possibility of integrating storage devices with renewable energy sources is being considered. The analysis of the averaged load schedules for the winter and summer periods is performed; the feasibility of using the drive to smooth out the peaks of the consumption load schedules is justified. A schematic solution for connecting an electric power storage device with a control system for a medium-voltage power supply network is proposed. The connection of the drive in such a system is provided on the 0.4 kV side using converter devices. The using of an AC-DC converter with a control system in such a system regulates the flows of active power in order to perform a two-way energy conversion in the case of energy accumulation by the storage device and energy return to the network.

Analysis of Reactive Power in Electrical Networks Supplying Nonlinear Fast-Varying Loads

This study concerns problems related to the assessment of reactive power in power networks with nonlinear fast-varying loads, such as electric arc furnaces, rolling mill drives, etc. The operation of this type of load is characterized by the introduction of interharmonic currents (including higher harmonics) into the power supply network and a relatively low power factor. Rapid changes in the RMS value of the current also cause voltage fluctuations and the related phenomenon of light-flickering. Therefore, there is a need to evaluate the power selection of compensating devices, taking into account the random nature of load changes and the distortion of current and voltage waveforms, in particular, interharmonic components, the impact of which has not been fully investigated so far. To analyze the random nature of load changes, autocorrelation functions were used, which allowed for the estimation of the expected values of the arc furnace current distortion coefficient (based on the recorded waveforms). In order to determine the parameters of reactive power compensating devices, and in particular capacitor banks, an autocorrelation function in the exponential-cosine-sine form was used, which meets the conditions of differentiation. This study contains comparative results of the reactive power of capacitor banks determined using different methods. The criterion for selecting capacitor bank parameters was the minimization of energy losses in the power supply network. The calculations presented in this study show that by taking into account higher harmonics and interharmonics in the voltage and currents of fast-varying loads, the installed power of the capacitor bank can be reduced by approximately 7%, and energy losses in the power grid can be reduced by 3–5%.

Predictive models of the dependability of electric power transmission (using the example of AO Tyvaenergo)

Aim. The paper analysed the damage rate of the electric power networks of AO Tyvaenergosbyt between 2014 and 2022 and preventively evaluates emergency shutdowns in the company’s networks in 2023. The author provides a brief historical reference regarding the company’s foundation, a description of the structure of its power supply network. The damage rate of elements, as well as main electrical equipment of the company’s power supply network were examined. The quantity of electrical power undersupplied to customers as the result of emergency shutdowns was analysed. The number of failures was classified depending on the amount of undersupplied electrical power. The paper studied the applicability of certain methods of prediction of the number of emergency shutdowns for the obtained interpolated series of preceding failures. The most appropriate method was established that was used for preventively evaluating the damage rate of the examined power networks for each month of 2023.Methods. The paper uses methods of mathematical analysis, general scientific methods of research, properties and capabilities of the MATLAB graphic interface and Excel tables. Statistical and cybernetical methods of prediction were considered for the purpose of predictive model development. The probability of failures within the examined power networks was evaluated. Equations were obtained for autoregression failure models that enable predictive evaluation of failure by months.The Results of the study may prove to be useful to the experts of Tyvaenergosbyt, as well as other power grid companies that are developing advanced emergency prevention activities aimed at improving the reliability of power supply.Conclusion. The approach to predictive evaluation of emergency shutdowns proposed in the paper showed that the most efficient method of predicting failures in a company’s power networks is the method of autoregression models using interpolation of data on preceding failures. The probability of prediction fulfilment is 95%.

Realization of the Online System for Consumption Monitoring and Power Quality Control in the Gruner Serbian Ltd Company

The paper presents the realization of the system for consumption monitoring and the system for power quality control in the hall 4 of the company GRUNER Serbian d.o.o. in Vlasotince, Serbia. The motivation for the establishment of the mentioned systems are machine failures within the warranty period for which the machine suppliers refuse to recognize the warranty, due to poor voltage conditions and frequent power sags within the industrial plant. Power quality problems are caused by external influences coming from the power supply network. For these reasons, a system of power etwork analysers was designed and implemented by the company Conseko d.o.o., Belgrade. This system monitors and records all relevant parameters of power quality (voltages, currents, active and reactive power, power factor, harmonic content, THD, etc.) in key parts of the hall 4 (molding, air conditioning, tool room, dining room, laboratory, etc.). In addition to this, the monitoring system provides complete insight into consumption and distribution of consumption at a given time interval, which represents an exceptional convenience for optimal distribution of internal consumption and financial calculation of power consumption of each subsystem, which directly affects to the economic profit. The Cloud subsystem is also installed in the system, so that all relevant parameters can be monitored in real time via a remote computer or through an application on a mobile phone.

Modeling “Wrong Side” Failures Caused by Geomagnetically Induced Currents in Electrified Railway Signaling Systems in the UK

AbstractThe majority of studies into space weather impacts on ground‐based systems focus on power supply networks and oil and gas pipelines. The effects on railway signaling infrastructure remain a sparsely covered aspect even though these systems are known to have experienced adverse effects in the past as a result of geomagnetic activity. This study extends recent modeling of geomagnetic effects on DC signaling for AC‐electrified railways in the UK that analyzed “right side” failures in which green signals are turned to red. The extended model reported here allows the study of “wrong side” failures where red signals are turned green: a failure mode that is potentially more dangerous. Railway lines using track circuit signaling, like those modeled in this study, are separated into a number of individual blocks. This study shows that a relay is most susceptible to “wrong side” failure when a train is at the end of a track circuit block. Assuming that each train is positioned at the end of the block it is occupying, the results show that the geoelectric field threshold at which “wrong side” failures can occur is lower than for “right side” failures. This misoperation field level occurs on a timescale of once every 10 or 20 years. We also show that the estimated electric field caused by a 1‐in‐100 years event could cause a significant number of “wrong side” failures at multiple points along the railway lines studied, although this depends on the number of trains on the line at that time.

Methods of contactless registration of information signals for the audit of information security of power supply systems and networks

Methods of contactless registration of information signals for the audit of information security of power supply systems and networks

Результаты исследований высших гармоник при эксплуатации судовых частотно-регулируемых асинхронных электроприводов

One of the directions of scientific and technological progress at sea-based facilities is the use of electrical technologies based on nonlinear elements. It is revealed that the use of such technologies leads to a deterioration in the quality of electricity, mainly due to higher harmonic. The results of theoretical and experimental studies of the higher harmonic components of voltage and current occurring during the operation of ship frequency-controlled asynchronous electric drives are presented. During operation of a frequency-controlled electric drive high current harmonics of mainly 5, 7, 11, 13 orders are emitted into the power supply network, which is due to the presence of a six-phase rectifier. This leads to distortion of the sinusoid of the supply voltage, since the higher harmonic components of the current, propagating through the electrical network, create corresponding voltage drops on its elements. Along with the main harmonic of the voltage of a given frequency, the higher harmonic components of the voltage flow from the autonomous voltage inverter to the stator winding of the asynchronous electric motor, which causes the higher current harmonics and torques of the forward and reverse current sequences in the stator and rotor windings. As a result additional heating of the stator and rotor windings occurs and vibrations of the asynchronous motor shaft at frequencies of 300 and 600 Hz occur. A method for measuring the vibration of a frequency-controlled asynchronous electric drive from the interaction of the moments of the reverse and forward sequences has been developed and experimentally confirmed. A method for calculating the intrinsic frequency of oscillations of the asynchronous motor-load machine system is proposed, confirmed by the example of a laboratory installation. To accurately calculate the natural frequency of the oscillatory system, it is necessary to experimentally measure the moments of inertia of the rotor of an asynchronous motor and the armature of a DC motor.

Isotropic ΙoT-Based Magnetic Flux Density Meter Implementation for ELF Field Measurements

This article presents the basic principles for an Extremely Low Frequency (ELF) IoT-based isotropic meter implementation, which can measure magnetic flux density from 100 nT up to 10 μT. The identical sensor probes are used for isotropic field measurements in the X, Y, and Z planes. The prototype has a flat response across the frequency range from 40 Hz to 10 kHz, detecting and measuring several magnetic field sources. The proposed low-cost meter can measure fields from the power supply network and its harmonic frequencies in the operating frequency band. The proposed magnetic flux density meter circuit is simple to implement and the measured field can be displayed on any mobile device with Wi-Fi connectivity. An Arduino board with the embedded Wi-Fi Nina module is responsible for data transferring from the sensor to the cloud as a complete IoT solution, supported by the Blynk application via Android and iOS operating systems or web interface. In addition, an ELF energy harvesting (EH) circuit was also proposed in our study for the utilization of the alternating magnetic fields (50 Hz) derived from the operation of several consumer devices such as transformers, power supplies, hair dryers, etc. using low-consumption applications. Experimental measurements showed that the (DC) harvesting voltage can reach up to 4.2 volts from the magnetic field of 33 μΤ, caused by the operation of an electric hair dryer and can fully charge the 100 μF storage capacitor (Cs) of the proposed EH system in about 3 min.

Use of Statistical Analysis Tools for ECG Processing

The purpose of the article is to study the algorithms of statistical and intellectual data analysis and their use for processing and analysing electrocardiograms (ECG). The methods and algorithms that form the basis of statistical data processing and analysis are considered. The research methods are based on the application of statistical methods and algorithms for the analysis and pre-processing of medical data. Pre-processing is a necessary step in data processing, which makes it possible to analyze more efficiently, build more accurate models and reduce their dimensionality. Scientific novelty. The article analyses classical statistical methods used at the first stage of data processing. Their effectiveness and necessity in medical data analysis are proved. The results of the work are demonstrated on real data processing, namely, on electrocardiogram processing. Conclusions. The application of statistical analysis methods for pre-processing medical data is considered on the example of ECG processing and analysis. The main statistical characteristics were calculated: mean, variance, standard deviation, mode, median, skewness coefficient, kurtosis coefficient, and coefficient of variation. The obtained data is used to estimate the law of data distribution, test hypotheses about the laws of distribution, and normalize data. A correlation matrix is constructed for the ECG observation matrix, eigenvalues and eigenvectors are calculated, and principal components are determined on their basis. The use of principal components makes it possible to reduce the dimensionality of the data for a deeper analysis. In this study, the amount of data was reduced by a factor of four. A discrete Fourier transform was performed. The analysis of the Fourier’s transform results made it possible to isolate high-frequency electromagnetic interference transmitted through the cable from the power supply network to the device, and the frequency of the interference was determined. Motion artefacts associated with the patient’s breathing were detected. The frequency of such interference is in the range from 1 to 4 Hz. The ECG points were classified and an ECG module was built for further analysis. The classification results made it possible to identify a set of points in the vicinity of R-peaks. This makes it possible to localize QRS complexes without using a complex mathematical apparatus. The results of medical data pre-processing allow to reduce the data dimensionality, identify the presence or absence of linear relationships, and evaluate the frequency characteristics of the data. Based on the pre-processing, it is possible to plan further research and build better models for data mining.

VIRTUAL MODEL OF THE SYSTEM "INDUCTION MOTOR - SOFTSTARTER WITH TWO CONTROLLED PHASES"

One of the most commonly used start methods of induction motors is starting by gradually increasing the supply voltage. At the same time, softstarters based on thyristors or triacs are used, which are cheaper in comparison with frequency inverters based on IGBT - transistors. In turn, the disadvantage of this method of starting with significant reduction of the starting torque, so the possibility of using such starters for various executive mechanisms requires careful research. In the presence of a limitation of power source power, especially in wartime conditions, the problem of limitation of starting currents, especially in the case of using starters with two adjustable phases, is actual. To take into account the multiplicity of starting currents for different types of mechanisms, a mathematical model of the system " induction motor - softstarter with two controlled phases" was created. The model differs from the known ones by the possibility of limiting the power of the power supply network, the appearance of the mechanical characteristics of the executive mechanism and the starting moment at voltage ramp start mode. Transient processes in relative units for the possibility of estimating the multiplicity of starting currents to determine the required power of the autonomous power source are presented. To assess the adequacy of the mathematical model, a research stand with measuring of motor winding currents using a current transformer and a microprocessor device with an oscillography function was created. In the work, a comparative analysis of the results of modeling and experimental studies on a physical model is carried out, herewith the discrepancy of the results did not exceed 10%. It was determined that when using a soft-start device with two adjustable phases, even with small voltages, the current multiplicity is quite high and requires the use of a power source of greater power, but less than in the case of direct start. Formulated conclusions based on research results and recommendations for further reduction of starting currents.

Assessing the viability and environmental impact of residential demand response programs: A case study in East Legon, Greater Accra, Ghana

Residential demand response programs hold significant potential for delivering cost benefits and enhancing the overall security of the power supply network. In the context of Ghana, the current state of such programs could be improved. Regrettably, utility companies in the country currently lack an understanding of customers' behavior related to electricity use, which hinders residential demand response implementation in Ghana. This paper aims to relieve the Ghanaian power network’s demand in peak hours through a residential demand response program by assessing consumer behavior related to electricity consumption in a day. This study presents East Legon as a case and employs the diversified demand method based on consumer behavior to assess residential demand response in Ghana. The results indicate that a 3 MW of demand can be relieved on the network in a day during peak hours. The annual energy savings resulting from this initiative is 40,479,991 kWh. A 1,032,239,780 kg of CO2 emissions due to this program can be avoided. Notably, the study demonstrates a positive Net Present Value (NPV) of GHS 350.00, signifying the financial viability of the demand response program in East Legon over the specified time horizon. The research underscores the significance of leveraging consumer behavior to optimize demand response programs, offering valuable guidance to policymakers and utility companies to enhance energy efficiency and sustainability in the region.

Mathematical Calculation of Synchronous Electric Motors Dynamic Stability

This paper considers the equipment and power supply schemes for urban water supply, heat supply and sewerage pumping stations. Mathematical calculations of the impact of the static and full centrifugal pumps pressure ratio on the dynamic stability of synchronous electric motors were carried out. An analysis of the influence of pump parameters and engine load on the run-down parameters and drive stability during power shutdowns was carried out. It has been theoretically proven and practically confirmed that ensuring the stability of pumping station drives and the reduction in enterprise losses during various short-term disruptions in power supply networks can be provided by means of a high-speed backup source with a response time of less than 9 ms, dynamic voltage dip compensators with a response time of less than 3 ms and uninterruptible power supply sources.