Filter For Mitigation Research Articles

An Optimal Compensation Method of Shunt Active Power Filters for System-Wide Voltage Quality Improvement

Conventional control strategy of a shunt active power filter (SAPF) for harmonic and unbalance mitigation is to locally compensate the harmonic and unbalance component of load current, which may not be economical enough for a multinode system with distributed nonlinear loads (NLLs) and unbalanced loads (UBLs). Actually the SAPF will influence voltage at neighboring nodes, therefore it is promising to optimize SAPF control method from a system perspective. For this purpose, first this paper analyzes the drawbacks of a local compensation method and proposes the optimization problem for the system-wide control of SAPF in a simple single-phase system. Next, the idea is extended to a complex multinode three-phase system, and a matrix model for harmonic and unbalance analysis is established. Finally, a matrix-based least square method is utilized to solve the optimization problem, thus a generalized SAPF optimal compensation method for system-wide voltage quality improvement is obtained. Based on the proposed method, a small amount of SAPFs can be scientifically utilized to improve the overall voltage quality of a multinode system with a large amount of distributed NLLs and UBLs, with fast response, good performance, and reduced cost. Simulations and experimental results are provided to verify the effectiveness of the proposed method.

Multi‐domain collaborative filter for interference suppressing

Filters with antenna arrays are widely used for interference suppression in the temporal domain, frequency domain, space domain and so on. Meanwhile, the interference mitigation performance of a single-domain-based filter depends on a noticeable difference between the target signal and interference in the corresponding domain. However, the interference cannot be efficiently suppressed by a single-domain-based filter when the difference in this individual domain is small. To solve this problem, a multi-domain collaborative oblique projection filter is proposed in this study. First, multi-domain spaces are theoretically derived to distinguish the target signal and the interference, and then a multi-domain oblique projection operator is provided to recover the original target and suppress the interference. Depending on the multi-domain spaces, the filter has excellent performance when the difference is insignificant in each individual domain, whereas the performances of the single-domain-based filter and cascade filter degrade significantly. Finally, a space–polarisation–frequency domain collaborative filter based on oblique projection is given as an illustration. Performance analysis and simulation results are provided to illustrate the superiority of the proposed filter for interference mitigation.

Optimal C-type filter for harmonics mitigation and resonance damping in industrial distribution systems

Single-tuned passive filters offer reasonable mitigation for harmonic distortion at a specific harmonic frequency with a high filtering percentage, but resonance hazards exist. Traditional damped filters offer high-pass filtering for the high-frequency range, but suffer from extra ohmic losses. C-type filters may operate in a manner similar to the tuned filters with low damping losses and marginal resonance damping capabilities. In addition, they can be designed as damped filters with increased resonance damping capability. In this paper, a methodology that facilitates sizing for the C-type damped filter parameters for harmonics mitigation and resonance damping in balanced distribution system networks is presented and discussed using the impedance-frequency index. This index evaluates the resonance damping capability provided by the damped filters analytically rather than the conventional graphical method of impedance-frequency scanning. It shows how to size shunt passive filters, while making a full use of their damping capabilities. It can disclose the parallel resonance frequencies of the equivalent system-filter impedance. A comparative study of the new approach and a conventional filter design approach, which aims to minimize total harmonic current distortion, is presented. Numerous simulation results are provided to clarify the proposed methodology, advantages, and disadvantages.

Performance of Grid-Connected Solar Photovoltaic Systems with Single-Tuned and Double-Tuned Harmonic Passive Filters

The generated solar photovoltaic power can be stand-alone or grid-connected. In both systems, power quality issues arise and can affect the network. The harmonic distortions can affect the system significantly if they are not mitigated. This paper presents the performance of grid-connected solar photovoltaic systems with single-tuned and double-tuned filters for harmonics mitigation. The design aspects of each filter are presented and discussed. The simulation results are analyzed and validated using ETAP software.

Comparison of Three, Five and Seven Levels Diode Clamped Multilevel Inverter Topologies based Shunt Hybrid Active Power Filter for Harmonics Compensation with Equal DC Link

The multilevel inverter is coming out as a new type of power inverter choice for high power applications. This type of inverter can constitute high voltage and decrease harmonics by its own circuit topology. This paper presents comparison of three, five and seven levels diode clamped multilevel inverter (DCMLI) topologies based shunt hybrid active power filter for harmonics mitigation of the nonlinear loads. The compensation process is based on synchronous reference frame method. Theoretical analyses and simulation results are obtained from an actual industrial network model in PSCAD. The simulation results are presented for a proposed system in order to demonstrate that the harmonic compensation performance meets the IEEE-519 standard.

Extended Kalman filtering for joint mitigation of phase and amplitude noise in coherent QAM systems.

We numerically investigate our proposed carrier phase and amplitude noise estimation (CPANE) algorithm using extend Kalman filter (EKF) for joint mitigation of linear and non-linear phase noise as well as amplitude noise on 4, 16 and 64 polarization multiplexed (PM) quadrature amplitude modulation (QAM) 224 Gb/s systems. The results are compared to decision directed (DD) carrier phase estimation (CPE), DD phase locked loop (PLL) and universal CPE (U-CPE) algorithms. Besides eliminating the necessity of phase unwrapping function, EKF-CPANE shows improved performance for both back-to-back (BTB) and transmission scenarios compared to the aforementioned algorithms. We further propose a weighted innovation approach (WIA) of the EKF-CPANE which gives an improvement of 0.3 dB in the Q-factor, compared to the original algorithm.

New Control Algorithm for Single-Phase Series Active Power Filter

This article presents a single-phase series active power filter for mitigation of the load voltage harmonic content while maintaining the voltage on the DC side regulated without the support of a voltage source. The proposed series active power filter control algorithm eliminates the additional voltage source to regulate the DC voltage, and with the adopted topology, a coupling transformer is not used to interface the series active power filter with the electrical power grid. The article describes the control strategy that encapsulates the grid synchronization scheme, compensation voltage calculation, damping algorithm, and dead-time compensation. The topology and control strategy of the series active power filter have been evaluated in simulation software, and simulations results are presented. Experimental results, obtained with a developed laboratorial prototype, validate the theoretical assumptions and are within the harmonic spectrum limits imposed by the international recommendations of IEEE Standard 519.

Shunt hybrid active power filter for harmonic mitigation: A practical design approach

The increasing importance of Power Quality problems has been responsible for several improvements in Active Power Filter (APF) typologies in the last decade. The increased cost and switching losses make a pure shunt APF economically impractical for high power applications. In higher power levels shunt Hybrid Active Power Filter (HAPF) has been reported to be a useful approach to eliminate current harmonics caused by nonlinear loads. This paper presents a control strategy and design criteria for transformer-less shunt HAPF with special attention to the integration of series passive filter. The paper also compares the performance improvement of passive harmonic filter when modified as shunt HAPF. Experimental results obtained verify the viability and effectiveness of the proposed design criteria and control algorithm.

The Simplified Control of Three-Phase Four-Leg Shunt Active Power Filter for Harmonics Mitigation, Load Balancing and Reactive Power Compensation

In this paper, the simplified control of three-phase four-leg shunt active power filter for harmonics mitigation, load balancing and reactive power compensation is proposed. In order to calculate the harmonics, current imbalance and reactive power, the load currents are detected and transformed to dq0 variables. By using the low-pass filter, the fundamental active power current can be separated from the d-axis current. Therefore, the commanded active power filter currents are consist of d-axis harmonic currents, q-axis and 0-axis currents. These components are regulated by the PI controller with feedforward utility voltage via the four-leg space vector inverter. Moreover, the design guidelines of space vector phase-locked loop (PLL), current controllers and DC-bus voltage controller are also presented. Validity of the proposed control schemes is confirmed by the simulation.

PHOTOVOLTAIC SYSTEM WITH A DC–DC CONVERTER FED SHUNT ACTIVE FILTER FOR POWER QUALITY IMPROVEMENT USING ICos Φ ALGORITHM

This paper presents an operation of photovoltaic (PV)-based shunt active filter (SAF) for significant energy conservation, harmonic mitigation and reactive power compensation. When the PV system generates excessive or equal power required to the load demand, then the coordinating logic disconnects the service grid from the load and with a consequent reduction of panel tariff and global warming gasses. The PV module is connected to the DC side of SAF through the DC–DC converter. Converter switch is controlled by fuzzy-based perturb & observe (P&O) maximum power point tracking (MPPT) algorithm and it eliminates the drawback in the conventional PV system. The reference currents are extracted by the fuzzy logic controller-based ICos Φ control strategy. This proposed PV-SAF, if connected at the terminals of a small industry or a home or a small enlightening institution can avoid the use of interruptible power supply and individual stabilizer. An emulation using MATLAB Simulink is presented to validate the advantage of the proposed system.

Optimal Op eration of Photovoltaic System with a DC - DC Boost Converter FED SAF Using ICosφ Algorithm

This paper presents an optimal utilization of Photovoltaic (PV) solar system based Shunt Active Filter (PV-SAF) for harmonic mitigation, real and reactive power compensation at the point of common coupling (PCC) throughout the day. This PV system operated SAF reduces the energy consumption by disconnecting the utility grid from the load through semiconductor switches, when the PV system generates excessive or equal real power to the required load demand. However, the reduction of energy consumption is always desirable for the reduction of panel tariff and global warming gasses. The PV module is connected to the DC side of SAF through the DC-DC converter with fuzzy based Perturb & Observe (P&O) Maximum Power Point Tracking (MPPT) algorithm to eliminate the drawback of the conventional PV system by tracking maximum power point of the PV array is presented. The reference currents extract by the Fuzzy logic controller based ICosΦ control strategy. This proposed PV-SAF, if connected at the terminals of a small industry or a home or a small enlightening institution can avoid interruptible power supply, use of individual stabilizer and potential panel tariff over a 12 hour period. A MATLAB simulink is presented to validate the advantage of the proposed system.

A Novel Design of UPQC with Kalman Filter for Mitigation of Voltage and Current Disturbances

In this project proposed a new concept of optimal utilization of a unified power quality conditioner. The series inverter of the UPQC is controlled to perform simultaneous voltage sag/swell compensation and load reactive power sharing with the shunt inverter. Kalman filter is designed to remove the harmonic components of the supply voltage and load current. The proposed method operates both in the time and frequency domains allowing the selective compensation of voltage and current harmonics with fast dynamical responses. The simulation is conducted by using MATLAB/SIMULINK. The simulation result shows the proposed UPQC has a good effect in the mitigation of the voltage sag.

Real time implementation of PI and fuzzy logic controller based 3-phase 4-wire interleaved buck active power filter for mitigation of harmonics with id–iq control strategy

The “shoot-through” failure, one of the most hazardous failure modes encountered in conventional inverter circuit which is used as the main circuit of the active power filter (APF). Shoot-through phenomenon has few distinct disadvantages like; it introduces typical ringing, increases temperature rise in power switches, causes higher Electromagnetic Interference (EMI) and reduces the efficiency of the circuit. To avert the “shoot-through”, dead time control could be added but it deteriorates the harmonic compensation level. A novel 3-phase 4-wire active power filter (APF) based on interleaved buck (IB) DC-to-AC converter with the instantaneous active and reactive current component (id–iq) control strategy is proposed here to mitigate the harmonics having PI and fuzzy logic (FLC) controllers. This interleaved buck (IB) DC-to-AC converter is an augmented version of the conventional phase leg configuration and is innately immune to “shoot-through” phenomenon, with the elimination of special protection features required in conventional inverter circuits. Here in this paper, a comparison has been made between the compensation capabilities of the 3-phase IB-APF with the PI and fuzzy logic controller (FLC) used by id–iq control strategy under different supply voltage conditions. The performance of the control strategies have been evaluated in terms of harmonic mitigation and DC link voltage regulation. Extensive simulations have been carried out in the MATLAB / SIMULINK environment and also implemented using Real-Time Digital Simulator Hardware (RTDS-Hardware).

DESIGN AND SIMULATION OF SHUNT ACTIVE POWER FILTER FOR ASSIUT CEMENT COMPANY DC MOTOR DRIVE

This paper introduces a design and simulation of an adaptive shunt active power filter (APF) for harmonic mitigation and power factor (PF) correction of 630 kW DC motor (DCM) drive (called By Pass Motor Fan in production line # 2 in Assiut cement company). Due to the presence of power thyristor converters, a very bad PF and different harmonic components exist in the system, especially in the input current to the DCM drive. All measurements needed for complete analysis at the Medium Voltage (MV) supply source side and at Low Voltage (LV) motor drive side are performed using professional power quality (PQ) analysers and their associated software programs. The studied system is modelled and simulated using MATLAB Simulink software. The instantaneous active and reactive current components id and iq control method is used in this study to drive the shunt active filter. Therefore the harmonic contents at MV supply source and at point of common coupling (PCC) with the DCM drive are reduced to the standard values. Both digital simulation and practical measurements are presented and consistent. The results show that a good dynamic and steady-state performance of the system is achieved.

Real time digital simulation of shunt active filter for mitigation of current harmonics with P-Q theory

The main objective of this paper is to develop PI and Fuzzy logic controllers to analyze the performance of instantaneous active and reactive power (p-q) control strategy for extracting reference currents of shunt active filters under balanced, un-balanced and balanced non-sinusoidal conditions. When the supply voltages are balanced and sinusoidal, then all controllers converge to the same compensation characteristics. However, when the supply voltages are distorted and/or un-balanced sinusoidal, these control strategies result in different degrees of compensation in harmonics. The p-q control strategy with PI controller is unable to yield an adequate solution when source voltages are not ideal. Extensive simulations were carried out; simulations were performed with balance, unbalanced and non sinusoidal conditions. Simulation results validate the dynamic behavior of Fuzzy logic controller over PI controller. The 3-ph 4-wire shunt active filter system is also implemented on a real time digital simulator (RTDS Hardware) to further verify its effectiveness. The detailed simulation and RTDS Hardware results are included. Key words: Harmonic compensation, shunt active filter (SAF), P-Q control strategy, PI controller, fuzzy controller, RTDS hardware.

A Current Source Converter-Based Active Power Filter for Mitigation of Harmonics at the Interface of Distribution and Transmission Systems

A medium-power current source converter (CSC)-based shunt active power filter (APF) system is designed and implemented to suppress the amplification of low-order harmonics at the medium-voltage (MV) interface bus between the distribution and transmission systems, owing to the presence of large shunt capacitor banks installed only for reactive power compensation. Four CSC-based APF modules designed at 1.0 kV are operated in parallel and connected to the 31.5-kV MV bus via a specially designed coupling transformer. In each APF module, a specially designed LC-type input filter eliminates the switching ripples, and active damping method embedded into the control software suppresses harmonic frequencies around the corner frequency of the input filter. The resulting system can operate at relatively high frequencies in the range from 2.0 to 3.0 kHz, depending upon which selected harmonics among 5th, 7th, 11th, and 13th are to be eliminated. Furthermore, in order to reduce the installed capacity of CSCs, selective harmonic amplification method is applied to the APF system described in the paper. MV APF system has been built as a mobile system for temporary connection to a problematic MV interface bus until a permanent solution is found for that location in the distribution system.

Modelling, simulation and implementation of optimisation algorithm based shunt active filter for harmonics mitigation of non-linear loads

Modelling, simulation and implementation of optimisation algorithm based shunt active filter for harmonics mitigation of non-linear loads

Mitigation of Arc Furnace Voltage Flicker Using an Innovative Scheme of Adaptive Notch Filters

This paper presents an innovative application of the adaptive notch filters for flicker disturbance extraction and mitigation. This paper demonstrates a new cascaded scheme of adaptive notch filters and regular notch filters. This suggested scheme is used for tracking the frequencies of flicker disturbances and for the instantaneous extraction of these disturbances. Furthermore, this paper exhibits the utilization of a developed compensation strategy that employs shunt and series power conditioners to intelligently mitigate voltage flicker that emanates from electric arc furnaces. The proposed schemes for frequency tracking, disturbance extraction, and flicker mitigation are verified by simulation results using real voltage and current flicker waveforms of the ac arc furnace.

A High-Temperature Superconducting Notch Filter to Suppress Cellular-Band Interference in Radiotelescopes

An experimental high-temperature superconducting four-pole filter for mitigation of the IMT 2000 cellular band in radiotelescopes is presented. The filter uses a novel capacitive cross-coupling to achieve a quasi-elliptic response. Composite right/left-handed (CRLH) zeroth-order resonators are used to avoid harmonic generation throughout the UHF and L-bands.

Fuzzy Controller Based 3Phase 4Wire Shunt Active Filter for Mitigation of Current Harmonics with Combined p-q and Id-Iq Control Strategies

As more and more variable frequency drives (VFDs), electronic ballasts, battery chargers, and static Var compensators are installed in facilities, the problems related to harmonics are expected to get worse. As a result Active power filter (APF) gains much more attention due to excellent harmonic compensation. But still the performance of the active filter seems to be in contradictions with different control strategies. This paper presents detailed analysis to compare and elevate the performance of two control strategies for ex-tracting reference currents of shunt active filters under balanced, un-balanced and non-sinusoidal conditions by using Fuzzy controller. The well known methods, instantaneous real active and reactive power method (p-q) and active and reactive current method (id-iq) are two control methods which are extensively used in active filters. Extensive Simulations are carried out with fuzzy controller for both p-q and Id-Iq methods for different voltage conditions and adequate results were presented. Simulation results validate the superior per-formance of active and reactive current control strategy (id-iq) with fuzzy controller over active and reactive power control strategy (p-q) with fuzzy controller.