Implementation of PSOANN Optimized PI Control Algorithm for Shunt Active Filter

This paper proposes the optimum controller for shunt active filter(SAF)to mitigate the harmonics and maintain the power quality in the distribution system.It consists of shunt active filter,Voltage Source Inverter(VSI),series inductor and DC bus and nonlinear load.The proposed hybrid approach is a combination of Particle Swarm Optimization(PSO)and Artificial Neural Network(ANN)termed as PSOANN.The PI controller gain parameters of kp and ki are optimized with the help of PSOANN.The PSOANN improves the accuracy of tuning the gain parameters under steady and dynamic load conditions;thereby it reduces the values of THD within the prescribed limits of IEEE 519.The PSO optimizes the dataset of terminal voltage and DC voltage present in shunt active filter for different load condition.The optimized dataset acts as the input for the controller to predict the optimal gain with minimal error and to generate the optimized control signal for the SAF.The proposed methodology is modelled and simulated with the help of MATLAB/Simulink platform and illustrated the few test cases considered for exhibiting the performance of proposed hybrid controller.The experimental results are measured with developed laboratory prototype and compared with the simulation results to validate the effectiveness of the proposed control methodology.

Control of an Active Filter by Duty Cycle Modulation (DCM) for the Harmonic Decontamination of a Three-Phase Electrical Network

This paper presents the control of the active filter by Duty Cycle Modulation (DCM) for the harmonic pollution control of a three-phase electrical system. Several research works have preceded this work, but most of them deal with the control by pulse-width modulation and the differences lie around the THD reduction performance, the quality of the wave obtained, the simplicity of the scheme and the cost of the control. For this purpose, we propose a very innovative approach to active filter control which aims at reducing the current THD at a lower rate than pulse-width modulation techniques improving at the same time the wave quality with a more simplified control scheme. First we present the schematic diagram of the active filter, then we present the design of the control of this active filter based on the real and imaginary instantaneous power method which uses the algebraic “Clark” transformation. The Duty Cycle Modulation controller is used to obtain the required control commands to be injected to the inverter. We then developed a simulink model of the active filter to validate this study. The simulations were performed in the Matlab/Simulink environment. The results obtained show a significant improvement on the harmonic current control techniques for the THD of 1.02% which was 26.25%, the elimination of noise in the signal and the simplicity of the control with an easier implementation than the pulse width modulation (PWM) make the Duty Cycle Modulation (DCM) control a very promising tool.

Harmonic Reduction in Wind Power Generating System Using Shunt Active Filter with SPWM Technique

Due to environmental conditions, the wind power generation is fluctuating in nature. This affects the electrical network interconnected with these systems. When the wind power generators are connected to the nonlinear loads, there is distortion in the waveform. These distortions should be within limits according to national and international guidelines framed for power quality. This paper presents a mitigation technique with a shunt active filter, which reduces harmonic distortion to the permitted limit. Sine pulse width modulation (SPWM) control scheme is used to control shunt active filter. This technique eliminates harmonic distortion and maintains unity power factor. The simulation for proposed method is carried out using MATLAB/SIMULINK and results are validated.

CCII-Based Inverse Active Filters with Grounded Passive Components

This paper introduces IAFs （inverse active filters） employing CCIIs （second generation current conveyors） and groundedpassive components. The IAFs enable ILP （inverse low-pass）, IBP （inverse band-pass） and IHP （inverse high-pass） characteristics byadding the circuit currents. Additionally, the circuit parameters ω0 and Q can be set orthogonally adjusting the circuit components.The achievement example is given together with simulation results by PSPICE.

An Integrated System for Active Filter and Photovoltaic Energy Conversion

This paper focuses on the implementation of a three-phase four-wire current-controlled Voltage Source Inverter （CC-VSI） as both power quality improvement and Photovoltaic （PV） energy extraction. For power quality improvement, the CC-VSI works as a grid current-controller shunt active power filter. Then, the PV array supported by the Hill- Climbing maximum power point tracking （MPPT） controller is coupled to the DC bus of the CC-VSI. The output of the MPPT controller is a DC voltage that determines the DC-bus voltage according to the PV maximum power. From computer simulation results, the CC-VSI is able to compensate for the harmonic and reactive power as well as to extract the PV maximum power.

A new shunt DC active filter of power supply in a steady high magnetic field facility

A DC active power filter is an indispensable part in a high power and high stability power supply system, especially in the power supply system of the Steady High Magnetic Field Facility, which requires that the current ripple should be limited to 50 parts per million. In view of the disadvantages of the series DC active power filter and shunt Pulse Width Modulation DC active filter, this paper puts forward a novel DC active filter by combining the advantages of the transistor regulator and the shunt type. The structure and principle of the new shunt linear active filter are introduced. Meanwhile, the design of several key components that construct the new shunt linear active filter is also analyzed. The simulation model and an experimental prototype of the shunt linear active filter are developed, and the results verify that the parameter design is reasonable and the shunt active filter has a good filter effect.

Simulation and reliability analysis of shunt active power filter based on instantaneous reactive power theory

This paper first discusses the operating principle of instantaneous reactive power theory. Then, the theory is introduced into shunt active power filter and its control scheme is studied. Finally, Matlab/Simulink power system toolbox is used to simulate the system. In the simulation model, as the most common harmonic source, 3-phase thyristor bridge rectifier circuit is constructed. The simulation results before and after the shunt active filter was switched to the system corresponding to different firing angles of the thyristors are presented and analyzed, which demonstrate the practicability and reliability of the proposed shunt active filter scheme.

DC active power filter based on model predictive control for DC bus overvoltage suppression of accelerator grid power supply

The China Fusion Engineering Test Reactor plans to build a 200 k V/25 A acceleration grid power supply(AGPS)for the negative-ion-based neutral beam injector prototype system.The AGPS uses a rectifier-inverter-isolated step-up structure.There is a DC bus between the rectifier and the inverter.In order to limit DC bus voltage ripple and transient fluctuations,a large number of capacitors are used,which degrades the reliability of the power supply and occupies a large amount of space.This work finds that due to the difference in the turn-off time of the rectifier and the inverter,the capacitance mainly depends on the rectifier current when the inverter is turned off.On this basis,an active power filter(APF)scheme is proposed to absorb the current.To enhance the dynamic response ability of the APF,model predictive control is adopted.In this paper,the circuit structure of the APF is introduced,the prediction model is deduced,the corresponding control strategy and signal detection method are proposed,and the simulation and experimental results show that APF can track the transient current of the DC bus and reduce the voltage fluctuation significantly.

Rapid transaction to load variations of active filter supplied by PV system

This paper deals with the analysis and control of a photovoltaic （PV） system connected to the main supply through a Boost converter and shunt active filter supplied by a PV system providing continuous supply of nonlinear load in variation. A robust control of a PV system connected to the grid while feeding a variable nonlinear load is developed and highlighted. This development is based on the control of the Boost converter to extract the maximum power from the PV system using the Perturb and Observe （P and O） algorithm in the presence of temperature and illumination. The proposed modeling and control strategy provide power to the variable nonlinear load and facilitates the transfer of power from solar panel to the grid while improving the quality of energy （harmonic currents compensation, power factor compensation and dc bus voltage regulation）. Validation of the developed model and control strategy is conducted using power system simulator Sim-Power System Blockset Matlab/Simulink. To demonstrate the effectiveness of the shunt active filter to load changes, the method of instantaneous power （pq theory） is used to identify harmonic currents. The obtained results show an accurate extraction of harmonic currents and perfect compensation of both reactive power and harmonic currents with a lower THD and in accordance with the IEEE-519 standard.

A simple digital control algorithm for three phase shunt active filter： simulation and experimentation

A novel and simple ifrea! control algorithm using digital signal processor （DSP） has been proposed and realized for a three phase shunt active filter （SAF）. The simulation and prototype construction of SAF is conducted to compensate the reactive power and harmonics in a distribution system. The major feature of the proposed ifreal algorithm is that it does not require unit vector templates and any transformations for the reference current genera- tion of SAF. This reduces the computational complexity and makes the control flexible and faster. The simulation is conducted in MATLAB/SIMULINK while DSP TMS320LF2407 is employed in the digital implementation of hysteresis current control （HCC） for experimentation. The hardware results correlate with the simulation results in reducing the total harmonic distortion （THD） of the source current and achieving unity power factor.

COMPARISON AND EVALUATION OF CURRENT REFERENCE GENERATION STRATEGIES FOR ACTIVE POWER FILTERS IN THREE-PHASE FOUR-WIRE SYSTEMS

For three phase four-wire active power filters （APFs）, several typical power theories and corresponding current reference generation strategies are induced, p-q, d-q, unify power factor （UPF） and instantaneous active current （IAC） methods are analyzed and compared with each other. The interpretation of active and reactive currents in non-sinusoidal and unbalanced three-phase four-wire systems is given based on the generalized instantaneous reactive power theory. The performance and the characteristic are evaluated, and the application conditions of current reference generation strategies are concluded. Simulation results under different source voltages and loads verify the evaluation result.

Design and analysis of dual-mode structure repetitive control based hybrid current regulation scheme for active power filters

An all-digital hybrid current regulation scheme for the single-phase shunt active power filter （APF） is presented. The proposed hybrid current control scheme integrates the deadbeat control and the dual-mode structure repetitive control （DMRC） so that it can offer superior steady-state performance and good transient features. Unlike the conventional schemes, the proposed scheme-based APF can compensate both the odd and the even order harmonics in grid. The detailed design criteria and the stability analysis of the proposed hybrid current controller are presented. Moreover, an improved structure which incorporates the proposed hybrid controller and the resonant controller for tracking specific order harmonics is given. The relationships between the resonant controller and different repetitive control schemes are discussed. Experimental results verify the effectiveness and advantages of the proposed hybrid control scheme.

Improved PLL Tuning of Shunt Active Power Filter for Grid Connected Photo Voltaic Energy System

This research work brings out the unique predictive current control method for attaining an efficient grid connected Photo Voltaic (PV) system by Shunt Active Power Filter (SAPF) as grid connected converter. The major objective of the research work is to address the presence of Direct Current (DC) component, frequency improvement, quicker theta response, voltage magnitude estimation in the input signal of the Phase Locked Loop (PLL) which is challenging. This work focuses on tuning the PLL block (Kp, Ki, Kv and Ko) through Artificial Bee Colony (ABC) optimization algorithm. The proposed ABC based modified three-phase PLL method is based on adding a new loop inside the PLL structure. In power converters, ABC algorithm is used to select the optimal switching states. The voltage vector which minimizes a cost optimization function is selected. Simulation is carried out for both balanced and unbalanced system and the results validate that the performance of the proposed approach is better in terms of harmonic compensation as per the IEEE standards within ±5%, power factor improvement of the system, quicker theta tracking and suppression of frequency jump with the interconnection of PV system.

Invertebrate community characteristics in biologically active carbon filter

Biologically active carbon （BAC） system was set up in a water plant of South China during January to December 2007,to study the invertebrate community characteristics of BAC filter.Thirty-seven invertebrate species were found,of which 28 belonging to rotifers.Filter operation could lead to an output of invertebrates in high abundances with the filtrate,and the maximum density could reach 5608 individuals/m 3.Average abundances in the effluent water increased in 27-33 folds in comparison to the influent water during the sampling period.Invertebrate community succession had the following trend：filter-feeding animals → small benthic invertebrates → large benthic and resistant invertebrates.Abundances of large-sized invertebrates （copepod adult and oligochaete） at bigger-media column were significantly higher than that at small-media column.The results implied the abundant species diversity of invertebrate in BAC filter.The relationship between invertebrate and biofilm still remain to be studied in detail.

Increasing the operating area of shunt active filters by advanced nonlinear control

This work is aimed to rigorously manage voltage saturation and maximum current constraints in Shunt Active Filters. In this respect, assuming 'unconstrained' control algorithms have already been defined to achieve standard objectives for such devices(i.e. current tracking for harmonic compensation and DC-bus voltage boundness), a plug-in unit, oriented to extend the system operating region and at the same time preserving good performance under large transients and overload conditions, is presented.This solution allows to improve availability, robustness and composability of Shunt Active Filters, which are expected to be key features in present and next generation complex and possibly 'smart' power grids. The proposed unit is composed by two parts.First, a suitable anti-windup strategy is defined in order to deal with control input saturation. Its main purpose is to preserve the original 'unconstrained error dynamics', in face of input saturation, while guaranteeing low computational burden and reduced performance impairment(the latter goal, in harmonic compensation context, leads to rather non-standard problem formulation).To this aim, the anti-windup acts on the current references through a suitably-designed additional dynamics. Then, in order to cope with current limitations, an additional strategy has been designed; again the current references is suitably shaped to comply with the features and bounds of the system, augmented with the above-mentioned anti-windup solution. The proposed scheme can be simply joined to any kind of unconstrained controller adopted to steer Shunt Active Filters. In this work, an Internal-Model-based current controller is adopted as a benchmark case. The proposed approach is validate through extensive simulation tests.

Carrier phase shifted SPWM based on current sourced multi-modular converter for active power filter

A novel current-source active power filter (APF) based on multi-modular converter with carrier phase-shifted SPWM (CPS-SPWM) technique is proposed. With this technique, the effect of equivalent high switching frequency con-verter is obtained with low switching frequency converter. It is very promising in current-source APF that adopt super-conducting magnetic energy storage component.

Simulation Research on a SVPWM Control Algorithm for a Four-Leg Active Power Filter

In this paper the topology of a four-leg shunt active-power filter (APF) is given. The APF compensates har-monic and reactive power in a three-phase four-wire system. The scheme adopted for control of the four-leg active power filter,a 3-Dimensional Pulse Width Modulation (PWM) technique,is presented. The theoretical deduction of a space vector PWM (SVPWM) algorithm is given in this paper. The paper also analyzes the distribution of the volt-age-space vector of the four-leg converter in αβγ coordinates and describes methods to determine the location of the voltage-space vector and to calculate duration time. Finally,the algorithm is implemented in simulation; the results show that the total harmonic distortion (THD) of the three phase-current waveforms is reduced. The neutral wire current,after compensation,is about 0 A showing that the topology of the four-leg shunt APF is feasible and the proposed scheme is effective.

A novel digital control strategy of three-phase shunt active power filter under non-ideal mains voltages

A novel control strategy for three-phase shunt active power filter (SAPF) was proposed to improve its performance under non-ideal mains voltages. The approach was inspired by our finding that the classic instantaneous reactive power theory based algorithm was unsatisfactory in terms of isolating positive sequence fundamental active components exactly under non-ideal mains voltages. So, a modified ip-iq reference current calculation method was presented. With usage of the new method, not only the positive sequence but also the fundamental active current components can be accurately isolated from load current. A deadbeat closed-loop control model is built in order to eliminate both delay error and tracking error between reference voltages and compensation voltages under unbalanced and distorted mains voltages. Computer simulation results show that the proposed strategy is effective with better tracking ability and lower total harmonic distortion (THD). The strategy is also applied to a 10 kV substation with a local electrolysis manganese plant injecting a large amount of harmonics into the power system, and is proved to be more practical and efficient.

Current control for a shunt hybrid active power filter using recursive integral PI

This paper presents a current control method for a shunt hybrid active power filter （HAPF） using recursive integral PI algorithm. The method improves the performance of the HAPF system by reducing the influence of detection accuracy, time delay of instruction current calculation and phase displacement of output filter. Fuzzy logic based set-point weighing algorithm is combined in the control scheme to enhance its robustness and anti-interference ability. The proposed algorithm is easy to implement for engineering applications and easy to compute. Experiment results have verified the validity of the proposed controller. Furthermore, the proposed recursive integral PI algorithm can also be applied in the control of periodic current as in AC drivers.

A 4TH ORDER FULLY INTEGRATED ACTIVE RC COMPLEX FILTER WITH NOVEL AUTOMATIC TUNING SYSTEMS

This letter introduces a 4th order active RC complex filter with 1.SMHz center frequency and 1MHz bandwidth. The total harmonic distortion of the filter is less than -60dB and the image rejection ratio is greater than 60dB. A novel technique is also proposed in this letter to automatically adjust the variation of the time constant. The advantages of the proposed method are its high precision and simplicity. Using 5bits control words, the tuning error is less than ±1.6%.