Efficiency increasing of a shipyard power supply system

When designing oil and gas industry facilities and petrochemical facilities, the issue of the organization of their power supply system does not lose its relevance. At the stage of the feasibility study, the options based on the use of renewable energy sources, as well as energy storage systems are not often considered due to the high cost of solutions. The absence of standard solutions for the use of renewable energy sources and energy storage systems, the incompleteness of the regulatory framework force designers to refuse to consider them when designing power supply systems. This article analyzes the theoretical aspects and practical examples of the use of additional non-traditional sources of power supply, contributing to the improvement of energy efficiency of power supply systems as a whole.

The article considers the problem of reactive power compensation in AC traction power supply systems, which is of particular importance in the context of the energy crisis caused by military actions, which is relevant for Ukraine. Reactive power is an important component of electric networks, which significantly affects the stability and quality of power supply. The article highlights the impact of reactive power on the efficiency of traction substations serving railway transport. Special attention is paid to the technical aspects of the problem and the analysis of the effectiveness of existing compensation methods, which is critically important for reducing electricity losses and increasing the overall efficiency of power supply systems. In conditions of outdated equipment and limited resources, the problem becomes more complicated, which requires the implementation of modern technological solutions. The paper analyzes main methods and devices for compensation of reactive power, in particular, such as capacitor units and synchronous compensators, as well as the use of modern technologies of flexible alternating current transmission systems (FACTS). Particular attention is paid to experimental studies conducted at a real traction substation, where reactive power was measured and the effectiveness of compensating devices was shown. Research results show that reactive power compensation allows to significantly reduce energy losses, improve the quality of electricity and increase the stability of the network. The article also discusses the prospects of implementing FACTS systems for dynamically regulating reactive power and improving the operation of electrical networks. The use of these systems can significantly increase the reliability and efficiency of the power system, especially in the context of the integration of renewable energy sources such as solar and wind power plants. This will ensure reliable power supply in critical conditions and increase the efficiency of Ukraine’s energy infrastructure.

Modern industrial enterprises feature the widespread use of non-linear loads, such as induction furnaces, which are powerful sources of higher harmonics. The deterioration of electric power quality, particularly non-sinusoidal voltage, poses serious risks to occupational safety, including overheated equipment, false activation of protection devices, and an increased likelihood of electrical trauma. The goal of this study is to analyze non-sinusoidal voltage indices in a power supply system with induction furnaces, assess the impact of static condenser accumulators on the level of higher harmonics, and identify associated threats to industrial safety. The object of the study is a power supply system of an industrial enterprise with induction furnaces. The methodology is based on experimental measurements using the PKK-57 analyzer. The measurements were taken at key network points with both connected and disconnected Static Capacitor Banks, followed by spectral and statistical analysis of the obtained data. As established, connecting static condenser accumulators instead of suppressing them causes a resonance amplification of individual harmonics. The level of the fifth voltage harmonic between phases 1 and 2 increased from 1.19 % to 8.14 %, which exceeded the standard by 8 %. Similarly, in phase currents, the fifth harmonics reached 18.93 %. This causes significant additional losses, overheating of conductors and transformers, and breaches the correct operation of microprocessor protection relays, thus directly threatening electrical safety. Using standard accumulators of static condensers in networks with non-linear loads is not permissible without a prior analysis of the harmonics’ composition, as it can cause sudden deterioration of electric power quality and generate critical risks to personnel and equipment safety. A promising field is the development and implementation of adaptive compensation systems, such as active harmonic filters and filter compensating devices, that can dynamically suppress resonance harmonics, simultaneously ensuring power efficiency and safe working conditions.

To ensure the functioning of the energy system, coordination and increase the efficiency of its parts need new control mechanisms. Generation, transmission and consumption of electricity needed control mechanisms that include integration of self-organizing power and heat supply systems, built on multi-agent principle. Also they must correspond intellectual basis, monitoring and accumulation. This includes effectiveness assessment of the state and analysis of technical, technological and organizational management mechanisms. One of the main parts is interaction principles of energy systems in accordance with European Community policy at various levels at liberalized electricity market. In most developed countries, demand management programs are widely used as a means of harmonizing the modes of generation and consumption in the power supply system. The main direct methods are set in the form of electricity tariffs. Indirect methods are set in the form of programs to manage electricity demand and the possibility of their application to manage electricity demand. Methods for estimating the unevenness of the daily schedule of electricity consumption and the factors influencing the technological environment are presented. The work aims at scientific and applied problem – finding methods of estimation and features of managing the demand for electricity. The use of the proposed estimation methods of electricity consumption influence non-uniformity on the level of power supplies system losses based on Frize QF power and optimization of consumers’ operation modes in the power supply system is considered. Approaches and optimization mechanisms of the daily electricity consumption on the example of a residential complex with the possibility of energy accumulation are offered

Hose-drawn traveler (HDT) is a significant type of sprinkler irrigation equipment in China. In arid and remote areas, where grid power is unreliable or unavailable, the water pumping system of the HDT typically depends on a complementary power supply (CPS) system integrating batteries, photovoltaic (PV) panels, and gasoline generators. However, the configuration of the CPS system is often determined empirically, which can lead to increased costs and compromised operational reliability. This paper aims to optimize the configuration of the CPS system based on the power demand of the water pumping system in HDT. We propose an optimization model for component sizing that considers both the annual costs and reliability of the power supply system. An improved particle swarm optimization (PSO) algorithm, incorporating a penalty function, is employed to determine the optimal configuration of the CPS system. The proposed optimization approach is then applied to an HDT operating in three typical regions in China: Golmud, Beijing, and Harbin. Finally, a comparative analysis of the configurations and annual cost of two CPS systems, PV-battery (PVB) and PV-battery-gasoline (PVBG), is conducted. Results show that for a given region, season, and power of water pump, the PVBG system needs a smaller PV panel area and lower battery capacity than the PVB system. For a fixed region and season, increasing power of water pump leads to a more significant rise in the annual cost of the PVB system than in that of the PVBG system. At high pump power levels, the PVBG system is more cost-effective, resulting in a lower annual cost than the PVB system. In Golmud, under identical seasonal and pump power conditions, both systems have lower annual cost than in Beijing and Harbin, suggesting that Golmud is a more suitable region for deploying CPS systems. The proposed method provides a reference for designing power supply systems of HDT irrigation.

To calculate short-circuit currents, voltage losses and reactive power in electrical networks, information on inductive resistances of cable lines is required. In the technical literature there are no exact parameters of single-core cables with voltage of up to 1 kV insulated by crosslinked polyethylene. This results in inaccuracies in the calculations of modes of electrical networks. The article considers the issues of determining the inductance and inductive resistance of power lines up with voltage of up to 1 kV made of single-core cables and insulated by crosslinked polyethylene. The analysis of formulas for determining the inductance given in different literature sources was fulfilled, that demonstrated a significant difference in the numerical values of the obtained calculation results. The formula that provides more reliable calculations of the inductance of the cable lines was identified. The influence of the permissible increase in the thickness of the insulation and the sheath of a single-core cable with voltage of up to 1 kV covered with cross-linked polyethylene on the inductive resistance was determined. The inductance and inductive resistance of single-core cables were calculated when the cables were arranged along the vertices of an equilateral and right-angle triangle, as well as in one plane. It was shown that the specific inductances and inductive resistances are 1.7–1.8 times greater in the plane with the distance between adjacent cables equal to the outer diameter of the cable than in the location is close to the triangle. When the cross sections of conductive cores are large and installations are multi-ampere, there is a surface effect and proximity effect, due to which the magnetic field intensity inside the core and its inductance decrease. Inductivities and inductive resistances of singlecore cables with voltage up to 1 kV were determined taking into account the influence of the surface effect and the proximity effect. The calculations that we performed have shown that the nonconsideration of the above-mentioned effects leads to significant errors in the determination of inductive resistances. The influence of one-core cables of armor made of steel tapes on inductive resistances is considered. An illustrative example shows that the inductive resistance of an armored cable with a cross-section area of the current-conducting core equal to 800 mm2 is about twice as large as the unarmored one. The use of single-core cables in three-phase electrical networks, armored with steel straps, ought to be prohibited by regulatory documents, since such cables dramatically worsen the efficiency of power supply systems.

In the article, various piezoelectric energy harvesting circuits including the standard full bridge rectifier (S-FBR), self-powered synchronous charge extraction (SECE) and optimized self-powered synchronous charge extraction (SECE-opt) circuits are discussed. The performance of each scheme, their ability to adapt to variable loads and overall power conversion characteristics were evaluated. The analysis showed that the self-powered SECE-opt scheme exhibits the highest efficiency due to its advanced switching technology and stable output power. It was experimentally found that the optimized SECE-opt circuit is the most suitable solution for low-power applications. It was also found that SECE and SECE-opt schemes significantly increase the amount of energy harvested compared to the standard S-FBR scheme. These techniques are particularly effective in harvesting energy from irregular and dynamic signals such as vibrations and wave oscillations. Thus, the use of SECE and SECE-opt schemes can significantly improve the efficiency of power supply systems for sensors and other low-power devices.

Accurate harmonic emission level evaluation is the basis of distinguishing the responsibility of harmonic pollution between power supply system and consumer. A new harmonic emission level evaluation method based on principal component analysis (PCA) regression is proposed in this paper. Firstly, the principle of principal component analysis regression method is stated. Secondly, harmonic impedance of supply system is evaluated by principal component analysis regression method. Finally, harmonic emission level of supply system and consumer is calculated according to the harmonic impedance of supply system. This method has a high accuracy in harmonic emission level evaluation. The effectiveness of the proposed method was verified by computer simulation results.

This paper presents the results of research on the influence of asymmetric and nonlinear load on the operating mode of a low-power turbine generator, which simulation takes into account automatic excitation and rotor speed controllers. The results of computer and physical modeling show the occurrence of the following negative effects: a noticeable negative-sequence current appears; the generator begins to generate higher harmonics into the network; the amplitude of the forced oscillations of the excitation current increases; additional mechanical vibrations of the rotor arise, which can lead to the accelerated wear and loss of stability. To ensure the operation of low-power generators with asymmetry and harmonic distortions, it is necessary to limit their load. As a criterion, the maximum current difference in the phases can be used, which should not exceed 12% of the rated current. In addition, it is required to use special means to protect generators: DC links; harmonic filters; negative-sequence protection of generators; automatics for limiting the excitation current.

The results of a study of the levels of current and voltage harmonics, in a power supply system feeding a vertical mill for cement grinding, are presented in this paper. The obtained results are analyzed and compared with regulations.

With the rapid development of social economy, electric energy plays an indispensable role in social life and has become an important symbol of the country’s comprehensive national strength. However, with the rapid development of power electronic technology, many nonlinear loads appear in the power system, which has become the most important harmonic source in the power system. Harmonics will not only affect the normal operation of various electrical equipment, but also damage the peripheral communication system and equipment of public power grid. Therefore, we must control the harmonics in the power grid. The traditional treatment scheme is to use LC passive filter (PF), but it can only filter out harmonics of a specific number of times. In addition,it is sensitive to power grid parameters, may produce resonance, so that the harmonics are amplified, and the volume of the filter device is huge. In order to overcome the above problems, active power filter (APF) appears, which can dynamically compensate harmonics according to harmonic frequency and size, and has excellent flexibility and practicability. However, in terms of cost, the cost of APF with the same capacity is much higher than that of PF. Therefore, based on the respective characteristics of PF and APF, this paper makes an in-depth research and design of hybrid active power filter (HAPF). In this system, the passive filter completes the main harmonic compensation and reactive power improvement, while the active filter is used to help the passive filter overcome the disadvantage of easy resonance.

Trends in the use of renewable energy sources to power buildings do not bypass objects for which maintaining a power supply is critical. This also applies to railway signal boxes. The aim of the research work was to test the multisource power supply system for a railway signal box with power electronic converter systems and a DC bus, built as part of the research project. The assumption for powering the railway signal box building was to use renewable sources, energy storage devices, and a 3 kV DC traction network as the second required power supply grid. Both power grids were connected by power electronic converters, and the power values of the converters were set based on the calculated power balance values using the values measured at the system nodes and the set constraints. The tests primarily tested the response of the power supply system to changes in load power and power generated by the photovoltaic source, as well as the charge level of the energy storage devices. The correctness of the control algorithm’s operation was assessed based on the recorded power values in the power supply system nodes. The tests were carried out for 60 scenarios that covered all normal and emergency operating conditions. During the tests, delays in response to changes in the power supplied to the converters and the values of circular power flow between the power grid connections were recorded. The recorded delays ranged from 2 to about 50 s and the circular power flows did not exceed 1500 W. Based on the results of the tests, it was found necessary to improve the power measurement system in the power supply system nodes and to improve the quality of communication and the transmission time of measurement data transmission time.

Management of harmonic voltage levels can impose significant economic impacts for both electricity suppliers and customers. For the case where harmonic voltage levels are high, economic costs include damage to equipment and associated loss of production due to high voltage harmonic levels as well as the costs associated with mitigation of harmonic currents, for example, harmonic filters. In the alternate scenario, ie. the case where harmonic voltage levels are acceptable, considerable expense may be incurred mitigating harmonic currents unnecessarily due to lack of knowledge of harmonic levels and/or network capabilities. As such, there is considerable potential for industry to make large economic gains if harmonic voltage levels can be better understood. Using data collected as part of an ongoing long-term power quality monitoring project, this paper details the characteristics of voltage harmonic behaviour on Australia electricity distribution networks.

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 article deals with the calculation of currents and voltages of the toothed frequency of asynchronous motors in power supply systems. The study is based on the analysis of electromagnetic transformations in asynchronous motors, taking into account the two-way toothness and magnetic asymmetry. The calculation of asymmetric currents of the toothed frequency is carried out by the method of symmetric components. Developed calculation algorithm and software. The article establishes the factors of influence on the levels of toothed harmonics of the current in the power supply systems.