Passive Filter Research Articles

Research on harmonic resonant fault mechanism and suppression measures of oilfield power grid based on fast mode analysis method

In recent years, with the use of electric drilling rig, electric fracturing pump, and other equipment, the harmonic resonance problem of oilfield power grid is becoming more and more serious. In view of the high time and space complexity and long calculation time of the traditional harmonic resonance analysis method, the improved power iteration method is combined with the traditional modal analysis method, and the harmonic resonance problem of the oilfield power grid is analyzed by the fast modal analysis method. At the same time, a new set of harmonic resonance amplification index is derived and verified, and the harmonic content amplification times in the resonant influence region and different busbars are revealed. And then a passive filter is used to suppress harmonic resonance, and the effectiveness of the scheme is verified by field tests. The results show that, in the frequency range of 0–1000 Hz, the resonant frequency points in the oil field are mainly related to the rectifier pulse number of the drilling rig and the frequency conversion device for fracturing. The proposed fast modal analysis method has the advantages of fast convergence speed and memory saving, which is helpful to accurately detect the harmonic resonance region caused by the multi-pulse frequency conversion device, and the harmonic resonance can be effectively suppressed by installing a filter at the main excitation bus of the resonant frequency.

An Integrated Power Decoupling Method for Single-Phase EV Onboard Charger in V2G Application

Instead of bulky passive filters, the active power decoupling (APD) method can be adopted to suppress the 2nd-order ripple power in the DC-bus of the single-phase electric vehicle (EV) onboard charging system. However, the traditional APD methods require additional power switches and energy storage devices, which increases the cost and significantly reduces the power conversion efficiency. To tackle these problems, an integrated method of utilizing the auxiliary power module to form a series-connected APD circuit is proposed in this paper. Without additional switches and energy storage devices, the APD circuit only needs to compensate less than 10% of the rated power, while realizing soft-switching operation. In addition, the corresponding control method can further reduce the voltage stress of the switches on the high-voltage side of the converter, and increase the efficiency of the system. Finally, a 2kW single-phase charging system prototype is built to verify the feasibility and effectiveness of the proposed method.

Simultaneous allocation of renewable energy sources and custom power quality devices in electrical distribution networks using artificial rabbits optimization

Abstract This study suggests an optimal renewable energy source (RES) allocation and distribution-static synchronous compensator (D-STATCOM) and passive power filters (PPFs) for an electrical distribution network (EDN) to improve its performance and power quality (PQ). First, the latest metaheuristic artificial rabbits optimization (ARO) is used to locate and size solar photovoltaic (PV), wind turbine (WT) and D-STATCOM units. In the second stage, ratings of single-tuned PPFs and D-STATCOMs at the RESs are determined, considering non-linear loads in the network. The multi-objective function reduces power loss, improves the voltage stability index (VSI) and limits total harmonic distortion. Simulations using the IEEE 33-bus EDN compared the ARO results with those of previous studies. In the first scenario, ideally integrated D-STATCOMs, PVs and WTs reduced losses by 34.79%, 64.74% and 94.15%, respectively. VSI increases from 0.6965 to 0.7749, 0.8804 and 0.967. The optimal WT integration of the first scenario outperformed the PVs and D-STATCOMs. The second step optimizes the WTs and PQ devices for non-linear loads. WTs and D-STATCOMs reduce the maximum total harmonic distortion of the voltage waveform by 5.21% with non-linear loads to 3.23%, while WTs and PPFs reduce it to 4.39%. These scenarios demonstrate how WTs and D-STATCOMs can improve network performance and PQ. The computational efficiency of ARO is compared to that of the pathfinder algorithm, future search algorithm, butterfly optimization algorithm and coyote optimization algorithm. ARO speeds up convergence and improves solution quality and comprehension.

Improvement of Power Quality in Grid Connected Wind Energy System

Abstract: This research covers industrial plant-connected wind turbine system control. An algorithm permits a control structure that uses a four-leg inverter linked to the grid to inject energy and operate as an active power filter, reducing load current disturbances and improving power quality. Algorithms enable this control structure. A four-wire system considers linear and nonlinear three-phase and single-phase loads. The utility-side controller supplies active and reactive power and adjusts for reactive, nonlinear, and unbalanced single- and intra-phase demands during wind turbine connection. Besides providing power, this is done. If there is no wind power, the controller uses the DC-link capacitor and grid-connected power converter to improve power quality. The proposed control structure is based on conservative power theory decompositions, which distinguishes it from previous techniques. This option separates the inverter control power and current references, giving a broad variety of adaptable, selective, and powerful functions. Real-time software benchmarking has tested the recommended control technique for comprehensive real-time implementation. The real-time simulator "FACTS" and the DSP microcontroller test and implement the control strategy in hardware-in-the-loop. These results confirmed our power quality improvement control, allowing us to omit passive filters. This created an electronic smart grid-based control system that was more efficient, adaptive, and reliable.

IoT-based monitoring, analysis and supervisory control of voltage harmonics in a three-phase system using four singles tuned lowpass filter

Total Harmonic Distortion is a vital part of communications, power distribution, and audio. In power distribution, it must be kept as low as possible. Voltage pollution occurs at the point of common coupling, which leads to a higher THD. Higher THD ensues thermal stress to the system where issues in the power system arise. Odd harmonic frequencies, specifically, the 5th, 7th, 11th, and 13th are the primary cause of the increase in THD. Several ways to reduce harmonics are the use of reactors, passive filters, and active front end solutions. This study is focused on minimizing the voltage harmonics by monitoring the voltage coming from a three-phase system by using four single-tuned filters that will tune out the unwanted harmful frequencies. The data will send through the IoT analytics platform which can then be viewed from ThingView, and the filters can be controlled through Arest.io. The system was compared to an oscilloscope then used Root-Mean-Square Error for system reliability test and yielded 0.097696 for data without filter and 0.048485 for data with a filter. Lastly, the system effectively decreased the THD by 32% compared to an unfiltered source.

Comparative analysis of THD for square-wave inverter at different conduction modes

This paper proposes conduction schemes for the most common six-switch voltage sources inverter. Also, a comparative study of the output THD for different conduction modes of switches for a three-phase square wave inverter is done, as the harmonic content of any electrical system is important to analyze its performance. The harmonic distortion of the load voltage and load current is taken as the main constraint to evaluate the performance of the three-phase inverter. So, control strategies for various loads are executed for different modulation schemes of inverter switches using MATLAB/Simulink software. Obtained results show that 150° conduction gives the least THD for output current, and 170° conduction gives the least THD for output voltage for three-phase inverters. Also, harmonic contents are reduced using a passive LC filter at the output of the inverter.

A Pneumatic Low-Pass Filter for High-Fidelity Cuff-Based Pulse Waveform Acquisition.

Cuff-based pulse waveform acquisition (CBPWA) devices are reliable solutions for non-invasive cardiovascular diagnostics. However, poor signal resolution has limited clinical applications. This study aims to demonstrate the improved signal quality of CBPWA devices by implementing passive pneumatic low-pass filters (pLPF). Conventionally, pressure sensor output resolution is a percentage of the operating range. Therefore, measurement of small pressure changes in a large range must sacrifice signal resolution to accommodate for the large mean pressures. We design a pLPF to obtain the running mean pressure and combine it with a high-resolution differential pressure sensor for isolating the signal's pulsatile component. Thirty-one volunteers participated in a device proof-of-concept study at Caltech. Volunteers were measured at rest in the supine position on the left arm. The filtering behavior is mathematically modeled and experimentally verified, showing good agreement between measured and predicted cutoff frequencies. In the human study, the device successfully captured high-fidelity pulse waveform measurements for all volunteers: a blood pressure (BP) reading was followed by inflate-and-hold acquisition in diastolic BP (DBP), mean arterial pressure (MAP), and supra systolic BP (sSBP). The study demonstrated the reliability and high signal resolution of pLPF for CBPWA. Considering the widespread use of the brachial cuff, a system for high-resolution CBPWA motivates the clinical implementation of non-invasive pulse waveform analysis (PWA).

Multi‐criteria decision‐making approach for optimal and probabilistic planning of passive harmonic filters in harmonically polluted industrial network with photovoltaic resources

AbstractNowadays, nonlinear loads are widely employed within the industrial applications that cause harmonic distortions in the network. Passive harmonic filters stand out as the preeminent and cost‐efficient remedy for mitigating the impact of harmonic distortions. Any changes in power system conditions such as load variability and photovoltaic resources uncertainty have a significant impact on the harmonic conditions which can affect the quantity and positioning of passive harmonic filters. Hence, in this paper, a method including an innovative optimization problem is proposed for probabilistic planning of passive harmonic filters considering system conditions variability, which is solved by heuristic methods and multi‐criteria decision‐making techniques. By doing this, a solution is obtained where grid losses and the passive harmonic filter costs are minimized and the power factor and frequency response are improved on selected buses. Also, in this paper, the index that gauges the severity of total harmonic distortion is proposed to determine the worst case of the network in terms of harmonic distortions which is so vital for system operators, especially the systematic approach to designing passive harmonic filters. To indicate the efficiency of the proposed approach, the electrical system of an actual Iranian copper mine of significant scale is employed, featuring the integration of non‐linear loads.

Multi-sensor remote sensing image alignment based on fast algorithms

Abstract Remote sensing image technology to the ground has important guiding significance in disaster assessment and emergency rescue deployment. In order to realize the fast automatic registration of multi-sensor remote sensing images, the remote sensing image block registration idea is introduced, and the image reconstruction is processed by using the conjugate gradient descent (CGD) method. The scale-invariant feature transformation (SIFT) algorithm is improved and optimized by combining the function-fitting method. By this way, it can improve the registration accuracy and efficiency of multi-sensor remote sensing images. The results show that the average peak signal-to-noise ratio of the image processed by the CGD method is 25.428. The average root mean square value is 17.442. The average image processing time is 6.093 s. These indicators are better than the passive filter algorithm and the gradient descent method. The average accuracy of image registration of the improved SIFT registration method is 96.37%, and the average image registration time is 2.14 s. These indicators are significantly better than the traditional SIFT algorithm and speeded-up robust features algorithm. It is proved that the improved SIFT registration method can effectively improve the accuracy and operation efficiency of multi-sensor remote sensing image registration methods. The improved SIFT registration method effectively solves the problems of low accuracy and long time consumption of traditional multi-sensor remote sensing image fast registration methods. While maintaining high registration accuracy, it improves the image registration speed and provides technical support for a rapid disaster assessment after major disasters such as earthquakes and floods. And it has an important value for the development of the efficient post-disaster rescue deployment.

Analysis and Mitigation of Harmonics Distortion with Optimization Capacitor Banks and Single-Tuned Passive Filters

Electrical system power supplies always require a completely sinusoidal voltage signal. But for a variety of reasons, utilities often struggle to maintain these desired conditions. Deviations of voltage and current waveforms from a sinusoidal form are called harmonic distortions. Harmonic distortions in power networks are increasing due to the widespread use of non-linear loads. In this article we will analysis at a single-tuned passive filter and optimization using a capacitor bank. Load-current analysis determines the efficiency of the filter application by calculating the load bus voltage and total harmonic distortion (THD). To simulate the work, the Electrical Transient Analyzer Program (ETAP) software was used. This system was created specifically for this simulation and does not represent a real system. This model tests the effects of injecting harmonic currents into a power grid through a variable speed drive (VFD). The filter is attenuated with a capacitor bank.

Design and Performance Analysis of New Multilevel Inverter for PV System

Multilevel inverters (MLIs) have recently attracted more attention in medium-voltage and high-power applications as they can provide an effective interface with photovoltaic (PV) systems. Conventional MLIs are used to generate higher voltage levels, which improve power quality and reduce the requirement for passive filters. However, recent research has focused on designing new MLI topologies using reduced switch counts and less voltage stress. This study, as such, proposes a new nine-level symmetric MLI for PV systems with a minimum number of switches. This decrease in the number of switches reduces the voltage stress across the switches and the number of driving circuits, which lowers the complexity of the control circuit and, as a result, lowers the cost and size of the system. This article compares the proposed MLI with other topologies based on the DC sources, switches count, gate driver circuits (Ngd), total standing voltage per unit (TSVPU), cost function (CF), and components count per level (CC/L). The proposed topology is integrated with the PV system. MATLAB software is used to evaluate the performance of MLI at step change in irradiance and under variable load conditions. The total harmonic distortion (THD) of the proposed topology is reduced with the implementation of phase disposition pulse width modulation (PD-PWM). In addition, PD-PWM is compared with phase opposition disposition pulse width modulation (POD-PWM) and alternative phase opposition disposition pulse width (APOD-PWM) modulation techniques. The simulation results reveal the improved performance of the proposed topology at variable irradiance and under varying load conditions. The comparison results reveal minimum (TSVPU), CC/L, CF, and switch count compared to existing topologies. Hence, the proposed topology of MLI is cost-effective and superior in all aspects compared to other topologies. In summary, it offers overall improved performance, and thus, it is feasible for the PV system.

Robust Integral Sliding Mode Control for Transient Voltage Support From Bidirectional Converter-Based Active Filters in Microgrids

The DC-AC conversion in microgrids leads to second-order oscillations in the DC side voltages and source currents. These oscillations are mitigated using either active or passive filters. Active filters are preferred, as they mitigate oscillations with lesser component size than passive filters. The active filters are regulated to absorb the harmonic ripples at the ripple frequency, and do not provide any voltage support during DC bus voltage fluctuations due to load changes. In this paper, a Robust Integral Sliding Mode Control (RISMC) is proposed to regulate Bidirectional Converter (BDC) based DC active filters to facilitate voltage conditioning along with reduction of second-order harmonics which are caused due to DC-AC conversions. The proposed RISMC enhances capability of the BDC active filters to provide DC bus voltage conditioning in case of transience during load variations and uncertain voltage fluctuations. The proposed control consists of a nominal dual-loop PI control which regulates the voltage of the storage capacitor of BDC and a non-linear integral sliding mode control which regulates DC bus voltage. The proposed control mitigates voltage and current ripples hence preventing them to propagate towards the sources while providing additional voltage support functionality. The proposed control is verified through simulations and experimentation.

Passive CM Filter Configuration for a Multistage Grid-Tied Solid State Transformer

<bold xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">This work proposes a common mode (CM) filter configuration for a grid-tied two-stage AC/DC solid state transformer (SST). The proposed CM filter utilizes passive components along with the heat-sinks of the individual power converter stages to mitigate the overall conducted emissions (CE) injected by the SST system into the grid. The working principle of the proposed CM filter is analyzed and elucidated using CM equivalent circuit models. In addition to CE reduction with the proposed CM filter, it is also demonstrated that the heat-sinks of the SST system can be closer to ground-potential while being impedance grounded. The effectiveness of the proposed CM filter is validated by experimentally measuring the CE of the grid-tied SST system using a Line Impedance Stabilization Network (LISN).</b>

A Dual Quasi Z-Source Based T-Type Five-Level Inverter With Improved HERIC Structure for Photovoltaic Applications

A new single-stage, T-type five-level inverter, which is based on a dual quasi Z-source, and an improved HERIC structure has been proposed in this paper. It is envisaged that the proposed power converter could find applications in the area of grid-connected PV generation. The conventional topologies, which are based on two-stage conversion are bulky and expensive. The proposed single-stage system overcomes these disadvantages. Furthermore, the issue of leakage current, which is of paramount interest in PV systems is addressed by the adaptation of a PWM scheme along with the employment of passive filters. It is shown that the leakage current is effectively suppressed by the elimination of the high-frequency transitions across the parasitic capacitance due to the combined effort of the PWM scheme and the filter. The proposed power converter also displays the capability of supporting reactive power, which is one of the essential requirements for the present-day PV inverters. The steady-state and the dynamic performances of the proposed power converter are assessed with simulation studies and are then experimentally validated. A comparative study of the proposed power converter with the existing quasi-Z-source-based power converters is also undertaken, which reveals the advantages of the proposed configuration.

Investigation of efficient multilevel inverter for photovoltaic energy system and electric vehicle applications

Introduction. This research presents a simple single-phase pulse-width modulated 7-level inverter topology for renewable system which allows home-grid applications with electric vehicle charging. Although multilevel inverters have appealing qualities, their vast range of application is limited by the use of more switches in the traditional arrangement. As a result, a novel symmetrical 7-level inverter is proposed, which has the fewest number of unidirectional switches with gate circuits, providing the lowest switching losses, conduction losses, total harmonic distortion and higher efficiency than conventional topology. The novelty of the proposed work consists of a novel modular inverter structure for photovoltaic energy system and electric vehicle applications with fewer numbers of switches and compact in size. Purpose. The proposed system aims to reduce switch count, overall harmonic distortions, and power loss. There are no passive filters required, and the constituted optimizes power quality by producing distortion-free sinusoidal output voltage as the level count increases while reducing power losses. Methods. The proposed topology is implemented with MATLAB/Simulink, using gating pulses and various pulse-width modulation methodologies. Moreover, the proposed model also has been validated and compared to the hardware system. Results. Total harmonic distortion, number of power switches, output voltage, current, power losses and number of DC sources are investigated with conventional topology. Practical value. The proposed topology has proven to be extremely beneficial for implementing photovoltaic-based stand-alone multilevel inverter and electric vehicle charging applications.

High-Frequency Oscillation Suppression Strategy for Flexible DC Transmission Systems Based on Additional Joint Damping

Flexible DC transmission systems experience negative damping characteristics in the high-frequency range due to the delay in the system control link. This can lead to interactions between the impedance of modular multilevel converters (MMCs) and AC transmission lines, resulting in high-frequency oscillation (HFO) issues. To resolve this problem, a simplified MMC control model was developed, taking into account the current inner loop control link. The Sobol method was employed to analyze the factors influencing the impedance characteristics of MMC. Additionally, a combined approach involving a virtual passive filtering method and an equivalent current sampling method was proposed to provide additional damping. The study compared and analyzed the impact of additional damping control on the impedance characteristics and system stability of MMCs. Lastly, a flexible direct current grid connection simulation model was constructed using PSCAD to validate the effectiveness of the proposed additional damping control strategy.

Chamfered edge filtering ultra-wideband antenna integrated with H-unit cell-loaded feed line for improved out-of-band rejection

Abstract This paper proposes a passive filtering antenna for ultra-wideband (UWB) applications. The edge chamfering technique is adopted to construct the UWB antenna. The designed UWB antenna has a fractional bandwidth of 135%. A low-pass filter (LPF) is embedded on the feed line of the UWB antenna to convert it into a narrowband antenna that works at 2.45 GHz with 29.5% fractional bandwidth by removing the high-frequency components. The LPF is a transmission line with a stepped impedance configuration loaded with an H-shaped unit cell. The proposed filtering antenna is fabricated and tested. The measured results indicate the gain is &gt;4.2 dBi and the radiation efficiency is &gt;75%.

Passive Power Line Communication Filter Design and Benchmarking Using Scattering Parameters

NB-PLC (narrowband power line communication) is a method of data communication that involves superimposing a relatively high-frequency signal (9 kHz to 500 kHz), which contains data, onto the power grid’s low frequency (50 to 60 Hz) signal. While using the existing power grid as a transmission medium is convenient, the power grid was not designed for this purpose, leading to challenges such as conducted emissions and infrastructure limitations. To overcome these technical challenges, passive filters are necessary. This article presents the design, simulation (using scattering parameters), and evaluation of an NB-PLC filter by comparing it to commercially available filters. Our proposed design and benchmarking methods enable the accurate prediction of the filter’s behavior in field conditions. After comparing our filter with commercially available filters, we observed that it exhibits superior characteristics. Specifically, our filter has the best insertion loss versus frequency, achieved three times higher attenuation at 50 kHz (−130 dB) compared to the best commercially available filter (−40 dB), and has a power consumption of 0.6 W, which is comparable to the most power-efficient commercial filter (0.5 W). Additionally, our filter has the second best input and output impedance of 3.6 Ω within the frequency range of 35–95 kHz.

Realization of Low-Loss Fully Passive Harmonic Rejection N-Path Filters

This work presents a low-loss fully passive harmonic rejection (HR) N-path filter that performs finite impulse response (FIR) filtering within its core by sequentially charging the baseband capacitors and exploiting combined charge sharing and capacitor stacking techniques. The proposed HR N-path filter achieves an in-band (IB) gain of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula> 2 to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$+$</tex-math> </inline-formula> 0.5 dB across the 0.25-2 GHz frequency range while consuming 2.3–15.7 mW of power. It achieves an HR ratio (HRR) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&gt;$</tex-math> </inline-formula> 46/48 dB with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&gt;$</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">$+$</tex-math> </inline-formula> 8/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$+$</tex-math> </inline-formula> 11 dBm third/ fifth-order harmonic blocker P1dB.

An active filtering strategy of LCL filter for inverter power supply of electromagnetic pump

The inverter power supply for an electromagnetic pump is a motor controller based on a three-phase inverter. This inverter needs to be followed by an LCL filter as a filter for connecting the electromagnetic pump. But the LCL filter has a large resonance spike at the resonance point. This can cause relatively large interference to the control system and also increase the harmonics of the inverter power supply output current. Therefore, it is necessary to suppress the resonant spikes of the LCL filter. In this paper, an active filtering strategy based on a trap is proposed by comparing the existing passive filtering strategies. The trap can be used to generate an anti-resonant peak at the resonance point of the LCL, which is used to cancel the resonant spike of the LCL filter. This method ensures the resonant peak suppression effect without affecting the filtering effect of the LCL filter.