Four-wire System Research Articles

LABORATORY PLATFORM FOR DEMONSTRATING THE SYMMETRICAL COMPONENTS ȚUGULEA POWER THEORY APPLIED ON GRID MODELS WITH NEUTRAL CONDUCTOR

In the context of the ever-increasing complexity of modern power systems, optimizing consumers’ performance to improve electrical energy quality becomes paramount. This article thoroughly examines the power transfer effects in the context of distorting and non-symmetrical regimes in three-phase, four-wire power systems, focusing on heavily nonlinear and unbalanced consumer influence across the grid. Particular emphasis is placed on the impact of these regimes on the parasitic active and reactive powers affecting linear and balanced consumers due to distorting and unbalanced ones. An essential aspect of this analysis is including the neutral conductor in the experimental circuit, enhancing relevance and a more profound understanding of consumer interactions in modern networks. Quantitative aspects of the phenomena involved are assessed from the perspective offered by SCPT (introduced by Andrei Ţugulea), allowing us to identify the source of non-symmetry and residual powers through comprehensive power balance equations for the active and reactive powers.

Receiving-End Voltage Compensation Method with NPC-Inverter-Based Active Power Line Conditioner in Three-Phase Four-Wire Distribution Feeder

This study proposes a receiving-end voltage compensation method employing a phase-specific reactive power control strategy with a neutral-point-clamped (NPC) inverter in a three-phase four-wire distribution system. The principle of the proposed receiving end voltage compensation method is explained. Further, the proposed control strategy can solve the problems of the three-phase, four-wire distribution system, which are an increase in the neutral-line current and the unbalanced voltage. Computer simulation is performed to confirm the validity of the proposed method. The simulation results indicate the receiving-end voltages can be compensated using the proposed method.

ВИМІРЮВАННЯ ТА КОМПЕНСАЦІЯ НЕАКТИВНИХ ПОТУЖНОСТЕЙ ТРИФАЗНИХ СИСТЕМ ЕЛЕКТРОЖИВЛЕННЯ ЗАСОБАМИ ПАРАЛЕЛЬНОЇ АКТИВНОЇ ФІЛЬТРАЦІЇ

In this paper, the power theory of three-phase power supply systems was further developed by substantiating new formulas for calculating the unbalance power of three-phase four-wire power supply systems based on the measurement of active and reactive powers of individual phases, which can be used to form compensation signals in distributed active filtering with centralized control. A new structural scheme for controlling an autonomous shunt active filter with extended functionality and increased speed is proposed, which can be used in both three-wire and four-wire power supply systems. Computer modeling confirmed the adequacy of the new formulas for calculating the unbalance power components and the effectiveness of the proposed active filtering strategies to minimize power losses in the transmission line. References 11, figures 3, table 1.

APPLICATION OF A NEURONETWORK FOR DETERMINING THE TYPE OF ELEMENTS OF A SYMMETRICAL COMPENSATION DEVICE OF AN UNSYMMETRICAL SYSTEM WITH A ZERO WIRE

In article the possibility of using neural networks in the field of increasing the energy performance of a four-wire power supply system with an uneven load in the phases is being investigated. An uneven load in the phases causes asymmetry of currents in the network and contributes to the increase in the current in the neutral wire, which has an extremely negative effect on both the supply itself and its consumers. To eliminate asymmetry and reduce the current in the neutral wire, you can connect a symmetrical compensating device. Such a device is a set of reactive elements, the parameters of which are determined by search optimization. To determine the type of the required element, the defined parameters are recalculated. That is, the solution of such a problem consists of two component sub-problems – structural and parametric synthesis. This approach provides a high accuracy of calculations, but has a significant drawback: the calculations are cumbersome. In order to simplify the solution of the synthesis problem, it makes sense to determine the type of elements using neural networks, which will significantly reduce the time and resources spent on calculating the values of the parameters of the symmetrical compensating device. The subject of the article is the study of the possibility of using neural networks to predict the types of reactive elements of the symmetrical compensating device. During of the study, the parameters and type of neural network were determined, which provide the most accurate prediction of the topology of the structure of the symmetric-compensating device. The input parameters of the neural network were formed from sets consisting of eight parameters – resistances and inductances of the transmission lines and the neutral wire. The target matrix was formed from a set of data sets consisting of six elements containing information on the types of elements connected (0 – capacitor, 1 – inductance) between phases and between phases and the neutral wire. During research, the results of a quasi-solution were obtained, the values of which turned out to be commensurate with the accurate calculations for determining the structure of the symmetrical compensating device of the power supply system with a zero wire. This indicates the high quality of the developed neural network. Applying the minimax strategy to the received results provides an opportunity to reduce the received values to 0 and 1 to ensure clarity of the results obtained by the neural network.

A multifunctional inverter power quality coordinated optimization strategy based on comprehensive evaluation

The large-scale integration of renewable energy sources and power electronic devices has led to increasingly dispersed and networked characteristics of power quality disturbances in distribution systems. Traditional control devices, limited by their fixed-point control, no longer meet the development needs of modern distribution systems. Considering the distribution and structural characteristics of the current new-type sources and loads, a multifunctional inverter power quality coordinated control strategy based on comprehensive evaluation is proposed. This strategy aims to achieve power quality coordinated control by utilizing optimal compensation capacity while the grid-connected inverter provides active power output. Firstly, the traditional ipiq power quality detection method is analyzed and improved to enable detection of harmonics, reactive power, and three-phase imbalance currents in single-phase systems or three-phase four-wire systems. Secondly, in the power quality assessment, a balanced algorithm is employed to obtain the comprehensive evaluation index of power quality, thereby improving the deficiencies of single-weight evaluation. Next, to ensure the grid-connected inverter achieves optimal power quality coordinated control with minimal compensation capacity, an optimization compensation function is established between compensation capacity and comprehensive power quality index. This function is optimized using non-dominated sorting genetic algorithm to enhance equipment utilization and system economy. Finally, the feasibility and effectiveness of the proposed method are validated through simulations, demonstrating the achievement of optimal capacity configuration for power quality coordinated control while ensuring active power output by the grid-connected inverter.

Currents’-Physical-Component-Based Reactive Power Compensation Optimization in Three-Phase, Four-Wire Systems

In this paper, we aim to address the limited capacity of compensation devices by enhancing their utilization rate by applying the currents’ physical component (CPC) theory for reactive power optimization in three-phase four-wire systems. When reactive currents cannot be fully compensated for, we propose using CPC theory to generate reference currents for the compensation devices. Weight coefficients associated with different reactive current components are introduced, enabling flexible combinations of these independent current components. The maximum output amplitude of the three-phase current from the compensation device serves as a constraint condition, allowing for the calculation of reference currents under various compensation targets. Additionally, a reactive current optimization compensation scheme focusing on loss reduction is selected. The simulated annealing–particle swarm optimization (SA-PSO) hybrid algorithm is employed to solve the optimization mathematical model. The discussed calculations, current waveforms, and voltage waveforms are generated using the constructed mathematical model and then used for a theoretical explanation. The simulation verifies the feasibility of the proposed method.

Enhancing power quality with optimized PI controller in three-phase four-wire wind energy system

Enhancing power quality with optimized PI controller in three-phase four-wire wind energy system

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.

Description of a three-phase, four-wire system with a nonlinear receiver and an asymmetric voltage source using CPC power theory

This article mathematically describes a three-phase, four-wire circuit in the case of a nonlinear, unbalanced load, asymmetry of the power source with a periodic, non-sinusoidal waveform. This description uses Currents' Physical Components (CPC) power theory for three-phase circuits. Determining the energy flow between the source and the load is possible by decomposing the phase current into components depending on the physical nature of the phenomena in this circuit. Mathematical relationships were determined enabling decomposition into components depending on the direction of energy flow and the causes of their creation. A calculation example using the determined relationships and calculation results has been presented. The presented computational concept is important for mathematical analyzes in circuits with nonlinear three-phase receivers. Knowing the nature of physical phenomena, it is possible to perform measures that limit the value of the current supplying the load.

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.

Research and development of a virtual instrument for measurement, analysis and monitoring of the Power Quality

This paper is about the design of a power quality monitoring system based on LabVIEW for factory power quality defined in the IEEE Standard 1459-2010 [1] for single-phase, three phase three-wire and three-phase four-wire power systems [1] and [2]. With LabVIEW as development platform, composed by some functional modules such as data acquisition, data processing, data storage, and data report, etc. defined in International standards concerning electrical power quality Standard EN 50160 [3] and [4]. This system has advantages of better analyzed affection and low cost, and can be extended easily.

Control strategy to improve the power factor with a hybrid filter

Nowadays an electrical system must provide adequate electrical power quality so that it meets the international standards. To do this, this paper develops a control strategy for an active compensator based on a hybrid filter topology. This topology is formed by an active power filter of series connection and a passive filter of parallel connection. The proposed strategy is based on minimizing the rms value of the voltage at the point of common coupling so that the source transfers the power demanded by the load. Thus, the determination of the reference signal is posed as a constrained optimization problem. The strategy was proposed for four-wire systems and it allowed the compensation of current harmonics, reactive power and neutral current. Finally, a simulation platform in Matlab-Simulink was developed. This allowed the verification of the new strategy for different types of loads.

Neural-Networks and Synchronous Reference Frame Applied in the Harmonic Compensation with a Three-Phase Parallel Active Power Filter

This paper presents an alternative method based on artificial neural network, which is used to obtain the reference currents for harmonic current suppression and reactive power compensation in a shunt active power filter applied to three-phase four-wire system. The neural network consists of a multilayer perceptron, which is trained to estimate the peak amplitude of the load fundamental component currents. The performance of the proposed artificial neural network is evaluated by computer simulation, and it is compared with the method based on synchronous reference frame

Power Quality Improvement on 11kV/440V Distribution System using DSTATCOM

At the PCC and source side, current and voltage harmonics are compensated by utilizing a distribution static compensator. In this work, we also compensated for voltage control and reactive power correction. An improved reference current switching signal is suggested using a synchronous reference frame control technique. The analysis is done on an 11kV/440V three-phase four-wire unbalanced nonlinear load distribution system. The DC link voltage and harmonic reduction of the suggested distribution system performance is compared with the PI and fuzzy logic controllers. Harmonic distortion is reduced, and reactive power is successfully compensated with the suggested method. These simulation results are obtained by MATLAB/SIMULINK software.

Compensation of Voltage Unbalance and Current Harmonics with a Series Active Power Filter.

A combined system of shunt passive and series active filter for a four-wire three-phase system has been designed and simulated with Matlab/Simulink. The system combined mitigates the source current harmonics and compensates also unbalance voltages reducing the problems of using only a shunt passive filter. Therefore, a new control method based in the power vectorial theory has been proposed. The compensation principle is presented in detail. To verify the effectiveness of the proposed control, simulation results are presented and discussed.

Control strategies for active power filters

In this paper a comparison between strategies for extracting the three-phase reference currents for active power filters is shown. The performance of these strategies will be evaluated under different source and load conditions. The study has been applied to a three-phase four-wire system in order to include imbalance. It will be shown that under balanced and sinusoidal voltages, harmonic cancellation and reactive power compensation can be achieved by all the methods. However, when the voltages are distorted and/or unbalanced, the compensation capabilities are not equivalent. It will be proved that some strategies do not offer an adequate solution when the mains are not ideal, including harmonics or imbalance.

A Robust Backstepping Controller Based on Nonlinear Observer for Shunt Active Filters to Improve Power Quality in Four-Wire Distribution Systems

This article introduces a novel approach to enhance the performance of LCL based active power filters (APFs) in four-wire distribution systems by employing a nonlinear current control strategy. The strategy combines backstepping control (BSC) and a nonlinear disturbance observer (NDOB) to effectively manage harmonic and interharmonic grid currents. By situating the shunt active power filter (SAPF) at the point of common coupling (PCC) via the LCL filter, the technique ensures that grid connected currents remain balanced and purely sinusoidal. The integration of NDOB with BSC aims to fortify the resilience of BSC against disturbances. Consequently, any disturbances occurring within the system are precisely estimated by the NDOB and subsequently mitigated through the BSC mechanism. Notably, this approach showcases robust adaptability across diverse scenarios, encompassing external disturbances, variations in filter parameters, nonlinear loads laden with harmonics and interharmonics, load imbalances, and non-ideal grid voltages. Its performance remains robust and stable even when disturbances are present. Comparative analysis with linear-based methodologies underscores the advantages of this approach, revealing quicker and smoother transient responses. The efficacy of the proposed technique is demonstrated through comprehensive simulation studies, substantiating its potential for significantly advancing power quality in complex distribution systems.

Optimal Planning of Hybrid AC/DC Low-voltage Distribution Networks Considering DC Conversion of Three-phase Four-wire Low-voltage AC Systems

Optimal Planning of Hybrid AC/DC Low-voltage Distribution Networks Considering DC Conversion of Three-phase Four-wire Low-voltage AC Systems

Implementation of Passivity-based Control of Four-Leg Inverter for Transformerless Three-Phase Solar Photovoltaic Systems

This study explores the application of a passivity-based control technique (PBC) with an artificial neuro-fuzzy inference system (ANFIS) in a grid-connected Solar Photovoltaic (SPV) generating system for estimating reference grid currents. To optimise the tracking of the maximum power point (MPPT) between the solar photovoltaic (SPV) system and the DC bus, a DC – DC boost converter (BC) is utilised. This converter is connected to a four-leg, three-level neutral-point-clamped converter (4-leg 3L-NPC), interfaced with a three-phase, four-wire distribution system. The four-leg 4-leg 3L-NPC of the SPV generating system with Space vector pulse width modulation technique (SVPWM) is utilised for reducing common-mode voltage (CMV), leakage current (LC), reactive power for zero voltage regulation, power factor correction, load balancing, and the elimination of load harmonic currents in the proposed distribution system.The performance analysis of the proposed system is conducted on the Matlab/Simulink platform. Additionally, a comparative analysis is presented, contrasting the proposed system with a 3-phase 4-leg T-type neutral-point-clamped converter (TNPC) employing the PBC technique followed by ANFIS.