Simulation of onboard power supply system for small hydrographic vessel «Vaygach»

Subject of research: power quality indicators, non-sinusoidal modes in power supply systems. Purpose of research: assessment of power factor components under non-sinusoidal modes for the conditions of industrial power supply systems with linear and nonlinear loads. Methods and objects of research: simulation modeling of electrical systems in the Matlab Simulink environment, analysis of complex non-sinusoidal modes. Main results of research: а computer simulation model of an industrial power supply system with linear and nonlinear loads, as well as the presence of harmonic distortions from the supply network, has been developed. The dependences of the power factor components in non-sinusoidal modes on variations in the resistance of the power system and the length of the supply line connecting the source and the load node were obtained.

The article is devoted to the development and testing of a methodology for analytical modeling of power supply systems that include multiple sources and multiple consumers of electricity, located at a distance from each other and connected by power transmission lines. The developed methodology will help designers assess the possibilities of distributing electricity among consumers while calculating the optimal voltages that need to be maintained at the nodes of the power sources, thereby achieving minimal voltage differences between the load nodes. The methodology is tested using a 10-node power supply system, in which the number of energy source nodes and load nodes is equal to 5. The modeling methodology is based on calculating the parameters of the power supply system using the node potential method, along with Ohm's and Kirchhoff's laws. The calculations utilize the method of complex amplitudes and are carried out according to a proposed iterative algorithm, the flowchart of which is presented in the article. The calculations are performed in the MathCAD environment using the mathematical framework of matrix computations. For this purpose, a conductance matrix and a node current matrix are constructed, and the node potential matrix is calculated in MathCAD. The paper demonstrates how to transit from a three-phase system to a single-phase system, with all calculations performed on a single-phase scheme. To obtain accurate results, formulas are derived for converting the parameters of the three-phase system into single-phase parameters, including the conversion of consumed load powers into complex impedances. The results of the modeling are presented in tabular form and as directed graphs, indicating the potentials of the nodes and the directions of active power flows. The results of modeling two variants of power supply systems are provided. The proposed methodology is recommended for assessing the parameters of power supply systems that include multiple sources of electricity and several load nodes. Keywords: power supply system, mathematical modeling, calculation methodology, node potentials, complex amplitudes.

The article discusses the issues of ensuring the quality of electricity in power supply systems. It is shown that during the operation of power supply systems in certain cases the quality of electrical energy can be violated, including due to the uneven load of the electrical network phases, that leads to a significant asymmetry of voltages in this network. The emergence of a large difference between the voltages in the phases of the electrical network inevitably leads to negative effects on various electrical equipment of both power supply organizations and consumers' electrical equipment, thereby creating conditions for the occurrence of technological and electromagnetic damage, which are the reasons for the appearance of financial losses and other negative consequences in case of electricity quality violations. The results of voltage unbalance measurements obtained by the authors of the article while monitoring the power quality are presented. These results show that during the operation of power supply systems, modes arise in which the voltage asymmetry in the zero sequence significantly exceeds the permissible values. It is shown on a computer model of the simplest power supply system that reducing the resistance of the neutral conductor can serve as a rather effective measure to reduce voltage unbalance, especially when inductive load prevails in the composition of consumers.

The recommended power quality (PQ) indices in electric power systems are defined based on the discrete Fourier transform (DFT). DFT is mostly evaluated applying fast Fourier transform (FFT) algorithm which requires signals to be periodic in nature. Hence, it evaluates PQ indices accurately for stationary PQ disturbances only. However, in case of nonstationary PQ disturbances signal is aperiodic and FFT results in erroneous assessment due to spectral leakage phenomena. Furthermore, FFT cannot provide time information of the PQ indices as computation is performed in frequency domain only. Which is significant shortcoming of the FFT when dealing with time-varying PQ disturbances to extract dynamic signature of the signal. Thereby, this paper presents a framework of redefining PQ indices for stationary and nonstationary PQ disturbances employing time-frequency distribution (TFD) method. Among all TFDs, reduced interference distribution (RID) represents the most suitable properties for analyzing time-varying PQ disturbances. Hence, in this work, it is employed to reformulate PQ indices typically used in electric power systems. The results of two synthetic examples considering stationary and nonstationary PQ disturbances imply that the RID-based redefined PQ indices are closer to the actual values. Also, they provide more accurate results than the existing transient PQ indices and traditional FFT-based method.

The article discusses the synthesis of a fuzzy controller for the SVC control system installed in the power supply system of an electric steel-arc furnace. Studies were conducted in the MatLab environment on a simulation model of the power supply system, in which the connection of an arc furnace through two step-down transformers is considered. In this case, the model of an arc furnace according to the equivalent circuit is implemented with variable active-inductive resistance. The static var compensator model consists of four capacitive filters and a thyristor-reactor group (thyristor-controlled reactors). Comparing the results of modeling control systems with a fuzzy controller and an adaptive PI controller showed that the fuzzy controller copes better with maintaining a given voltage level and reactive power compensation. In a system with a fuzzy regulator, a smaller voltage deviation from the setpoint is observed, the transient process is shorter and the voltage more accurately reaches the specified level. In addition, the article considers the possibility of correcting one of the input variables in order to take into account the switching of the operating modes of the arc furnace.

In power supply systems powered from mainline railroads’ traction substations, the problem of ensuring the electric power quality is acute. One of the effective ways to solve it is the use of smart grid technologies, an important segment of which are automatically controlled distributed generation plants. The article presents the results of computer simulation of transients during an increase in traction load, which leads to deterioration of power quality in non-traction consumers’ power supply systems. The purpose of the study was to determine the efficiency of using distributed generation plants to improve the power quality in power supply systems of on-site facilities powered from mainline railroads’ traction substations. Particular attention was paid to the setting and algorithms of the automatic controllers of the distributed generation plant synchronous generator and their influence on the indicators of the transient process and the power quality in the power supply system. The studies were conducted in the MATLAB development and simulation environment. Their results indicated that the presence of distributed generation plants allows to improve the power quality factors at the busbars of non-traction consumer; concordant setting of controllers provides the possibility for additional improvement of these indicators. The use of prognostic controllers ensures maintaining of power quality factors at a constant level when changing the generator load. The use of direct current link and prognostic controllers almost completely eliminates voltage asymmetry and harmonic distortions, significantly reduces the oscillability and value of voltage overshoot and generator rotor speed of the distributed generation plant.KeywordsRailroad power supply systemsDistributed generation plantsSynchronous generatorsAutomatic voltage controllerAutomatic speed controllerPrognostic controllersPower qualityModeling

The article is devoted to choosing ways to improve the technological reliability of regional electric network (REN) to ensure reliable power supply. At the operational stage, the task of increasing operational reliability is assigned to the enterprise asset management system of the territorial network organization (TNO), as a REN operator. Technological reliability is ensured by an operational dispatch control system, which uses the existing reserves in the network to support the technological process of electricity supply to electricity consumers in case of network equipment failures. The relevance of improving the technological and operational reliability of power supply system (PSS) requires the development and improvement of methods for analyzing and assessing the TNO's readiness to provide power transmission services. The indicators adopted in Russia reflect the level of technological reliability of PSS. However, these indicators do not reflect the technical condition of the equipment, or identify causal relationship between an equipment failure and an interruption of power supply. The research is aimed at identifying “bottlenecks” from the technological reliability standpoint and substantiating maintenance and repair, and technical re-equipment and reconstruction measures to improve operational reliability. A PSS model is proposed reflecting the technical condition of the network equipment, the operational readiness of automation systems, the availability of structural, functional and load redundancy in the REN. A method is suggested for calculating the PSS reliability indicators, where the developed indices reflect the degree of development of the network technical potential and the role of the aforesaid nodes in the PSS. The method makes it possible to identify the network parts, where it is necessary to introduce new technologies. In contrast to a well-known method, which is based on expert estimates of probabilities of different circuit-mode states of the network and on the calculation of normal and post-emergency modes, a less timeconsuming formalized procedure for analyzing and evaluating the network structural and functional reliability is proposed. The results obtained allow to increase the validity of the decisions made both at the operational stage and the design stage.

The parameters of complex power supply schemes of tram lines, which are required for simulation modeling, were studied: statistical characteristics of traction loads of feeders and voltage on the tires of traction substations. It was established that the distribution function of the feeder feeding the tram depot corresponds to the logarithmic normal law, the distribution function of the modules of the idle voltage deviation and the angles between the idle voltages of adjacent traction substations to the truncated normal law. It is proposed to modernize the information bases of electric traction network parameters with complex power schemes to increase the efficiency of modeling the modes of operation of sections of urban electric transport. A method of calculating instantaneous schemes has been developed, which allows to create algorithms that do not depend on the degree of complexity of the scheme. A method of simulation modeling of complex power supply systems of electric transport based on the synthesis of the matrix method of calculating instantaneous circuits and the method of statistical tests for modeling the organization of traffic of trams and trolleybuses is proposed. Algorithms and simulation models of traction power supply systems of urban electric transport have been developed, taking into account the modes of operation of power systems. A single simulation complex has been created that takes into account the traffic schedules of trams and trolleybuses, power flows in power supply systems, which makes it possible to obtain generalized dependences of power flows and energy losses, and to increase the accuracy of calculations of electrical parameters to 5–7%. Adequacy of the simulation model to the real process was verified by experimental data on a number of two-track, single-track sections of electric traction networks and complex power supply schemes of traction substations. The error in determining the integral indicators of costs and energy losses does not exceed 5%, and the rms currents – 3%. The use of simulation modeling in the design of traction power supply systems allows to improve the quality of electrical engineering calculations of complex power supply schemes and to propose energy-efficient power supply modes.

This paper deals with the development and the applications of a computational transient model of the VINCI cryogenic expander cycle upper stage rocket engine, tested in the frame of the FLPP Expander Demonstration Program managed by the European Space Agency (ESA). Snecma has been developing a transient system model of the VINCI engine since the beginning of the engine development, and the constant use of transient simulation was one of the major factors contributing to the success of the first two VINCI engines test campaigns. Simulation results have been found to be in good agreement with the measurements from the very first tests. The model accurately predicts the engine global behavior during start-up and shutdown, as well as the engine steady-state performance, and it also describes correctly the transient behavior of complex subsystems such as the combustion chamber or the turbopumps. This paper provides an overview of the physical content of the VINCI engine transient model. Simulation results from the model are compared with engine test data, and the model representativeness is discussed in detail. A focus is made on highly unsteady phenomena, such as valve maneuverings, and their effects on the whole engine behavior. I. Introduction HIS paper deals with the development and the applications of a computational transient model of the VINCI rocket engine. The VINCI is a cryogenic expander cycle engine, basis of a demonstration program preparing an application on the European launchers, in the frame of the European Space Agency (ESA) Future Launcher Preparatory Program (FLPP). The VINCI development in 200 5 and 2006 was conducted in the frame of the predevelopment of a cryogenic upper stage, under contract from the Centre National d’Etudes Spatiales (CNES), the French Space Agency, on behalf of ESA. The Space Engines Division of Snec ma in Vernon, France, acting as a prime contractor, is in charge in particular of the engine overall system design and integration. Snecma has been developing a transient system model of the VINCI engine since the beginning of the engine development, in order to predict its behavior during start-up and shutdown transients, as well as during potential failure scenarios. This model can also be used to identify possible undesirable unsteady effects that may occur during the engine transient operation phases, and to assess the consequences of any design changes. The constant use of tran sient system simulation has been one of the major success factors of the first two VINCI engines test campaigns that took place from May to July 2005 (M1 engine) and from November 2005 to February 2006 (M2 engine). During a test campaign, the model was used on a systematic basis in order to perform risk analysis for the subsequent tests, and to gain a physical knowledge of the engine behavior complementary to the one coming from raw measurements. Thanks to the intensive modeling work done at Snec ma, and to the experience gained from subsystem and component tests, simulation results were found to be in good agreement with measurements. A fairly good agreement was obtained from the very first tests, despite the fact that the VINCI engine is the first cryogenic expander cycle engine ever built and tested in Western Europe. The model accurately predicts the engine global behavior during start-up and shutdown, as well as the engine steady-state performance, and it also describes correctly the transient behavior of complex subsystems such as the combustion chamber or the turbopumps. This publication provides an overview of the physical content of the VINCI engine transient model, including the modeling process of the different subsystems. Simulation results from the model are compared with engine test data, and the model representativeness is discussed in detail. A focus is made on highly unsteady phenomena, such as valve maneuverings, and their effects on the whole engine behavior.

China's high-speed railway adopts a single-phase AC power supply system. In order to balance the three-phase load on the grid side, the railway traction power supply system sets up a phase-separated area every 30km for commutation power supply. At present, most of the phase-separated areas of China's railways use automatic power-off and over-power phase mode. Before the train enters the neutral section, it will receive a signal to automatically disconnect the on-board circuit breaker to cut off the connection between the catenary and the train load. When the train passes through the articulated electrical phase separation, after on-site observation, the voltage drop between the pantograph and the catenary will break down the air when the pantograph slides on the neutral line and begins to gradually separate from the left branch catenary, resulting in repeatedly burning pantograph arcs. Since the on-board circuit breaker has been opened, the high-voltage cables on the train have no load current. The current through the arc in this process can only come from the stray capacitance of the neutral line, the voltage transformer on the high-voltage side of the train, the on-board cables to the car body and so on, this arc current will cause the overvoltage of the catenary. Combined with the Mayr arc model and the Cassie arc model, an improved Habedank arc correction model was built, and the distributed parameter line model of the traction power supply system and the pantograph-catenary multiple arcing model were jointly established. The influencing factors of split-phase overvoltage are derived from the multiple transient processes of the circuit caused by repeated arcing, and the variation law of split-phase overvoltage is obtained.

The Internet of Everything (IoE), which aims to realize information exchange and communications for anything with the Internet, has revolutionized our modern world. Serving as the driving force for devices in the IoE network, power supply systems play a fundamental role in the development of the IoE. However, due to the complexity, multifunctionality and wide‐scale deployment of diverse applications, power supply systems face great challenges, including distribution, connection, charging technologies, and management. In this review, some challenges and advances in the development of both power supply systems and their units are presented. In the overall system‐level field, establishing sustainable and maintenance‐free power supply systems through wireless connections, efficient power management and integrated energy harvesting and storage systems is highlighted. Additionally, the main performance metrics of power supply units are discussed, including energy density, service life, and self‐power ability. In addition, some directions of power quality assessment for both the system and unit levels of power supply systems are presented, aiming to provide insight into the future development of high‐performance power supply systems for the IoE.

New technological platform of Russia's power generation industry, based on smart grids concept, provides for a broader application of distributed generation plants. These plants can operate as parts of existing grids, or be pooled in micropower systems (network clusters). The article is dedicated to the issues of distributed generation plants application to raise efficiency of non-traction consumers power supply systems. In this case, a special attention was paid to enhancing the quality power supplied to non-traction consumers via application of the distributed generation plant which is controlled by concordantly set generator automatic voltage regulators (AVR) and automatic speed governors (ASG). The study was carried out in Matlab environment on a created railroad power supply system model. Turbo generators having power 2.5 MVA and rated rotational speed 1,000 rpm and 3,000 rpm were simulated in order to assess distributed generation plant effect on power supplied to nontraction consumers, damping speed of voltage and rotational speed when variations in power generation system operation occur. The studies conducted helped to detect that application of distributed generation plant with concordantly set AVR and ASG makes it possible to enhance power quality for non-traction consumer and ensure dynamic stability and resilience of railroad line power supply system.

This paper analyzes the advantages of bilateral power supply systems for electrified railway. Firstly, the equilibrium current is analyzed under different external power supply conditions. A method of reducing the equilibrium current is proposed, and the voltage loss of the traction substation caused by this method is solved. Next, the electrical performances of traction power supply system are analyzed, including current distribution, impedance and voltage loss. Finally, the model of bilateral power supply system was built, and the theoretical analysis was simulated and verified by Matlab/Simulink.

Power quality has become a common concern of customers and utilities in improving respective profits in the context of an open electricity market. Power electronics is the essential technology to control power quality in accordance with customer requirements and utility standards. This paper first summarizes power quality definitions and indices used in IEEE and IEC standards. It clarifies the problem to be solved and the role of power electronics devices. Then the overview of power quality control methods and equipments employing power electronics devices is explained. The control methodology discussed in this paper includes various schemes of future distribution and power supply system now under development.

This paper presents a surface contact static stress of a spur gear system combined with dynamic characteristic using transient Finite Element Method (FEM). Traditionally, the static stress analysis is done separately with dynamic properties due to limitation of complex equation and avoiding of error occurred. However, in this paper, static stress information is combined with the dynamic mechanism due to the time consuming during the design and analysis stage. A transient FEM analysis is carried out to formulate and solve large systems of algebraic equations in order to obtain a relationship between the contact parameter and the kinematics function. The methodology of the research is started with static stress analysis on tooth surface contact of a pair of the spur gear. Finite element modeling is run by choosing a certain static condition. The loading conditions are applied suitable with the gear mechanism. Degree of freedom controlled is based on the transmission system. The process is repeated until diagnosing work is satisfied. The result of the surface contact stress is visualized at each condition. Modeling of spur gear system is continued by combining stress analysis with dynamic characteristic via transient finite element method. Analysis of gear mechanism is obtained by investigate the stress distribution on real time application. Time range is set at the beginning of the analysis. Duration of the analysis is depended on a time frame chosen. By the transient FEM analysis, the stress occur at each step of the work cycle is performed. Results of the kinematics functions are derived and qualitative kinematics variations due to contact changes in time-step domain is identified. The simulation results from static and transient FEM are compared due to the validating procedure. The finite element results are in good agreement compared with the theory calculation.