Variable Pole Flywheel Motor‐Generator for Clean Power, UPS and IPS Energy Storage Module Applications

This paper presents a simplified sinusoidal uninterruptible power supply (UPS) system. The proposed scheme includes features such as high power factor, low total harmonic distortion and good dynamic response at the AC output voltage. In addition, the scheme has the desirable characteristics, of high efficiency, simple circuit and low cost compared with a traditional standalone multiple stages UPS with power factor correction. The paper also presents the circuit operation, the analysis and, experimental results of the proposed UPS scheme. The proposed UPS approach is a good solution in low. power applications (/spl les/500 W).

In this paper, a high-performance single-phase transformerless online uninterruptible power supply (UPS) is proposed. The proposed UPS is composed of a four-leg-type converter, which operates as a rectifier, a battery charger/discharger, and an inverter. The rectifier has the capability of power-factor collection and regulates a constant dc-link voltage. The battery charger/discharger eliminates the need for the transformer and the increase of the number of battery and supplies the power demanded by the load to the dc-link capacitor in the event of the input-power failure or abrupt decrease of the input voltage. The inverter provides a regulated sinusoidal output voltage to the load and limits the output current under an impulsive load. The control of the dc-link voltage enhances the transient response of the output voltage and the utilization of the input power. By utilizing the battery charger/discharger, the overall efficiency of the system is improved, and the size, weight, and cost of the system are significantly reduced. Experimental results obtained with a 3-kVA prototype show a normal efficiency of over 95.6% and an input power factor of over 99.7%.

Wireless sensor nodes have huge energy demand for their operations; they are deployed in remote locations for various applications like weather, industrial, satellite, construction, banking, and medical. Sensor nodes require continuous or uninterrupted power supply during their life cycles. When the available renewable power sources are not sufficient to run the system, the batteries are required to deliver a continuous and uninterrupted power supply. The main focus of proposed model is to design and develop a smart dual battery management system along with a hybrid energy harvesting model that can provide reliable and efficient power support to the sensor node. The problem under consideration also focuses on reducing the state of health degradation of batteries by applying a smart battery charging methodology using an ANFIS (adaptive neuro‐fuzzy inference system) controller. The proposed power management system ensures and meets the expected objectives such as switching of power sources, smart battery charging methodology (constant current and constant voltage [CC‐CV]), and dual battery power support using ANFIS controller. The result was obtained through the simulation and hardware prototype of the proposed system work flawlessly to meet the desired objective with partial charging and discharging of batteries for the prevention of battery degradation and also enhance the lifespan of the batteries.

This paper presents a multilevel double conversion uninterruptible power supply (UPS) for higher efficiency and effective size/weight reduction. The main circuit of this UPS features a transformerless three-level circuit topology resulting in high double conversion efficiency (over 96%) and considerable size/weight reduction. This design also includes a customized IGBT power module and a double bidirectional chopper. The customized IGBT module reduces parasitic inductances and hence improves reliability by lower electrical and thermal stresses. The double bidirectional chopper reduces ripple current and then also offers a contribution to UPS compactness. Test results using a 225kVA-prototype confirm the improvement in efficiency and the high performance of the proposed UPS.

Solar PV application is one of the leading solution in Renewable energy resources to satisfy power demand in energy industry. This research explores the online solar-Off grid power generation to server room of Computer Centre-I in an educational institution located near Cauvery delta region of Tamilnadu state in India. Solar PV panels along with the combiner box, MPPT Charge controller have been integrated with existing Uninterruptible Power Supply (UPS)-Battery pair. IOKVA of existing UPS-Battery powered from 9KW PV panels. Design, Performance and cost-benefit analysis of the whole system addressed with necessary future development.

With the development of photovoltaic power generation and energy storage technology, scale of photovoltaic power station and energy storage power station increasing. After a large area of power outages, photovoltaic power station based on the energy storage can be considered as a black-start power. In this paper, the sustained and effective output of photovoltaic power plant is analyzed and evaluated according to power forecasting data of photovoltaic power station as a criterion for photovoltaic power station used as black-start power. A system black-start scheme optimization model is proposed with target of maximizing the total power provided by photovoltaic power station and energy storage combined system in the start-up time of the conventional thermal power units to be started. Also, photovoltaic power station based on energy storage assisting power grid black start process is presented. Numerical example is used to demonstrate the feasibility of using photovoltaic power station and energy storage system as system auxiliary black-start power and validity of system black-start optimization model.

This article proposes a dual‐receiver wireless power transfer (WPT) system that can simultaneously achieve load‐independent constant current (CC) output and constant voltage (CV) output to charge different types of power modules inside an automated guided vehicle (AGV). In this system, a solenoid coil is wrapped around a Q coil and a piece of ferrite, which acts as the transmitter and receiver charging plate. The solenoid coil wound around the Q coil are naturally decoupled from each other, eliminating additional magnetic coupling interferences in the system, while also enhancing compactness. Furthermore, the two output ports of the proposed system are independent of each other and possess complete electrical isolation characteristics. Firstly, the comprehensive theoretical analysis of the proposed magnetic coupler decoupling characteristics is conducted. Secondly, the circuit model of the dual‐receiver WPT system that simultaneously achieves CC and CV outputs and zero phase angle (ZPA) operation is mathematically derived. Thirdly, the implementation of inverter zero voltage switching (ZVS) and the impact of the change of the second‐stage receiver series compensation capacitance on the system CC and CV output characteristics are analyzed in detail. Finally, an experimental prototype with the first‐stage receiver output voltage of 54 V and the second‐stage receiver output current of 3.5 A is built. The experimental results are consistent with the theoretical analysis.

Future prospects of high Tc superconductors-coated conductors and their applications

Main task of power semiconductor converter is transfer of electrical energy from its input to the output and to the load. This energy flow is provided by control of the switching process of one or more semiconductor devices. Based on converter application it is necessary to choose correct control algorithm for selected switching frequency of converter. Algorithm itself has to be utilized with suitable hardware platform, whereby through the set of instructions the turn on and turn of control pulses are generated. Control system also has to secure other important functions for secondary processes. Nowadays a huge number of converter topologies exists, whereby each type should be suited for different conditions of use. For example uninterruptible power supply must generate constant output voltage with constant frequency and constant amplitude for wide range of output power. Converters for electric drive applications have to control their speed through generation of three phase voltage system with configurable amplitude and speed. From mentioned above it is clear to say that for each topology of power converter, the different type of control modulation (PWM Pulse Width Modulation, PSM Phase Shift Modulation, FM Frequency Modulation) and different structure of regulator has to be used. Therefore selection of suitable control system depends on number of various factors, which are output power of converter, type of switching devices, type of load, possibility of hardware implementation and ways of switching. In the field of DC/DC converters for switching power supplies, the main focus is on implementation of digital control, which means use of microcontrollers or DSP with implemented control algorithms and functions for communication with user as well. Analog control systems are well known and its design procedure is mastered, so it is easy to convert analog (continuous) controller into discrete and consequently implementing in microcontroller and DSP. But this approach ignore sample and hold effect of A/D converter and computing time of microprocessor. For proper discrete controller design, the method named direct digital design can be used. This method uses transfer function of converter in discrete form, including effect of sampling and computation delay. For controller design purposes, transfer function of converter is necessary. This transfer function is based on model of power stage of controller. For PWM converters such as buck, boost, etc. the averaging method is widely used, but for new resonant topologies such as LLC converter, with this averaging method, the control to output transfer function cannot be used. In this chapter, new simulation based method for obtaining the transfer function of converter is discussed. This method uses MATLAB and OrCad PSPICE environments for

To meet the dynamic charging requirements in practical applications, the WPT system must not only achieve constant current and constant voltage output independent of the load, but also have a certain degree of adaptive fault tolerance. However, some existing methods suffer from issues such as an excessive number of compensating components and the requirement for additional communication circuits. To avoid the aforementioned problems, this paper proposes a phase‐shift control method based on active rectification and utilizes the LCL‐S compensation topology, which possesses constant voltage output characteristics. Constant current output independent of load is achieved by adjusting the phase‐shift angle of the active rectifier. Based on this, by adjusting the phase‐shift angle of the active rectifier, a wide range of constant voltage and constant current output can still be achieved during coil offset, which effectively simplifies system control and increases system stability. In addition, to further improve the dynamic response speed and control accuracy of the system when it is in CC output, fuzzy control is added to regulate the rectifier. Considering that the compensation components will change with temperature in practical conditions, this paper explores in detail the impact of each compensation component on the system output. Finally, an experimental prototype is built to verify the feasibility of the theoretical analysis, with the output voltage controlled at 30 V and the output current at 2 A. Experimental results show that, within the coupling coefficient range of 0.21–0.32, the fluctuation rates of the system output voltage and output current are only 1.0% and 1.5%, respectively.

As a hopeful solution to help the shipping sector achieve the greenhouse gas (GHG) abatement goal of the IMO by 2050, the application of hydrogen-powered ships has attracted more and more attention. To solve the problem of hydrogen supplement for offshore polymer electrolyte membrane fuel cell (PEMFC) ships, this paper presents a scenario design for the integrated application of coastal hydrogen-powered ships and offshore wind power, and analyzes its techno-economic feasibility. This model concept considers the problems in offshore hydrogen transportation and offshore wind power development together. It provides a feasible integrated scheme and operation mode for the combination of offshore wind power and hydrogen energy storage. A transformation scheme is also provided for the marine ranch ships, and these PEMFC-powered ships are combined with the hydrogen production of offshore wind farms. The analysis results show that the integrated utilization model is economically feasible and with a significant effect on decarbonization. It also shows great potential for further expansion to other coastal areas.

N/S co-doped three-dimensional graphene hydrogel for high performance supercapacitor

Energy storage system is an effective means to overcome the fluctuation of wind power generation and improve electrical network stability. This paper briefly introduces the impact of wind power generation on the grid and different battery energy storage technologies first. Demonstration projects of combined wind power generation and energy storage systems is then discussed. This is followed by an outline of three main operating modes of the combined wind power generation and energy storage using batteries, including smoothing wind power fluctuation, tracking wind power schedule output and load shifting. Current status of control strategies and storage capacity for the combined wind power generation and energy storage systems are then presented. Finally, further research needed for the combined system is discussed and improvement on the economic aspects is concluded to be a key aspect for future research.

Integrating residential photovoltaic (PV) power generation and energy storage systems into the Smart Grid is an effective way of reducing fossil fuel consumptions. This has become a particularly interesting problem with the introduction of dynamic electricity energy pricing, since consumers can use their PV-based energy generation and controllable energy storage devices for peak shaving on their power demand profile, thereby minimizing their electricity bill. A realistic electricity pricing function is considered with billing period of a month, comprising both an energy price component and a demand price component. Due to the characteristics of electricity price function and energy storage capacity limitation, the residential storage control algorithm should 1)utilize PV power generation and load power consumption predictions and 2)account for various energy loss components during system operation, including energy loss components due to rate capacity effect in the storage system and power dissipation of the power conversion circuitry. A near-optimal storage control algorithm is proposed accounting for these aspects. The near-optimal algorithm, which controls the charging/discharging of the storage system, is effectively implemented by solving a convex optimization problem at the beginning of each day with polynomial time complexity. For further improvement, the reinforcement learning technique is adopted to adaptively determine the residual energy in the storage system at the end of each day in a billing period.

This experimental study investigates the duty-cycle passive times modifications for a low power wireless sensing system (WSS) designed for energy harvesting technology when its input power level and energy storage size are varying. The different low power WSSs presented in the literature feature specific designs aimed at solving particular problems, and due to their specificity their performance indicators are not directly comparable. As a result of this incompatibility, one cannot identify a correlation between the input power, energy storage element size, passive and active time variations to evaluate the potential usability of the system for static or dynamic testing. The present work covers this result comparison gap induced by the incompatibility factor, providing the experimental data obtained as a result of input power level and energy storage size variation for the same low power WSS, thus generating a reference point for the advanced designer and also for the inexperienced user. The experimental results illustrate that, by varying the storage capacity of a low power WSS, its input power range can be enlarged by up to 20 times.