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The combined operation of renewable energy and pumped storage unit (PSU) has become an important researching tendency in rural electrification, for handling the variable characteristics of power as well as load demand, particularly in standalone applications. Recently, adjustable-speed pumped storage unit (ASU) has been developed as an evolutionary version of fixed-speed pumped storage unit (FSU) due to its adjustable power in pumping mode, larger output range and higher efficiency in generating mode, but presents an increased capital outlay in terms of equipment. Therefore, it is a meaningful topic to appraise the economic benefit of using ASU as energy storage device for the hybrid system, which has rarely been studied quantitatively. In this paper, a scheduling model composed of a photovoltaic generator, a wind turbine, a diesel generator and a PSU, is presented and the technical features of two different PSUs are analysed. The main purpose of the proposed model is to highlight the potential of the ASU to reduce the operation cost for the developed hybrid system. The simulations have been carried out using Cplex called by Matlab. Two scenarios are investigated, including a summer and a winter case. The results show that using the ASU for the developed hybrid system, 46.7% fuel can be saved on a summer day and 11.24% fuel saving can be achieved on a winter day compared to the case where the FSU is used as the energy storage device.

With the fast development of information technology (IT) industry, the demand and market volume for off-line power supplies keep increasing, especially those for telecommunication, computer servers and data centers. As the capital expenditure was measured by the square footage occupied rather than power consumption, the development of high power density converter system is of greater interesting. The rising energy prices have resulted in the cost of power and cooling exceeding the purchase cost in less than two years. Therefore, highly efficient power conversion is required for the power converter system. Generally, the power supply unit (PSU) for power distribution system (PDS) in data center and telecom are the standard two-stage approach which normally consists of power factor correction (PFC) circuit and isolated DC-DC converter. The two-stage power conversion has demonstrated excellent performance and high reliability, since the design can be optimized for each stage. However, limitations to prevent the existing two-stage PSU to fulfill future requirements for the PDS in data center and telecom applications are revealed, and a very promising and fundamentally different approach with the single-stage isolated converter is proposed in this dissertation. The development of single-stage converters with the option of placing the energy storage outside of the PSU creates new degrees of freedom regarding e.g. simplified rectifier racks in telecom and data center. This provides tangible benefits in the form of space saving, better airflow for power unit in rectifier racks and improved lifespan. The three-phase isolated buck matrix-type rectifier, capable of achieving high power density and high efficiency, is identified as an excellent candidate for the medium power level (5 kW~10 kW) single-stage power supply design. Nevertheless, the matrix-type rectifiers are known for their relatively complex modulation and commutation techniques, and lack of ride-through capability such as the stringent case of one phase loss operation. This dissertation work provides comprehensive study on the commutation method and modulation scheme design for the isolated buck matrix-type rectifier. It aims to analyze the operation principle of the rectifier and propose viable modulation and commutation schemes for this rectifier under both three-phase and single-phase operation. The method is verified by the hardware experiments of the PSUs with high efficiency (> 98%) and high power density (> 70 W/in3 ) for 54 V and 380 VDC applications. The prototypes demonstrated in the experiments show the effectiveness of the proposed modulation and commutation schemes for industry.

Stable working voltage is critical for integrated systems to keep functioning, yet it suffered from instantaneous high-power demands and the resulting voltage disturbance. An on-chip micro supercapacitor (MSC) with superb capacitance density can act as a promising high-power supply unit to satisfy power demands and stabilize the system. However, severe capacitance decay of MSC under fast charge/discharge rate greatly weakens the device power output thus making it incompetent. This work demonstrates an on-chip high-power MSC featured by the improved capacitance density, fast charge/discharge ability and scaling-down capability. The improvement is brought by the applied mesoporous gold as electrode framework, which offers fast electronic/ionic pathway and reduces porous effect under high charge/discharge rate; as well as the uniform MnO 2 active layer, which is decorated by an electrochemical potential-modulated deposition method, providing large pseudocapacitance. Moreover, the asymmetric electrode structure is constructed to expand the single device operation voltage. As a result, a large steady capacitance density of 9 mF/cm2 and small capacity loss of 28% at high scan rate of 1 V/s have been achieved, leading to an unprecedented power density of 138 mW/cm 2.

Two-stage cascade architecture is widely used in the modular power supply applications. In order to reduce the additional component number caused by the cascading structure, the power switch integration technique is proposed in numerous literature studies. However, the power switch integration leads to both the efficiency degradation and the abnormal gain of the stage employed. In this article, the four-switch noninverting buck–boost converter is merged with the LLC resonant converter. The proposed integration method has no awful influence on the efficiency and the gain of the LLC stage. Meanwhile, the soft switch capability of the integrated bridge can be enhanced due to the accumulation of the two currents of the buck–boost stage and the LLC stage during dead time. Moreover, the current of the two-stage will commutate to cancel out with each other during the conduction period, reducing the conduction loss and improving the overall efficiency. The benefits of the integrated bridge make the proposed converter appropriate for the high-frequency and high-efficiency application. Finally, a 720-W 1-MHz prototype is built to prove the performance of the proposed converter. The prototype achieves a peak efficiency of 96.4% and the input voltage range of 250–420 V.

In order to improve the investment accuracy of power grid projects, this paper takes distribution network investment as the research object, and proposes a distribution network precision investment method based on a three-level strategy of region, power supply grid, and power supply unit. Firstly, building a precise investment index system for the investment scale of the regional distribution network, and calculate the investment situation through the precise investment calculation formula of the regional distribution network. Secondly, building a time sequence evaluation system for the overall construction of the power supply grid of the distribution network, and then study the prioritization method based on investment projects. The time sequence method for the overall construction of the power supply unit of the distribution network and the multi-objective optimization precision investment method based on the target grid framework. Finally, the effectiveness and operability of the above precision investment method are verified through empirical application.

This study is based on the design of a portable automatic water level control switch that is capable of switching on the pump when the water level in the overhead tank goes low and switches it off as soon as the water level reaches a pre-determined level to prevent dry-run of the pump in case the level in the underground tank goes below the suction level. The water in the tank is measured by the conductive probes and displaced via the LED indicators. At maximum-set capacity the pump is de-energized to automatically switch off, thereby stopping the inflow of water into the tank. The design approach involves three major stages which are: the power supply unit, the sensing unit, and the motoring and relay unit. The uniqueness of this work is the use of discrete components such as transistors to achieve water level control. This approach is more economical, simpler and easier to implement than the sophisticated programmable logic controllers and computerized microprocessors. Keywords: discrete components; conductive probes; sensors; relays; pump

The article presents the results of a gamma- spectrometer study with a low- capacity scintillation (NaI(Tl)) detection unit, with software GammaVision v.8, adopted to solve certification problems, including for measuring activities close to zero. The list of factors influencing the presentation of the minimum detected activity (MDA) in the report protocol is analyzed software GammaVision v.8. To perform the measurements, the company´s ORTEC gamma-spectrometer with a low-capacity detection unit a type digiBASE-RH, in which a high-voltage power supply unit, amplifier, digital multi-channel analyzer with USB-connection to a computer with the installed driver are installed, was used. The peak search in the library was performed using a compressed version of the library, which contains two nuclides 137Cs and 40K. Methods of calculating MDA are based on the intensity of accounts. Nuclide activity is calculation for all peaks in the library, the energy of which is in the selected energy ranges for analysis. Measurements and calculations MDA under the given conditions of research for five methods depending on time of measurement and geometry of measurements are carried out. It is shown that the level of MDA can be reduced by choosing the optimal conditions, time of measurement and geometry of measurements. Recommendations are given for the use of capacity for counting sample, which will reduce the amount of substance required for analysis and optimize the time spent on measuring the counting sample. In a prospect it is expedient to undertake a study of dependence of MDA from the physical properties and radionuclide composition of the substance for the counting sample and the dependence from the uncertainty in the equation MDA.

High-voltage direct current circuit breakers (HVDC CB) are one of the key technologies of multi-terminal DC systems and DC grids. Different from other equipment that use a large number of power electronic devices, the HVDC CB cannot obtain its power from the primary system at high potential, making the power supply of the complex multiple electrical potential equipment in HVDC CB a challenge. In this study, the authors propose an HV isolated power supply system based on the multi-output high-frequency isolated power supply unit and the cascaded isolation transformer network. This power supply system can support the 500 kV CB to turn-off 25 kA current with 800 kV overvoltage.

A raw domestic wastewater (DWW) was treated using a modified electrocoagulation and conventional electrocoagulation (EC) experimentally. The EC process was modified by providing the plate connected by earth as earthen system and compared it with the conventional system under same operational conditions. The initial medium strength COD ranged from 500 to 700 mg/l was used. A bench scale electrocoagulation unit has been operated under batch operational conditions along nine months. The electrocoagulation unit has been consisted of transparent basin containing iron and aluminum electrodes which are connected to a power supply unit. The system was operated under different operational conditions by applying voltages 9, 18, and 27 volts. The treatment retention time ranged from 30 to 60 min. and inter change the polarity of plates periodically every 10 min. The experimental results confirm that, earthen system plays a vital role to get fast reliable removal efficiency compared with the conventional system. The modified earthen system achieved removal of 97% for COD with retention time of 30 minutes and volts of 9 V (six plates) instead of 60 min in case of conventional system under same operational conditions. The removal efficiency was controlled accurately by changing the number of charged plates, retention time, and volt values. The modified system save the consumption material electrodes and energy and reduced retention time to 30 min. compared with the conventional electrocoagulation system

Data processing for Internet of Things (IoT), and Internet and Communications Technologies (ICT), is increasing with unpresented rates, something that has led to an increased requirement for Power Supply Units (PSU). A respectful 1% of global energy consumption is due to data processing in datacenters. The global datacenter energy consumption is rising the last few years due to the 5G technology and the low latency and high-speed requirements. In the same manner IoT applications, and energy industries are rising, and is estimated that an impressive 70% of global energy is passing through converters such as PSUs. This work analyses the main constituent components in each individual conversion stage of a PSU and proposes the most appropriate designs for higher efficiency. The theoretical analysis is verified by simulations using the PSIM Thermal Module. Finally, this paper suggests techniques and trade-offs that must be exploited for the optimized PSU design with higher energy efficiency under varying parameters.

Power consumption of data centers has increased rapidly over recent years. Of late, 48 V power architecture has attracted more interest in data centers as it offers more efficient architecture. This paper focuses on the implementation of the DC-DC stage of the power supply unit for narrow range 48 V datacenter bus architecture. The paper presents a nearly 99% efficient 400 V-48 V LLC with a very high power density and low profile fully integrated on PCB. The LLC topology is chosen as it can achieve soft-switching, allowing one to push the switching frequency and increase the power density. A matrix of four transformers is used to reduce the termination loss of the secondary synchronous rectifier and achieve better thermal management. The number of secondary turns is optimized to achieve the best trade-off between winding loss, core loss, and power density. A matrix of four resonant inductors is also designed to reduce the proximity effect between inductor windings and reduce inductor PCB winding loss. The converter integrates a matrix of four transformers and resonant inductors on a 6-layer PCB and single-core for easier manufacturability and lower cost. A prototype is tested for the proposed converter at 250 kHz with 98.8% efficiency and 600 W/in3 power density with an 11 mm profile.

This paper gives a summary of design and hardware development of consistent and vigorous space borne power supply unit for synthetic aperture radars with the variation of input voltage of 24V to 38V. The available battery raw bus voltage in satellite is 28V DC nominal. This power supply unit can use for various radio frequency (Exciter and Receiver) and digital circuits (processor). The power supply unit (PSU) consists of two converters in which the converter-1 consist of single output of 15V/0.6A and converter-2 consists of three outputs of +5.3V/12A, +5.4V/4.5A & -5V/0.6A. The total output power of PSU is 100.4W with the input voltage variation of 24V to 38V DC (28V DC nominal) at an operating frequency of 140 KHz. The power supply unit is implemented by using single switch Forward Converter Topology with saturable inductor and Low Drop out (LDO) as post regulators is used to get the required regulated outputs. The PSU has been designed and developed with bias feedback using Voltage mode feed forward control technique.

Pumped storage power station is an important regulating tool for peak load regulation and frequency regulation of the power grid, especially its primary frequency regulation function, which is of profound significance for the safety and stability of the power grid. As the core equipment of the pumped storage power station, the reversible design of the pump turbine makes it easy to have hydraulic fluctuation and mechanical instability when the unit runs to the “S” characteristic area, which will cause the frequency oscillation of the generator under the condition of primary frequency regulation. Therefore, some innovative work is studied in this paper: (1) an accurate hydraulic-mechanical-electrical coupling system mathematical model of pumped storage unit regulation system (PSURS) is established based on full characteristic curve of the pump turbine and seventh-order synchronous generator and excitation system; (2) the dynamic response characteristics of primary frequency regulation of pumped storage unit (PSU) under different water heads and different frequency disturbances are analyzed by numerical simulation; (3) in view of the unstable condition of the unit under the large frequency disturbance when it operates in the low head and small load area, the objective optimization function considering the ITAE index of hydraulic, mechanical, and electrical factors is proposed; and (4) fractional-order PID controller and the bacterial-foraging chemotaxis gravitational search algorithm (BCGSA) combined optimization strategy is used for PSURS optimization regulation and parameter optimization. The results show that the joint optimization strategy proposed in this paper has smaller objective function value, and makes the PSURS pass through the unbalanced area quickly, with better primary frequency regulation speed and smaller regulation depth.

This paper describes the thermal lag correction for Glider Payload Conductivity Temperature Depth Profiler data with a poor sampling rate. In particular, the thermal lag correction is more vulnerable to the influence of temperature data. According to variations in salinity with depth and the vertical downcast speed of the glider, salinity data are divided into five parts, and a method based on Morison et al. is proposed to determine the correction parameters. At 40–94 dbar and 140–280 dbar, the salinity difference is dominated by the temperature difference. At 94–140 dbar, the salinity difference is immune to the temperature difference and has a greater influence on the thermal lag-induced salinity error correction. After the sectional correction, the accuracy of the typical salinity interval is upgraded from 0.011 to 0.006 psu, which shows the effectiveness of this sectional method on correcting temperature difference.

Following the invention of resonant power converters, lots of new topologies with significant improvements considering increase in efficiency and power density are arising. One of the possibilities how to optimize operational behavior of the converter is modification of its power stage through implementation of resonant components or resonant tanks. Proposed paper describes this methodology, while perspective circuit topology of LCCT resonant DC–DC converter is deeply studied from operational point of view. Proposed converter was experimentally verified based on the knowledge received from theoretical analysis of operational characteristics. Steady-state operational analysis was realized together with dynamic condition investigation (start-up, short circuit), while simulation results are compared to experimental in order to prove validity of the simulation model. Presented analysis of the operation of LCCT converter explores proper behavior related to the redundancy, ensuring its suitability for modular concept of power supply even the efficiency reduction due to higher magnetizing current is evident. Consequently, the considerations are taken for the use of the proposed converter within the modular power supply in parallel input/parallel output configuration covering application of the server’s power supplies. The LCCT converter modules for target parameters of application use have been designed. Modular power supply system was experimentally verified from the efficiency point of view, while various operational scenarios related to interleaved operation are considered. Main focus during experimental measurements of modular operation are related to investigation of the influence on output current and voltage ripple and total system efficiency when one, two, or three modules are operated in various conditions related to power sharing and phase-shift change. Through this approach, the optimal settings of mentioned parameters (number of operating modules, load share, phase shift between modules) are received targeting the best efficiency for individual operational state (flat characteristic of efficiency for any load and low ripple current and/or voltage).

This paper aims to study the optimal successive start-up strategy of two hydraulic coupling pumped storage units (PSUs) based on multi-objective control. Firstly, a successive start-up model of a pumped storage power station (PSPS) with two PSUs is established. Secondly, the analysis of the impact of successive time interval ΔT is carried out. Thirdly, a novel optimization scheme multi-objective with two PSUs owning different parameters (MODP) is proposed for start-up optimization. For comparison, three optimization schemes named single objective with two PSUs sharing the same parameters (SOSP), single objective with two PSUs owning different parameters (SODP) and multi-objective with two PSUs sharing the same parameters (MOSP) are also tested. Finally, according to the four optimization schemes, i.e. SOSP, SODP, MOSP and MODP, the optimization model is established and performed separately in MATLAB 9.1 based on a real case. The results indicate that the change of ΔT has a great effect on the transient process of 1# PSU, but less effect on the transient process of 2# PSU. ΔT should be chosen as a decision variable in the successive start-up optimization. For the successive start-up of a PSPS with two PSUs, the multi-objective scheme is superior to the single-objective scheme. The scheme of different parameters is superior to the scheme of sharing parameters. Among four schemes, MODP scheme is the best. The MODP scheme can obtain the Pareto Set that provides more choices for decision makers, which is flexible in engineering applications. MODP is a general method for successive start-up strategy optimization.

Pulsed power supply systems are employed in many fusion projects and in other scientific applications. A novel power supply approach and a first prototype unit were specifically developed to feed pulsed loads (low duty cycle), as the resistive or superconducting coils used to produce high magnetic fields for some seconds or longer. Thanks to the integrated energy storage, the high pulsed power required for the load is not drawn directly from the electrical grid. In fact, a huge amount of energy can be stored at low power (even through a single-phase 10 A plug, as normally used for household appliance). A significant fraction of the energy stored in the load can be recovered for successive operations. Without such energy storage, all the power supply devices and the upstream chain must be oversized and installed only in locations provided with adequate power. The first power supply unit (2 kA) was able to replace a previous system with comparable performances, but the old system occupies an extremely larger volume and needs a 20-kV connection at the input. Moreover, a specific solution was implemented to achieve a very fast (600 kW) energization of the magnets. The energy storage capability is intrinsically scalable: the setup can be rearranged and the storable energy can be updated even after the installation (for example, to increase the pulse duration).

With the rapid proliferation of cloud computing, the energy cost of datacenters and the impact of reactive power on the grid have become major concerns. This paper presents two energy management control schemes for distributed uninterruptible power supply (UPS) architectures utilizing lithium-ion ultracapacitors (LIC) for improved system efficiency and reactive power mitigation. One scheme is proposed for low-power servers with an internal dc bus, while another is proposed for medium-to-high-power server racks with an in-rack dc bus. The LIC and the dc bus interface with a bidirectional dc–dc converter, which allows the power supply unit to run in the optimal operating region for the improved system efficiency and power factor. The server-level UPS architecture is experimentally tested using a 200-kHz, bidirectional, multiphase dc–dc converter with hysteretic current-mode control, while achieving 33% reactive power mitigation. Based on the SciNet datacenter in Toronto, ON, Canada, a rack-level distributed UPS architecture is built in MATLAB, and system-level simulations indicate a 37% reduction in the reactive power.

At the French-German Research Institute (ISL), several railgun setups are used to investigate different military scenarios. One compelling scenario for a railgun application is the long-range artillery. For this, it is required to be able to handle multimegaampere currents to accelerate heavy launch packages of velocities above 2 km/s and to do so as efficient as possible. The NGL-60 is a 6-m-long open-barrel breech-fed railgun with a square caliber of 60 mm. With this railgun, it will be possible to fully utilize the currently available 10-MJ capacitor-based power supply unit (PSU). To validate the concept of the NGL-60 design, a 2-m-long prototype was installed. Subsequent tests showed that the railgun design is able to handle currents above 2 MA without structural damages or electrical failures. After the successful test series with the prototype, the construction of the full NGL-60 started and is finished by now. In this report, results from the prototype tests are reported, and the first experiments with the 6-m-long NGL-60 are presented.

This paper discusses electrical distribution for refrigerated containers (reefers) in port terminals, characterized as parks of uniform distributed loads. Power systems of uniform distributed loads need configurations with modularity whenever possible, to ensure an easier installation, operation, and maintenance with significant cost reductions. This paper shows what has been the practice at ports in the past to provide Low Voltage (LV) supply to reefers from medium voltage (MV)/LV substations to cluster of reefer outlets panel with group of outdoor receptacles, used to connect power supply cord to each reefer. In the new method of power distribution system for the reefers, it is suggested to use a main MV underground distribution and portable containerized MV/LV transformer substations with close coupled LV distribution panel including reefer outlets. This potable power supply unit can be installed inside the reefer racks to supply locally a modular LV distribution to the reefers. This new method of supplying power to reefer racks has benefits over the past practice. It can offer a relevant flexibility for expansions and endorses development of new fitting components.