Voltage Source Research Articles

Wideband oscillation analysis of VSC-HVDC connected DFIG wind farm

This paper investigates the wideband oscillations of a doubly fed induction generator (DFIG)-based wind farm connected via a voltage source converter-based HVDC (VSC-HVDC) system across the full frequency band. A small signal model of the system is developed to facilitate this analysis. Oscillation mode characteristics are then examined through eigenvalue analysis and participation factors. The study further explores the impact of strongly correlated factors on typical wideband oscillation modes and their inter-mode interactions. Findings reveal that interactions between the DFIG wind farms and the VSC-HVDC system can induce new super-synchronous oscillations. Additionally, a damping coupling is observed between the medium-frequency oscillation interactive transformation mode and the stator-line mode.

Experimental Investigation of Modified Level Shift PWM with Capacitor Voltage Balancing on Single Phase Modular Multilevel Converter

Modular Multilevel Converters (MMCs) are a prominent voltage source converter topology that is rapidly gaining popularity in medium/high power/voltage applications, including high-voltage DC transmission systems and electric vehicle systems. However, MMC has the critical issue of unbalanced submodule capacitor voltages and circulating current. The MMC distributes DC-link energy evenly among its submodule capacitors, rather than storing it in a large capacitor like conventional voltage source converters. In MMC, the submodule floating capacitors interface the DC input voltage and AC output voltage. Therefore, capacitor voltages must be balanced. The existing capacitor voltage control struggles to handle many gate pulses at medium and high voltages. An effective control scheme is needed to solve the issues mentioned earlier. This paper presents a performance analysis of a 1-Φ MMC using a modified level shift PWM technique based on Universal Control Modulation Scheme (UCMS) and a sorting-based capacitor voltage balancing algorithm. MATLAB/Simulink software implements the proposed control method for a 1-Φ , seven-level MMC. The outcomes of the simulation demonstration reveal that phase disposition PWM offers less harmonic distortion of output phase voltage than the other level shift PWM techniques, such as phase disposition PWM and alternate phase disposition PWM. The simulation results also demonstrate the effective use of the sorting-based capacitor balancing algorithm to regulate the voltages of the submodule capacitors. Finally, the real-time GUI tool validates the simulation results using an experimental prototype of 1-Φ MMC with the dSPACE MicroLabBox 1202.

Self-Voltage Balanced Switched-Capacitor Seven-Level Inverter for Asymmetrical Solar PV Source Applications

In this paper, a novel structure of self-voltage balanced switched-capacitor-based seven-level inverter (SVB-SCSLI) is proposed for asymmetrical input energy source applications. SVB-SCSLI develops a seven-level staircase waveform with a minimum number of semiconductor devices compared to existing multilevel inverters (MLIs). The proposed converter is more suitable for the solar PV system where unequal DC voltage sources are available. The SVB-SCSLI also resolves the main difficulty of connecting many inverters in parallel to achieve staircase voltage. Besides, it attains voltage balancing capability at DC-link by holding constant capacitor voltage at every cycle. The detailed loss and steady-state analysis of the SVB-SCSLI are examined. Furthermore, the proposed converter’s efficiency improves with better power quality than other topologies reported in the literature. Finally, a prototype is fabricated, and experimental results are presented to validate the feasibility of SVB-SCSLI.

Stabilized voltage source inverter for sensitive loads in nuclear installations

The present paper proposes a novel design of a stabilized single-phase voltage-source inverter with pure sinusoidal output voltage for photovoltaic systems employed for feeding sensitive loads in nuclear installations. Such types of loads require a voltage source with quite stabilized magnitude and frequency and pure sinusoidal shape that is free from higher-order harmonics. The inverter is based on an H-bridge four insulated gate bipolar transistors (IGBTs) with gate drivers and optocoupler isolators. A control system based on a fast DSP unit and a microcontroller is designed for cancelation of the higher-order harmonics to produce a pure sinusoidal output with almost zero total harmonic distortion (THD). The sinusoidal purity, frequency and magnitude stabilization are achieved through pulse width modulation (PWM) controlled by a fast-response feedback system that measures the time wave form of the output voltage applied to the load and then calculates the THD, frequency and amplitude. The sinusoidal shaping is performed with aid of a sinusoidal shaping filter (SSF) to fasten the operation of higher-order harmonic cancellation. The frequency measurement is achieved through a frequency counter whereas the amplitude measurement is carried out through a differential amplifier that amplifies the difference between the output voltage of the inverter (while being applied to the load) and reference voltage that determines the desired amplitude. A prototype of the entire system of the proposed voltage-source inverter is fabricated for experimental evaluation of its performance. It is shown through simulation and experimental work that the proposed control system of the inverter output voltage is able to stabilize both the amplitude and frequency of the voltage applied to the load irrespective of the load impedance. Also, it is shown that the THD of the output voltage is -57dB\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$-57 \ ext{ dB}$$\\end{document} (0.00025%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$0.00025 \\%$$\\end{document}), which is almost zero. Moreover, the switching losses are considerably reduced and can be negligible owing to the use of the appropriate IGBTs. The efficiency of the proposed inverter is obtained by simulation taking into account all types of losses. Also, the dependence of the inverter efficiency on the load current is investigated. The average efficiency of the proposed voltage-source inverter is shown to be higher than 97%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$97\\%$$\\end{document}.

Power quality enhancement in the wind energy distribution system using HHO algorithm based UPFC

ABSTRACT This study proposes using a Wind Energy Conversion System (WECS) to power a Unified Power Flow Controller (UPFC) Direct Current (DC) capacitor, maintaining appropriate voltage levels. This arrangement allows UPFC adjustment to improve Power Quality (PQ). The main issue rapid growth of nonlinear loads causes sudden variations in source voltage, resulting in a reduction in power quality within seconds. UPFC is used to address these concerns. This work uses the Harris Hawks Optimizer (HHO) to improve the performance of the UPFC. To begin, the aim function parameters are defined, including voltage, current, active power, and reactive power. Thus, these characteristics are used to generate control pulses for the series and shunt active power filters. HHO is used to find the best solution and predict the ideal UPFC control signal. Additionally, voltage instability and power dissipation decrease under different load conditions. Thus, system power supply quality improves. To evaluate the effectiveness of the proposed technique, two scenarios were identified: fault circumstances and engine speed changes. MATLAB/Simulink was used to implement the suggested strategy and compare it to established methodologies like Grey Wolf Optimization (GWO), Modified Particle Swarm Optimization (MPSO), and Whale Optimization Algorithm (WOA).

A hybrid methodology based battery power management and torque control of open-end winding induction motor drive for electric vehicles

This paper proposes a hybrid strategy for an isolated battery-powered induction motor drive with two stages fed by an inverter and open-end winding, designed for electric vehicle applications. The hybrid approach, termed EOO-RERNN, combines the Eurasian Oystercatcher Optimizer (EOO) and Recalling Enhanced Neural Network methods. RERNN predicts the control pulses generated by EOO, which are utilized to control the voltage source inverter (VSI) switches. The system comprises dual motors, two battery packs (BPs), and VSIs supplying power to both the rear motor (RM) and front motor (FM). The primary objective of the EOO-RERNN technique is to regulate each DC-link's power share to maintain equilibrium in the electric vehicle's charge. Direct Torque Control (DTC) is employed due to its quick and precise torque response and tolerance for parameter variations. Proper tuning is required to control the state of charge battery level. The EOO-RERNN method is implemented in the Matrix Laboratory (MATLAB) platform, with performance contrasted to other methods such as Wild Horse Optimizer (WHO), Grasshopper Optimization Algorithm (GOA), and Heap-Based Optimizer (HBO). Simulation results indicate a motor speed of 4850 rpm for the EOO-RERNN method.

Enriched PQ-based bridgeless isolated one-stage sepic PFC converter for power solutions

ABSTRACT This article deals with an enriched power quality (PQ) based bridgeless isolated one-stage (BIOS) Sepic PFC converter as a cost-effective power solution. The presented revamped bridgeless structure on the front-end avoids unnecessary capacitive coupling and assures less current harmonic distortions, better power factor (PF) at the AC mains to confirm the permissible power quality (PQ) metrics as per IEC 61,000-3–2 standards. This PFC circuit is modelled to be operated on discontinuous inductor current mode (DICM) to reveal the innate zero current switching (ZCS) and power factor correction (PFC) capability. The added merits of DICM and high-frequency isolation involve lesser number of sensors, part count, control complications, size and cost associated with the entire power conversion. Further, the hardware setup of 250W/48 V power solution is assembled to testify the performance of the developed circuit. From the experimental outcomes it is notable that this power solution retains the bettered PQ profile within the perceivable limits even under broad range of source voltage and load discrepancies. Finally, the extensive loss modelling of the power circuit is formulated to evaluate the actual efficiency of the entire power conversion.

Solving dynamic electric circuit with nonlinear hysteretic inductor using harmonics interpolation method

SummaryThe aim of this paper is to present a methodology for solving а dynamic electric circuit with nonlinear hysteretic inductor without the use of hysteresis model or equivalent circuits. A consideration of nonlinear and hysteretic behaviour of the magnetic core under quasistatic conditions is based on applying harmonics interpolation method (HIM) to the measured magnetising field strength waveforms. A dynamic behaviour of the magnetic core is considered through the application of the statistical theory of losses (STL). A considered electric circuit consists of AC voltage source connected in series with shunt resistor, additional linear resistor and inductor, as well as a nonlinear hysteretic inductor. The solution for electric current of the circuit is obtained by solving equation derived from Kirchhoff's laws through a series of successive iterations. Coupling of electric and magnetic part of the circuit is obtained from fundamental laws of electromagnetism. Methodology is validated for four cases of the considered electric circuit — without additional elements, with one additional or both additional elements, for sinusoidal voltage source amplitudes of 2, 4, 6, 8 and 9 V and frequency of 50 Hz. Validation is repeated for frequencies of 100, 200 and 300 Hz while keeping the ratio of the amplitude to frequency constant. Detailed theoretical approach and methodology, comparisons between measured and calculated results, as well as adequate discussion are presented.

Low‐carbon pyrolysis of vacuum gas oil by non‐thermal plasma

AbstractThe constant growth in the share of renewable electricity and the need to reduce CO2 emissions create prospects for the development of non‐thermal plasma (NTP) pyrolysis of heavy oil. NTP pyrolysis requires only electricity and does not require heating of raw materials to high temperatures, which significantly reduces the carbon footprint during processing. This paper investigates the characteristics of NTP pyrolysis of vacuum gas oil under the action of electric microsecond discharges in the liquid phase, depending on the voltage of the current source 300–700 V to optimize energy consumption, conversion of raw materials, and increase the yield of commercial demand products.

Collaborative Planning and Comprehensive Evaluation Method for Energy Storage System and Flexible Interconnection in Distribution Networks Considering Island Operation

Introduction: When the superior power grid fails and loses power, due to the traditional single power supply radial grid structure of low-voltage substation areas, all loads in the lowvoltage substation area will lose power, causing a poor electricity consumption experience for low-voltage users. To enhance the resilience of low-voltage distribution areas against faults and power outages from higher-tier power grids, a collaborative planning and comprehensive evaluation method for grid-forming energy storage systems (GFM-ESS) and flexible interconnection in distribution networks, considering island operation, is proposed. Method: This method integrates GFM-ESS and flexible interconnections, taking islanding operations into account. Firstly, the structure of GFM-ESS and voltage source converters is analyzed. The control modes of GFM-ESS in parallel or off-grid scenarios are also scrutinized. Secondly, minimizing the annual comprehensive cost and the annual power outage load are the objective functions. A bilevel programming model for GFM-ESS and flexible interconnection of lowvoltage distribution networks, considering island operation, has been established. Moreover, a comprehensive evaluation method based on the analytic hierarchy process for proposed lowvoltage distribution network structural schemes is introduced. An evaluation index system is established to assess the rationality of these proposed network structural planning schemes. Finally, the superiority of the proposed collaborative planning method is verified through a comparative analysis of three planning methods. Result: The proposed collaborative planning method can effectively ensure the continuous power supply of low-voltage distribution networks under the fault scenario of the upper power network. Conclusion: Moreover, the rationality of the results obtained from the proposed collaborative planning method is verified through a comprehensive evaluation method of grid structure schemes based on the analytic hierarchy process. The proposed comprehensive evaluation method can determine which two areas are optimal for grid planning. result: The superiority of the proposed collaborative planning method was verified by comparative analysis of three planning methods. And the rationality of the proposed collaborative planning method results was verified by the comprehensive evaluation method of grid structure schemes based on analytic hierarchy process.

A reduced vector model predictive controller for a three-level neutral point clamped inverter with common-mode voltage suppression

This paper presents a novel, state-of-the-art predictive control architecture that addresses the computational complexity and limitations of conventional predictive control methodologies while enhancing the performance efficacy of predictive control techniques applied to three-level voltage source converters (NPC inverters). This framework's main goal is to decrease the number of filtered voltage lifespan vectors in each sector, which will increase the overall efficiency of the control system and allow for common mode voltage reduction in three-level voltage source converters. Two particular tactics are described in order to accomplish this. First, a statistical approach is presented for the proactive detection of potential voltage vectors, with an emphasis on selecting and including the vectors that are most frequently used. This method lowers the computational load by limiting the search space needed to find the best voltage vectors. Then, using statistical analysis, a plan is presented to split the sectors into two separate parts, so greatly limiting the number of voltage vectors. The goal of this improved predictive control methodology is to reduce computing demands and mitigate common mode voltage. The suggested strategy's resilience is confirmed in a range of operational scenarios using simulations and empirical evaluation. The findings indicate a pronounced enhancement in computational efficiency and a notable diminution in common mode voltage, thereby underscoring the efficacy of the proposed methodology. This increases their ability to incorporate renewable energy sources into the electrical grid.

Research on Voltage Coordinated and Stability Control of Condensers Based on Reactive Power Replacement

Abstract In this research, we investigated condenser voltage coordination and stability control systems by analyzing voltage coordinated control mode among excitation, voltage coordination and stability as well as automatic-voltage reactive power control systems. By using dynamic excitation regulation and steady-state regional voltage source control replacement, dynamic reactive power quickly output under fault condition as well as optimized regional reactive power under steady state were realized. The correctness and practicability of the proposed strategy was verified through engineering application. Adopting the reactive power displacement of voltage coordination control system to solve local voltage instability problem after UHV DC blocking. The proposed method realized multi-time scale emergency, recovery and steady-state control of the system under steady and dynamic states.

Rectenna and Patch Microstrip Antenna Proposal for Energy Harvesting in S-band CubeSats

Abstract A proposal of a 2.4 GHz rectenna is presented as a complementary device for the electrical power system (EPS) in CubeSats, with the goal of maintaining its size regulations and providing an extra voltage input to the existing methods, like solar cells and batteries, thus possibly increasing the CubeSat’s durability. The antenna design was done in CST STUDIO SUITE, adjusting different parameters that optimize its performance. There is also an analysis of the rectenna elements, and the equations needed to do it. For the rectifier section of the rectenna, the software ADVANCED DESIGN SYSTEM (ADS) was used, using a band-pass filter and a 3-stage Dickson voltage amplifier. These elements are essential to ensure an optimal and efficient performance of the rectenna that provides an extra voltage source for the subsystems of a nanosatellite.

Control of wind energy conversion systems with permanent magnet synchronous generator for isolated green hydrogen production

This paper addresses the design and analysis of the control system for a Wind Energy Conversion System (WECS) with a Permanent Magnet Synchronous Generator (PMSG) and its application for isolated green hydrogen production. The designed control maximizes the wind turbine (WT) power generation by regulating the electrolyzer current consumption, where the electrolyzer operates as a controlled load, ensuring power balance in the system and enabling the generation of maximum power from the WECS without the use of any energy storage system. The system involves directly integrating a WECS with an alkaline electrolyzer (AEL), and its configuration includes a WT with a PMSG, an AC/DC voltage source converter (VSC) acting as the generator side converter (GSC), and a DC/DC converter acting as the electrolyzer side converter (ESC) with Maximum Power Point Tracking (MPPT) control for the WT. The proposed control system has been fully modeled and tested through simulations in Matlab/Simulink, demonstrating its reliable performance under variable wind speeds. Simulation results illustrate how, over rated wind speeds, the pitch control limits the rotational speed and power to their maximum values, and at under rated wind speeds, the ESC control regulates the AEL current following the MPPT of the WT, while the GSC control maintains the DC bus voltage at its designated nominal value. Overall, the proposed control system shows robust and effective performance across the entire range of possible operational points, ensuring no wind generation power losses by following the maximum power point.

MEDIUM-POWER DRIVE INSTALLATIONS BASED ON TRIPLE VOLTAGE SOURCE INVERTERS ADJUSTED BY ALGORITHMS OF SYNCHRONOUS MULTI-ZONE PWM

This paper presents short overview of the development and dissemination of specialized schemes and algorithms of space-vector-based synchronous multi-zone pulsewidth modulation (MZ PWM) for control of triple inverters of the medium-power variable speed drives characterized by relatively low switching frequency of inverters. It insures providing synchronization and symmetry of the basic voltage waveforms in triple-inverter-based configurations of drive installations on the base of standard voltage source inverters (VSIs). It assures also minimization of magnitudes of even-order harmonics and undesirable subharmonics in spectra of the basic voltages of drive installations, leading to reducing of losses in the corresponding apparatuses and to increasing of its efficiency. Examples of application of the basic techniques of multi-zone PWM for regulation of three typical structures of triple-VSI-based medium-power motor drives are presented. Modeling and simulations give a behavior of drive installations based on triple inverters adjusted by algorithms of synchronous MZ PWM. References 12, figures 11, table 1.

Design of a High Frequency Stability Control Algorithm for Flexible DC Systems

Abstract The suppression scheme of flexible DC high-frequency oscillation needs to be based on model construction. Related literatures have established a high-order linearization model of converter station, gradually revealing the influence of control system and its parameters on impedance characteristics. In order to ensure the full utilization of renewable energy, it is necessary to deeply study the interaction characteristics between multi-terminal VSC-HVDC (Voltage Source Converter based High Voltage Direct Current Transmission) and the receiving power grid, and design a grid-friendly control strategy. In this paper, a VSC-HVDC high-frequency stability control algorithm is established, and a double-ended VSC-HVDC bidirectional VSC stable switching controller is constructed. The switching sequence generated by the controller replaces the control sequence generated by the previous PWM (Pulse width modulation) modulation, so as to weaken the influence of the inner loop current control parameters on the stable operation of the system. The simulation results show that the reactive power fluctuation amplitude of PI control on the inverter side is 0.031 p.u, and the stabilization time is 0.43s. The reactive power fluctuation amplitude of bidirectional VSC stable switching control is less than 0.012 p.u, and the stability time is less than 0.2s. When the single-phase grounding wire is short-circuited, the bidirectional VSC regulator switch has better control performance than the PI regulator switch. Compared with the traditional PI controller, the proposed controller has better stability. The system can quickly enter a stable and non-overshoot operation state, and achieved good control effect.

An Impulse Equivalent VSC Model for Large Power Grids Containing Multiple Converters

Abstract This paper explores the impulse equivalent method for constructing voltage source converter (VSC) model in large power grids containing multiple converters. It addresses the challenge of simulation cycle mismatch with device switching moments and proposes a cross-cycle correction method. The method enhances the VSC electromagnetic transient (EMT) simulation model, making it suitable for large-scale power grid simulations. The approach is validated through case studies, confirming its accuracy and computational efficiency for complex power electronic networks.

Sequence impedance modeling of grid-following LC-type voltage source converter

Sequence impedance modeling of grid-following LC-type voltage source converter

RLC resonator with diode nonlinearity: Bifurcation comparison of numerical predictions and circuit measurements

A nonlinear RLC resonator is investigated experimentally and numerically using bifurcation analysis. The nonlinearity is due to the parallel combination of a semiconductor rectifier diode and a fixed capacitor. The diode’s junction capacitance, diffusion capacitance, and DC current–voltage relation each contribute to the nonlinearity. The closely related RL-diode resonator has been of interest for many years since its demonstration of period-doubling cascades to chaos. In this study, a direct comparison is made of dynamical regime maps produced from simulations and circuit measurements. The maps show the variety of limit cycles, their bifurcations, and regions of chaos over the 2D parameter space of the source voltage’s frequency and amplitude. The similar structures of the simulated and experimental maps suggest that the diode models commonly used in circuit simulators (e.g., SPICE) work well in bifurcation analyses, successfully predicting complex and chaotic dynamics detected in the circuit. These results may be useful for applications of varactor-loaded split ring resonators.

An Output-Capacitorless LDO regulator with fast transient response and high PSRR

Abstract A fast transient response and high supply voltage rejection ratio (PSRR) output-capacitor-less low-dropout (OCL-LDO) regulator with a dual power transistor structure is proposed in this paper. The designed flip voltage follower (FVF) structure and the proposed back-gate control loop improve the transient performance of the system. The proposed PSRR enhancement circuit transmits the power supply voltage fluctuation 1:1 to the gate of the power transistor so that the influence of the power supply voltage fluctuation on the output voltage of the LDO is offset by the difference between the gate and source voltages of the power transistor. The simulated results have shown that the proposed OCL-LDO regulator achieves full range stability from 100 μA to 50 mA. The output voltage undershoot is reduced by more than 100 mV when the load current is stepped from 1 to 50 mA in 500 ns without the load capacitor. The PSRR enhancement circuit increases the PSRR of the LDO from 1 KHz to 10 MHz by more than 20 dB.