Active Filter Function Research Articles

Uninterruptible Power Supply Topology Based on Single-Phase Matrix Converter with Active Power Filter Functionality

Uninterruptible Power Supply Topology Based on Single-Phase Matrix Converter with Active Power Filter Functionality

A Voltage Source Inverter-Based Hybrid Renewable Energy Source for Improving Power Quality

The power demand is quickly rising day by day and however, the available industrial sector needs the demand for power high. Therefore, different loads and different output sources can be employed between supply and demand. This approach intends to assess the current condition need for power quality, without distortion, and Bus interface management with fully integrated PV-based MPPT (Maximum power point tracking) and Wind-based rotor winding induction generator. Solar energy is directly converted into electrical energy using a Photovoltaic (PV) system. The PV cell is the fundamental component of a PV array and can be created by grouping cells and the voltage and current that are accessible at a PV device's contacts. In solar PV, the MPPT technique and boost converter are used to maximize the buck or boost and feed it to the single-phase Pulse Width Modulation (PWM) to the inverter. The rectifier circuit rectifies the AC input source and is connected through the controller; simultaneously, the DC-DC converter converts the DC input and bucks or boosts up the from the input sources. The voltage source inverter is combined with shunt active power filter functionality, which is further used to interface the DC-shunted wind-solar hybrid model to the grid. A voltage source inverter has more efficiency and both different input sources are connected via a DC bus. In this method, both DC and AC output loads are connected, managing the desired output voltage with efficient and better output results, and analyzing the total harmonics distortion method using Mat-lab simulation.

Design and Verification of Cascaded Multilevel STATCOM Active Filter Function

STATCOM can be used as both dynamic reactive power compensation device and active power filter to improve the power quality of a power grid. This paper describes the active filter function implemented into an existing STATCOM control. The paper explains firstly the filtering control system of the STATCOM, starting from the introduction of active power filter principle, harmonic current detection and tracking control. After that, the parameter design, open-loop characterization and simulation verification of the proposed filtering control scheme are carried out. The PSCAD simulation results show that the active filtering control scheme proposed in this paper can effectively reduce the harmonic content in the system and has good stability.

Experimental Validation of Active Filter Functionality for Distributed Photovoltaic Farms

Experimental Validation of Active Filter Functionality for Distributed Photovoltaic Farms

Analysis of a Multifunctional Inverter Active-Filtering Function Influence on the Small-Signal Stability of Inverter-Based Islanded AC Microgrids

This paper deals with the small-signal analysis of islanded AC microgrids, considering the coexistence of voltage-controlled converters (VCC) operating under droop control law and current-controlled converters (CCC) operating as multifunctional inverters. Thus, the CCCs can deliver power from a non-dispatchable energy source and, depending on the operation mode, they can perform the active filtering function (AFF), which consists of injecting the harmonic currents associated with the local non-linear loads (NLL) resulting in a microgrid power quality (PQ) improvement. However, the transient characteristics following a local NLL step highly depend on the CCC operation mode. When AFF is disabled, the CCC output is almost not affected by the local NLL step. Instead, the harmonic extraction algorithm dynamics affect the CCC output when AFF is enabled. As a result, the overall system dynamic behavior is significantly affected, since microgrids are low-inertia and small power systems. A generic small-signal model is derived to study these effects, and its accuracy is then validated through simulated and experimental results. It was found through time-domain and frequency-domain sensitivity analyses that the AFF significantly affects the CCC PLL and the dynamic interactions between the microgrid network and the inverter's internal control loops.

DC-Link Voltage Dynamics of Three-Level Four-Wire Grid-Connected Converters During Harmonics Injection Operations

As the amount of decentralized electric power generation is steadily growing, not only the direction of power flow, but the overall behavior of the grid changes. This includes that harmonic voltages in the supply grid become more problematic. To deal with this problem, inverters of decentralized renewable energy resources can help to mitigate these harmonic grid voltages by injecting harmonic currents. However, this so-called active filter functionality leads to additional stress of the DC-link capacitor due to inevitable oscillations of the DC-link current and voltage. Hence, this paper for the first time presents an analytical derivation of these DC-link oscillations caused by a harmonic current injection into the grid. The analysis is presented for 2-level and 3-level inverters with split DC-link in a 4-wire configuration. Simulation and experimental measurement results show the validity of the proposed analytical calculations. Furthermore, the impact of these DC-link harmonics on the capacitor lifetime is discussed. An exemplary scenario with a 10 kW photovoltaic inverter mitigating a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$5^\mathrm{th}$</tex-math></inline-formula> harmonic grid voltage shows a possible lifetime reduction of the DC-link capacitor of up to 52% due to the oscillations in the DC-link voltage and current. Thus, this paper aims to raise awareness of converter designers regarding this lifetime reduction, so that they take these oscillations into account during the design process and avoid unexpected early failure of the DC-link capacitor.

Research on new electric vehicle AC charging pile technology based on active filter function

The AC charging pile is the main energy supply facility for household electric vehicles, which uses a vehicle mounted charger to charge the power battery. The current standard of the State Grid Corporation of China clearly stipulates the function of the AC charging pile and does not take into account the impact of the harmonics of the vehicle mounted charger on the power grid. Therefore, in view of the deficiency that AC charging piles cannot suppress the current harmonics of the vehicle mounted charger, application of the active power filtering technology to the design of AC charging piles is proposed to form a new type of AC charging pile with better functions. In the experimental prototype that was built, for vehicle mounted chargers with two load characteristics, the composite control method of traditional PI control and repetitive control is adopted, where the new AC charging pile effectively suppresses the harmonics of the vehicle-mounted charger. Experiments show that the AC charging pile using active power filtering technology cannot only improve the power quality of the grid side but also reduce the impact of harmonics on the power metering and billing system, ensuring the stability of the charging communication system.

Simulation model of unity power factor uninterruptible power supply topology using single-phase matrix converter

This paper presents a computer simulation model of the unity power factor uninterruptible power supply (UPS) topology using single-phase matrix converter (SPMC) that focuses on the switching integration for both rectifier and inverter operations. The proposed integrated switches capable of controlling the SPMC to operate as a rectifier operation to charge the DC battery during the normal operation and to switch the SPMC to operate as an inverter during power outage conditions continuously and instantaneously using a single power converter circuit. The use of a single power converter circuit can solve the typical UPS system that requires at least two separate power converter circuits, thus contributing to the higher power semiconductor losses and complicated control circuits. With the proposed circuit topology, it can improve the power density of the power electronics converter system resulting in low power losses. The active power filter (APF) function has been used to improve the supply current waveform to follow the shape of the sinusoidal reference current to be in phase with the supply voltage waveform, thus reduce the total harmonic distortion (THD) level and improve the power factor. To verify the proposed operation, the selected simulation results are presented, and the proposed work has been done through the MATLAB/Simulink.

Research on Control Strategy of Grid-connected Inverter with Active Filter Function

Grid-connected inverters incorporate distributed energy sources such as photovoltaics and wind energy into the micro-grid. Due to the volatility of distributed energy generation and the presence of a large number of non-linear loads in the micro-grid, harmonic wave seriously affect power quality. The grid-connected inverter with active filtering function is formed by adding the harmonic wave suppression function to the grid-tie inverter, which not only realizes the inverter grid connection but also achieves the purpose of harmonic wave compensation. The traditional model predictive control (MPC) has the characteristics of strong robustness and fast dynamic response, but its high switching frequency causes serious heating of the inverter. In response to the above problems, combined with hysteresis control theory, a model control strategy based on hysteresis is proposed in this paper, which improves the accuracy of grid-connected current of the grid-connected inverter with active filter function and inhibits the harmonic component of the system, verifying the effectiveness of the strategy.

Design of Soccer League Optimization Based Hybrid Controller for Solar-Battery Integrated UPQC

Nowadays, integration of renewable energy source like solar, wind etc in the grid is encouraged to reduce the losses and meet the demand. However, the integration of these renewable sources, power electronic devices, non-linear and un-balanced loads leads to the power quality issues this motivated power researchers for the development of new controllers and techniques. This paper develops a soccer-league algorithm based optimal tuned hybrid controller for the unified power quality conditioner associated with the solar power and battery-storage systems with the Boost converter and Buck Boost converter. The UPQC simultaneously performs both the functions of Shunt active power filter and series active power filter. The proposed optimally designed controller adapts both the properties of fuzzy logic-controller and SOL algorithm tuned proportional-integral controllers. The K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</sub> , K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sub> values of shunt and series controllers are treated as control variables, which are optimally tuned by SOL to satisfy the objective function. The key contributions of the proposed work are the reduction of total harmonics in current waveforms thereby enhancing the power factor, quick action to maintain the constant DC-Link capacitor voltage during the solar irradiation variations, elimination of voltage sag/swell/ large disturbance, and appropriate compensation for the un-balanced networks and loads. The performance investigation of SLOHC was carried-out with four test studies for different combinations of unbalanced/balanced loads and supply voltage of 3-phase distribution network. Comparative analysis was carried out with those of standard methods like a genetic algorithm, biogeography-based optimization, and proportional-integral controllers. The proposed method reduces the total harmonic distortion to 2.06%, 2.44%, 2.40%, and 2.32% which are much lower than those of existing methods available in literature. The design has been performed on MATLAB/simulink software.

Three-Level T-Type Quasi-Z Source PV Grid-Tied Inverter With Active Power Filter Functionality Under Distorted Grid Voltage

Distributed energy resources (DER) such as solar photovoltaic (PV) interfaces with the utility grid by high-efficiency power electronic converters. This equipment is sometimes underutilized in terms of its power capacity; thus, the remaining capacity can be used to provide support to the distribution system. In this sense, this work assesses the performance of the three-level T-type quasi-impedance source inverter (3L-T-type qZSI) injecting not only active power to the grid, but also providing support to it by injecting reactive power and acting as an active power filter (APF) simultaneously. The global control strategy of the grid-connected inverter is derived from the instantaneous <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$i_{d}$ </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">$i_{q}$ </tex-math></inline-formula> power theory. The combination of an improved deadbeat current controller and a level-shifted carrier-based pulse-width-modulation (PWM) technique, using both the upper shoot-through (UST) and the lower shoot-through (LST) alternating states, allows a successful tracking of the current references. Both the dc-link voltage control and the neutral-point balancing are properly achieved by taking the advantage of the shoot-through (ST) states and the redundant states simultaneously. These control actions are implemented by simple proportional-integral (PI) controllers. The simulation and experimental results demonstrate the above-mentioned functionalities and verify the stability and good dynamic response of the grid-connected 3L-T-type qZSI.

Battery energy storage system with functions of wide AC voltage range and battery current filtering

ABSTRACT This paper develops a power conversion interface for a battery energy storage system (BESS). The power conversion interface is composed of a bidirectional DC-DC power converter and a three-port DC-AC power converter, and it has the functions of wide AC voltage range and battery current filtering. The three-port DC-AC power converter has a high-voltage DC port, a low-voltage DC port and an AC port. The high-voltage DC port and low-voltage DC port are, respectively, connected to the output of the DC-DC power converter and the battery set, and the AC port is connected to the grid. The three-port DC-AC power converter generates a five-level voltage or a three-level AC voltage at the AC port according to the amplitude of grid voltage. The bidirectional DC-DC power converter has two functions. One is to generate a higher DC voltage to the high-voltage DC port, and the other is to perform a DC active filter function for attenuating the low-frequency ripple of the charging/discharging current for the battery set. All or part of the charging/discharging power for the battery set is only processed by the three-port DC-AC power converter, which can improve the efficiency of the BESS. A hardware prototype with a digital signal processor controller is developed to verify the performance of the developed power conversion interface for the BESS.

Multistep Finite Control Set Model Predictive Control of Photovoltaic Power Generation System with Harmonic Compensation

Photovoltaic (PV) power generation is the main aspect of new energy power generation, and it is an important means to achieve the goal of carbon neutrality. When the PV system is connected to the grid, the nonlinear load of the grid will affect the power quality and consume reactive power. This paper proposes a PV power generation grid-connected system to improve power quality, with an active power filter (APF) function. Through the maximum power point tracking (MPPT) method, PV power generation can operate at the maximum power point and play the function of harmonic and reactive power compensation at the load side. To improve the dynamic performance of the grid-connected PV system and harmonic compensation simultaneously, multistep finite control set model predictive control (FCS-MPC) is adopted for the grid-connected module. The whole system does not need additional equipment, as it plays the role of two devices and effectively reduces the input cost. In this paper, the proposed structure and multistep FCS-MPC are verified in MATLAB/Simulink. The results show that the system injects the maximum power into the power grid at the same time when the load changes and compensates the harmonic generated by the nonlinear load of the power grid so that the total harmonic distortion of the power grid can meet the operation standard, and the system has good dynamic performance and steady-state performance.

Hysteresis Controlled Based Power Quality Improvement in a Renewable Energy Source Connected to Utility grid with BESS Based STATCOM

This Paper presents a control strategy of the grid interconnected inverter Renewable Energy Sources (RES). This system can achieve the maximum benefits from these grid interconnected inverter when installed in 3-phase 4-wire distribution system. Increasing electrification of daily life causes growing electricity consumption and the rising number of sensitive or critical loads demand for high quality electricity. One of the main problems facing today is that related with the transmission and distribution of electricity. Due to the rapid increase in global energy consumption and the diminishing of fossil fuels, the customer demand for new generation capacities and efficient energy production, delivery and utilization keeps rising. Utilizing distributed generation, renewable energy and energy storage can potentially solve problems as energy shortage. With the increase in load demand, the Renewable Energy Sources (RES) are increasingly connected in the distribution systems which utilizes power electronic Converters/Inverters. The inverter can perform as a multi function device by incorporating active power filter functionality. The inverter can thus be utilized as: 1) power converter to inject power generated from RES to the grid, and 2) shunt APF to compensate current unbalance, load current harmonics, load reactive power demand and load neutral current. All of these functions may be accomplished either individually or simultaneously. This new control concept is demonstrated with extensive MATLAB/Simulink simulation studies and validated through digital signal processor-based laboratory experimental results.

Engineering the spectral profile of photon pairs by using multi-stage nonlinear interferometers

Using the quantum interference of photon pairs in N-stage nonlinear interferometers (NLIs), the contour of the joint spectral function can be modified into an islands pattern. We perform two series of experiments. One is that all of the nonlinear fibers in pulse pumped NLIs are identical; the other is that the lengths of N pieces of nonlinear fibers are different. We not only demonstrate how the pattern of spectral function changes with the stage number N, but also characterize how the relative intensity of island peaks varies with N. The results well agree with theoretical predictions, revealing that the NLI with lengths of N pieces of nonlinear fibers following binomial distribution can provide a better active filtering function. Our investigation shows that the active filtering effect of multi-stage NLI is a useful tool for efficiently engineering the factorable two-photon state—a desirable resource for quantum information processing.

Modified grid side converter control technique for DFIG connected to nonlinear loads

ABSTRACT In this work, a grid side converter (GSC) control with integrated shunt active filtering function using space vector pulse width modulation (SVPWM) technique is proposed to mitigate harmonics produced by the nonlinear loads. This method is focused on removal of harmonics from the grid currents by supplying compensating currents through GSC of DFIG. The proposed control technique improves power quality and reduces Total Harmonic Distortion of the grid current. Simultaneously, it is also capable to control active power and regulate DC link voltage during variable wind speeds in the presence of nonlinear loads. Performance of the proposed technique is compared with the conventional technique considering grid-connected 2.6 MW DFIG-based wind energy conversion system using MATLAB Simulink. Performance analysis has been carried out to check the behavior of the proposed SVPWM-based modified GSC control technique to mitigate the grid current harmonics considering wide variations in various parameters. The simulation results validate the effectiveness of the proposed scheme since it achieved grid current THD within limits of 5% as per IEEE-519 standards for all wind speeds.

Active power filter with hysteresis current control loop using rectifier boost technique

&lt;span lang="EN-US"&gt;This paper presents the Hysteresis Current Control (HCC) to improve the power quality of power electronic converters. The development of HCC was implemented using Active Power Filter (APF) function based on rectifier boost technique to control the range of upper and lower bands. Through this technique, the supply current waveform followed the shape of the sinusoidal reference signal, thus, the distorted input current waveform becomes sinusoidal and in the same phase with the input voltage. As a result, the THD level and switching losses can be reduced, thus improving the power factor of the power supply system. In order to verify the proposed operation, validation of the proposed HCC was done through MATLAB. Selected simulation results are presented.&lt;/span&gt;

Active Bridge Rectifier With DM EMI Reduction Based on Linear Reverse Operation of MOSFETs

A new linear control scheme for operating power MOSFETs in the third quadrant (i.e., synchronous rectifier (SR) operation) is proposed and applied to electromagnetic interference (EMI) mitigation of switching converters. MOSFETs operating in the third quadrant exhibit electrical characteristics equivalent to a voltage-controlled voltage source between the gate-source and the drain-source voltages. Such operation is an alternative to typical SR mode, allowing fast control of the ac drain-source voltage. It is applied to active bridge rectifiers (ABRs) that can produce the necessary high-frequency voltage compensation signal to reduce differential-mode EMI. The ABR can then play the role of ac line rectification and EMI reduction at the same time. Its characteristics are modeled, and experimental verifications are carried out on a boost-type power factor corrector (PFC). The EMI performance of the PFC is improved with the proposed technique. The proposed technique facilitates the reduction of passive filter size and gives the potential of integrating active filtering function into the ABR as a solid-state front-end module. The idea can, thus, help increase the power density of power converters.

Binary Hybrid Multilevel Inverter-Based Grid Integrated Solar Energy Conversion System With Damped SOGI Control

This paper presents a binary hybrid multilevel inverter (BHMLI) based grid-connected solar energy conversion system (SECS), controlled by damped second-order generalized integral (DSOGI). The BHMLI architect has a cascaded half-bridge array, which modifies the DC-link of the H-bridge of the voltage source inverter, and results in approximate reference waveform. It reduces the dV/dt of the H-bridge switches and improves output waveform quality. The DSOGI control damps the oscillations and overshoots and provides longer service period of low power switches at transient conditions. It is implemented in the multilevel inverter application for the first time in literature. The SECS is designed to inject active power to the grid, and also mitigates the harmonic and reactive power demands of the load. The cascading of n' half-bridges and one H-bridge generate (2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">(nC1)</sup> - 1) output voltage levels. The maximum power extraction from solar photovoltaic (PV) array is achieved through incremental conductance (IC) algorithm based maximum point tracking (MPPT) operation of the DC-DC converter. An isolated single-input multiple-output single-ended primary inductance converter (SIMO-SEPIC) realizes it. SECS with 15-level BHMLI is analyzed with extensive simulation as well as with a hardware prototype. Moreover, the shunt active filter functionality of the system at various load conditions are verified and maintained the grid power quality within the IEEE-519 standard throughout the operation. The laboratory developed setup is tested for 5 kW, 400 V, three-phase system, and the experimental analysis at steady-state and dynamic variations of load-side and insolation variations validate the theoretical claims.

Development of active power filter using rectifier boost technique

&lt;span&gt;The development of active power filter (APF) using rectifier boost technique has been identified to compensate for the pulsating nature of the distorted supply current waveform of non-linear load. In this work, investigation is carried out on the operation of rectifier without any filters function. This is then extended to operate the rectifier converter with an active power filter function. APF function is implemented by enabling the closed-loop control using standard proportional integral control to rectify the distorted supply current to become continuous, sinusoidal and in-phase with the supply voltage waveform. Consequently, the total harmonic distortion (THD) level was reduced to meet the acceptable limit defined in the standard of IEEE-519 1992. The selected simulation results obtained from MATLAB/Simulink are presented to justify the proposed filter structure.&lt;/span&gt;