Average DC Voltage Research Articles

Digital twin modeling and intelligent optimization for rail operation safety assessment

Currently, the use of fixed empirical parameters combined with traditional algorithms to construct train parameter prediction models for estimating train energy consumption is often used. However, due to changes in train related parameters, there is a significant error between the estimated results of this method and the actual values, which cannot reflect the true state of train operation. It affects the subsequent maintenance and repair of trains, thereby affecting the safety of the entire subway operation system. To address the above issues, a train traction power flow model based on digital twin technology is proposed. The swarm intelligence optimization algorithm is not used to correct model parameters. By correcting the deviation of train passenger load, accurate prediction of train energy consumption can be achieved. The experimental results show that the power flow model constructed by the research institute can reduce the power error of single interval trains by over 11.91%. The average DC voltage error of the train power flow model after parameter correction is 0.19%. The average DC current error is 12.07%. The root mean square error range of passenger capacity for similar day neural network models is [0.0521,0.0811]. The experimental results indicate that the model constructed by the research institute can accurately predict train energy consumption and ensure the safety of the subway operation system.

Performance Prediction of D.C. Motor Fed From Half-Controlled Bridge Rectifier

Controlled rectification is the process of obtaining a controlled output DC voltage from a constant AC voltage. This can be used in the speed control of the DC motor to provide rapid torque control and a quick starting response. In this work, a three-phase half-controlled bridge rectifier has been used. The average output DC voltage varies smoothly by varying the firing angle (α). Different methods of analysis such as state-space and Fourier-series, are used to obtain the performance of the DC motor fed from the bridge-rectifier supply. However, these methods do not deal with the prediction of the discontinuous conduction phenomenon which occurs during the operation of the DC motor with a variation of delay angle. This paper deals with the prediction of performance characteristics during the operation of the DC motor fed by a 3-phase half-controlled bridge rectifier, including the transient as well as steady-state operation with a variation of delay angle as well as application of load torque at starting.

Wideband RF rectifier circuit for low-powered IoT wireless sensor nodes

This paper proposed a broadband RF-rectifier circuit. The design is matched through a combination of a wideband resistance compression network (RCN) with a modified short-stub matching network (MN) for Terminal-1 (T1) and a Π-MN for Terminal-2 (T2). The RCN incorporates the two terminals using a transmission line (TL) of 50 Ω. The TL-MN parameters are analyzed and evaluated in the design using closed-form equations. The HSMS2850-based prototype model demonstrates that the peak RF-to-DC power conversion efficiencies (PCE) realized at 3 dBm input power (Pin) are (76.92%, 70.53%, 69.75%, 67.54%) for (1.82, 2.13, 2.45, and 2.67 GHz), respectively. The prototype is terminated with a 1 kΩ load terminal (RL) and attained a maximum average output DC voltage VDC of 2.52 V. The model is tested in the ambient environment and achieved a T1(T2) VDC of 0.350(0.230) V. This approach also mitigated the impact of impedance variations imposed by diode non-linearity. The RF harvester drive a low-power evaluation module (EVM) for T1(T2) at 0.600(0.470) V.

Implementation of PV Based Multilevel Inverter to Improve Power Quality using Fuzzy PI and PSO PI Controllers

Power quality is the primary issue to be taken into consideration in modern electrical systems, particularly on the distribution side, to protect sensitive loads. Long-term uses can never run out of renewable resources. Connecting STATCOM at the distribution side enhances the power factor by improving the quality of the current waveform. The reactive power range that needs adjustment by utilising PV arrays on the STATCOM's DC side. Increases due to the large rise in terms of the PV power plants' size and capacity. Cascaded H Bridge multilevel topologies can increase the flexibility and effectiveness of PV modules. The suggested approach in this paper gives outcome of reduced peak over shoot, rise time, settling time, steady state error, percentage of ripples and total harmonic distortion which improves the power quality. PV system with cascaded H bridge multilevel inverters STATCOM for harmonic suppression and to make reactive powerless. To produce modulation indices for H Bridge switching, synchronised reference frame theory is modified. H bridges' average DC voltage is managed by a PI controller, and controller gains are obtained using fuzzy, PSO, and the trial-and-error approach. To confirm the viability of the suggested approach, simulation results using MATLAB/SIMULINK are shown. The experimental setup of proposed method is carried out to validate the inverter response.

Commisioning Test of 3 x 3kW Solar Power Plants for Laboratory Purpose

A laboratory is an important part in the learning and teaching process, therefore, it is necessary to improve both in terms of equipment and laboratory management standards. State Polytechnic of Ujung Pandang has carried out the design process for a solar power plant (SPP) system with a capacity of 3 x 3 kW to support the learning process related to alternative and renewable energy lectures and practicum. One part of the procedure for activating newly installed laboratory equipment is the commissioning test. From the commissioning results, the results show that 3 x 300 Wp and independent 375 Wp SPP can work well with an average DC voltage rating of 80 V and for AC loads with an average voltage of 220 V. All types of loads, both AC and DC can work properly after going through the DC Couple and AC Couple with the inverter.

Perancangan Permanent Magnet Synchronous Generator Sultan Wind Turbine V-5

Wind is an inexhaustible source of energy so that the use of wind energy change systems will have a positive impact on the environment. Sultan Wind Turbine is a vertical axis wind turbine called the Vertical Axis Wind Turbine (VAWT). Synchronous generator is a machine that converts mechanical energy into electrical energy. Permanent magnet synchronous generator (PMSG) is a generator that uses permanent magnets to generate an air gap field instead of using an electromagnet. The purpose of this study is to design a 100 W PMSG generator for Sultan Wind Turbine using the MagNet infolytica software, then the results of looking for simulations at various speeds and various loads, after that to determine the value of the output power and efficiency at each loading and RPM. The design of this generator is the first design that is adapted to previous research where this design will optimize the simulation of previous designs that were applied to the Sultan Wind Turbine v-5. A method for designing a permanent magnet synchronous generator simulation of the sultan wind turbine which will be tested in developing its performance using the J.R. Handershot. In this design using MagNet Infolytica software to find the values ​​of Voltage and Current along with Torque obtained from simulations with the finite element method, then data processing is carried out in Excel to find the value of output power and efficiency. The results obtained in this study are by changing the geometric shape. able to produce with a rotating speed of about 100 rpm to 150 rpm at a load of 5 ohms, namely 125, 86 Watt to 231.59 Watt. The average DC voltage is 33.5 volts, the average DC current is 6.65 Ampere, the torque is 23. 24 Nm, the input power is 365.14 Watts, the output power is 231.59 Watts and the efficiency ranges from 58% to 79%.

Parametric Stability Assessment of Single-Phase Grid-Tied VSCs Using Peak and Average DC Voltage Control

A type of peak-value dc voltage control (denoted as PK control) was proposed in the literature for supporting the use of a smaller dc-side capacitance when the single-phase voltage source converter is operated as a static synchronous compensator. Although it was demonstrated to operate stably under several conditions, it will be revealed in this article how the PK control will suffer from a more severe small-signal stability issue under nonideal grid conditions than the conventional method of controlling the average value of the dc voltage (denoted as Avr control). Especially, it will be shown how the PK control is sensitive to some of the control parameters. To obtain these results, a parameter-oriented stability analysis method is developed in the linear time-periodic framework. Then, it is utilized for parametric stability assessments of the Avr and PK control. Finally, both frequency- and time-domain experimental results verified the effectiveness and accuracy of the applied method in the presented analysis.

New Modulation Method for Three-Phase Matrix Converter: Mathematical Theory and Demonstration Test Results

This study proposes a new modulation scheme for three-phase matrix converters. A three-phase matrix converter consists of three inverters that operate in the same order but with different usage rates. This modulation scheme uses a classic comparator of carrier and control signals. The only physical quantity used for modulation is the zero-cross signal of the input voltage. When using this method, the output voltage is obtained by multiplying the average dc voltage by the control signal. The input current is obtained by multiplying the “average dc current” by a sine wave. This scheme has many advantages over traditional methods. Four types of tests were conducted and the results showed that the method can be applied in practical use. The proposed method is a standard modulation method that can be used for widely used matrix converters, such as voltage source inverters.

Using Nonlinear Load DC Variables as Inputs for Harmonic Current Reduction

This paper introduces and discusses new inputs for a single-phase shunt active power filter (SAPF) using nonlinear load equivalent resistance estimation control strategy. The inputs are an average DC voltage and current of a current source nonlinear load. By using a MATLAB Simulink simulation tool, a model of single-phase AC system connected to the SAPF and nonlinear load is designed and its vital voltage and current variables are simulated. Various simulation results are presented and analysed in order to validate the effectiveness of proposed inputs. As a conclusion, the proposed control strategy with new inputs successfully achieved its objective to mitigate harmonic current and to compensate the reactive power with good performance.

Frequency and Voltage Regulation in Hybrid AC/DC Networks

Hybrid ac/dc networks are a key technology for sustainable electrical power systems, due to the increasing number of converter-based distributed energy resources such as solar or wind. In this article, we consider the design of control schemes for hybrid ac/dc networks, focusing especially on the control of the interlinking converters (ILCs). We present two control schemes: first for decentralized primary control and second a distributed controller to achieve secondary control objectives as well. In the primary case, the stability of the controlled system is proven in a general hybrid ac/dc network, which may include asynchronous ac subsystems. Furt hermore, it is demonstrated that power sharing across the ac/dc network is significantly improved compared to previously proposed dual-droop control. The proposed scheme for secondary control guarantees the convergence of the ac system frequencies and the average dc voltage of each dc subsystem to their nominal values. An optimal power allocation is also achieved at steady state. The applicability and effectiveness of the proposed algorithms are verified by advanced simulations on a test hybrid ac/dc network in Simscape Power Systems.

Resistorless current mode precision rectifier using EXCCII

In this paper, a new current mode precision rectifier circuit is proposed using a single EXCCII and two nMOS transistors. The novelty of the circuit is that it can provide all the possible rectified outputs, namely ± full wave as well as ± half wave simultaneously without any alteration of topology. Moreover, it has low input impedance and high output impedance, which is suitable for fully cascadable operation. It is suitable for a very high frequency of operation. The operating frequency is found to be 125 MHz and above. The temperature, average DC voltage output, noise, power consumption, input dynamic range (± 500 µA), Monte-Carlo and total harmonic distortion analysis are carried out to check the performance quality. The conversion of sinusoidal signal to root-mean-square circuit is also included here as an application of the proposed rectifier The proposed circuit is simulated using Cadence ORCAD PSpice simulator with 0.18 µm CMOS technology parameters. Simulation results agree well with the theoretical analysis.

Simulasi Pemodelan Sistem Eksitasi Statis pada Generator Sinkron terhadap Perubahan Beban

Excitation system is one of the most important parts of synchronous generators, where the system functions to provide dc power to the field generator coil. Iin this study, a static excitation system consisting of transformers and connected thyristors in bridge configuration has been implemented in synchronous machines that operate as 206,1 mva capacity generators, 16,5 kv using the help of matlab simulink r2017b software. By adjusting the load given to the generator, variations in excitation currents can affect the amount of output voltage generated by the generator so that it can increase and decrease the induced voltage. In full load conditions, namely p = 175 mw, q = 100 mvar, the results of the study show that when the simulation is run at alpha 0 °, it is known that the average value of dc voltage is 496,4 v, excitation current is 1057 a and voltage generator output has increased beyond its nominal voltage of 16,72 kv. in this case, to maintain the terminal voltage, the excitation current must be reduced by increasing the angle of shooting of the thyristor to an alpha angle of 45 °, so that the average dc voltage can be reduced to 479,3 v, as well as the excitation current to 985,9 a. the generator output voltage at the alpha 45 ° angle is obtained according to its nominal value of 1,.5 kv.

A coordinated DC voltage control strategy for cascaded solid state transformer with star configuration

Cascaded solid-state transformer (SST) can be directly connected to the high-voltage distribution grid, and it has broad applications in the future smart grid, traction locomotive, and renewable energy integration. However, the reliability of the cascaded SST is seriously influenced by the DC voltage and power imbalance issues with this configuration. This paper presents a coordinated DC voltage control strategy for cascaded SST with star configuration, in which the average DC voltage and the balancing DC voltage are controlled separately without current sensors in dual active bridge (DAB) modules. This strategy not only reduces the cost and the complexity of the control system but also realizes the unbalanced reactive compensation to some extent. Simulation and experimental results verify the feasibility and validity of the proposed method

Event-Triggered Communication Based Distributed Control Scheme for DC Microgrid

Development of microgrids and wide spread deployment of renewable generation and energy storage systems have highlighted the need for distributed control schemes to achieve maximum utilization and coordination among all the connected resources. In DC microgrids, the key goals of system-wide control are droop-based current sharing and network dc-voltage regulation. These may be achieved using a consensus algorithm secondary control that a) averages all the node voltages dynamically and maintains them at a nominal value and b) based on information from neighboring source currents to converge to a consensus in current sharing. Achieving the dynamic consensus may impose significant communication burden when implemented using conventional periodic communication methods. In this paper, an event-triggered communication based dynamic consensus algorithm is proposed that helps achieve both the stated goals of proportional current sharing along with average DC voltage regulation in a DC microgrid. The convergence and stability of the modified dynamic consensus algorithm and event triggering condition is proven using Lyapunov's stability criterion. The proposed control is applied to a DC microgrid system for secondary control of voltage and current regulation, and the performance of the proposed technique is validated under various operating conditions and disturbance in the communication system in both simulation and hardware environment.

A 0.18 $$\upmu$$ μ m CMOS voltage multiplier arrangement for RF energy harvesting

This work presents a two-stage voltage multiplier (VM) useful in RF energy harvesting based applications. The proposed circuit is based on the conventional differential drive rectifier, in which the input RF signal has been level shifted using a simple arrangement. This signal is then used to drive the next stage, which has been formed by using gate cross-coupled transistors. As a result, the load driving capability of the proposed architecture increases. The load in this work has been emulated in terms of a parallel RC circuit. The architecture has been implemented using standard 0.18 $$\mu$$ m CMOS technology. The measurements of the two-stage conventional VM (CVM) and proposed VM circuits were performed at ISM frequencies 13.56, 433, 915 MHz and 2.4 GHz for R $$_L$$ of values 1, 5, 10, 3 and 100 K $$\Omega$$ with a fixed value of C $$_L$$ equal to 20 pF. The performance evaluation has been done in terms of the power conversion efficiency (PCE) and average output DC voltage. The measured results show an improvement in PCE of 5% (minimum) for 13.56, 433 and 915 MHz frequencies, and up to 2% improvement for a frequency value of 2.4 GHz at the targeted load condition of 5 K $$\Omega ||$$ 20 pF, when compared with the measured results of the CVM circuit.

Y結線モジュラーマルチレベル変換器STATCOMにおける対称座標法を用いた直流キャパシタ電圧制御法

STATCOMs have attracted attention as var compensators on electric power distribution systems. In this study, a star-connected modular multilevel converter (MMC) was applied to STATCOM. The voltage across the strings of the star-connected MMC was 1/√3 times that of a delta-connected MMC. MMCs can be interconnected without a transformer because they have high equivalent carrier frequency through phase-shifted pulse-width modulation. The dc capacitor voltage control of a star-connected MMC is relatively complex compared with delta connected MMCs, which have a circulation current as a control parameter. Relevant literature suggests that conventional dc capacitor voltage controls of MMCs for STATCOMs might be difficult to operate when the output reactive power is zero var. This paper presents a new dc capacitor voltage control method using symmetrical components. The overall control block mainly consists of two parts: average dc and dc capacitor voltage controls. The proposed dc capacitor voltage control and reactive power control were verified through experiments.

Fabrication and characterization of magnetically tunable metal-semiconductor schottky diode using barium hexaferrite thin film on gold

Barium Hexaferrite (BaM) is an extensively studied magnetic material due to its potential device application. In this paper, we study Schottky junction diodes fabricated using gold and BaM and demonstrate the function of a spintronic device. Gold (50 nm)/silicon substrate was used to grow the BaM thin films (100-150 nm) using pulsed laser deposition. I-V characteristics were measured on the Au/BaM structure sweeping the voltage from ±5 volts. The forward and reverse bias current-voltage curves show diode like rectifying characteristics. The threshold voltage decreases while the output current increases with increase in the applied external magnetic field showing that the I-V characteristics of the BaM based Schottky junction diodes can be tuned by external magnetic field. It is also demonstrated that, the fabricated Schottky diode can be used as a half-wave rectifier, which could operate at high frequencies in the range of 1 MHz compared to the regular p-n junction diodes, which rectify below 10 kHz. In addition, it is found that above 1 MHz, Au/BaM diode can work as a rectifier as well as a capacitor filter, making the average (dc) voltage much larger.

Modified Quasi-Steady State Model of DC System for Transient Stability Simulation under Asymmetric Faults

As using the classical quasi-steady state (QSS) model could not be able to accurately simulate the dynamic characteristics of DC transmission and its controlling systems in electromechanical transient stability simulation, when asymmetric fault occurs in AC system, a modified quasi-steady state model (MQSS) is proposed. The model firstly analyzes the calculation error induced by classical QSS model under asymmetric commutation voltage, which is mainly caused by the commutation voltage zero offset thus making inaccurate calculation of the average DC voltage and the inverter extinction advance angle. The new MQSS model calculates the average DC voltage according to the actual half-cycle voltage waveform on the DC terminal after fault occurrence, and the extinction advance angle is also derived accordingly, so as to avoid the negative effect of the asymmetric commutation voltage. Simulation experiments show that the new MQSS model proposed in this paper has higher simulation precision than the classical QSS model when asymmetric fault occurs in the AC system, by comparing both of them with the results of detailed electromagnetic transient (EMT) model of the DC transmission and its controlling system.

The Use of Reflection Mode Ultrasonic Transceiver Sensor in Pipeline Inspection Guage to Monitor Pipeline Internal Corrosion

Aging gas transmission pipelines are prone to internal corrosion due to the presence of carbon dioxide and hydrogen sulphide in the natural gas constituents. Commonly, the in-line inspection tool known as Pipeline Inspection Gauge (PIG) is applied to perform the corrosion inspection of the pipeline. This paper describes an ultrasonic instrumentation system for PIG to monitor internal corrosion of pipeline. The system consists of ultrasonic transceiver sensor, ultrasonic driving circuitry and data acquisition system. The hardware is equipped with a sensor carrier which is propelled along the test pipeline. The time of flight (TOF) of the ultrasonic wave is measured and was used to evaluate the internal corrosion of pipeline. An initial experimental instrument was set up to perform the distance measurement test at a frequency of 390 kHz, to simulate the changes of pipe wall thickness due to corrosion effect. Surface anomalies were created at different positions to simulate the changes of pipe wall thickness due to the corrosion effect. Variation in measured distances implied the existence of the surface anomalies. The results of the simulated surface anomalies showed that the percentage error was less than + 5%. The large value of average DC voltage gave indication of distance increment due to the depth of the surface anomalies. The developed ultrasonic instrumentation system is capable to monitor the internal corrosion of pipeline.

Deterministic Josephson vortex ratchet with a load

We investigate experimentally a deterministic underdamped Josephson vortex ratchet-a fluxon particle moving along a Josephson junction in an asymmetric periodic potential. By applying a sinusoidal driving current, one can compel the vortex to move in a certain direction, producing an average dc voltage across the junction. Being in such a rectification regime, we also load the ratchet, i.e., apply an additional dc bias current I(dc) (counterforce) which tilts the potential so that the fluxon climbs uphill due to the ratchet effect. The value of the bias current at which the fluxon stops climbing up defines the strength of the ratchet effect and is determined experimentally. This allows us to estimate the loading capability of the ratchet, the output power, and the efficiency. For the quasistatic regime we present a simple model which delivers straightforward analytic expressions for the above-mentioned figures of merit.