Point Voltage Research Articles

Design and Performance Evaluation of Fuzzy Controller based Energy Storage Enabled Statcom for Electrical Distribution Network

In order to fulfill the demand for power, the production of locally accessible resources, such as solar and wind energy, has increased dramatically during the past ten years. Their integration into the distribution of electrical network (EDN) has affected the operation of the network. Variations in the real power flow and an increase in reactive power demand have impacted the EDN voltage/frequency profiles and distribution transformer strain. Hence to improve the voltage regulation and reduce the active power fluctuations, there is a need for a system network of electrical distribution (EDN). It has the ability to support both reactive and active power. Thus, the energy storage device with STATCOM is introduced i.e. an energy storage device linked to Statcom (EsSt) has been proposed in this paper. The Common Coupling Point (CCP) voltage can be adjusted by energy storage connected to Statcom (EsSt) to satisfy the amount of power required actively at EDN. The EsSt has an integrated battery storage system and may be controlled using a voltage source converter by employing the proper control strategy to deliver the necessary energy support and VAR compensation. The voltage at the dc-link has been integrated using DC-DC converter based half bridge. The use of conventional PI controllers provides poor transient response. To improve the transient performance, It is suggested that a fuzzy logic controller be used in place of the PI controller. Analysis of comparison using MATLAB. The rule-based fuzzy logic controller performs better than the PI controller, according to the Simulink environment.

A unified SVPWM fault tolerant control algorithm for single leg fault reconstruction topology of two-level inverter

To improve the reliability of Two-level three phase voltage source inverters, a uniform fault tolerant strategy based on space vector pulse width modulation is proposed for different leg faults. The reconstructed topologies of inverters with different bridge arm faults are different, which makes the basic voltage vector phase of each reconstructed topology inconsistent, resulting in different calculations. Therefore, the coordinate transformation is applied to place the basic voltage vectors of each reconstructed topology on the synchronous stationary αβ coordinate system so that the calculations of the reconstructed topology under different bridge arm faults are unified, thus reducing the complexity of fault-tolerant control. Aiming at the three-phase current asymmetry caused by the neutral point voltage oscillation in inverter topology reconstruction, a transient compensation method of neutral point voltage offset for the α-axis component of the reference voltage vector is introduced to suppress the adverse effects. The compensation method directly offers a neutral point voltage offset value after Clarke transformation and corrects the α-axis component of the reference voltage vector, avoiding the integral calculation in the conventional voltage compensation algorithm. The correctness and effectiveness of the proposed fault-tolerant control strategy are verified experimentally.

Global Maximum Power Point Tracking of Photovoltaic Module Arrays Based on an Improved Intelligent Bat Algorithm

In this paper, a method based on an improved intelligent bat algorithm (IIBA) in cooperation with a voltage and current sensor was applied in maximum power point tracking (MPPT) for a photovoltaic module array (PVMA), where the power generation performance of a PVMA was enhanced. Due to the partial shading of the PVMA from climate changes or the surrounding environment, multiple peak values were generated on the power–voltage (P-V) curve, where the conventional MPPT technology could only track the local maximum power point (LMPP), hence the reduction in output power of PVMAs. Therefore, the IIBA-based MPPT was proposed in this paper to solve such issues and to ensure the capability of a PVMA in tracking the global maximum power point (GMPP) and utilization for enhancing the output power of a PVMA. Firstly, the Matlab/Simulink software was used to establish a boost converter model that simulated the actual 4-series–3-parallel PVMA under different shaded conditions, where the P-V curve with 1-peak, 2-peak, 3-peak and 4-peak values were generated. Subsequently, the tracking paces of the conventional bat algorithm (BA) were adjusted according to the gradient of the P-V curve for a PVMA. At the same time, 0.8 times the maximum power point (MPP) voltage Vmp under standard test conditions (STCs) for a PVMA was set as the initial tracking voltage. Lastly, the simulation results proved that under different environmental impacts, the proposed IIBA led to better performances in tracking both dynamic and steady responses.

Collaborative Control of Reactive Power and Voltage in a Coupled System Considering the Available Reactive Power Margin

This article proposes a hierarchical collaborative reactive power and voltage control method aimed at meeting the internal voltage requirements of a coupled system composed of centralized new energy stations such as wind and solar power and traditional thermal power units, with particular attention paid to the reactive power regulation ability of power units in new energy stations. This method is implemented in two layers: At the transmission layer, the overall reactive power compensation capacity of thermal power units and stations on the transmission lines within the system is determined according to the engineering requirements of different node voltages in the coupled system, the regulation voltages of the high-voltage grid-connected points and the point of common coupling (PCC) of the stations are found, and the actual regulation voltages of the PCCs of the stations are given as commands. At the station layer, based on determining reactive power distribution between power units and continuous reactive power compensation devices within each station, voltage optimization is carried out using the voltage command issued by the transmission layer as a reference. At the same time, consistency coordination between the transmission layer and the station layer is achieved based on the Analytical Target Cascading (ATC) method at different layers. Finally, simulation analysis was conducted on a regional coupled system in Dalian. The results showed that the method proposed in this paper can effectively control the voltage safety requirements of each region and PCC in the coupled system and, to some extent, improve the economic efficiency of system operation.

Optimized low switching frequency modulation with neutral point voltage control for three-level converters

Optimized low switching frequency modulation with neutral point voltage control for three-level converters

A new framework for improving MPPT algorithms through search space reduction

In this article, a novel framework for improving maximum power point tracking (MPPT) is presented. A robust initialization of the MPPT algorithm is implemented, and the search space is reduced by rapidly predicting the maximum power point (MPP) voltage. In order to accomplish this, unknown parameters required to establish an empirical irradiance-free relationship between the open circuit voltage and MPP voltage were derived using three most prevalent PV panel models. The P&O MPPT algorithm implements this framework, which establishes a systematic boundary to confine the MPP voltage to a reduced search space by virtue of this relationship. The evaluations performed on three distinct varieties of commercial PV panels demonstrated that the PV panels modeled in this study exhibit a high degree of conformity with the data provided by the manufacturers. Furthermore, the estimation of MPP voltage allows for a reduction of the search space by as much as 2% of its initial area. The efficacy of the proposed MPPT algorithm is found to be 96.64%, higher than that of the P&O and other implemented contemporary algorithms, when evaluated against a common platform and rapidly changing climatic conditions. Real-world climatic experiments are performed in order to assess the feasibility of the established research. The experimental results indicate that the established irradiance-free MPP voltage has a mean error of merely 0.0128V. Furthermore, the combined output power generated by the MPPT proposed algorithm under experimental conditions is comparatively superior in performance.

An Algorithm for a Space-Vector Pulse Width Modulation with a Hybrid Switching Sequence for a Three-Level Neutral Point Clamped Voltage Source Inverter

This paper proposes a new algorithm for a space-vector pulse width modulation (SVPWM) with a hybrid switching sequence (SS) designed to control a three-level (3L) neutral point clamped (NPC) voltage source inverter (VSI). Based on the advantages of five-stage and seven-stage SS, we designed a hybrid SS to improve four key parameters in the system: inverter output current quality, neutral point (NP) and common-mode (CM) voltage levels, and switching losses of power switches. The proposed algorithm flexibly regulates meeting the four criteria depending on the system operating conditions by changing the regulation coefficient. The paper obtained an approximate dependence to determine the optimal regulation coefficient for any values of the inverter modulation coefficient when operating jointly with an active-inductive load. The effectiveness of the proposed algorithm is confirmed by computer simulation in the MatLab+Simulink environment, as well as the results of experimental studies. The paper presents the experimental dependences of static state spaces, including the distortion coefficient of higher current harmonics at the inverter output, the maximum error of the NP voltage, the number of switching pairs of power switches, and the pulse duty factor of CM voltage, depending on the inverter modulation coefficient and the regulation coefficient of the hybrid SS. The results showed that in the algorithm for a SVPWM with a hybrid SS, the number of switchings of power switches is reduced by an average of 13.5 % while maintaining the NP voltage balance and the quality of the curve at the inverter output at an acceptable level, close to a seven-stage SS (the deviations do not exceed 0.5 % and 0.2 %, respectively). The average CM voltage coefficient decreased by no more than 4.5 %. The indicators improve the energy saving, the weight-size parameters, and the operational reliability of the 3L NPC VSI. The application area of the algorithm is much wider and includes the control of power switches of active front ends, grid converters for electricity storage systems, active power filters, and power conditioners. DOI: https://doi.org/10.52783/pst.237

Analysis of a Grid-Tie Solar Power System for Efficient Transition between Grid-Connected Modes

Abstract: Solar Photo Voltaic (PV)-battery energy storage based micro-grid with a multifunctional Voltage Source Converter (VSC) is presented in this research paper. Whenever the grid fails, this system operates in SA mode automatically, thereby without causing any interruption in supplying the load. Similarly, it automatically shifts to the GC mode, when the grid is restored. The VSC functions in current control for GC mode, and it operates in voltage control for SA mode of operation. This system is capable of extracting the maximum power from the solar PV array irrespective it is operating in the GC mode or SA mode. It regulates the dc-link voltage to the maximum power point voltage of the PV array. If the absence of the battery is detected, then the control is automatically shifted to VSC for performing the extraction of the maximum power of the PV array

Enhancing Power Quality with PDO-FOPID Controller in Unified Power Quality Conditioner for Grid-Connected Hybrid Renewables

Addressing the pressing research problem of power fluctuations and grid harmonics in the integration of renewable energy, our proposed control strategy utilizes the Prairie Dog Optimization Fractional Order Proportional Integral Derivative (PDO-FOPID) controller within a Unified Power Quality Conditioner (UPQC) system. This innovative approach is tailored to mitigate harmonics and meet load requirements in grid-connected hybrid renewables. The UPQC system is instrumental in regulating coupling point voltage, countering voltage and current harmonics to enhance overall power quality. The PDO-FOPID controller dynamically adapts control parameters to system dynamics and load changes, ensuring a stable power supply despite the variability of renewable sources. Simulations in MATLAB/ Simulink confirm its superiority over traditional control strategies, such as PI, sliding mode, and fuzzy control, in harmonics mitigation, load fulfilment, and power stability. By effectively addressing these challenges, our proposed solution not only contributes to resolving a critical research problem but also advances the seamless integration of Hybrid Renewable Energy Sources (HRES) into power systems, thereby enhancing overall grid performance and the efficacy of renewable energy integration.

Dual-Mode Graphene Field-Effect Transistor Biosensor with Isothermal Nucleic Acid Amplification.

Despite a substantial increase in testing facilities during the pandemic, access remains a major obstacle, particularly in low-resource and remote areas. This constraint emphasizes the need for high-throughput potential point-of-care diagnostic tools in environments with limited resources. Loop-mediated isothermal amplification (LAMP) is a promising technique, but improvements in sensitivity are needed for accurate detection, especially in scenarios where the virus is present in low quantities. To achieve this objective, we present a highly sensitive detection approach of a dual-mode graphene-based field-effect transistor (G-FET) biosensor with LAMP. The G-FET biosensor, which has a transparent graphene microelectrode array on a glass substrate, detects LAMP products in less than 30 min using both observable color changes and Dirac point voltage measurements, even in samples with low viral concentrations. This dual-mode G-FET biosensor emerges as a potential alternative to conventional RT-PCR for severe acute respiratory syndrome-associated coronavirus (SARS-CoV)-2 detection or point-of-care testing, particularly in resource-constrained scenarios such as developing countries. Moreover, its capacity for colorimetric detection with the naked eye enhances its applicability in diverse settings.

Comprehensive Analysis of Vienna Rectifiers for Renewable Resources

The issue of energy has emerged as a significant subject of concern in contemporary discourse. The significance of the advancement of novel energy sources is progressively growing. Relevant strategies should aid in the advancement of power electronics. The rectifier is a commonly used electronic component that finds application in many circuits involving electronic equipment. Its primary function is to convert alternating current into direct current, which is then supplied to the load. The Vienna rectifier is a widely used rectifier that has garnered significant attention and scrutiny from professionals in the field of power electronics on a global scale. This article begins by illustrating the use of power electronics technology, specifically focusing on the charging pile circuit. It proceeds to discuss the classification and current research status of rectifiers. Subsequently, the article provides an overview of the circuit layout and operational principles of the Vienna rectifier circuit. This section provides an overview of the approaches and features used to optimize the operating performance of Vienna rectifiers in four key areas: current control, voltage control, neutral point voltage balance management, and harmonic stability control. This research will ultimately provide a forecast about the future development trend of Vienna rectifiers, together with a comprehensive overview of all improvement attempts.

Millman’s Theorem revisited

In this work we present some results bearing on Millman’s Network Theorem (MNT for short) with a specific focus towards its application to three phase power systems. First we present an original, insightful proof of the Theorem that simultaneously provides the foundation for the Universal Single Phase Equivalent Circuit (USPEC) framework. Next we introduce two modifications that generalise the standard MNT and render it better adapted to the analysis of three-phase power circuits. The first result is a vectorised version based on the USPEC method which allows a very concise calculation of load voltages and the second is aimed at the calculation of neutral point voltage unbalances in more general power circuits. We illustrate the practical application of these results with the help of several commented examples and besides we provide the Matlab/Octave scripts used to perform the analyses

New Space-vector hysteresis current control with neutral point voltage balancing applied on three-level VSI for wind power conversion

This paper presents a new space-vector hysteresis current control (SV-HCC) with neutral point voltage balancing applied on a three-level NPC-VSI. The last supplies a rotor winding of the doubly fed induction generator (DFIG). The proposed control technique controls the power delivered from the wind generator to the electrical network by controlling the rotor currents of the DFIG. It is based firstly on the detection of area and sector in which the error vector tip of the rotor current can be located, secondly, on the neutral voltage sensing. And then on the application of an appropriate voltage vector among the 27 voltage vectors of the three-level NPC-VSI to accomplish two main goals: 1- Controlling the active and reactive powers delivered by the wind generator to the electrical network. 2- Balancing the neutral point voltage of the three-level VSI.

Improved virtual space vector modulation for neutral point voltage oscillation and common-mode voltage reduction in neutral point clamped three-level inverter

Improved virtual space vector modulation for neutral point voltage oscillation and common-mode voltage reduction in neutral point clamped three-level inverter

Optimal Connection Voltage of Soft Open Point and Shore-to-Ship Power Converters for Enhanced Capacitive Reactive Power Operation

Optimal Connection Voltage of Soft Open Point and Shore-to-Ship Power Converters for Enhanced Capacitive Reactive Power Operation

Minimization of Common Mode Voltage and Capacitor Voltage Unbalance of 3-Phase 4-Wire 3-Level NPC inverter using 4D-SVM

This paper elucidates the implementation of Four-dimensional Space Vector Modulation (4D-SVM) for reduction of Common Mode Voltage (CMV) and Capacitor Voltage Unbalance (CVU) of 3-phase 4-wire 3-level Neutral Point Clamped inverter (3L-NPCI). CMV and CVU are major drawbacks of neutral point clamped inverter circuit; It leads to affect the performance of inverter in terms of bearing failure, unequal voltage stress across various switching devices, the magnitude of load current increases, increases in total harmonic distortion (THD), tripping of ground fault relays and malfunction of various sensitive electronics and control unit. The 4D-SVM algorithm is developed to reduce the CMV and CVU; with help of the nearest state vector (NSV) control method CMV range is reduced and by proper utilization of large and small vector capacitor voltage unbalance is minimized. 4D-SVM for 3-phase 4-wire 3-level includes 81 switching state vectors with a non-redundant switching concept. This algorithm is implemented without using any trigonometric equations, lookup tables, and angle determinations. This proposed system provides a comprehensive analysis of 4D-SVM for reduction of CMV range and CVU for the 3L-NPCI system. The minimization of CMV and CVU is achieved using MatLab-Simulink and FPGA processor for simulation and experimental results respectively.

Impact of gate electrode on free chlorine sensing performance in solution-gated graphene field-effect transistors.

Free chlorine is widely used to disinfect water used for drinking and food processing. This requires highly sensitive, simple, and capable continuous-measurement sensors to enable the concentration of free chlorine in water to be monitored and controlled. Free chlorine sensors based on solution-gated graphene field-effect transistors (GFETs) are a suitable platform for highly sensitive and continuous measurements. However, their sensing mechanisms require further elucidation to improve their performance. In this study, we focused on the gate electrode and investigated its influence on the sensing performance. Using the free chlorine sensor based on the solution-gate GFET, we showed that the Dirac point voltage in the transfer curve changed significantly as the free chlorine concentration changed, and the electric double-layer capacitance of the gate electrode decreased. Furthermore, we demonstrated that a solution-gated GFET using graphene or boron-doped diamond as the gate electrode could be used to detect changes in the free chlorine concentration in the concentration range of tap water. The sensing performance in the low concentration range benefits from the wide potential window of carbon-based electrodes, which do not have electrochemically active sites. Using these carbon-based materials as gate electrodes, GFETs have the potential to be used as durable sensors that are resistant to surface fouling and oxidation.

A Modulation Strategy to Operate Five-Level HC Inverter at Wide Power Factors With Enhanced Neutral Point Voltage Balancing Capability

A Modulation Strategy to Operate Five-Level HC Inverter at Wide Power Factors With Enhanced Neutral Point Voltage Balancing Capability

A parallel input parallel output current fed front end DC‐DC converter‐based solid state transformer utilised in grid connected mode PV applications

AbstractThe presented work operated a PIPO Current fed front end converter‐based solid‐state transformer (SST) for maximum power point tracking (MPPT) and voltage boost operation in medium power range PV applications. The proposed system employed the perturb and observe (P&O)‐based MPPT technique and upheld the ZVS and ZCS operations of all primary side switches and secondary side rectifier diodes, respectively. The proposed system introduced a new fundamental extractor titled ‘Pre‐filter double fundamental signal extractor (DFSE) based multi‐layered DFSE (p‐DFSE‐MDFSE)’ and utilised it in the grid controller for synchronisation and harmonics mitigation operation. The primary goal was to achieve a compact size, reduced weight and cheaper magnetic component‐based front‐end converter of SST on the PV array side and a fast, secure and trustworthy mitigation control of current harmonics on the utility grid side. The proposed system was inspected on the OPAL‐RT (RT‐LABv2021.3.2.307) platform for various grid anomalies, and its conduct was found to be well within the IEEE 519 norms.

Modeling of graphene photodetector based on photogating effect for circuits simulation

Abstract Graphene photodetectors based on the photogating effect offer the advantages of high responsivity. However, physical model of these photodetectors which is suitable for circuit design are still missing at present time. This paper aims to develop a physical model of the detector by introducing a ‘virtual back-gate’ method, which translates incident optical power into the Dirac point voltage of the transfer curve. Additionally, a physical model of the detector is established by combining the ‘virtual back-gate’ and ‘photo-gate’. To investigate the relationship between input optical power and photocurrent, a detector PSPICE model is developed using the gate-controlled current sources realized through the ‘virtual back-gate’ and ‘photo-gate’. A capacitive transimpedance amplifier circuit is employed for simulation verification. The research presented in this paper serves as a valuable reference for the circuit design of two-dimensional material photodetectors based on the photogating effect.