DC Load Research Articles

A Bidirectional Isolated Dual-Phase-Shift Variable-Frequency Series Resonant Dual-Active-Bridge GaN AC–DC Converter

This article presents a novel single-stage series resonant dual-active-bridge (SR-DAB) for grid-con- nected bidirectional ac–dc energy storage applications. The single-phase SR-DAB is connected to the grid with an unfolding bridge on the ac side. Three SR-DABs are utilized to connect to a three-phase grid. A control scheme that combines dual-phase shifts and variable frequency is proposed to achieve zero voltage switching and power factor correction over a wide range of ac and dc voltages and loads. A series of comparisons in terms of inductor root mean square current, turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> current of all transistors are conducted at different loads to prove the advantage of the proposed converter over the traditional dual-active-bridge-based ac/dc converter. A GaN-based hardware prototype connecting the 480Y/240/208 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta$</tex-math></inline-formula> three-phase grid to a 48-V battery was developed with a peak efficiency of 97.2%.

Power Management in DC Microgrid by the DC-DC Converters

Abstract: DC loads have proliferated rapidly on the market today and DC micro grids with renewable energies are being built as a potential solution to meet the rising demand for electricity. As different energy sources such as solar, wind, fuel cell, and diesel generators can be incorporated into the DC grid, it is important to control the power flow between the sources. An attempt is made in this paper to study the hybrid system consisting a three energy sources, namely wind energy, photovoltaic power source and Battery. Each of the three energy sources is controlled so as to deliver uninterrupted power supply to the load. A control strategy for the management of power flows with solar and wind energy sources in DC micro grid are discussed. Given that voltage profile regulation is critical in a standalone system, a dedicated converter should be used to maintain the voltage of the DC connection. The battery circuit regulates DC charging voltage, while the full power is derived from Solar and Wind to power the attached DC bus charges. An algorithm is developed to manage power flow between three outlets. The algorithm is evaluated in MATLAB / SIMULINK environments for different charging conditions and variations in solar and wind energy.

A High-Voltage Gain Non-Isolated DC–DC Converter Designed for Bipolar DC Microgrids

DC microgrids are now starting to attract huge attention from researches and engineers. Among the several DC microgrid architectures, bipolar DC microgrids are advantageous to accommodate a wider range of DC loads. However, due to mismatched loads connected to the two poles, bipolar DC microgrids may show voltage balancing issues. In this context, this article presents a new high input-to-output voltage gain, non-isolated DC–DC converter specifically designed for bipolar DC Microgrids. The proposed converter supports the balance of voltages at both bipolar DC microgrid poles, as the converter can transfer energy between the two poles in an unbalanced way. The description, theoretical support, and operation of the proposed converter will be presented. The theoretical assumptions will be complemented with several results obtained from computer simulation tests. The simulation tests will be compared to laboratory results from an experimental prototype. The obtained results confirm the theoretical properties of the proposed converter.

Implementation of Modified SEPIC Converter for Renewable Energy Built DC Microgrids

The nonavailability of fossil fuels and the shortcomings of nonconventional energy sources taking place in the environment lead the research and development towards alternative and clean energy sources such as renewable energy sources. Renewable or nonconventional energy resources are being used to meet ever-increasing energy demand. The photo voltaic (PV) energy is the right choice of renewable energy for small voltage DC distribution systems, due to their advantages. But this energy source can produce low output power at the utility grid. Hence, to step up this low input voltage to high value for a range of high-voltage applications, DC-DC converters are integrated to the DC microgrids by means of PV system. The present work elaborates the modified SEPIC converter (MSC) designed based on the traditional SEPIC with a boost-up module. In comparison with conventional or traditional SEPIC converter, the proposed MSC produces high voltage gain and continuous current to the DC microgrids. Furthermore, MSC is operated with only one controlled switch. The proposed converter design improves the efficiency, output voltage, and continuous output current of the DC microgrids. This entire work is completed with PSIM, and finally, numerical simulation results prove the possibility of the MSC with PV-powered DC microgrids, and also the dynamic response of MSC for DC microgrid loads enhances the regulated output voltage and continuous output current of DC loads.

Design of an efficient MPPT optimization model via accurate shadow detection for solar photovoltaic

Abstract The output of Solar Panels is directly dependent on the intensity of direct Sunlight that is incident on the panels. But this efficiency reduces due to shadow effects for rooftop-mounted panels. These shadows can come from other solar panels, nearby buildings, or high-rise structures. It is possible to optimize Maximum Power Point Tracker (MPPT) controllers, which draw the most power possible from PV modules by forcing them to function at the most efficient voltage to increase the output of solar panels even while they are in the shade. Thus, the MPPT analyses the output of the PV module, compares it to the voltage of the battery, and determines the best power the PV module can provide to charge the battery. It then converts that power to the optimum voltage to allow the battery to receive the maximum level of currents. Additionally, it can power a DC load linked directly to the battery. Existing shadow detection and MPPT control models are highly complex, which increases their computational requirements, thereby reducing the operating efficiency of the solar panels. This text discusses a novel Saliency Map-based low-complexity shadow detection model for Solar panels to overcome this issue. The proposed model initially extracts saliency maps from connected Solar panel configurations and evaluates the background for the presence of shadows. Based on the intensity shadows, the model tunes MPPT parameters for optimal voltage &amp; current outputs. Due to this, the model can maximize Solar panel output by over 8.5%, even under shadows, making it useful for various real-time use cases.

A new rule-based self-reconfigurable energy management control of grid and batteries connected hybrid regenerative solar power system for critical loads

Renewable energy sources are increasing and diversifying day by day. For this reason, new and more efficient controller designs are being developed on diversified renewable energy sources. Thus, renewable energy power systems can vary with the development of both topological, power system element controllers and energy management system controllers in line with the desired demands. In this paper, Hybrid Regenerative Power System (HRPS) can operate at low power with a designing a novel Central Energy Management System (CEMS) that is suitable for the critical AC & DC loads and it is efficient thanks to the regenerative effect. Equipments in this power system were firstly created and they are connected each other to obtain HRPS at MATLAB-Simulink environment. After the HRPS topology emerged, power flow scenarios are automatically operated according to the proposed Energy Management System (EMS) on the HRPS topology with using real irradiance and temperature spectrums. Then, according to the consequences obtained, how efficient the power system is in itself was calculated and when compared to the literature, it was emphasized in which cases it was advantageous compared to other EMS studies.

Efficiency Improvement for Wireless Power Transfer System via a Nonlinear Resistance Matching Network

The primary control is widely adopted to obtain a constant voltage output under a wider load range. However, for traditional full-bridge inverters under phase-shift control, due to the loss of soft switching, the system transmission efficiency will decrease rapidly. This problem can be improved by using a half-bridge inverter; however, the power transferred to receiving devices utilizing a half-bridge inverter is inadequate under a small dc load value. To solve these urge issues, a resistance matching network (RMN), constructed by a resonant inductor and capacitor, is added before the full bridge rectifier part of this paper. Owing to the nonlinear resistance conversion characteristics of the proposed RMN structure, the variation range of the equivalent AC impedance before the rectifier end can be compressed into an optimum range to enhance the poor transmission efficiency during the coils part. Simultaneously, when the DC load is small, the power capability of the whole system can be enhanced by increasing the equivalent ac load value; as a result, the insufficient power capability of the half-bridge inverter can be relieved. Finally, a 36 V output WPT system based on the proposed RMN and phase shift control is constructed. Additionally, the experimental results prove the feasibility of the theoretical analysis results.

Novel Isolated Multiple-Input, Multiple-Output Multidirectional Converter for Modern Low-Voltage DC Power Distribution Architectures

This work introduces a multiple-input, multiple-output (MIMO) isolated converter for low-power applications involving residential DC nanogrids and nanogrids. The topology has a multiport characteristic that allows for the integration of loads and sources with distinct ratings, e.g., photovoltaic (PV) modules, battery banks, DC loads, and the AC grid. The structure relies on a DC-DC multi-winding multidirectional flyback converter that operates as power interface and can minimize the number of power conversion stages while enabling flexible power flow control. Owing to its multidirectional characteristic, a port can be responsible for supplying or absorbing energy using duty cycle control or phase-shift control, respectively. Since the operating modes of the converter are decoupled, a predictive controller is capable of managing the power flow among the ports independently. Simulation results are presented and discussed to evaluate the control system robustness and its performance in power flow management.

Multi-Agent-Based Controller for Microgrids: An Overview and Case Study

A microgrid can be defined as a grid of interconnected distributed energy resources, loads and energy storage systems. In microgrid systems containing renewable energy resources, the coordinated operation of distributed generation units is important to ensure the stability of the microgrid. A microgrid needs a successful control scheme to achieve its design goals. Undesirable situations such as distorted voltage profile and frequency fluctuations are significantly reduced by installing the appropriate hardware such as energy storage systems, and control strategies. The multi-agent system is one of the approaches used to control microgrids. The application of multi-agent systems in electric power systems is becoming popular because of their inherent benefits such as autonomy, responsiveness, and social ability. This study provides an overview of the agent concept and multi-agent systems, as well as reviews of recent research studies on multi-agent systems’ application in microgrid control systems. In addition, a multi-agent-based controller and energy management system design is proposed for the DC microgrid in the study. The designed microgrid is composed of a photovoltaic system consisting of 30 series-connected PV modules, a wind turbine, a synchronous generator, a battery-based energy storage system, critical and non-critical DC loads, the grid and the control system. The microgrid is controlled by the designed multi-agent-based controller. The proposed multi-agent-based controller has a distributed generation agent, battery agent, load agent and grid agent. The roles of each agent and communication among the agents are designed properly and coordinated to achieve control goals, which basically are the DC bus voltage quality and system stability. The designed microgrid and proposed multi-agent-based controller are tested for two different scenarios, and the performance of the controller has been verified with MATLAB/Simulink simulations. The simulation results show that the proposed controller provides constant DC voltage for any operation condition. Additionally, the system stability is ensured with the proposed controller for variable renewable generation and variable load conditions.

A Novel DC Transmission and Distribution System with 100% New Energy Consumption

With the continuous development of new energy technology and the continuous improvement of people’s green and low-carbon awareness, distributed photovoltaic, wind power, and other new energy are more and more widely used. On the other hand, the development of new industries, such as electric vehicle charging stations and data centers, has increased the DC load significantly, showing the characteristics of the coexistence of AC and DC user loads. Therefore, it is of great practical significance to study how to effectively utilize new energy and realize the direct power supply of AC and DC loads to achieve the dual carbon goal. Combined with the development trend of new energy and DC transmission, this paper proposes a ±10 kV DC transmission and distribution architecture with 100% new energy consumption, which can realize the complete local consumption of new energy and reliable power supply for diversified AC and DC loads, maximizing the reduction of power loss caused by AC-DC conversion. This paper discusses the key devices and key technologies in the above architecture and analyzes the advantages and disadvantages and application scope of various methods in the current research results.

ANFIS MPPT with power management strategy to harvest reliable power from standalone PV systems to residential loads

&lt;span lang="EN-US"&gt;In recent decades, the matching between the growing energy demand and generation is becoming the challenging task to the researcher’s leads for the development of standalone solar photo voltaic (SSPV) power system. The SSPV system is more suited for electrification of essential loads uses DC power as it offers high efficiency. This work aims to model and simulate SSPV with lead acid battery is used as a DC source. The proposed series shunt charge controller with power management strategy (PMS)is designed and modeled to control the power flow among SSPV, battery and the load. adaptive neuro fuzzy inference system (ANFIS) controller effectively regulates the output voltage by controlling duty ratio of the suitable converter for driving a DC load. A PMS is developed for selecting the operating mode of SSCC by sensing and regulating the battery voltage within 11.6-12.95 V. Here, the 250 Wp panel has been employed to charge a 12 V, 34 AH battery. The practicability of SSPVB system is verified under various loaded conditions using MATLAB/Simulink for a period of 24 hours. A simulation result proves that this SSPV Battery system is capable to electrify the essential loads in rural and isolated areas and also reduce the dependency of grid power.&lt;/span&gt;

A Parameter Tuning Method for a Double-Sided Compensated IPT System With Constant-Voltage Output and Efficiency Optimization

A parameter tuning method is critical for inductive power transfer (IPT) systems because it ensures constant output and reduces reactive power. This is especially true for the double-sided <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> (DS- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> ) compensated IPT system due to its high parameter tuning freedom. This article proposes a parameter tuning method for the DS- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> compensated IPT system. By reconfiguring key resonant parameters, the load-independent constant voltage (CV) output and zero phase angle (ZPA) can be achieved without varying operating frequency. Based on this, two compensation factors for the primary and secondary compensation inductances are defined, and the performance of the IPT system under different compensation factors and the optimal matching criterion of these two factors are investigated in detail. By optimizing these two compensation factors, the overall system efficiency is improved over the entire power range without affecting the property of CV and ZPA. A 2-kW experimental prototype is built to validate the practicability of the proposed tuning method. The experimental results indicate that when the dc load varies from 13.4 to 134 Ω, ZPA can always be achieved, and the output voltage fluctuation is only 4.6 V. The peak efficiency reaches 92.14% at a 1.6-kW output power.

Experimental Validation for Artificial Data-Driven Tracking Control for Enhanced Three-Phase Grid-Connected Boost Rectifier in DC Microgrids

This article introduces the control and operation of a grid-connected converter with an energy storage system. A complete mathematical model was presented for the developed converter and its control system. The system under study was a small microgrid comprising an AC grid that is feeding a DC load through a converter. The converter was connected to the AC grid through an R-L filter. The classical linear controllers have limitations due to their slow transient performance and low robustness against parameter variations and load disturbances. In this paper, machine-learned controllers were used to dealing with those drawbacks of the traditional controller. First, a study for conventional nested loop Proportional Integral (PI) was introduced for both outer and inner loops PI-PI controller. A Data-Driven Online Learning (DDOL) controller was then proposed. A comparison between the normal traditional PI-PI controller and the proposed DDOL ones was made under different operating scenarios. The converter control was tested under various operational conditions, and its dynamic and steady-state behavior was analyzed. The model was done through a MATLAB Simulink to check the normal operation of the network in a grid-connected mode under different load disturbances and AC input voltage. Then, the system was designed, fabricated, and implemented in a hardware environment in our Energy Systems Research Laboratory (ESRL) testbed, and the hardware test results were verified. The results showed that the proposed DDOL controller was more robust and had better transient and steady state performances.

Microgrid-Based Wind and Solar Power Generation on Moon and Mars

This letter proposes a DC microgrid for sustainable power generation on the Mars/Moon for a human inhabitation base. The proposed microgrid includes: (i) A wind turbine (WT) system with a dual rotor generator (DRG) whose output is rectified using a passive rectification state and connected to the microgrid common DC bus with a fixed voltage using a DC-DC converter. (ii) Solar panels that use Passive Emitter and Rear Cell (PERC) material suitable for in-space application whose data are available to the authors; the solar panels are connected to the DC bus using a DC-DC converter. (iii) Battery energy storage system (BESS) that uses a modified lithium-ion material that is space-tested and connects to the DC bus via a bidirectional DC-DC converter. The microgrid feeds three loads, a constant DC load, a 3-phase AC load, and a Mars Rover charger station. A maximum power point tracking (MPPT) controller is proposed for the WT and solar system while a supervisory controller is developed that manages the power flow strategy from the sources to the loads based on the BESS state of charge (SoC). The letter discusses conditions of the Mars/Moon, the challenges for sustained power generation and provides simulation results for the steady-state and transients analyses.

Hosting capacity enhancement of hybrid AC/DC distribution network based on static and dynamic reconfiguration

AbstractThe hybrid AC/DC distribution networks will have a crucial role in the future of smart grids due to their adaptiveness to a variety of DC loads and energy resources. Thus, it is necessary to assess and enhance the Hosting Capacity (HC) of these hybrid networks for the integration of Renewable Energy Sources (RESs). One way to increase the HC without further expansion in the grid is using the potential of Network Reconfiguration (NR). This paper proposes an HC enhancement model that includes AC/DC distribution NR. Two types of NR are considered, namely static, that is, embedding the NR capabilities at the planning stage, and dynamic, that is, using remotely controlled switches as an Active Network Management (ANM) scheme. Besides, two unique potential sources of hybrid AC/DC distribution networks that could be used for the HC enhancement are included, that is, reactive power control of Voltage Source Converters (VSCs) and the mesh operation capability. The problem is formulated as a mixed‐integer linear optimal power flow that aims to maximize the RESs HC under thermal and voltage constraints. Also, stochastic programming is utilized for managing the RESs uncertainties. The simulation results show the accuracy and efficiency of the proposed formulation from various perspectives.

Perencanaan dan Pembuatan Real Time Monitoring System Dari Pada Modul Active Solar Photo Voltaic Tracker Berbasis Internet Of Things

There are still monitoring system in Solar Power Plant that do it manually using measuring and recording tools directly. This makesthe data obtained is also limited. From here the idea emerged to develop a monitoring system using the IoT concept so that monitoring onSolar Power Plant that can be monitored just by looking at the website page, so current and voltage data can be easily monitored. In addition,the resulting display is easy to analyze because the display can be digital and can be monitored with a PC or Smart Phone. This monitoringsystem is used to monitor the current and voltage of a solar power plant with solar cell capacities of 50WP, 80WP, and 100WP. The SolarPower Plant that used is an active type of solar tracker. In the application of using Solar Power Plant that, there is a current and voltagestarting from the solar cell output, accumulator output, AC load input, and DC load input. The monitoring results that have been carried out willthen be automatically sent to the Thingspeak application using the SIM800L Module. The thingspeak application will send data in the form ofnumbers and graphics in real time. By comparing the value of the measurement results on the Arduino and the Thingspeak application, thevalue of the percentage of reading errors on the measuring instrument is obtained. 3. In accordance with the tests that have been carried out,the percentage of read errors / errors can occur because of the reading accuracy of the current sensor measurements and AC-DC voltagesensors with different thingspeak applications. Each sensor has a percentage value of 0.16% AC &amp; DC voltage sensor measurement error,1.2% AC &amp; DC current sensor, and 2.8% data transmission observation.

Design MPPT with Anfis Method on Zeta Converter With DC Load

Maximum power point tracking (MPPT) for PV (Photovoltaic) systems is provided in this research using artificial intelligence-based control. The design of MPPT system with Anfis Method on the Zeta Converter with DC Load is used to optimize the work of the Photovoltaic which will be used for DC load sources. The MPPT process consists of four main stages, namely module training data, determining input and output data, determining the number and type of membership functions and ANFIS training data. Zeta converter works like a buck boost, which can increase or decrease the voltage which is an advantage in designing systems with very volatile Photovoltaic sources. Zeta Converter is used to get higher efficiency, smaller input and output current ripple values and smaller core losses in the inductor. To improve the efficiency of system performance, An MPPT algorithm for the adaptive neuro fuzzy inference system (ANFIS) that is programmed into a microcontroller controls the zeta converter. ANFIS control is used because the response is faster and more effective. The combined simulation's findings demonstrate that the ANFIS control was successful, and the system can now produce the best possible power from Photovoltaic ipanelsiiniMPPT mode by boosting efficiency by up to 19.96%.

A novel predictive control based management strategy considering smart PHEV in digital twin simulation

A combined layout predictive control and H2 / H∞ control is proposed using gain-scheduled control rules for DC-DC boost converters (DDBCs) fed through constant power load (CPL) for improving the stability of the DC bus voltage during extensive disturbances considering the DC loads such as plug-in hybrid electric vehicle (PHEV) demands. Accordingly, to track the reference signal, linear parameter variables with bounded disturbances are applied to express its kinematic error. In this method, the linear matrix inequality (LMI) statuses for the error following layout are solved for the purpose of stabilizing the controller. Afterward, stability constraints have been defined so that the LMI auxiliary variables may be regarded as upper bounds. Furthermore, by allowing more free matrices, conservatism could be reduced. Lastly, the suggested controller has been validated theoretically by a simulation test with a variety of operational conditions, and the performance and efficiency of the controller has been proven. The suggested method can track reference signals with a low steady-state error in different scenarios such as; alternation in the CPL’s desired power; alternation in reference voltage signal; alternation in input voltage. This has been done in solar-based energy systems using digital twin simulation.

A New Five-Port Energy Router Structure and Common Bus Voltage Stabilization Control Strategy

Multi-port energy routers are a core device that integrates distributed energy sources and enables energy-to-energy interconnections. For the energy routing system, the construction of its topology, the establishment of internal model switching and the control of common bus voltage stability are the key elements of the research. In this paper, a five-port energy router structure is proposed, including a PV port, an energy storage port, a grid-connected port, a DC load port, and an AC load port. Among them, the energy storage port and the grid-connected port involve bidirectional energy flow, which are the core ports of control. For the system state, a model switching strategy is proposed based on the topology and the port energy flow direction. When the external conditions change, the system can be stabilized by means of a quick response from the energy storage port. When the energy storage is saturated, the state is switched, and the grid-connected port works to achieve system stability. The rapid stabilization of the bus voltage and the free flow of energy are achieved by combining the fast response of the model predictive control with the properties of multiple model switching. Finally, the feasibility of this energy router topology and control strategy is verified by building simulations in MATLAB.

System Simulation Comparison of Sliding Mode and PID Controller for Buck Converter

In this paper, the performance of the closed loop sliding mode controller (SMC) is compared with the conventional PID controller for DC-DC buck converter. We specifically address the comparison of the two controllers from system simulations point of view by first developing the system model of the DC-to-DC buck converter circuit and designing a suitable SMC controller.Using MATLAB/SIMULINK system simulations, the performance of the SMC controlled buck converter is compared with the PID controller in terms of the overshoot, rise time and settling time of the load voltage and currents. The simulation results demonstrated the high performance of the SMC controlled buck converter in accurately tracking the reference voltage, eliminating the overshoot, improving the settling time but with slower rise time as compared with the PID controller. The transient time response of the SMC controller can be further improved by tuning the system control parameters to attain improved rise time. Such SMC based buck converter can be used for the design of a stable direct current power supply for DC loads such as DC motors used for water pumps or other applications.