Showing papers on "Active filter published in 2016"
TL;DR: In this paper, a concept of active filter integration for single-phase AC/DC converters is reported, which can provide simultaneous functions of power factor correction, DC voltage regulation, and active power decoupling for mitigating the lowfrequency DC voltage ripple, without an electrolytic capacitor and extra power switch.
Abstract: Existing methods of incorporating an active filter into an AC/DC converter for eliminating electrolytic capacitors usually require extra power switches. This inevitably leads to an increased system cost and degraded energy efficiency. In this paper, a concept of active-filter integration for single-phase AC/DC converters is reported. The resultant converters can provide simultaneous functions of power factor correction, DC voltage regulation, and active power decoupling for mitigating the low-frequency DC voltage ripple, without an electrolytic capacitor and extra power switch. To complement the operation, two closed-loop voltage-ripple-based reference generation methods are developed for controlling the energy storage components to achieve active power decoupling. Both simulation and experiment have confirmed the eligibility of the proposed concept and control methods in a 210-W rectification system comprising an H-bridge converter with a half-bridge active filter. Interestingly, the end converters (Type I and Type II) can be readily available using a conventional H-bridge converter with minor hardware modification. A stable DC output with merely 1.1% ripple is realized with two 50-μF film capacitors. For the same ripple performance, a 900-μF capacitor is required in conventional converters without an active filter. Moreover, it is found out that the active-filter integration concept might even improve the efficiency performance of the end converters as compared with the original AC/DC converter without integration.
135 citations
TL;DR: A transformerless hybrid series active filter using a sliding-mode control algorithm and a notch harmonic detection technique and a computational delay compensation method, which accurately generates reference voltages, is implemented on a single-phase distribution feeder.
Abstract: In this paper, a transformerless hybrid series active filter using a sliding-mode control algorithm and a notch harmonic detection technique are implemented on a single-phase distribution feeder. This method provides compensation for source current harmonics coming from a voltage fed type of nonlinear load (VSC) and reactive power regulation of a residential consumer. The realized active power filter enhances the power quality while cleaning the point of common coupling (PCC) from possible voltage distortions, sags, and swells initiated through the grid. Furthermore, to overcome drawbacks of real-time control delay, a computational delay compensation method, which accurately generates reference voltages, is proposed. Based on an improved compensation strategy, while the grid current remains clean even with a small compensation gain, voltage disturbances initiated by the power system are obstructed by the compensator, and the PCC became free of voltage harmonics and protected from sag and swell. Simulation and experimental results carried on a 1.6-kVA prototype are presented and discussed.
109 citations
TL;DR: The filtering action of SAPF is able to achieve the total harmonic distortion (THD) of supply current within the limit specified by an IEEE-519 standard.
Abstract: This paper presents a three-phase shunt active power filter (SAPF) for mitigating power quality problems at the distribution level. Power quality problems such as harmonics, reactive power, and unbalancing in the loads are mitigated for both unity power factor and voltage regulation modes. A three-phase voltage-source converter (VSC) is used as an SAPF for performing all these functions. The linear optimum discrete time filtering technique namely Wiener filtering-based control algorithm is developed for the extraction of reference supply currents from distorted load currents. The performance of Wiener filter is compared with least mean square (LMS) adaptive filter-based control algorithm. Experimental validation of proposed control algorithm has been performed on a prototype developed in the laboratory. The filtering action of SAPF is able to achieve the total harmonic distortion (THD) of supply current within the limit specified by an IEEE-519 standard.
108 citations
TL;DR: In this paper, the design of an electromagnetic interference (EMI) filter for a low-voltage high-current induction-motor drives supplied by dc power grids is presented.
Abstract: This paper presents the design of an electromagnetic interference (EMI) filter for a low-voltage high-current induction-motor drives supplied by dc power grids. In order to effectively design the EMI filter, a suitable common-mode/differential-mode (CM/DM) separation technique has been used. Due to the high operating currents, the software-based separation technique using time-domain measurements has been applied. The proposed technique allows the CM and DM sections of the EMI filter to be properly selected in a more economical way, i.e., without the need of a dedicated hardware or costly radio frequency (RF) instrumentation. The design has been done according to a power-density criterion. The effectiveness of the proposed CM/DM separation technique and the EMI filter features/performance has been assessed by experimental tests, carried out with an 1.1-kW pulsewidth modulation (PWM) inverter-fed induction-motor drive, supplied by a 48-V dc power grid.
94 citations
TL;DR: This paper proposes an active filter integrated single-phase qZSI topology to transfer the low-frequency (second harmonic) power ripple directly from the ac load to the active filter ac capacitor, and comparative evaluation and experimental results verify the proposed new topology system.
Abstract: The second harmonic pulsating power flows through the dc side of a single-phase quasi-Z-source inverter (qZSI), which requires bulky capacitor banks and inductors to suppress low-frequency ripple of dc-link voltage and inductor currents in the passive ripple reduction way. However, the resultant huge qZS network seriously deteriorates the system reliability, efficiency, volume, weight, and cost. This paper proposes an active-filter-integrated single-phase qZSI to transfer low-frequency power ripple directly from ac load to active filter's ac capacitor, so that low-frequency power ripple does not present in dc side anymore and constant inductor currents and constant capacitor voltages are ensured. Thus, much small qZS impedance is employed to only smooth high-frequency ripple and active filter's capacitor supports ac voltage (large ripple allowed) with small capacitance. The operation principle, parameter design method, and modeling and control strategy of the proposed topology are investigated. Comparative evaluation, simulation, and experimental results verify the proposed new topology system.
92 citations
1 Oct 2016
TL;DR: In this article, the authors present the different applications, challenges and trends for traditional active and passive harmonic filters for reduction of harmonic distortion and optimization of the power quality, and analyze the advantages and disadvantages of active versus passive filter technologies.
Abstract: The goal of this paper is to present the different applications, challenges and trends for traditional active and passive harmonic filters for reduction of harmonic distortion and optimization of the power quality. Emphasis is put on real cases applied in the industry for passive tuned filters and for active harmonic filters analyzing the advantages and disadvantages of active versus passive filter technologies.
91 citations
17 Jul 2016
TL;DR: A hierarchical control structure is proposed that includes two control levels that manages the compensation level of voltage harmonic distortion of sensitive load bus (SLB) and effectiveness of the proposed control scheme is demonstrated through simulation studies.
Abstract: This paper proposes a control architecture of distributed generators (DGs) inverters and shunt active power filters (APFs) in microgrids to compensate voltage harmonics in a coordinated way. For this, a hierarchical control structure is proposed that includes two control levels. The primary (local) control consists of power controllers, selective virtual impedance loops and proportional-resonant (PR) voltage/current controllers. The secondary (central) control manages the compensation level of voltage harmonic distortion of sensitive load bus (SLB). Compensation of SLB harmonics by control of DGs may cause excessive voltage harmonics at the terminal of one or more of DGs interface inverters and/or overloading of the inverters. After occurrence of each case, active power filter (APF) participates in harmonic compensation and consequently the compensation efforts of DGs decrease to avoid excessive harmonics or overloading of interface inverters. Effectiveness of the proposed control scheme is demonstrated through simulation studies.
88 citations
TL;DR: In this article, the authors presented a modeling technique for a hybrid commonmode (CM) filter, which is composed of an active filter and a passive filter to reduce the size and weight of conventional passive EMI filters.
Abstract: Hybrid electromagnetic interference (EMI) filters (HEFs), which are composed of an active filter and a passive filter, have been proposed to reduce the size and weight of conventional passive EMI filters in literatures. However, accurate models that can be used to predict the stability and performance of HEFs have not been developed. To cope with this, this paper presents a modeling technique for a hybrid common-mode (CM) filter. The technique can be applied to the modeling of other HEFs. Critical component models were first developed for the HEF. HEF's overall model was further developed based on these individual component models. Experimental results validated that the developed model can successfully predict the stability and performance of active/hybrid CM filters.
81 citations
TL;DR: In this paper, an active filter with resonant current control is proposed to suppress a harmonic resonance in the distribution power system, which is similar to the so-called whack-a-mole phenomenon.
Abstract: A shunt active filter operated as a harmonic conductance is able to suppress a harmonic resonance in the distribution power system. However, due to the inherent phase-lagging in digital signal processing, the active filter really behaves as a harmonic admittance instead of conductance. This may induce unintentional harmonic amplification at other locations in the feeder when starting the active filter, which is similar to the so-called whack-a-mole phenomenon. This paper presents an active filter with resonant current control to suppress a harmonic resonance. The current control is realized by parallel-connected bandpass filters tuned at harmonic frequencies to ensure that the active filter functions as an approximately pure conductance. The conductance at dominant harmonic frequencies can be separately and dynamically adjusted to guarantee the damping performance. In addition, in order to address the harmonic resonance, the line distributed-parameter model of a radial feeder is developed considering harmonic damping by variable conductance and admittance, respectively. Simulation results show that the active filter with the resonant control provides a better damping performance compared with other control methods. A lab-scale prototype circuit rated at 220 V/20 kVA also validates the effectiveness of the proposed method.
70 citations
TL;DR: A model predictive direct power control (DPC) is proposed to achieve the purpose of this new topology through predicting the capacitor voltage of APF at each sampling period and ensuring the APF power to track the second harmonic power of single-phase qZSI.
Abstract: The active power filter (APF) that consists of a half-bridge leg and an ac capacitor is integrated in the single-phase quasi- Z -source inverter (qZSI) in this paper to avoid the second harmonic power flowing into the dc side. The capacitor of APF buffers the second harmonic power of the load, and the ac capacitor allows highly pulsating ac voltage, so that the capacitances of both dc and ac sides can be small. A model predictive direct power control (DPC) is further proposed to achieve the purpose of this new topology through predicting the capacitor voltage of APF at each sampling period and ensuring the APF power to track the second harmonic power of single-phase qZSI. Simulation and experimental results verify the model predictive DPC for the APF-integrated single-phase qZSI.
69 citations
24 Jun 2016
TL;DR: In this article, a single-phase grid-side pulsewidth-modulated converter with an LCL filter is proposed to suppress the high-frequency resonance of high-speed railway (HSR) lines.
Abstract: High-frequency harmonic resonance has been a frequently encountered issue in railway traction power-supply system (TPSS), since high-speed trains that are equipped with ac–dc–ac traction drive system were serviced in China high-speed railway (HSR) lines. This high-frequency harmonic resonance is excited when the frequency of harmonic components introduced by the grid-side traction ac–dc converter in trains matches the inherent resonance frequency of TPSS. Traditional solutions for this HSR high-frequency resonance focus on providing damping to the TPSS. In this paper, with a focus on avoiding the resonance excitation, a solution from the trains’ perspective through the adoption of a single-phase grid-side pulsewidth-modulated converter with an LCL filter in high-speed trains is proposed. Compared with the traditional traction system topology with an ${L}$ -type filter, the total inductance value of an LCL filter is designed to be the same with that of an ${L}$ -type filter and there is only an additional small capacitor adopted in the proposed solution. Therefore, the design in this paper meets the space and weight requirements of the traction converter system. In this paper, an all-parallel 27.5-kV 50-Hz autotransformer-fed power-supply system and the proposed grid-side LCL filter-based converters are modeled and simulated in real-time hardware in loop experimental platform. The results show that the proposed solution can effectively suppress the high-frequency resonance of TPSS.
TL;DR: In this article, a new type of electric spring (ES) with current-source inverters (CSIs) is proposed to improve the performances of ESs, where the input current is separated into fundamental part and other components with the help of the single phase dq 0 transformation.
Abstract: A novel control strategy of direct current control and harmonic suppression function, similar to the control of active power filter (APF), is proposed using a new type of electric spring (ES) with current-source inverters (CSIs) to improve the performances of ESs. Compared with the existing control methods, total harmonic distortion can be greatly reduced by changing voltage-source inverters to CSIs and also by replacing voltage control with direct current control. System performance can also be improved further by an additional harmonic suppression function, of which the control is similar to APF where the input current is separated into fundamental part and other components with the help of the single-phase dq 0 transformation. The concept of ESs can also be interpreted more clearly by the proposed direct current control. Operating principles of the proposed ES and control are well illustrated. The effectiveness of the control strategy has been validated by the simulation results.
TL;DR: An optimal active power filter (APF) based on modular multilevel converter (MMC) without load current and lower arm current sensors is proposed, which indicates a low hardware resource utilization and calculation delay of the designed controller.
Abstract: An optimal active power filter (APF) based on modular multilevel converter (MMC) without load current and lower arm current sensors is proposed. Its control algorithm mainly includes predictive harmonic current control, fundamental frequency control, and dc voltage control. Comparing to direct current control, the first two subcontrollers transfer the harmonic and fundamental active/reactive power current to voltage references, which are suitable to generate the modulation signals to MMCs as well as two-level converters. Their full digital optimization structures combined with the MMC voltage and current control are detail discussed and implemented on field programmable gate array. The synthesis result indicates a low hardware resource utilization and calculation delay of the designed controller. The experimental results on an MMC-based APF prototype verified the static and dynamic performances of the proposed algorithm.
TL;DR: In this article, the authors presented an improved self-charging algorithm by introducing a new feature known as step size error cancellation for better performance of DC-link capacitor voltage control in single-phase shunt active power filter (SAPF).
Abstract: This study presents an improved self-charging algorithm by introducing a new feature known as step size error cancellation for better performance of DC-link capacitor voltage control in single-phase shunt active power filter (SAPF). Previous works of self-charging algorithms were focused only for steady-state operation by using either proportional-integral (PI) or fuzzy logic control (FLC). However, in a certain operation of any power system, dynamic operation may also happen. Thus, by introducing step size error cancellation as an additional feature to the self-charging algorithm, both steady state and dynamic operations can be covered. For evaluation and comparison analysis, self-charging with PI and FLC algorithms have been developed too. All the algorithms were simulated in MATLAB-Simulink, respectively, together with the single-phase SAPF. For hardware implementation, the proposed algorithm was programmed in TMS320F28335 digital signal processing board. The other two conventional self-charging algorithms were also programmed for comparison purposes. From the results and analysis, the proposed self-charging with step size error cancellation shows the best performance with high accuracy, fast response time and less overshoot and undershoot. It performs well in both steady state and dynamic operations as compared with both previous self-charging techniques which only work well in steady-state operation.
TL;DR: A novel wide-bandwidth second-order voltage-mode all-pass filter derived from a canonical single transistor bandpass filter that operates at multigigahertz frequencies and achieves the highest delay-band width product compared to previously published CMOS all- pass filters known to the authors.
Abstract: This brief presents a novel wide-bandwidth second-order voltage-mode all-pass filter derived from a canonical single transistor bandpass filter. The core of the circuit consists of only one transistor, two resistors, and two energy storage elements. The operation of the proposed filter is validated experimentally. A filter implemented in an IBM 0.13- $\mu\mbox{m}$ CMOS was measured to have a 55-ps group delay across a 6-GHz bandwidth while consuming 18.5 mW from a 1.5-V supply. This work experimentally demonstrates a CMOS all-pass filter that operates at multigigahertz frequencies and achieves the highest delay-bandwidth product compared to previously published CMOS all-pass filters known to the authors.
TL;DR: In this article, a sensorless control strategy for pulsewidth modulated active filters is presented, which uses only two current sensors, which are located in the grid interface, and does not require algorithms for disturbance estimation.
Abstract: This paper presents a sensorless control strategy for pulsewidth modulated active filters. The complete solution uses only two current sensors, which are located in the grid interface. The compensation is performed by the imposition of sinusoidal current references in the grid, and does not require algorithms for disturbance estimation. The virtual flux concept for grid synchronization and multiple quasi-resonant compensators in the current scheme are employed for selective harmonic mitigation. A discretization analysis is presented in order to obtain a precise digital realization of the current controllers. It is proposed as a regulator for the direct-current bus voltage in the active filter, which employs only information of the modulated voltage and is compatible with the previous sensorless synchronization solution. Experimental results from a 1-kVA prototype converter are presented, covering the solution with and without the voltage sensor in the direct current bus. Analyses of stationary and transient responses are performed by using a six-pulse diode rectifier as nonlinear load.
TL;DR: In this paper, a double-resistive active power filter (D-RAPF) system consisting of a terminal RAPF and an attenuation-rAPF for each individual harmonic is proposed.
Abstract: Harmonic propagation between power-factor correction capacitors and system inductors seriously deteriorates power quality in a radial power distribution feeder. Installation of a resistive active power filter (RAPF) at the end bus only suppresses harmonic propagation, not attenuates harmonic voltages. This paper proposes a double-resistive active power filter (D-RAPF) system consisting of a terminal-RAPF and an attenuation-RAPF for each individual harmonic. The terminal-RAPF operating as the characteristic impedance of the feeder is installed at the end bus to suppress harmonic propagation at all harmonic frequencies. The attenuation-RAPF, whose control gain can be set according to the requirements of the harmonic voltage distortion limit, is installed at a specific position for each individual harmonic to attenuate the corresponding harmonic voltages. The D-RAPF system not only suppresses harmonic propagation and attenuates harmonic voltages more effectively, but also has the same rated power capacity as the RAPF. However, both the harmonic damping performance and the rated power capacity must be considered to choose the D-RAPF system or the RAPF when a harmonic current source exists at a position between the attenuation-RAPF and the terminal-RAPF. Simulation and experiment results verify the theoretical analysis and demonstrate the effectiveness of the D-RAPF system.
TL;DR: The analysis shows that in comparison with the LLCL filter, the L(LCL)2 filter not only has lower voltage drop and less total inductor size, but also has improved performance in decreasing high-order current harmonics.
Abstract: In order to reduce the influence of the grid harmonic currents and voltages, harmonic compensation is regularly implemented for a grid-tied inverter. In this study, a new topology of a higher order power filter for single-phase grid-tied voltage-source inverters, named L(LCL) $_{2}$ , is presented. The subscript is added to the name to prevent confusion with the LLCL filter. In the proposed design, the inverter side inductance is divided into three parts, and the grid side inductor is removed. Also, an additional resonant branch at the double of the switching frequency is added to the traditional LLCL filter to attenuate high-frequency harmonics. The overall inductance of the recommended filter is smaller than the LLCL filter. A comparative study and discussions on the subject of the traditional LLCL filter and the proposed L(LCL) $_{2}$ filter have been conducted and assessed through an experimental hardware implementation on a 700 W, 120 V/60 Hz single-phase grid-tied inverter. Furthermore, a straightforward engineering design benchmark is suggested to discover parameters of the L(LCL) $_{2}$ filter. Moreover, stability analysis, loss analysis and an optimization of the L(LCL) $_{2}$ filter parameters have been conducted in this study. The analysis shows that in comparison with the LLCL filter, the L(LCL) $_{2}$ filter not only has lower voltage drop and less total inductor size, but also has improved performance in decreasing high-order current harmonics.
TL;DR: In this article, the authors presented design methods to configure a shunt capacitor as a C-type filter or a third-order high-pass filter with guaranteed resonance-free performance.
Abstract: Harmonic resonance has become an important concern for the application of shunt capacitors in recent years. A potential solution to address this challenge is to convert a shunt capacitor into a passive filter. This paper presents design methods to configure a shunt capacitor as a C-type filter or a third-order high-pass filter with guaranteed resonance-free performance. The concept of resonance-free condition is first introduced in this paper. It is then used to develop filter design methods that always meet the resonance-free condition. The two filter configurations are also compared. It was found that the third-order high-pass filter has more advantages than the C-type filter. Another useful finding of this work is that the filter parameters, as determined using the proposed design methods, are independent of the system conditions. As a result, a lookup table for the filter parameters has been created to facilitate immediate use by the industry.
TL;DR: In this article, a three-level hysteresis current-control (HCC) strategy is proposed for three-phase four-switch shunt active power filters to reduce the cost, switching losses and improve the reliability of system.
Abstract: In this study, a three-level hysteresis current-control (HCC) strategy is proposed for three-phase four-switch shunt active power filters. The four-switch topology which utilises four switching devices together with two series connected capacitors is able to reduce the cost, switching losses and improve the reliability of system. In this topology, when the current control of phases A and B is achieved successfully, the current control of phase C which is connected to the midpoint of the series connected capacitors is achieved automatically. The current control is achieved by using a three-level HCC strategy. An important consequence of using this control strategy is that it enables access to the zero level of the input voltage of active filter so that a switching device is only switched when the current error is negative, while it remains off when the current error is positive. Furthermore, the imbalance in the capacitor voltages is eliminated by adding a feedback term (the difference in the capacitor voltages multiplied by a suitable gain) to the current control. The proposed control strategy offers a reduced switching frequency, losses and cost. The steady-state and dynamic performance of the proposed control strategy is verified through simulations and experimental studies.
6 Jan 2016
TL;DR: In this paper, a constant frequency space-vector hysteresis-band current control (CF-SVHCC) was proposed for three-level active power filter applications when applied to isolated neutral point (INP) systems.
Abstract: This paper proposes a new constant frequency space-vector hysteresis-band current control (CF-SVHCC) in the stationary reference frame (SRF) for three-level active power filter applications when applied to isolated neutral point (INP) systems. CF-SVHCC is designed based on two recognized modulation methods: 1) space-vector modulation and 2) adaptive hysteresis current control. The proposed technique consists of a simple circular hysteresis strategy around the current-error vector in SRF with the purpose of employing the zero- and nonzero-voltage vectors of the three-level voltage source inverter. CF-SVHCC continuously estimates an adaptive outer hysteresis-band in the SRF using the inverter switching signals by a simple and fast artificial neural network method called the adaptive linear neuron algorithm. The main part of CF-SVHCC is a supervisory control unit that operates in the SRF to avoid interphase dependency and systematically uses the voltage vectors associated with the estimated outer hysteresis-band to prevent a high switching frequency and, in turn, maintain the switching frequency constant. CF-SVHCC retains most benefits of the conventional HCC and also introduces additional advantages, including a constant switching frequency and the interphases independency in three-phase INP systems.
TL;DR: In this article, an independently tunable mixed-mode (including voltage, current, transadmittance, and transimpedance modes) universal biquad filter using one FDCCII, one differential difference current conveyor (DDCC), two grounded capacitors, four grounded resistors, and two floating resistors is presented.
Abstract: This paper presents an independently tunable mixed-mode (including voltage, current, transadmittance, and transimpedance modes, i.e. four modes) universal biquad filter using one fully differential current conveyor (FDCCII), one differential difference current conveyor (DDCC), two grounded capacitors, four grounded resistors, and two floating resistors, which can realize all four modes five universal filtering responses (lowpass, highpass, bandpass, notch, and allpass). The proposed biquad filter has versatile input/output functions which not only realize all four modes five universal filtering functions in single-input multiple-voltage/current-output (SIMO) type but also provide all of them in multiple-input single-voltage/current-output (MISO) type without changing the filter topology. The proposed circuit permits both independent tunability (for ω 0 and ω 0 / Q ) and orthogonal controllability (for ω 0 and Q ) by adjusting grounded resistors without control factors matching conditions. No floating capacitors are used, and all the active and passive sensitivities are low. Moreover, in some modes, the proposed circuit still maintains the following advantages for five universal filtering responses: (i) cascadable feature, (ii) no component-value constraints, and (iii) no need of extra inverting or non-inverting amplifiers. H-spice simulations with TSMC 0.18 μm 1P6 M CMOS process technology and experimental results validate theoretical predictions.
TL;DR: This brief presents an ultra-low-power low-noise chopped capacitively coupled instrumentation amplifier (CCIA) that is suitable for neural recording applications and compares favorably with the state of the art.
Abstract: This brief presents an ultra-low-power low-noise chopped capacitively coupled instrumentation amplifier (CCIA) that is suitable for neural recording applications. An active high-pass filter is embedded in the ripple reduction loop (RRL) to suppress the residual noise and relax the capacitor size. Multiple chopping is employed to further reduce the residual output ripple due to the RRL offsets. A dc servo loop (DSL) using a 14-nA pseudofeedback amplifier is proposed to achieve a subhertz high-pass corner while using only a 15-pF on-chip capacitor. The complete CCIA is implemented in a standard 0.18- $\mu\text{m}$ CMOS process. It occupies an area of 0.23 mm2 (including the DSL) and consumes 1.7 $\mu\text{A}$ from a 1.25-V supply, achieving a noise efficiency factor of 2.9 that compares favorably with the state of the art.
TL;DR: Model predictive control (MPC) is proposed in this paper as a framework for generating APF current references that will minimize the harmonic distortions of the overall system within a given APF rating.
Abstract: This paper proposes a system-oriented approach for mitigating harmonic distortions by utilizing a single active power filter (APF) in an electrical grid with multiple buses. Common practice for the control of APFs is to locally compensate the load current harmonics or to mitigate voltage harmonics at a single bus. However, the operation of an APF in a multibus system will influence the voltages at neighboring buses. It is, therefore, possible to optimize the APF operation from a system perspective instead of considering only conventional local filtering strategies. For such purposes, model predictive control (MPC) is proposed in this paper as a framework for generating APF current references that will minimize the harmonic distortions of the overall system within a given APF rating. A diesel-electric ship, with two buses supplying separate harmonic loads, with an APF located at one of the buses, is used as study case. The operation with online MPC-based optimization of the APF current references is compared to two benchmark methods based on conventional approaches for APF control. The results demonstrate that the MPC generates current references that better utilize the APF current capability for system-wide harmonic mitigation.
14 Mar 2016
TL;DR: The design and control of a bidirectional battery charger for Electric Vehicles, and its operation as an active power filter when connected to the local home electrical grid, are discussed and proven to comply with the existing power quality standards.
Abstract: This paper discusses the design and control of a bidirectional battery charger for Electric Vehicles, and its operation as an active power filter when connected to the local home electrical grid. The charger is also designed and controlled in order to operate during the charging of the battery from the grid and the injection of the power back to the grid when needed. The whole system is simulated using Matlab/Simulink, and the results are shown during the operation of each case, along with a management system of these different operation modes. The simulation results are analyzed, discussed and proven to comply with the existing power quality standards.
TL;DR: In this article, an LCL filter with non-linear inverter-side inductor is used to reduce the filter volume and cost, while a cost-effective filter is used at the inverter output, acceptable total harmonic distortion is achieved.
Abstract: In grid-connected inverters, utilisation of an appropriate output filter is vital to improve power quality. However, the filter, which comprises of capacitor and inductor(s), should be cost effective. In this study, an LCL filter with non-linear inverter-side inductor is used to reduce the filter volume and cost. In order to harness the undesirable non-linear behaviour of the LCL filter's inductor, a new control scheme based on proportional-resonant controller is proposed. The control strategy is based on combinational feedback of inverter-side and grid-side currents, with online adaptive estimation of non-linear inductor. With this scheme, the harmonic compensators’ gains can be reduced, while stability margins and dynamic response are improved. Therefore, while a cost-effective filter is used at the inverter output, acceptable total harmonic distortion is achieved. Experimental tests based on a 7 kW digital signal processor controlled prototype inverter are provided to verify the proposed control strategy for grid-connected inverters with LCL output filter benefiting from low-cost non-linear inductor.
TL;DR: The predictive power control with active damping function is proposed for matrix converter (MC) by modifying the reference values of load active power and input reactive power, and the input filter resonances which are liable to be excited by predictive control are effectively suppressed.
Abstract: In this paper, the predictive power control with active damping function is proposed for matrix converter (MC). In every sampling period, the values of load active power $p_{L}$ , load reactive power $q_{L}$ , and input reactive power $q_{i}$ at the period after next are predicted. The best switching state is selected based on the minimum cost function g for the next sampling time interval, where $g$ is the sum of the absolute errors between the reference and the predicted values. Since $p_{L}$ , $q_{L}$ , and $q_{i}$ are equally important for MC control, their weighting factors are fixed at 1, rather than being adjusted empirically. On this basis, a novel active damping control strategy is realized by modifying the reference values of load active power and input reactive power. By applying the active damping function, the input filter resonances which are liable to be excited by predictive control are effectively suppressed. Experimental results have verified the feasibility and validity of the proposed strategy.
1 Oct 2016
TL;DR: In this paper, a review of control techniques related to harmonic filters for harmonic mitigation is presented, together with the advantages and disadvantages of using active filters in harmonic mitigation compensation, depending on the situation, the use of one technique instead of the other makes the difference of achieving a better harmonic mitigation.
Abstract: The use of active filters for harmonic mitigation compensation is increasing together with the improvement of their control techniques. Depending on the situation, the use of one technique instead of the other makes the difference of achieving a better harmonic mitigation or not. In this paper, a review of control techniques related to harmonic filters for harmonic mitigation is presented, together with the advantages and disadvantages. From the literature review it was observed that new techniques are being used and classical ones are being improved.
TL;DR: In this paper, an active method for eliminating common mode voltage (CMV) in multilevel inverters which is independent on the inverter topology or its modulation scheme is proposed.
Abstract: The adverse effect of common-mode voltage (CMV) in pulse-width modulation inverters is widely acknowledged. Various approaches for mitigating CMV effect in PWM inverters have been proposed in the literature but they either show limited effect or impair the utilization of the drive. This paper proposes an active method for eliminating CMV in multilevel inverters which is independent on the inverter topology or its modulation scheme. In particular, the proposed method does not restrict the modulation index range of the drive. A detailed analysis of the active filter circuitry and a closed-form feed-forward control law are provided. Finally, selected simulation and experimental results are presented to validate the theoretical part.
TL;DR: In this paper, a virtual active power filter (APF) is proposed to improve the power quality of a grid connected hybrid ac/dc MG, where the dc subgrid and the IC are integrated to form a virtual APF.
Abstract: The coexistence of ac and dc subgrids is going to be inevitable in microgrids (MGs). This study introduces a virtual active power filter (APF) to improve the power quality of a grid connected hybrid ac/dc MG. In this approach, the dc subgrid and the IC are integrated to form a virtual APF. Thus, an enhanced control method for IC is proposed that improves the performance of hybrid ac/dc MG under non-linear load conditions considering power quality of both ac and dc subgrids. The proposed control ensures acceptable power quality for both inverter-based and rectifier-based power transfer between ac and dc subgrids. Furthermore, the IC provides stable dc bus voltage for the dc subgrid and exchange power between the ac and dc buses, properly. A hybrid ac/dc MG is simulated using PSCAD/EMTDC software and various set of simulation studies is presented to validate the effectiveness and advantages of the proposed control method. Furthermore, experimental results are provided to validate the mentioned properties. These features have not been previously discussed in the literature for virtual APF in hybrid ac/dc MGs, where existing APFs are mostly presented for unidirectional power flow applications such as distributed generators.