Conventional Power Supply Research Articles

Small-Signal Modeling and Interaction Analysis of LCC-HVDC Systems Based on Harmonic State Space Theory

High-voltage direct current (HVDC) technology based on Line Commutated Converter (LCC) is widely used in modern power systems due to its numerous benefits. However, as a typical power electronic device, LCC-HVDC has caused significant changes in the dynamic behavior of modern power systems due to largely replaced conventional power supplies in power systems. The interactions among sending-terminal and receiving-terminal system become stronger and have caused some stability issues, but the mechanism behind this has yet to be fully revealed. In order to analyze the interactions among sending-terminal and receiving-terminal system of LCC-HVDC, a small-signal model of modular HSS modeling is proposed based on Harmonic State Space (HSS) theory. Comparison of time-domain response with detailed switching model shows that the proposed can well reflect the dynamic behavior of the detailed switching model. Based on the model, the influence of controller’s parameters on system stability is analyzed, as well as the dynamic interactions of LCC-HVDC among sending-terminal and receiving-terminal system are investigated. Analytical results demonstrate that there exists interactions among sending-terminal and receiving-terminal system which have an influence on the stability of the system.

Management and development of a residential energy storage system: A case study Jordan

The use of renewable energy generation (REG) and energy storage systems (ESSs) strategies have a considerable possibility in delivering resilience for renewable energy sources (RESs). Thus, combining REG and ESSs strategies to fix operational, economic, ecological, and power-concerning governmental issues have been received particular concern from power system (PS) operators and planners globally. In this concern, developing countries (Jordan), which are poor in traditional energy resources, have proposed different supportive issues and experiences for the common use of ESSs strategies in the situation of distribution PSs. Therefore, this article performs a universal solution to this problem possessed to construct the infrastructure substantially to achieve high penetration of RE in the PS. Based on this, the article firstly studies the necessity of using REG and ESSs strategies in RE-based distribution PS. So, the current approaches and motivation programs used in various countries for the growth of RERs in optimum composition with ESSs and REG strategies are offered. The results of this study suggest that the use of an ESS is very important for the management and development of residential Solar Energy (SE) applications. Most respondents (85.3%) said that the use of a domestic ESS is critical to the management and growth of demand and supply for RE. To improve main grid efficiency and reduce demand for conventional power supplies, Jordanian engineers and experts recommend that consumers should install ES devices in their homes.

Survey of Topology Morphing Control Techniques for Performance Enhancement of Galvanically Isolated DC-DC Converters

This paper provides a systematic survey on the topology morphing control techniques used in the galvanically isolated dc-dc converters. Existing techniques are broadly categorized based on the part where a converter changes its topology: at the input side, at the output side, and the advanced techniques that cannot be categorized in the first two groups. The techniques span from the simple reconfiguration between the full- and half-bridge switching cells similar to the conventional power supplies with universal ac input to the advanced multi-track topology and reconfigurable resonant tanks. In addition, the described variety of application examples proves the wide application range and versatility of the topology morphing control. These include fault tolerance, efficiency curve flattening, input voltage range extension, and other properties. Hence, this article provides a single comprehensive source for researchers and engineers willing to enter the topic of topology morphing control.

Analysis on the coupling characteristics of frequency stability and voltage stability in weak connected power grid with high ratio of clean energy

In order to relieve the energy pressure and promote the clean transformation of energy structure, the new energy represented by wind power and photovoltaic power generation is connected to the grid on a large scale. However, due to the small inertia of the new energy unit, the proportion of conventional power supply decreases, and the system has the problems of frequency stability and voltage stability. In this paper, the reactive power distribution, voltage and frequency stability characteristics of the long chain connection channel of weak connection power network are studied. Combined with the actual situation of simulation and calculation of power grid A, the influence of photovoltaic centralized access on the load frequency characteristics of weak connection power network is analyzed, and some suggestions are put forward.

Review of the Multi-Input Single-Inductor Multi-Output Energy Harvesting Interface Applied in Wearable Electronics

Along with the industrialization and popularization of the wearable electronics, an increasing number of the wireless sensor nodes (WSNs) are deployed. Nevertheless, the conventional battery-based power supply system has no longer satisfied the requirement of large-scale WSNs in terms of battery life, which emerges the energy harvesting (EH) technique. In order to combine various of energy sources and drive multi-loads, the multi-input single-inductor multi-output (MISIMO) EH interface applied to wearable electronics is spotlighted. In this mini-review article, the solutions for improving power conversion efficiency (PCE) and output quality in MISIMO EH interface are summarized. Furthermore, the future trends of MISIMO EH interface are also presented.

A multipurpose power supply for constant current, constant voltage, and constant power applications.

Constant current (CC), constant voltage (CV), and constant power (CP) find numerous applications in different stages of the power supply chain and are often a part of various industrial and commercial needs. Although several conventional power supplies are available in the market to provide CC, CV, and CP, their outputs are specific and limited to one or two of these power modes. In light of this, this paper introduces a multipurpose power supply that can deliver power in all three modes (CC, CV, and CP) irrespective of load dynamics. A novel branch type resonant converter comprising three inductors and a capacitor is investigated for the designand development of the power supply. Consumers can choose their preferred mode of operation by switching the operating frequency. This multipurpose power supply subsidizes the space, technology, time, and economy required for three individual supplies and bags magnificent features such as simple control with efficiency greater than 95% in the CC mode and above 80% in CV and CP modes, subjected to loading constraints. The versatility of the power supply is validated by a hardware prototype tested at different load conditions. Regardless of the changes in load resistance, the proposed power supply remained rigid and efficient in each of the mentioned modes.

Research on energy control of low voltage PV storage microgrid

Abstract Renewable energy sources cannot guarantee long-term and stable output supply when they are given energy consumption at the load end. At the same time, traditional solar and utility power supply systems cannot guarantee the priority of using solar energy to generate electricity, which has certain limitations. In this regard, an energy control strategy for achieving smooth and no backflow switching and prioritizing the use of clean energy solar energy under a joint power supply system of a solar power grid and a municipal power grid is proposed, which is used for a conventional combined power supply system of a contactor switching circuit. A topology of low voltage power grid is proposed, which effectively reduces the impact on the solar power grid and the municipal power grid during the system switching process combined control mode for controlling the current phase and repetitive control at the output end of the solar power grid in the combined power supply mode, and adding a feedforward control method for the grid voltage is adopted to ensure that the solar grid and the municipal power prioritize the use of clean energy solar energy and, at the same time, ensure the maximum utilization of solar energy. This paper chose the combined power supply system with the solar power grid and the municipal power grid as the object of this research. The topology structure and controlling strategy of the power supply system were comprehensively and deeply researched, and on this basis, the combined power supply system prototype was designed on the foundation of DSP28335 and CPLD. Moreover, hardware parameters are designed in the system, and an energy management optimization algorithm based on the system is developed on the corresponding experimental platform. The experimental results show that the proposed energy control strategy can effectively reduce the impact on the solar power grid and the municipal power grid during the system switching process, ensure that the solar power grid and the municipal power grid have no backflow combined power supply and give priority to the use of clean energy solar energy.

Influence of a short reverse positive HPPMS pulse on the deposition of CrAlN

In conventional high power impulse magnetron sputtering processes (HPPMS) short pulses of a negative voltage are used to maintain the discharge. A new approach to accelerate ionized species towards the substrate position and subsequently improved coating properties is the use of a power supply, which generates a reverse positive pulse immediately after the negative pulse. In the present paper the influence of the frequency f and the pulse on time t on for a CrAlN process on the coating properties is investigated. All experiments were carried out on an industrial scale coating unit. In the present investigations coatings deposited by three different duty cycles are compared. For each duty cycle one coating was deposited using a conventional power supply and one coating using a power supply with a positive pulse. The positive pulse was clearly detected. It was found that the height of the positive pulse depends on the chosen pulse parameters. Furthermore, higher values of the peak power were found when using a power supply with a positive pulse, which should influence the ionization of the sputtered material. Regarding the chemical composition, a decreasing nitrogen content of the coatings was found when using a positive pulse. The investigations of the deposited coatings showed a denser morphology and increased values of the indentation hardness when using a power supply with a positive pulse compared to a conventional power supply. In addition to the higher indentation hardness, even the amount of plastic work showed increasing values for the power supply using a positive pulse compared to the conventional power supply. Furthermore, increased values of the roughness for coatings deposited on cemented carbide were found when using a positive pulse. The coatings deposited on cemented carbide showed a higher adhesion when using a positive pulse. • Higher peak power when using a short reverse positive pulse • Improved mechanical properties when using a positive pulse • Preferred (200) orientation for the use of a short reversed positive pulse and low duty cycles • Improved adhesion when using a positive pulse

Optimal resonant frequency analysis for underground wireless power transfer with metal tube interference

Magnetic resonant wireless power transfer (MR-WPT) has several advantages over conventional wired underground power supply methods. However, MR-WPT inevitably encounters metal conductors, which reduce the system efficiency through the eddy loss induced in the conductor by high-frequency electromagnetic waves. In this paper, the effect of resonant frequency variations caused by metal tube interference with the aim of maximizing the system efficiency is studied. According to the variation in the resonant frequency, the system efficiency is analytically derived by an equivalent circuit model. Electromagnetic simulations are carried out to further analyze the metal tube interference on the system. The results demonstrate the existence of an optimal resonant frequency that maximizes the system efficiency. Aluminum tube interference produces a lower optimal resonant frequency and higher efficiency than a 304 stainless-steel tube. When the metal tube is slotted, the optimal slot width and number of slots enhance the maximum efficiency and reduce the optimal resonant frequency and frequency drift. With slot widths of 2 and 8 mm, the system efficiency reaches ∼67% at 40.1 kHz and 55% at 48 kHz, respectively. Finally, different types of slotted tubes are fabricated, and the theoretical results are experimentally verified.

A new creep monitoring system and its utilization for the creep behavior of Çankırı rock salt

Creep experiments are of paramount importance for assessing the long-term stability of rock engineering structures. The major issue in creep tests is how to keep sustained loading constant on samples and to monitor displacement and other parameters throughout experiments without any interruption for long durations. Available cantilever type creep devices capable of carrying out various creep tests have been recently improved and used in this study. In addition, an impression creep device capable of applying a tip pressure up to 134 MPa for an indenter of 3 mm in diameter has been used with a purpose as an index creep testing technique. All devices are equipped with displacement transducers and acoustic emission sensors, which operate independently from conventional electrical power supply. The new monitoring system used in these creep devices is described and its utilization for evaluating creep responses of rock salt samples from Çankırı Province of Turkey are presented and discussed.

Switched Inductor Z-Source Inverter with Modified Space Vector Pulse Width Modulation for Uninterruptible Power Supply

This paper implies the modified space vector pulse width modulation for switched inductor z-source inverter-based uninterrupted power supply. In a conventional inverter-based uninterrupted power supply system, efficiency is reduced because of additional devices. The output voltage of the proposed switched inductor z-source inverter with modified space vector pulse width modulation will be increased by using the boost factor concept, which is not possible in conventional inverters. This inverter has a shoot-through operating state along with the active state and zero state; hence, voltage boost capability is raised. The shoot-through pulses are uniformly allocated within the zero state in each phase in order to increase the output voltage. Hence, voltage due to zero state is condensed in order to generate shoot-through state and the active states remain the same. Theoretical results for the proposed uninterrupted power supply based on switched inductor z-source inverter with modified space vector pulse width modulation technique are verified and validated by using MATLAB/Simulink software.

Ns-pulsewidth pulsed power supply by regulating electrical parameters for AFM nano EDM of nm-removal-resolution

Nano electro discharge machining (nano EDM), as a frontier processing method in the research stage of exploration, has an important application prospect in the machining of metal and alloy materials for achieving nanoscale removal resolution. A pulsed power supply used in nano EDM is expected to limit a single pulse energy to nJ order of magnitude for improving the removal resolution of single pulsed discharge even to nanoscale. One developing direction is to decrease pulsewidth of the pulsed power supply. Conventional pulsed power supplies hardly output a single pulse and continuous pulses with nanosecond (ns) pulsewidth, resulting in too large single pulsed energy of μJ order of magnitude usually. In this research, a novel pulsed power supply is designed for realizing the ns-pulsewidth with controllable pulsewidth and peak voltage. The key novelty lies in a cascaded circuit with two triodes working in the state of ultra-fast avalanche conduction, where pF capacitors are applied to adjust the pulsewidth and pulsed energy precisely. Performance tests verified that a single pulse of 5 ns pulsewidth or continuous pulses up to 9 MHz can be outputted. Furthermore, nano EDM experiments of single pulsed discharge are carried out under the conditions of nanometer (nm) discharge gap and nm-tip tool electrode based on an atomic force microscope (AFM) system. The special results are achieved: a single pulsed energy can reach down to 1.75 nJ by outputting a pulsewidth of 10 ns, and a nano-EDM crater is only about 182 nm in diameter with regular shape and little recasting. Those results verify the possibility of AFM-tip-based nano EDM for machining nanostructures.

A 3-Leg Inverter-Based High-Frequency Welding Power Supply Capable of AC 220 and 440-V Operation

In this article, a dc/dc topology is proposed for welding power supply that achieves a high conversion efficiency of over 94%, requiring ac 220 and 440 V operation. The secondary-side structure of the proposed topology is the same as that of conventional welding power supplies but the primary side consists of a three-leg inverter structure and a high-frequency transformer with two primary windings connected in series. Due to this structure, it is possible to operate in a wider input voltage range than conventional welding power supplies without significant loss of performance. In addition, it has the advantage of achieving high conversion efficiency over the entire input voltage range by reducing primary current stress and secondary rectifying voltage stress due to an increase in turn-ratio, and a reduction in circulating current. This advantage allows the use of mosfets rather than insulated gate bipolar transistor (IGBTs) with low operating frequency, which are often used in conventional welding power supply applications. Using a mosfet reduces the size of the power-stage passive devices, thereby reducing the overall system size. The performance of the proposed topology is verified in prototypes with a switching frequency of 100 kHz, an input voltage of 311/622 V, an output of 50 V, and a 6.0 kW class specification.

An IGBT-Based High-Voltage Crowbar for Minimizing the Fault Current Interruption Time and Injected Fault Energy During the Vacuum Arc Fault in Microwave Tubes

In conventional high-voltage power supplies used for driving the microwave tubes, the shunt crowbar, which generally consists of series-connected thyristors, protects the microwave tube against the vacuum arc fault. In the case of arc fault, the thyristor-based crowbar is closed as a parallel path and diverts the fault current through itself. It avoids serious damage to the microwave tube. However, thyristor switches usually have a limited rate of rise of ON-state current (di/dt), which necessitates placing a series inductor in the crowbar path. Thus, satisfying all protection limits of microwave tubes-including the injected fault energy and the fault current interruption time-is a challenging task for the thyristor-based crowbar. In this article, an insulated-gate bipolar transistor (IGBT)-based crowbar is employed to overcome this problem. Taking the advantages of IGBT switches, the proposed crowbar satisfies all the protection limits of the microwave tubes. Theoretical analysis, simulation studies, and experimental tests are utilized to compare the crowbar performance in the presence of the conventional crowbar and the IGBT-based crowbar.

3상 3스위치 PWM 전류원 정류기를 이용한 고역률 단조용 유도가열 전원 장치

Induction heating can convert electrical energy to thermal energy with high conversion efficiency and quick heating. Currently, a current source rectifier/inverter-fed parallel resonant circuit is widely used as an induction heating power supply for forging applications. Conventional induction heating power supplies have low power factor characteristics and high input power current THD characteristics, or have disadvantages of complicated control and high price. In this paper, we propose an induction heating power supply using a three-phase three-switch PWM rectifier to compensate for the above-mentioned shortcomings. The power factor of the input stage is kept close to 1, and the DC link current is uniformly well controlled regardless of fluctuations in the load voltage. In addition, through the SOGI PLL & FLL control algorithm, the current source inverter tracks the frequency and phase of the load resonance voltage well. The prototype of the induction heating power supply is designed and manufactured with a rated power of 40 kW and its characteristics and performances are confirmed through the experimental results. The proposed induction heating power supply using the three-phase three-switch PWM rectifier is expected to be widely used in the forging applications.

TENG-Bot: Triboelectric nanogenerator powered soft robot made of uni-directional dielectric elastomer

Abstract A soft robot employing dielectric elastomer actuators (DEAs) exhibits a flexible body and dexterity locomotion in unstructured environments. However, conventional power supplies required by DEAs pose an obstacle for small-scale robotic system. Triboelectric nanogenerator (TENG) is capable of harvesting kinetic energy from the environment to generate matching power for DEA. Yet, a TENG-driven, DEA-based robot is hindered due to the nonlinear and insufficient mechanical transmission in robotic motion. In this paper, we developed an uni-directional DEA-driven soft robot. It aligns the direction of DEA in extension with the robot motion to achieve high efficient energy conversion, yielding a maximum crawling velocity of 110 mm (2.2 body-length) /sec and a payload capacity of 40 g. Then a TENG-Bot, that is a TENG-soft robot conjunction system, is built using a freestanding TENG. With the benefit from the simple structure, and the high efficiency of the robot, the electrical energy generated by the TENG can directly drive the robot without additional control panels. Experiments demonstrate a linear relationship between the sliding speed of the TENG and the velocity of the soft robot, a direct control correspondence. The TENG-Bot offers a route for developing self-powered soft robots by harvesting the environment motion.

An Economical -Technical Comparison of Solar Electrical Water Pumping System Versus Conventional Electrical Water Pumping System for Agricultural Purposes in the Area of “Awjila”

This paper presents a simplified comparison to show the economic feasibility of the use of solar pumps versus conventional pumps in dripping based cultivation, such as vegetables and palm trees, especially in the agricultural area about Awjila. Some technical specifications of two models of solar pumps with two different capacities - large and small - were compared. Also compared the effect of was the productivity of the two pumps on the effectiveness of desired coverage of irrigation plans intended to palm trees and vegetables. A direct comparison was made also between the traditional pumping costs and the solar pumping of agricultural water in a particular case of a well located 500 meters from the line of conventional AC power supply. In this paper we relied on computer program approach using a trusted specialized code made by an international company manufacturing water pumps operating mainly on solar energy technology. Depending on the extrapolation and digital simulation of the processes for agricultural irrigation; solar water pumping technique recorded very high techno-economical performance rates over the traditional electrical pumping. Satisfactory results were obtained for water flows that suggest the use of smaller solar pumping systems and lowest-cost over the larger systems in the case under consideration and the like. The results have shown that solar systems have prominent economic advantage over conventional systems in the medium and long range. In general results of this research, have proven, that where water is generally available, it can successfully and at high economic feasibility benefit from the tremendous solar energy potential and its equipment in the promotion of productive long term agriculture anywhere even if is not far from the traditional transmission lines of electric power. And as solar pumping technique provides is beneficial for job opportunities, agricultural, industrial and human investment and sustainable development in many of the same regions; they need support by a set of policies, laws, facilities with financial incentives leading to the realization of this vision within the economic feasibility conditions, and including the provision of funding and market activation with human habilitation.countries through dividing them into oil producing countries and non- oil producing ones .In the third axis, tools of econometrics are used to predict the international trend and that of the Arab countries , both oil and non-oil to renewable energy . The last part estimates the standard model about the possible impact of moving energies on economic growth rates in the Arab countries. The study concluded that the growing renewable energies will be different in the constituent countries of the study sample, in addition to the weak impact of the move towards renewable energies on economic growth in the Arab countries.

Application of a Pulsating Voltage Drive to an Anode-Layer-Type Hall Thruster

Hall thrusters typically exhibit a discharge-current oscillation with a few tens of kilohertz, which negatively affects the power supply and induces electromagnetic interference (EMI). A pulsating boost chopper power supply (chopper PS), which applies a varying voltage to the Hall thrusters, was developed to shift the discharge-current frequency to an acceptable frequency because discharge-current oscillation is unpredictable and can emit EMI. In this study, a 1-kW anode-layer-type Hall thruster was driven with a chopper PS to evaluate the dependence of performance on the chopping frequency because past investigations tested the chopper PS with only magnetic-layer-type Hall thrusters. The experiments showed that the thruster using a conventional DC power supply induced discharge-current oscillation at 32 kHz (i.e., thruster-originated natural frequency). Meanwhile, the chopper-PS drive shifted the discharge-current frequency to the chopping frequency unless the chopping frequency was more than 52 kHz. Conversely, for a chopping frequency over 52 kHz, the dominant frequency of the discharge current returned to the thruster-originated natural frequency. Moreover, the thruster performance above the 40-kHz chopping frequency was comparable to that using a conventional DC power-supply drive. Furthermore, the chopper-PS drive successfully suppressed amplitudes of discharge-current oscillation and ion wall loss to the guard ring by 50%.

Simulation Evaluation of Fast Frequency Response Capacity of New Energy Power Stations

The number of new energy power stations in China is boosting in recent years, a large number of conventional power supplies have been replaced, resulting in severe problems in controlling the frequency of power grids and easily leading to frequency issues of the state power grid. When large frequency disturbance occurs in power grid, renewable energy stations can participate in primary frequency regulation of power grid and provide support for system frequency, and the primary frequency regulation capability of the large power grid in sending end is significantly enhanced. In this study, a simulation evaluation method was proposed for the FFR controller of new energy power stations based on the RT-LAB real-time simulation analysis platform. The FFR controller was connected to in the simulation model of the state power grid via I/O physical interfaces and MODBUS communication, so as to conduct the step disturbance test, anti-disturbance performance verification test and automatic generation control (AGC) coordination test and hardware-in-the-loop simulation test of the controller. Results of the tests proved that the test method proposed in this study is accurate and reliable, and help improve the performance of a new energy power station in the state power grid.

Power losses reduction in a variable linear power supply using the LM317 voltage regulator

In this work, the design and development of a new variable linear power supply, using the LM317 regulator, is proposed. The originality of this power supply is related with the control of the rectifier circuit, which is based on a reference of voltage, superimposed on the output voltage. This reference is used in the control strategy to maintain a constant voltage between the input and the output voltages of the LM317 regulator. Due to this strategy, the heating losses are greatly reduced, allowing to increase the efficiency of the regulator to about 90%, and to reduce the requirements of the cooling system. Moreover, drawbacks of conventional power supplies are mitigated, where the developed variable linear power supply delivers a current of 3 A and a variable output voltage, from 1.2 V to 30 V. The LM317 regulator was modeled by its thermal equivalent structure associated with a heatsink to study the heat transfer problem. The modeling was performed on the Matlab Simulink software, and the theoretical results were validated by a set of experimental tests using the LM317 regulator.