Harmonic Compensation Research Articles

Influence of Background Voltage Distortion on Operation of Passive Harmonic Compensation Devices

This paper discusses the issues of assessing the influence of external distortion sources on the functioning of a shunt passive harmonic filter. In this study, we evaluated the overload of a passive harmonic filter based on determining the contributions of distortion sources. A method was proposed for assessing the contributions of distortion sources, which allowed us, regardless of background distortions, to determine the contributions of consumer loads, as well as the contribution of background distortions. The simulation was carried out using the Simulink MatLab software (version R2023a). Several scenarios were considered in which the following values were varied: supply feeder impedance, level of background distortions, consumer electrical load composition, and passive filter parameters. It was found that the contribution of the background distortion source decreases with increasing impedance of the supply grid. It was determined that the consumer load contribution is independent of background voltage harmonics and can be used to estimate the overload of a passive harmonic filter. It was shown that it is necessary to take into account the overload of the passive filter by currents from background distortion sources, which did not exceed 135% of the rated rms current for the conditions under consideration. A mathematical model was proposed to estimate the overload of a passive filter in the presence of background voltage distortions. This model was obtained during analytical studies and allows one to evaluate the overload of a passive filter, taking into account the short circuit ratio, detuning frequency and power of the passive filter, and the share contribution of background distortion sources.

A Direct Adaptive Controller With Harmonic Compensation for Grid-Connected Converters

Grid-connected converters are uncertain time-varying systems, whose controllers must deal with the relevant inductive content and high harmonic distortion of the sampled voltages. Adaptive controllers are feasible control strategies for these applications, because their gains are continuously adjusted in response to system perturbations, and they are also robust to unmodeled dynamics and exogenous disturbances. However, adaptive controllers are not necessarily capable of rejecting all harmonic components on grids with high harmonic distortion. Therefore, this work presents a Robust Model Reference Adaptive Control-based with an adaptive super-twisting sliding mode, which is improved with a harmonic compensation strategy in which additional control actions to deal with the harmonic contents of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$5^{th}$</tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$7^{th}$</tex-math></inline-formula> , <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$11^{th}$</tex-math></inline-formula> , and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$13^{th}$</tex-math></inline-formula> of the fundamental component of the electrical grid are incorporated into the control structure. Experimental results are provided of a 7.5 kW converter connected to a distorted and unbalanced grid with an LCL filter, where the developed control structure presents a total harmonic distortion (THD) of 2%, while the controller without harmonic compensation obtains a 2.5% THD.

The Role of Power Electronic Converters in Microgrid Technology: A Review of Challenges, Solutions, and Research Directions

The paper is on the role of power electronic converters in microgrid technology: A review of challenges, solutions and research directions. The objective of the paper is to perform a comprehensive overview of the role of power electronic converters in microgrid technology, focusing on challenges, solutions, and research directions. Findings revealed that major challenges of power electronic converters integration in microgrid technology are voltage and frequency regulation issues, power quality issues, creative management and coordination challenges, and Integration of renewable energy sources. The solutions to these problems are advanced control algorithms such as Model Predictive Control (MPC); deployment of active power filters or harmonic compensators to reduce harmonic distortion and improve power quality; iimplement a centralized control system with centralized monitoring controllers to coordinate the operation of several converters and ensure consistent operation; and combining multiple renewable energy sources in a hybrid energy system to diversify generation sources and reduce the gap. The future research directions include, among others, advanced control strategies, grid-forming converters, wideband semiconductor, and cyber-security and Resilience. The paper concludes that the integration of power electronic converters into microgrid technology presents both opportunities and challenges. Although these converters play an important role in the efficient conversion, distribution and utilization of energy in microgrids, they face various technical and practical challenges. To mitigate these challenges, the implementation of advanced control strategies, grid-forming converters, etc., is inevitable.

Experimental Characterization of Reference Currents for Harmonic Compensation: Case of the TLC Hybrid Filter

Experimental Characterization of Reference Currents for Harmonic Compensation: Case of the TLC Hybrid Filter

Analysis of Harmonic Compensation for Grid-side Current of Series Sixfold-circuit “Phase-hopping” AC-AC Frequency Converter

Background: A series sixfold-circuit “phase-hopping” AC-AC frequency converter (SSCPH-AAFC) is an extension of traditional AC-AC frequency converters. Compared to traditional frequency converters, it has the advantages of energy-saving, low cost, and simple control. Additionally, it can increase the upper limit of the frequency conversion to the power frequency. Through multiplexing processing, it reduces the harmonic content of the output waveform, making it suitable for applications, such as large-capacity fan or pump speed control. Objective: Although SSCPH-AAFC reduces harmonic content, the harmonic content of the single- phase and three-phase grid-side currents still reach 14.65% and 10.20%, respectively. To meet national standards for practical application, a compensation circuit needs to be designed to further reduce grid-side current harmonics. Methods: To address harmonic problems, a targeted single-phase current open-loop compensation method was designed based on the analysis of the current waveform defect. The method compensated for harmonics by selecting appropriate trigger angles and reducing the harmonic distortion rate of the power grid to meet the necessary application standards. Results: The method was simulated and analyzed using MATLAB, and the results showed that after single-phase open-loop compensation, the total harmonic distortion (THD) of the grid-side current for a single-phase SSCPH-AAFC was 2.64%, and for a three-phase SSCPH-AAFC, it was 1.80%. Conclusion: This method has a good effect and can meet the standard requirements.

Design of a novel control hysteresis algorithm for photovoltaic systems for harmonic compensation

Solar photovoltaic (PV) system design and integration with an existing AC grid is growing very fast in recent years and used by many of them as they are pollution-free, structure is limited and maintenance free. From the factors considering, the performance of PV system depends upon the inverter output voltage tested for linear, non-linear, with harmonic, and without harmonic loads. Generated due to the nonlinear loads. Better inverter control techniques are developed to maintain grid power quality. This article discusses the analysis and comparison of pulse width modulation (PWM) converters with unique and state of the art nonlinear control schemes and various modulation approaches. The primary objective of this research is controlling an active filtering hysteresis PWM converter with no sensors. A simple structure with hysteresis current control method total harmonic distortion (THD) is lower when compared with the sinusoidal pulse width modulation (SPWM) method. The said claims are supported by employing computer simulations using MATLAB/Simulink and different control approaches, such as proportional plus integral and artificial neural network controllers.

Harmonic compensation from battery energy storage systems (BESS)

Harmonic compensation from battery energy storage systems (BESS)

A control method for the single-phase three-leg unified power quality conditioner without a phase-locked loop

The single-phase three-leg unified power quality conditioner (UPQC) can achieve the functions of voltage compensation, reactive power compensation, and harmonic compensation. However, traditional control algorithms require a phase-locked loop to obtain the real-time phase angle of the grid voltage, which undoubtedly increases algorithm complexity. To simplify the phase-locked calculation, this paper proposes a control method without the phase-locked loop for the single-phase three-leg UPQC. In the proposed scheme, the instantaneous value of the grid voltage is employed to realize the grid integration control. Then, the load voltage reference is calculated in real time using a second-order generalized integrator. Moreover, a simple algorithm for reactive power and harmonic compensation is discussed, further simplifying the control algorithm. Finally, a small-scale experimental platform is built, and the effectiveness of the proposed method is verified by the experimental results.

Modular buck-boost transformerless grid-tied inverter for low voltage solar panels

This paper deals with a transformerless AC module for low DC voltage output photovoltaic solar panels. The DC to AC converter was designed to be a single-phase grid-tied inverter, and is based on a buck-boost topology with current mode control to shape the current and to adjust delivered power. The common ground node prevents voltage fluctuations and increases people´s safety. Low power inverters tend to be less efficient than larger ones and are prone to higher harmonic distortion. To overcome these drawbacks, special care was taken in designing the power stage, and harmonic compensation was included in the control stage. The inverter has MPPT capability and operates with unity power factor. Inverter´s operation is analysed, and some simulation results are presented. A 220Wp two-stage single-phase AC module prototype, with 240V and 50Hz sine-wave output, was build and connected to a low voltage photovoltaic solar panel. Experimental results for this plug-and-play converter are here presented.

Harmonic compensation using a single phase active filter

This work presents the implementation of a single phase parallel active filter for harmonic compensation. The idea is to optimize the processed power by the active single-phase filter restricting the compensation only to harmonic currents without processing the linear reactive one. It is made a comparison study of processed power by a conventional active power filter compensating the entirely reactive power and another compensating only the harmonic contents. It is presented the control methodology employed, the power circuit design and the results obtained through a 500VA experimental prototype.

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.

Comparison between Active power filter with selective control and conventional control for harmonic in photovoltaic systems

In order to to improve the power quality from energy generated by the photovoltaic systems connected to the network, this paper presents the results of two types of filters, first the active power filter with conventional control scheme and second, active power filter with a selective control scheme in order to reduce the harmonic content injected by the inverter in a photovoltaic system. The results are presented and compared by means of harmonic distortion (individual and THD). This is a novel proposal, since studies before to this, always have been interested in the compensation of harmonics arising from non linear loads but rarely from a voltage source, as in this case.

Parameter estimation of biased harmonic signal

This paper deals with the problem of asymptotically estimating amplitude, frequency and phase of a sinusoidal signal by adopting the theory of invariant relations proposed in analytical mechanics [8] and further investigated in [9, 10] (see also [11]). The problem of frequency, amplitude and phase estimation of a sinusoidal signal has attracted a remarkable research attention in the past and current literature. The reasons of this interest rely on several engineering applications where an effective and robust solution to this problem is crucial. To mention few, it is worth mentioning problems of harmonic disturbance compensation in automatic control, design of phase-looked loop circuits in telecommunication, adaptive filtering in signal processing, etc. In principle, the method of least squares, Fourier analysis, Laplace transform provide a potential solution to the corresponding problems. However, these methods may not be suitable, for example, for control algorithms with real-time data processing. The goal of this paper is to suggest a further contribution to this task by showing how to solve the problem at hand through the observer’s theory. The method of invariant relations is used for the asymptotically observation scheme design. This aproach is based on dynamical extension of original system and construct of appropriate invariant relations, from which the unknowns variables can be expressed as a functions of the known quantities on the trajectories of extended system. The final synthesis is carried out from the condition of obtaining asymptotic estimates of unknown parameters. It is shown that an asymptotic estimate of the unknown states can be obtained by rendering attractive an appropriately selected invariant manifold in the extended state space. The asymptotic convergence of the estimates of the sought phase vector components to their true value is proved. The simulation results demonstrate the effectiveness of the proposed method of solving the state observation problem of the harmonic oscillator. It should be noted that a more general approach, which forms an appropriate method for solving observation problems for nonlinear dynamical systems due to the synthesis of invariant manifold, was proposed as a modification of the I&amp;I method (Input and Invariance) of stabilization of nonlinear systems in [12, 13].

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

Compensation of Voltage Harmonics for LCL-filtered Inverters in Islanded Microgrids

In a microgrid (MG), it is possible to have some sensitive loads that require high voltage quality. In this paper, a new technique is proposed for selective compensation of main voltage harmonics in islanded MGs. The proposed technique is capable of adjusting the compensation percentage in proportion with the existing disturbance in the sensitive load bus (SLB) and sharing the compensation workload among DGs in proportion with their nominal power. This compensation, is performed by controlling of the interface inverters of distributed generation (DG) units with LCL filters. Also, to decrease the asymmetry among phase impedances of MG and mitigate the voltage distortion after the output LCL of filters, a novel structure is proposed to generate selective virtual impedance. At fundamental frequency, the proposed structure of the virtual impedance improves the control of the fundamental component. On the ather hand, at main harmonic frequencies, it tries to adaptively improve nonlinear load sharing among DG units and mitigate the voltage distortion after the output LCL filters. Simulation results in MATLAB/SIMULINK environment show the efficiency of the proposed approach in improving load load sharing and decreasing voltage harmonics.

Shunt Active Power Filter with Selective Harmonics Compensation for LV distribution grid

A Shunt Active Power Filter (SAPF) employable in a Low Voltage distribution grid four-wires model is presented. The use of this device helps to improve Power Quality compensating harmonic currents, reactive power and current unbalances of a disturbing loads. Each compensating function can be activated or disabled according to the specific requirements of the application. A selective harmonic compensation is also possible, in order to avoid possible resonances at specific frequencies. A current hysteresis modulation with predictive calculation of threshold bands achieving fixed switching frequency is adopted for a fast dynamic response. The compensation performance of the proposed active power filter and the associate control scheme under steady state and transient conditions is demonstrated through digital simulations.

A composite strategy for designing efficient harmonic compensators in grid connected inverters with reduced power

The harmonic controlling schemes are very important for renewable energy applications. The power efficient applications are playing significant role in grid connected inverter applications. The measures like power factor, real & reactive power, voltage at (grid, inverter and converter side), current at (grid, inverter and converter side) are need to be improve for efficient power balancing purpose. The earlier models like liner disturbance controlling LADRC, Proportional-Resonant (PR) Control with Comb Filter (PRC-CF) and PI controlling are outdated. Therefore, PR–NF–STFT-Fuzzy logic controller is proposed to cross over the above limitations. This proposed methodology can improve the PRFI-HC dynamic response, PRFI-HC of inverter current and PRFI-HC voltage. Grid-connected inverters may use the suggested approach to emit high and low frequency harmonics. In the event of many external harmonic's sources, a different analysis statement is provided to indicate the highest achievable individual grid current harmonic. At resonance frequencies, the effect of the series damping resistor on the inverter's harmonic rejection capability is examined. The suggested harmonic structure of the converter is matched by the simulations and testing findings.

Analysis and Compensation of Dead Time Harmonics Based on Time Compensation Strategy in the Single-Phase Full-Bridge Inverters

A short period, called dead time, is implemented to prevent power switching devices from shoot-through in voltage-source inverters (VSI). While adding dead time is required in the switching signals, it also causes negative effects on inverter operation such as distortion at output voltage due to significant number of harmonic components, and reduction in voltage magnitude of fundamental components. Eventually, the negative effects caused by dead time have to be compensated with compensation schemes. Different modulation schemes, which are called unipolar and bipolar switching, can be implemented in VSI, which in return might change the dead time effect. Although analysis of bipolar switching on the dead time effect has been implemented, analysis of unipolar switching is not addressed by most. In this paper, the effect of dead time on unipolar sinusoidal pulse width modulation (SPWM) is analyzed, the principle of the proposed compensation strategy is described in detail and the time compensation method with unipolar SPWM scheme is implemented using microprocessor-STM32F407G. The technique is intensively simulated and the evaluated through experimental results on resistive and resistive-inductive loads by comparing uncompensated and compensated states. Simulation and experimental results are presented to demonstrate and confirm the validity of the proposed dead-time compensation method.

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.

A Solar Series Grid Following Harmonic Compensator with Enhanced Grid Current Shaping and Active Power Injection Capability

A Solar Series Grid Following Harmonic Compensator with Enhanced Grid Current Shaping and Active Power Injection Capability