Passive Filter Research Articles

Event-based passive filtering for Markov jump singularly perturbed complex networks

Event-based passive filtering for Markov jump singularly perturbed complex networks

Improve power quality and stability of grid - Connected PV system by using series filter

As the world increasingly focuses on renewable energy sources, grid-connected PV systems will continue to play a critical role in meeting our energy needs. This integration has brought many benefits, but has also created various problems related to power quality and stability at the connection points. Various techniques are used to improve the power quality, such as passive filters, tuned passive harmonic filters, and active filters. This paper presents the use of a series active filter on the DC side of grid-connected PV systems to improve their power quality, stability, and dynamic performance. The proposed filter consists of an inductor, two capacitors, and four transistor-diode pairs, the operation of which is controlled by a sinusoidal pulse width modulation (SPWM) scheme. The MATLAB/Simulink is used to build and validate a comprehensive mathematical model of the studied system. The transfer function of the system is identified and its transient response is studied under various test input signals. A Bode plot is also generated to assess the impact of the integration of this component on the stability of the system. The results showed that incorporating the filter resulted in a significant reduction in the total harmonic distortion factor (Thd%) for both the voltage and current waves at the inverter output. Moreover, it improved the transient response characteristics of the system by significantly reducing the maximum overshoot value of the system response with respect to the test input signals. The results indicate that the stability of the system is improved after the filter addition, as evidenced by the increased gain margin and phase margin in the system Bode plot.

Improvement of the Source Current Quality for a Shunt Active Power Filter Operating Using Hysteresis Technique with Stabilized Switching Frequency

Determining the current reference for a shunt active power filter (SAPF) can be carried out in many ways. Once the reference is determined, it can be shaped by SAPF switches with the use of pulse width modulation (PWM)/hysteresis control techniques. There are many variants of shaping the compensation waveform using these techniques. Nevertheless, regardless of the PWM/hysteresis technique adopted, a switching frequency current component appears in the system. It acts as a carrier used to inject a compensating current into the grid. Once the compensating current has been entered into the grid, the switching component should be reduced in it. This can be performed using RLC passive filters in various variants. The article discusses a variable/stabilized frequency hysteresis current control technique adapted for SAPF regulation with the use of current closed-loop control (source current direct control). For this technique, the passive filter should be placed outside the current control loop. The article focuses on examining the effectiveness of the interaction of the RLC filter with SAPF acting with such a control technique.

LADRC‐based non‐characteristic harmonic suppression strategy for pumped storage power plants

AbstractThe static frequency converter (SFC) in a pumped storage power plant often causes harmonic problems in the dragging processes, which may lead to the false operation of automatic devices in the power station, and even damage to the power equipment. These harmonics caused by SFC contain both characteristic and non‐characteristic degrees, and the components are more complex. Hence, the existing harmonic suppression methods using active power filter or passive power filter compensation all have some problems. The SFC starting control strategy based on linear active disturbance rejection control (LADRC) is proposed here to reduce the non‐characteristic harmonics. First, the factors affecting the non‐characteristic harmonic content are analysed, and a mathematical model of the conventional SFC starting transfer function is established. On this basis, the LADRC controller is used as the speed loop of SFC starting to replace the proportional integral (PI) controller. The stability is judged by drawing the Bode plot and the zero‐pole plot. Finally, a Matlab/Simulink simulation model of LADRC‐based SFC starting is established in a pumped storage power plant with actual parameters, and simulation accurate measurements verify the effectiveness of the proposed control strategy for non‐characteristic harmonic current suppression.

Topology design of variable speed drive systems for enhancing power quality in industrial grids

In the last two decades, a rapid increase in the utilization of non-linear loads within electrical grids has been observed. Consequently, elevated levels of harmonics are found in both voltage and current waves, and adverse effects on power quality are caused. In this context, the variable speed drive (VSD) systems are considered a significant non-linear contributor. To mitigate the harmonic content in VSD systems, various techniques are explored, such as electronic smoothing inductor incorporation in the DC-link, active filters utilization at the grid side, and passive filters integration. A technique centered on the reconfiguration of the DC-link in the VSD systems is proposed in this paper to improve the overall performance of the VSD systems. The configuration comprises two transistors and two diodes, along with smoothing inductors and a capacitor to enhance power quality in the VSD systems. The utilization of three-stage sine pulse width modulation (SPWM) control technology ensures accurate control of the switches, generating optimal control signals that enhance the power quality of the voltage and current waves at the grid side. The effectiveness of the proposed approach is tested via time-domain simulation in MATLAB/Simulink under both constant and variable loading conditions and is verified using a laboratory prototype. The obtained results demonstrate a notable improvement in power quality, showcasing reduced total harmonic distortion (THD) in AC voltage and current waveforms, as well as minimized ripple factor in the DC-link when compared to existing methods.

An inherent fault current blocking modular series multilevel converter using half-bridge sub-modules for grid integration

This paper proposes an inherent fault current blocking modular series multilevel converter (MSMC) using half-bridge (HB) sub-modules (SMs) for grid integration. The proposed converter uses passive filters to decouple the AC and DC side. Compared to conventional three-phase modular multilevel converters (MMCs) that use half-bridge sub-modules (HBSMs), the new MSMC design significantly reduces the number of switching devices required. Furthermore, one of the features of the proposed MSMC is its inherent ability to limit fault currents, which is achieved through its unique topological configuration whereas the conventional HB-MMC is susceptible to DC and AC faults. Despite these advancements, the new MSMC design retains all the desirable characteristics of conventional HB-MMCs, ensuring compatibility and ease of adoption. The paper thoroughly examines the operation of the MSMC under both steady-state and fault conditions. It also discusses the equivalent voltage decoupling circuit, energy balancing which is essential for the proper functioning of the converter. Additionally, the pre-charging process of the sub-module capacitors, a critical step for ensuring the safe start-up of the converter, is discussed in detail. Furthermore, Extended topologies can be derived from proposed topology for different applications.

Enhancing safety in narrow-band transformerless PLC couplers with a passive symmetrical filter

As the demand for efficient data transmission over existing power infrastructure grows, power-line communication (PLC) systems have become increasingly vital. However, integrating communication signals with high-voltage power lines poses significant safety challenges, emphasizing the need for reliable, safe, and high-performance components. To address cost and safety concerns, this article introduces a symmetrical third-order band-pass filter design that employs a transformerless coupler, avoiding the expense and bulk of traditional transformers while enhancing both equipment and human safety in narrow-band PLC systems. The design, functionality, and safety considerations are discussed, with a focus on implementing a passive analog Butterworth filter, chosen for its flat frequency response in the passband. Additionally, we address the safety aspects of transformerless couplers in PLC applications, emphasizing their reliability and efficiency in maintaining signal integrity while minimizing the risks associated with high-voltage environments. Simulations validated the proposed design, confirming its effectiveness in achieving the desired frequency response. The design is cost-effective due to the elimination of the transformer and ensures safety through the strategic rearrangement of the coupler components, which isolates the power line from the communication side.

Pursuance of a passive filter for a multi-coil EV charger employing a solar connected system to enhance power quality

Pursuance of a passive filter for a multi-coil EV charger employing a solar connected system to enhance power quality

ZnO Hexagonal Nano- and Microplates Modified with Nanomaterials as a Gas-Sensitive Material for DMS Detection-Extended Studies.

The detection of dimethyl sulphide (DMS) at levels between ppb and ppm is a significant area of research due to the necessity of monitoring the presence of this gas in a variety of environments. These include environmental protection, industrial safety and medical diagnostics. Issues related to certain uncertainties concerning the influence of high humidity on DMS measurements with resistive gas sensors, e.g., in the detection of this marker in exhaled air, of the still unsatisfactory lower detection limit of DMS are the subject of intensive research. This paper presents the results of modifying the composition of the ZnO-based sensor layer to develop a DMS sensor with higher sensitivity and lower detection limit (LOD). Improved performance was achieved by using ZnO in the form of hexagonal nano- and microplates doped with gold nanoparticles (0.75 wt.%) and by using a well-proven sepiolite-based passive filter. The modification of the layer composition with respect to the authors' previous studies contributed to the development of a sensor that is highly sensitive to 1 ppm DMS (S = 11.4) and achieves an LOD of up to 406 ppb, despite the presence of a high water vapour content (90% RH) in the analysed atmosphere.

A new hybrid fixed and adaptive gains control algorithm to reduce power losses on LLCL filter-based renewable energy conversion systems with systematic parametrization using Grey Wolf optimizer

Currently, there is a transition in the energy matrix around the world, where traditional sources of energy generation are continually being replaced by energy generation systems based on renewable sources to mitigate the climate crisis. In this bias, this work presents the mathematical modeling of an LLCL filter, used to connect power generation systems based on renewable energy sources to the electrical grid, and presents a novel hybrid fixed-and adaptive gains control strategy for current injection into the grid using this system. The developed hybrid controller is composed of a proportional–integral controller and a direct robust adaptive controller. The first term of the controller guarantees the reference current, while the second term of the controller is used for disturbance rejection. Furthermore, a systematic procedure for the controller’s parametrization based on Grey Wolf Optimizer is also provided. The control of the current injected into the grid is carried out considering the LLCL filter without passive damping resistors in the filter structure to avoid power losses due to the passive filter elements. Additionally, the LLCL filter model considers minimal parasitic resistances to evaluate the controller’s performance and optimize it for the application of interest, aiming to maximize the system performance by ensuring a short transient regime due to the fast closed-loop system response. Simulation results indicate high performance of this optimized control strategy with small tracking error even considering grid impedance variations.

Determination of the Effect of Harmonics on the Performance of Single-Phase Low Voltage kWh Meters

Low-voltage installation systems with 450 VA and 900 VA power are one of the most commonly used electricity distribution systems in Indonesia. In the previous study, adjustments to the load of household needs were clearly made, and measurements were made at the load of 450-900 VA because some users received payment subsidies. Two types of kWh meters in accordance with standards in Indonesia are used by testing the readings of analog and digital kWh meters, which are loaded according to the load pattern. The load used is varied based on the load pattern that has been described in Table IV. Installation evaluation in the form of installing filters and improving the cross-sectional area value is carried out. After the installation of the passive filter, the power quality at 450 VA and 900 VA full load conditions improved, with the power factor in the electrical system of the 450 VA home installation increasing from 0.916 to 1. Keywords: harmonics, kWh meter, electrical energy, non-linear load, Home Installation

Harmonics mitigation in distribution networks comprising smart online electric vehicles chargers based on equal sharing algorithm

This study focuses on analyzing the distribution network's performance due to the scheduled integration of electric vehicles (EVs). In this context, an online equal sharing scheduled algorithm is utilized to monitor and manage the charging process of EVs inside the charging stations (CSs). By this way, the planned charging demand may aid in minimizing the power stresses at the point of common coupling (PCC). Afterwards, the penetration of CSs into practical distribution networks is investigated and resolved from power quality perspectives. Meanwhile, voltage and current harmonic distortions of 3.3 % and 8.3 %, respectively resulted at the PCC due to installing these harmonic injection sources. It is worth mentioning that diverse topologies of passive filters are interrogated in this research for harmonics mitigation purposes. Single tuned passive filters demonstrate their superiority over other architectures in harmonics suppression with the simplest and most cost-effective solution. Additionally, the overloading stresses over the installed package substation of about 7 % are also alleviated permitting the CS to charge with full capacity. Finally, this work presents a forward step in the fields of EVs smart charging and harmonics mitigation in practical distribution gids.

Comparison and Optimization of the Use of Passive and Active Power Filters to Mitigate Harmonics in Distribution Networks with non-linear loads

Comparison and Optimization of the Use of Passive and Active Power Filters to Mitigate Harmonics in Distribution Networks with non-linear loads

Optimal Passive Power Line Communication Filter for NB-PLC Applications

Narrowband Power Line Communication (NB-PLC) involves transmitting data by overlaying a high frequency low amplitude signal (ranging from 9 kHz to 500 kHz) onto the low-frequency high amplitude signal (50 Hz to 60 Hz) of the power grid. While using the existing power grid for communication is convenient, it was not originally designed for this purpose, leading to challenges such as conducted emissions and infrastructure constraints. To overcome these technical obstacles, power line filters (PLFs) are a viable solution. The results of our research work, focusing on the optimization of PLFs for NB-PLC to ensure their design fits the needed use case while avoiding over-engineering, are presented in this article. Our study concentrates specifically on the filtering of PLC signal and conducted emissions up to 500 kHz. Building upon a PLC PLF extensively discussed in our previous work—which blocks the PLC signal in the CENELEC-A frequency band regardless of its placement within the electrical installation, sometimes leading to over-engineering—this research aims to adapt the filter order and components for a variety of real scenarios in CENELEC-A, FCC, and ARIB frequency bands. By characterizing different filters, our work provides tailored solutions for these scenarios and serves as a framework for future filter designs in PLC applications.

Research on the Control and Modulation Scheme for a Novel Five-Switch Current Source Inverter

Different from the voltage source inverter (VSI), the current source inverter (CSI) can boost the voltage and eliminate the additional passive filter and dead time. However, the DC-side inductor current is not a real current source and is generated by a DC voltage supply and an inductor. Under different switching states, the DC-side inductor will be charged or discharged, which leads to the DC-side inductor current being discontinuous or increasing. To solve the control problem of the DC-side inductor current of the CSI, a novel single-phase CSI topology with five switching tubes for grid-connected applications is proposed. Firstly, the reference calculation method and the hysteresis loop control scheme for the DC-side inductor current are proposed, and the adjustable and constant DC-side inductor current are obtained. Since the PWM signals cannot be directly implemented to the switching tubes, the modulation strategy for the single-phase CSI is proposed in this paper. Then, an active damping method based on the feedback capacitor voltage is presented to suppress the resonance peak caused by the LC filter on the grid side. Finally, the math model of the AC-side structure is established, and the optimal proportional-resonant controller parameters’ design method is explored by the amplitude–frequency characteristic curves. The simulation and experiment are implemented for the proposed CSI topology. The results show that a high-quality power with a good control performance can be obtained with the proposed CSI topology.

Optimal passive LCL filter design for grid-connected converters in weak grids

In an era characterized by the increasing integration of renewable energy sources into the power grid, the stability and resilience of the grid have become paramount, especially in areas with weak grid infrastructure. One effective approach to mitigate the adverse effects of grid disturbances and harmonics is passive LCL (inductor-capacitor-inductor) filters. However, designing these filters for optimal performance under varying conditions remains challenging. This research paper presents an effective approach to addressing this challenge by utilizing the power of evolutionary algorithms, specifically Multi-Objective Particle Swarm Optimization (MOPSO) and Multi-Objective Genetic Algorithm (MOGA), to design optimal passive LCL filters for weak grid environments. The proposed method aims to enhance grid resilience by optimizing the filter parameters to consider a weak grid's unique characteristics and uncertainties. Minimizing the resonance frequency has succeeded in achieving power quality and stability improvements related to changes in grid impedance. The proposed approach achieves power quality and stability improvements related to changes in grid impedance and dealing with fragile conditions, which is the main scope of this paper.© 2017 Elsevier Inc. All rights reserved.

High attenuation electromagnetic interface filter for effective processing of audio signals

Suppressing the noise or unwanted signal from the raw signal makes the system work efficiently. Electromagnetic interface (EMI) can cause the system/device to lose the data, damage the electronic equipment, interrupt the audio, or video signals, lead to poor reception, etc EMI filters are used in telecommunications, military equipment, satellite communication, etc At the industry level, EMI filters are used for home appliances, medical equipment, motor controls, test equipment, etc In this paper, active and passive EMI filters are designed to avoid or attenuate EMI or noise (unwanted EMI signal) and implemented on Xilinx Nexys 4 Artix 7 FPGA board. The filters provide a significant improvement in the attenuation of the EMI. MATLAB tool is used to design the filters, which are highly immune to undesired signals, give better stability, and perform over a wide range of frequencies. Depending on the filters’ coefficients, the frequency response will be changed. Phase response and amplitude response of the EMI filters are calculated. Insertion loss of the active filter is 1.5836, and for the passive filter, 1.9382. The gain of active and passive filters is 0.7359 and 0.912 respectively. The return loss of the active and passive EMI filters is 20 dB. HDL code is generated using MATLAB for the implementation of filter on FPGA. Using MATLAB HDL coder for implementing is new and it simplifies the design, as a result development time is reduced. Xilinx Vivado tool is used for the implementation of active filter. The total on-chip power is 0.146 W. Dynamic power is 0.049 W, and device static power is 0.097 W. The utilization of LUTs and slice registers are less, compared to the previous filter implementation, which leads to reduce the cost of hardware implementation.

Optimizing Power Quality in Distribution Systems: A Three-Phase Three-Level Shunt Hybrid Active Filter with Multilevel Inverter Approach

This paper presents an advanced solution for improving power quality in distribution systems through the implementation of a Three-Phase Three-Level Shunt Hybrid Active Filter (SHAF) with a Multilevel Inverter. The SHAF, utilizing a Three-Level Neutral Point Clamped Voltage Source Inverter actively mitigates harmonics, with a comprehensive performance analysis considering the impact of active and passive parameters on power quality improvement. The proposed system incorporates TPTL (Three phase 3-Level) NPC inverter technology to reduce switch ratings and enhance harmonic compensation. Various passive filters are integrated into the SHAF to assess performance. Simulation results, validated with MATLAB/Simulink, confirm the efficacy of the proposed system. Comparative analysis against conventional shunt passive filters, including Single Tuned, Double Tuned, High Pass, C-type High Pass, and a two-level shunt active filter with diverse passive filters, reveals a significant improvement of over 53% compared to two-level active filters and more than 16 times compared to shunt passive filters.

Method for determining the harmonic contribution of consumer installations based on the application of passive filters

AbstractThe paper presents a new method for estimating the contribution of distortion sources based on the application of passive harmonic filters. The method does not require the measurement of harmonic network impedance and is based on the measurement of harmonic currents of the grid, consumers and passive harmonic filters. Evaluation of the consumer contribution using a passive harmonic filter is necessary to select the parameters and connection points for harmonic reduction devices. A feature of the method is the correct determination of share contributions, regardless of background harmonic distortions. Based on this method, a single consumer can evaluate both the harmonic contributions of its own loads, even in the presence of background distortions, and the harmonic voltage distortions in the case of installing harmonic reduction devices. The research results are confirmed in laboratory conditions with various combinations of electrical loads connected both at the grid side and at the consumer side. For such conditions, the proposed method was compared with existing methods, among which are methods based on the measurement of harmonic voltage vectors, harmonic current vectors and active harmonic power. The application of the developed method was demonstrated using the example of a gas production field.

Seasonal oxidative dynamics and isotopic fractionation of NOx and SO2 in Ostrava, Czech Republic: Insights from stable isotope analysis

The city of Ostrava, NE Czech Republic, is known for its industrial pollution. It has well-characterized emission sources and stable air movement patterns. These features are conveniently used to generalize on atmospheric NOx and SO2 oxidation processes. In 2021, we conducted a series of sampling campaigns to assess the isotopic fractionation conducive to NO3− and SO42− aerosols in PM10. These sampling campaigns were timed to capture varying atmospheric conditions, including climatic inversion periods, providing also insights into urban emission dynamics over the course of the year. Gaseous NOx and SO2 were collected on passive filters, while their oxidized forms, NO3− and SO42, were captured on PM10 particle filters, enabling us to analyze the transformation dynamics of these pollutants. Isotopic analyses distinguished the sources of NOx emissions—coal combustion (δ15N = −3‰) and vehicular emissions (δ15N = −7 ‰)—and allowed quantifying isotope fractionation during their conversion to NO3− (εNOx-NO3- = 11.5 ± 1.15 ‰). This fractionation, however, was influenced by seasonal variations, and appears to be notably affected by NH4NO3 decomposition during warmer months. The correlation of the NO3− to NOx ratio with PM10 and atmospheric moisture highlighted the interplay between particulate matter and humidity in relevant atmospheric transformations. Similarly, for SO2, primarily emitted from coal combustion (δ34S = −2‰), we identified distinct fractionation patterns during oxidation to SO42− encompassing both kinetic (εSO2-H2O = −1.3 ± 0.5‰) and equilibrium (εSO2- SO42- = 2.24 ± 0.67‰) effects. The SO42−/SO2 ratio was correlated with PM10 but showed no dependence on humidity. Significantly, atmospheric inversion conditions accelerated oxidation, modifying the fractionation patterns for both NOx (εNOx-NO3- = 7‰) and SO2 (εSO2- SO42-= −0.9 ± 0.3‰). Our methodology elucidates pivotal mechanisms in atmospheric pollution transformation, underlined by the tracing of NOx and SO2 to aerosol conversions via δ15N and δ34S isotopic analyses. The isotope fractionation underscores equilibrium processes in oxidation reactions, while the effect of PM10 and humidity reveals the complexity of these atmospheric oxidative transformations. The role of wet deposition in removing SO2 highlights an essential pathway in the atmospheric sulfur cycle.