Control Of Active Filter Research Articles

Energy efficiency comparison of shunt active filter's control strategies for three phase four-wire power system

In the presented article, the values of the components of the total power of the three-phase four-wire power supply system for non-sinusoidal asymmetric modes, the condition for achieving a unit value of the power factor and the minimum value of the power losses were clarified. The obtained results were applied to compare the energy efficiency of shuntl active filters (SAF) using different control strategies. Based on the proposed apparent power formula, a new calculation formula for the experimental determination of the power factor has been obtained. It is proved that only the proportional-vector control strategy of the, which uses a reference vector of phase voltages with the optimally weakened zero sequence component, provides a unit power factor and the minimum possible power losses, exceeding other possible strategies in these indicators. It was shown that other known proportional-vector algorithms for forming the source currents of a three-phase four-wire power system with an integral value of the proportionality factor do not provide a unit value of the power factor. To confirm the energy efficiency of the proposed control algorithm for SAF in the MathWorks ® Simulink ® 2012a computer simulation was carried out. The model of a three-phase four-wire power system with a shunt active filter and a nonlinear load in the form of a three-phase rectifier with zero output, assembled according to the Mitkevich scheme and operating on the active resistance was investigated. The results of computer simulation confirmed the advantage of the proposed SAF control algorithm in value of power factor up to 7% in comparison with the algorithm of S. Fryze with full preservation of the zero-sequence component and up to 0.5% in comparison with the algorithm of P. Salmeron, J. Monton with complete suppression of the zero-sequence component. Ref. 9, fig. 3, tabl. 1.

Implementation of Empirical Mode Decomposition Based Algorithm for Shunt Active Filter

In this paper, an online empirical mode decomposition (EMD) based algorithm is proposed for the control of a shunt active filter (AF). Standard EMD algorithm has worked on the principle of time-scale difference between the upper maximum values and lower minimum values of a signal, and for a long time it has been considered good for offline analysis of signals. This paper deals with the real-time application of EMD for the control of AF under balanced and unbalanced loads. Linear interpolators are employed for construction of upper and lower envelopes to avoid computation complexity. Moreover, customized iterative computations for extraction of intrinsic mode functions maintain the efficiency of algorithm. The algorithm extracts the fundamental component of load current and helps in estimating reference currents. Simulations are performed on MATLAB/Simulink platforms. Simulation results are verified with experimental results of a developed prototype of shunt AF.

Self-Regulating Active Power Filter Compensation Scheme for Hybrid Photovoltaic-Fuel Cell Renewable Energy System for Smart Grid Applications

This paper presents a low cost DC and AC active power filters to enhance the power quality of hybrid hydrogen Fuel Cells (FC) and Photovoltaic arrays (PV) renewable energy system through reducing the complexity of design and control of active harmonic filters that effectively mitigate power system harmonics. Its main goal was therefore to design, model and test through computer simulation, active power filters that successfully interface FC and PV to form hybrid PV/FC renewable energy system that enhance the system output power quality through the stabilization of load bus voltage and reduction of harmonic currents. Two active power filters schemes were proposed in this paper. The first system consists of a unique two stage DC Power Filter (DCPF) to regulate the DC bus voltage to its set point. The second interface scheme is the active AC Power Filter (ACPF) which served to reduce harmonic three-phase currents on the AC bus. The AC filter used on the AC bus utilizes a hysteresis current controller to generate the switching. Computer models of these two interface schemes were built and simulation studies were carried out using the Matlab/Simulink. The simulation results demonstrate the success of both power filters at meeting their primary objectives through the increased voltage stability and reduction of the Total Harmonic Distortion (THD) of current that was observed as a result of their introduction into the power system.

Model Predictive Control for Shunt Active Filters With Fixed Switching Frequency

This paper presents a modification to the classical Model Predictive Control (MPC) algorithm and its application to active power filters. The proposed control is able to retain all the advantages of a finite control set MPC while improving the generated waveforms harmonic spectrum. In fact, a modulation algorithm, based on the cost function ratio for different output vectors, is inherently included in the MPC. The cost function-based modulator is introduced and its effectiveness on reducing the current ripple is demonstrated. The presented solution provides an effective and straightforward single loop controller, maintaining an excellent dynamic performance despite the modulated output and it is self-synchronizing with the grid. This promising method is applied to the control of a shunt active filter for harmonic content reduction through a reactive power compensation methodology. Significant results obtained by experimental testing are reported and commented, showing that MPC is a viable control solution for active filtering systems.

陀螺稳定平台扰动的自抗扰及其滤波控制

陀螺稳定平台扰动的自抗扰及其滤波控制

Wind Turbine Inverter Robust Loop-Shaping Control Subject to Grid Interaction Effects

An $\mathcal{H}_{\infty}$ robust control of wind turbine (WT) inverters employing an inductor-capacitor-inductor (LCL) filter is proposed in this paper. The controller dynamics are designed for selective harmonic filtering in an offshore transmission network subject to parameter perturbations. Parameter uncertainty in the network originates from the grid and the number of WTs connected. Power converter-based turbines inject harmonic currents, which are attenuated by passive filters. A robust high-order active filter controller is proposed to complement the passive filtering. The $\mathcal{H}_{\infty}$ design of the control loop enables desired tracking with integral effect while bounding the induced change. The design was tested in an aggregated model of the London Array offshore wind power plant and compared with traditional Proportional-Integral (PI) controller designs. Robust stability and performance and a reduction of control effort by 25% are obtained over the full envelope of operation.

Artificial Intelligence Based Controller for Series and Shunt Active Filters for Power Quality Improvement

Neural network based p-q theory control strategy for shunt active power filter and neural network based synchronous reference frame (SRF) theory control strategy for series active power filter are proposed in this paper to compensate power quality issues related to current and voltage respectively through Unified Power Quality Conditioner (UPQC) in three phase four wire (3P4W) distribution system for various balanced/unbalanced loads and balanced /unbalanced/ distorted source conditions. The Artificial Neural Network (ANN) controllers are designed to replace the low pass filters (LPF) and proportional-integral controllers of the conventional control strategy. ANN controllers are also implemented to maintain voltage across the capacitor and as a compensator to compensate neutral current under varying conditions of source and load. The proposed control strategies mitigate harmonic/reactive currents and voltage harmonics, ensure balanced and sinusoidal source current from the supply mains that are nearly in phase with the supply voltage. The performance of the UPQC with proposed ANN controllers is validated and investigated through simulations using MATLAB software. The simulation results prove the efficacy of the proposed neural network based control strategy under varying source and load conditions.

Power active filter control based on a resonant disturbance observer

Active filters are power electronics devices used to eliminate harmonics from the distribution network. This article presents an active disturbance rejection control scheme for active filters. The controller is based on a linear disturbance observer combined with a disturbance rejection scheme. The parameter tuning is based on a combined pole placement and an optimal estimation based on Kalman–Bucy filter. Proposed scheme is validated through simulation and experimental work in an active filter.

A novel strategy for shunt active filter control

The present paper proposes the use of an advanced algorithm based on the instantaneous powers theory for harmonics current compensation. A fast and exact computation of harmonic references is more than crucial for any active filter control strategy, especially during the transient time and frequency domains. The proposed method contains mainly two stages, the first one is based on a self-tuning filter (STF) to perform instantaneous synchronized sine and cosine fundamental waveforms. These two signals are used to calculate the instantaneous active and reactive powers using the well-known PQ theory. The second one is based on a new proposed method to accelerate the power ripple cancelation in the PQ active and reactive powers. An analytic study is conducted to show the effectiveness of these methods which is consolidated by simulation and experimental results.

New Method to Harmonic Isolation Based on High Selectivity Filter to Control of Shunt Active Filter with Experimental Validation Using DSPACE System

This paper presents a new control method of a parallel active power filters based on improved harmonic isolation with hardware implementation. The harmonic isolator is based on High Selectivity Filters (it can be tuned at any frequency) and the current control technique consists in a modulated hysteresis current controller. This active filter is intended for harmonic compensation of a diode rectifier feeding a RL load. The study of the active filter control is divided in two parts. The first part deals with the harmonic isolator which generates the harmonic reference currents and is implemented into a DSPACE DS1104 prototyping card. The second part focuses on the generation of the switching pattern of the IGBTs of the inverter by the modulated hysteresis current controller, implemented into an analogue card. The use of High Selectivity Filters instead of classical extraction filters allows extracting directly the voltage and current fundamental components in the α-β axis at high performances. The effectiveness of the new proposed method is verified by computer simulation and by experimental study.

A Modified Current Controller for H-Bridge Active Filter to Reduce Harmonics in Single Phase System

— this paper presents a digital current controller for H-bridge pulse width modulation (PWM) converters, whose sampling frequency equals quadruple of the switching frequency,. This current regulator detects the ac current and manipulates the voltage reference not only at the upper and lower peaks of the PWM triangle carrier but also at its zero crossings. A modified deadbeat current regulator is proposed to suppress the current oscillation induced by the voltage error, based on the theoretical analysis. Experimental results are shown to verify the control performance of the proposed current regulator. Moreover, a proposed current regulator is applied to a single-phase active power filter to demonstrate the effectiveness in harmonic compensation. Index Terms—Current regulators, digital control, DSPs, pulsewidth modulation (PWM), shunt active filters.

Real-Time Implementation of Type-2 FLC–Based Shunt Active Filter Control Strategies (p–q and Id–Iq) with Different Fuzzy MFs for Power Quality Improvement

Abstract This research article proposes the shunt active filter (SHAF) control strategies (p–q and Id–Iq), which are used to improve the power quality of the electrical network by mitigating the harmonics with the help of Type-2 fuzzy logic controller (Type-2 FLC) different membership functions (MFs). Three-phase reference current waveforms generated by proposed scheme are tracked by the three-phase voltage source converter in a hysteresis band control scheme. The performance of the proposed control strategies has been evaluated in terms of harmonic mitigation and DC link voltage regulation under various source conditions. In order to maintain DC link voltage constant and to generate the compensating reference currents, we have developed Type-2 FLC with different fuzzy MFs (trapezoidal, triangular and Gaussian). The SHAF with proposed Type-2 FLC using Gaussian MF is able to eliminate the uncertainty in the system and SHAF gains outstanding compensation abilities. The detailed real-time results using real-time digital simulator are presented to support the feasibility of proposed control strategies.

Diagnostic and Active Filtering of Harmonics Generated by Compact Fluorescent Lamps

Use of nonlinear loads, such as power converters, fluorescent lamps and adjustable speed motor drives, is expected to grow rapidly. All of these loads inject harmonic currents. This paper presents the active filtering of the harmonic distortion generated by the compact fluorescent lamps (CFL). The Instantaneous active and reactive power theory (the p-q Theory) is used to design the control of parallel active filter. The control scheme has been verified using Matlab/Simulink with SimPower Systems through a set of simulation tests under different load conditions. Also, the tuning of the active power filter is performed to improve the quality of the electrical power supply.

Design and Application of Power Active Filter Harmonic Extract Technology

Active filter topology and principle are introduced. Harmonic data processing method is proposed . The method can greatly reduce the amount of computation of the controller to improve real-time. In addition, the working principle of the active filter topology and control strategies are introduced and analyzed. Results verify the correctness of the algorithm and the feasibility of the design.

Direct power control of shunt active filter using high selectivity filter (HSF) under distorted or unbalanced conditions

This paper describes the design of a new configuration of direct power control (DPC) based on high selectivity filters (HSF) to achieve near-sinusoidal source current waveforms under different source voltage conditions. The proposed method uses the high selectivity filters instead of the classical extraction filters (low pass filters). The basic idea of the proposed DPC is to choose the best inverter voltage vector in order to minimize instantaneous active and reactive power errors using two hysteresis comparators. Their outputs associated with a switching table, control the active and reactive powers by selecting the optimal switching states of the inverter. Simulation results have proved excellent performance, and verify the validity of the proposed DPC scheme, which is much better than conventional DPC using low pass filters.

A Lyapunov-Based Control for a Single-Phase Shunt Hybrid Active Filter

In this paper, we analyze the control effect of the Lyapunov control strategy on the single-phase shunt hybrid active power filter based on the averaged state space model. The control law is derived by constructing an appropriate Lyapunov control function, and the switching signals is obtained through the pulse width modulation (PWM). The simulation results show that the Lyapunov-based control for a single-phase shunt hybrid active filter is of stability feature, and has good harmonic compensation performance. It presents better harmonic elimination compared to the the traditional PI and LQR controller.

V2G Technology to Design a Smart Active Filter for Solar Power System

This paper presents the implementation of Vehicle to Grid (V2G) technology for designing a shunt active filter to improve power quality of solar generation. A system model with solar generation and a dynamic model of PHEVs are introduced here based on third order battery model. A simple battery scheme is proposed for the control of the charging and discharging of the PHEVs using a power electronic interface. The active filter controller is designed based on the instantaneous power theory (p-q theory) to improve the wind generator performance through compensating the oscillating real and reactive power from PHEVs. Simulations have been carried out and demonstrate that PHEVs have the potential to work as active filter with solar power generator to improve power quality, dynamic power factor correction and harmonics current compensation. DOI: http://dx.doi.org/10.11591/ijpeds.v3i1.1711

Shunt power electronic buffer as active filter and energy flow controller

Abstract The considered shunt active power filter can be controlled not only to compensate non-active current in the supply source, but additionally to optimize energy flow between the source and the load. In such a case the filter shapes the source current to be active and simultaneously regulates its magnitude. The presented filter/buffer can operate properly even when the load contains AC or DC variable energy source of any characteristic. The device can optimize energy flow for a single load, but also for a group of loads as well. The distinctive feature of the employed control method of the filter/buffer is that certain changes of energy stored in the device are utilized as the source of information concerning the active current of the load. This control method is very flexible and can be implemented to nearly all structures of active filters, for DC, single- and multiphase circuits.

Fast Harmonic Estimation of Stationary and Time-Varying Signals Using EA-AWNN

Field measurement of harmonic distortion is a fundamental requirement for monitoring, analysis, and/or control of power system harmonics. Fast and accurate estimation of time-varying harmonics is a key to realize many objectives of the smarter and cleaner grid such as harmonic source identification, improved active filter control for mitigation of harmonics, and smart meters for harmonic pollution metering. This paper presents a fast and accurate approach for real-time estimation of moderate time-varying harmonics of voltage/current signals. The proposed method is based on estimation of signal parameters via rotational invariance technique (ESPRIT)-assisted adaptive wavelet neural network (AWNN). The AWNN provides quick estimates (twice every fundamental cycle with only half-cycle data as input) of the dominant harmonics, whereas the ESPRIT complements it to handle time-varying signals with higher accuracy. The salient features of the proposed method are validated on the simulated and experimental signals of stationary and time-varying nature.

A comparative study on the active power filter control strategy for independent and small power system

Aiming at the serious influence on the power frequency stabilisation for independent power system when its loads are largely changed, a control strategy of active power filter is presented. Firstly, the principle of second-order direct type IIR (infinite impulse response) digital notch filter is described, and the frequency real-time detection model is established based on least mean power (LMP, p = 3) adaptive algorithm to track the notch filter parameters. Then, combining the instantaneous reactive power theory and hysteresis current method, the simulation model of active filter control strategy with power frequency’s change is established. Finally, the simulation results proved that the active power filter model can track the changing frequency quickly and compensate harmonic current accurately. Therefore, the power quality and reliability of the small power grid are enhanced.