Three-Phase Four-Wire Research Articles

A New Design and Implementation of a Three-Phase Four-Wire Shunt Active Power Filter for Mitigating Harmonic Problems caused by Compact Fluorescent Lamps

A New Design and Implementation of a Three-Phase Four-Wire Shunt Active Power Filter for Mitigating Harmonic Problems caused by Compact Fluorescent Lamps

Small-Signal Stability Analysis of Three-Phase Four-Wire System Integrated With Single-Phase PV Inverters Considering Phase to Phase Coupling

Small-Signal Stability Analysis of Three-Phase Four-Wire System Integrated With Single-Phase PV Inverters Considering Phase to Phase Coupling

Budeanu’s Distortion Power Components Based on CPC Theory in Three-Phase Four-Wire Systems Supplied by Symmetrical Nonsinusoidal Voltage Waveforms

Budeanu’s power theory, in its fundamental version, describes single-phase sinusoidal and nonsinusoidal systems. Over time, this elementary description has been extended to three-phase three-wire and four-wire systems, regardless of power conditions. Initially, three-phase systems were considered as three independent single-phase systems. A distinct approach was introduced by Czarnecki in his power theory (Currents’ Physical Components—CPC). The energy description and reference of the equivalent parameters of the load are comprehensive in the context of three-phase systems; Czarnecki treats such systems as a whole. This paper introduces a mathematical model to expand the basic Budeanu theory for three-phase four-wire (3-p 4-w) systems powered by symmetrical and nonsinusoidal voltage sources. The proposed approach is based on mutual elements between the fundamental Budeanu theory and the CPC theory, treating the 3-p 4-w system as a whole. In the extended Budeanu theory model, equations for the Budeanu reactive current and the Budeanu complemented reactive current are derived. The article also demonstrates their orthogonality concerning the remaining components, indicating that each of the seven components can exist independently of the others. Furthermore, in the extended Budeanu theory, it is possible to identify which equivalent parameters of the load are responsible for the individual currents (powers) and which components are associated with the total distortion power proposed by Budeanu in 1927. All of the calculations were performed in Matlab/Simulink 2023b software.

A Novel Three-Dimensional Sigma–Delta Modulation for High-Switching-Frequency Three-Phase Four-Wire Active Power Filters

This article presents a new modulation technique called three-dimensional sigma–delta (3D-ΣΔ) modulation for high-frequency three-leg four-wire voltage source converters (VSCs) that use wide-bandgap (WBG) semiconductors. These WBG devices allow for the use of high switching frequencies with a greater efficiency than silicon devices. The proposed 3D-ΣΔ technique enables operation at a variable switching frequency, resulting in a significant reduction in switching losses compared to classical pulse-width modulation (PWM) techniques. Moreover, the 3D-ΣΔ technique uses a fast-processing 3D quantiser that simplifies implementation and considerably reduces computational costs. The behaviour of the 3D-ΣΔ modulation is analysed using MATLAB/Simulink and PLECS. The experimental results performed on an active power filter that uses silicon carbide (SiC) MOSFETs demonstrate an improvement in converter efficiency compared to the conventional SPWM technique. Additionally, the experimental results show how 3D-ΣΔ allows for the compensation of harmonics and homopolar currents, thereby balancing the electrical grid currents. The experiments also show that the proposed 3D-ΣΔ modulation outperforms an SPWM technique in terms of power quality, since the former achieves a larger reduction in the harmonic content of the power grid. In conclusion, the proposed modulation technique is an attractive option for improving the performance of four-wire converters in active power filter applications.

Three-phase four wire shunt active power filter based on Simplified Backstepping technique for DC voltage control

This work presents a simulation of Three-Phase Four-Wire Shunt Active Power Filter (SAPF) destined to suppress harmonic currents generated by nonlinear loads. The SAPF guarantee also the compensation for unbalanced nonlinear load currents, reactive power and harmonic neutral current. The identification method is based on the synchronous reference frame. In order to have good performances of DC voltage control, simplified Backstepping control for three-Phase four-Wire (SAPF) system is proposed. Complete simulation of the resultant active filtering system validates the efficiency of the proposed simplified Backstepping control law over to the traditional control with PI controller.

Improved Structure for Three-Phase Four-Wires Hybrid Active Power Filters

This paper presents a novel three-phase four-wire low power rating flexible hybrid active filter with a power factor, harmonic and neutral currents capability for distribution systems. The passive filter is tuned to compensate the two largest harmonics components and the power factor of the load. A selective algorithm is employed in order to enable the active filter to compensate only the desirable harmonic components. Simulation results are presented in order to verify the performance of the proposed hybrid filter.

Three-Phase Four-Wire Transformerless Unified Power Quality Conditioner Based on AC-DC-AC Nine-Leg Converter and Shunt Converter

Three-Phase Four-Wire Transformerless Unified Power Quality Conditioner Based on AC-DC-AC Nine-Leg Converter and Shunt Converter

Analysis and Design of SiC Three-Phase Four-Wire Five-Level E-Type STATCOM Inverter

Analysis and Design of SiC Three-Phase Four-Wire Five-Level E-Type STATCOM Inverter

State-Space Averaged Model of Three-Phase Four-Wire Shunt Active Power Filter Based on Current-Controlled VSI

This work presents a universal state-space average model of three-phase four-wire shunt active power filter based on current-controlled voltage-source inverters. In this type of inverters two topologies are commonly used, namely the Four-Leg Full-Bridge (FLFB) topology, and the Three-Leg Split-Capacitor (TLSC) topology. Combining these topologies, a third topology can be obtained, namely the Four-Leg Split-Capacitor (FLSC) topology. This last topology exhibits very interesting characteristics for active filter applications. By means study of FLSC topology a state-space average model can be obtained, which will allow long-time simulations with a low cost of computation time. The behaviour of FLFB and TLSC converters can be obtained as particular cases of this universal model. Likewise, a generic technique for injected current control is proposed, offering as main advantage a decoupled control of the different legs, so full-bridge converters can be implemented without using space-vector based current control techniques.

Analysis of the Mechanism and Control of the Unbalanced Operation of Three-Phase Four-Wire Inverters

In this paper, a solution is proposed to the problem of the unequal phase imbalance of output voltage caused by a three-phase, four-wire, split capacitor inverter when the load is unbalanced. First, the triple-loop control strategy was used to solve the unequal amplitude problem. This method used the feedforward + feedback composite control strategy on the inductor current inner-loop and voltage mid-loop to decrease the disturbance of the power and load. And the Root Mean Square (RMS) of voltage on the outer-loop completed the control of amplitude for the three-phase voltage. Second, to solve the imbalanced phase problem, the imbalance operation mechanism of the three-phase four-wire inverter was analyzed. It is known from the analysis that the phase imbalance is related to the DC-side splitting capacitance. The function relations between the DC-side capacitance and phase angle between each phase was simulated by MATLAB. But, it was too complicated to calculate the magnitude of the capacitance value through the functional relationship. In order to simplify the design of the DC-side splitting capacitor, the relations among the imbalanced current, the voltage fluctuations of the DC-side capacitor and the harmonics of load voltage were analyzed. In addition, by following the requirement of the national standard about the harmonics of load voltage, a DC-side capacitor design was mentioned to decrease the influence of imbalanced phase. Finally, simulation and experimental results show that the three-phase load voltage is stable, the THD value is less than 3%, and three-phase voltage unbalance is less than 2%, thus verifying the effectiveness of the proposed DC-side split capacitor design and control strategy.

D-Q Impedance Modeling and Stability Analysis of a Three-Phase Four-Wire System With Single-Phase Loads

D-Q Impedance Modeling and Stability Analysis of a Three-Phase Four-Wire System With Single-Phase Loads

Research into a Method of Forming Neutral Point Voltage in a Three-Phase Four-Wire Voltage Inverter

Three-phase four-wire voltage inverters are commonly used in energy complexes based on distributed generation sources (solar panels, wind power plants, hydrogen fuel cells) and accumulator batteries. They allow to power loads, including single-phase ones, which require neutral point connection. In these cases, phase voltage formed by spatial pulse-width modulation (PWM) methods considerably differs from sinusoidal waves and has high total harmonic distortions of voltage and current curves. This article is devoted to research into the authors’ control method of a three-phase four-wire inverter, allowing for the rectification of the form of phase voltage supplying the load when applying the most common PWM (SVPWM, DPWMMIN, DPWMMAX, GDPWM) methods. The description of the method and its research results by simulation modeling and test bench are presented in the article. The simulation modeling was carried out by the developed Simulink-model of the three-phase four-wire inverter and its control system. The modeling results showed that the method application ensures sinusoidal voltage form when applying any PWM method. At this, THDU was reduced from 21.56% to 4.39%, while THDI was reduced from 21.16% to 1.69%. Experimental tests were carried out by a test bench featuring an uninterruptible power supply source. The authors researched the inverter operation as a component of the test bench under the control of the proposed method to form neutral point voltage. The experimental test results coincided with the simulation modeling results.

Oscillation Suppression Strategy of Three-Phase Four-Wire Grid-Connected Inverter in Weak Power Grid

As the penetration of renewable energy increases year by year, the risk of high-frequency oscillation instability increases when a three-phase, four-wire split capacitor inverter (TFSCI) is connected to the grid with complementary capacitors in weak grids. Compared to the three-phase, three-wire inverter, the TFSCI has an additional zero-sequence current loop. To improve the accuracy of the modeling and stability analysis, the effect of the zero-sequence loop needs to be considered in the impedance-based stability analysis. Therefore, a correlation model considering multi-perturbation variables is first established, based on which the inverter positive, negative, and zero sequence admittance models are derived, solving the difficult problem of impedance modeling under small perturbations. Secondly, an admittance remodeling strategy based on a negative third-order differential element and a second-order generalized integrator (SOGI) damping controller is proposed, which can improve the stability of positive, negative, and zero-sequence systems simultaneously. Finally, the effectiveness of the oscillation suppression strategy is verified by simulation and experiment.

Modelling of Bidirectional Three-Phase Four-Wire Three-Level NPC MLC under Single-Loop Current Sensorless Control

Single-loop current sensorless control allows for abolishing of the instantaneous current measurement in the control system using only a single control loop with voltage feedback to stabilise the DC-bus voltage. This approach eliminates current sensors in the control circuit, benefiting from saving space on the printed circuit board and minimising power dissipation in the current measurement circuitry. This paper focuses on the single-loop current sensorless control applied to bidirectional three-phase four-wire three-level NPC MLC by simulation analysis and demonstrates the performance of the proposed current control algorithm in the rectifier and inverter modes and the step response with power direction change and grid-voltage change. In capacitor voltage balancing, an additional controller is applied, which is capable of compensating for the voltage asymmetry caused by adding a 2.5 kOhm resistor in parallel to one of the DC-bus capacitors. Our results demonstrate good performance of the proposed control method both in the inverter and rectifier modes, showing stable current shape in the low power and full power modes with acceptable harmonics content, meeting the requirements of the IEC 61000-3-2 standard for Class A devices. The analysis showed that the proposed control approach is suitable for industrial application.

Adaptive Interval Type II Fuzzy Logic Controller with Interface Inductor Bank Pulse Generator Based Three-Phase Four-Wire DSTATCOM Device for Power Quality Improvement

It goes without saying that the electrical distribution system is facing many power-quality issues these days. The main cause of these issues is the wide spread of nonlinear load integrated with the electrical distribution system. Moreover, the DSTATCOM device with interface inductor has different control algorithms. These encompass proportional integral controller, Interval type I fuzzy logic and interval type II fuzzy logic along used for improving the power quality issues. Before integration with the electrical distribution grid, these controllers need the tune processing. The combination of DSTATCOM with the load, which is different from the tuned one, and the wrong selection of the interface inductor leads to the failure of DSTATCOM device in the mitigation of source current harmonics. This study suggests that the use of adaptive interval type II fuzzy logic with the interface bank pulse generator based DSTATCOM device with self-tunning process and self-selection of the interface inductor would be suitable for all load types integrated into the distribution system within the rated power of DSTATCOM device. The adaptive interval type II fuzzy logic with the interface bank pulse generator based DSTATCOM device mitigates the source current harmonics and gives fast DC capacitor bus voltage response. Employing the suggested control algorithm based DSATCOM device makes the DC capacitor voltage signal settling time at almost 50 ms and total harmonic distortion of the source current at almost 4% for all cases of the load connected with the distribution system within the rated power of DSTATCOM device.

A Novel Continuous Control Set Model Predictive Control for LC-Filtered Three-Phase Four-Wire Three-Level Voltage-Source Inverter

In this article, a novel continuous control set model predictive control (CCS–MPC) is proposed for an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -filtered three-phase three-level four-wire voltage-source inverter (3P-4W-3L-VSI). The proposed MPC algorithm provides independent control of each phase of the 3P-4W-3L-VSI under various unbalanced load conditions, which shows superior performance under unbalanced loads. Furthermore, different from conventional MPC methods, the CCS–MPC achieves fixed switching frequency, hence simplifying the design of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> filters. In addition, dc offsets are introduced to the proposed modulation to effectively balance the neutral-point voltage of the 3P-4W-3L-VSI. Experimental results are presented to verify the effectiveness of the proposed MPC algorithm.

Power Sharing in Three-Level NPC Inverter Based Three-Phase Four-Wire Islanding Microgrids With Unbalanced Loads

The droop-based control schemes are widely used for power-sharing and control of the isolated microgrids. The conventional droop control scheme with inner current and voltage controllers can work effectively under ideal voltage. However, the existence of unbalance tends its performance to worsen. This paper aims to propose an enhanced droop control method to improve the power-sharing, and maintain the distributed generators’ (DGs) terminal voltages and the system frequency under the balanced as well as unbalanced loads. The enhancements of the proposed control scheme include the droop controller, inner current and voltage controller, and virtual impedance loop. The proposed virtual impedance deals with the accurate sharing of powers in the case of unequal line impedance and the control of zero sequence current. Moreover, to enable the proposed control to compensate for the unbalance, three-level neutral point clamped (NPC) inverters are used to form a three-phase four-wire microgrid. With this control scheme, the voltage unbalance factors (VUFs) of the DGs’ terminal voltages are reduced from 4% to less than 1%, negative sequence reactive powers, which are also an indication of unbalance, have been reduced significantly, and the system frequency is maintained within the standard permissible limit of 2.5%. Furthermore, a local load controller is also proposed to control the reactive loading of the DGs when they have local loads supplied from their terminals. The investigations have been carried out under simulation as well as lab-based environments to validate the efficacy of the proposed control method.

Reduced Reference Frame Transformation Assessment in Unbalanced Three-Phase Four-Wire Systems

Three-phase four-wire systems require a reference frame similar to that used in 3-phase 3-wire system configurations that allow them to be easily analysed, modelled and controlled. A new reference frame called Reduced Reference Frame (RRF) was presented by the authors in a previous work to satisfy these objectives. This is based on the locus of the voltage space vector which is used to perform a transformation applied to 3-phase 4-wire systems. This paper uses the proposed RRF to demonstrate the benefits of this transformation under different conditions of load or voltage imbalance. To this end, the different types of imbalances considered are studied by comparing the results in the classical αβγ axes, the so-called <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mno</i> -transform specifically developed for 3-phase 4-wire systems and the RRF coordinates. In addition, a theoretical identification of some types of imbalances is done comparing the simulation results and the fundamentals of the RRF.

A Stability Quantitative Analysis Method of Three-Phase Four-Wire Grid-Connected Systems Considering Frequency Coupling and Sequence Components Coupling

A Stability Quantitative Analysis Method of Three-Phase Four-Wire Grid-Connected Systems Considering Frequency Coupling and Sequence Components Coupling

Small-Signal Stability Analysis of Three-Phase Four-Wire System Integrated With Single-Phase PV Inverters Considering Phase to Phase Coupling Effect Under Asymmetric Grid

Small-Signal Stability Analysis of Three-Phase Four-Wire System Integrated With Single-Phase PV Inverters Considering Phase to Phase Coupling Effect Under Asymmetric Grid