Shunt Active Power Filter System Research Articles

Study on the design and switching dynamics of hysteresis current controlled four‐leg voltage source inverter for load compensation

In a variable switching frequency control scheme, it is challenging to design the voltage source inverter (VSI) parameters without knowing the maximum and minimum switching frequencies. The switching frequency variation depends on the system parameters. Therefore, the expression for frequency variation in one inverter topology does not hold in other topologies. The design of hysteresis current controlled four-leg shunt active power filter (APF) requires the switching dynamics analysis to ensure satisfactory performance of the inverter. In this study, a detailed analysis on the switching dynamics of hysteresis current controlled four-leg VSI and design of various inverter components for compensating unbalanced and non-linear loads are presented. The results obtained from these analyses can be used in any applications involving hysteresis current controlled four-leg VSI. These results are supported by detailed simulation studies conducted on a three-phase four-leg shunt APF system using Matlab/Simulink. The theoretical studies and design of passive components are also verified by conducting experiments on a prototype of four-leg shunt APF developed in the laboratory.

A comparative analysis of DFPI correctors and different techniques to regulate a shunt active power filter

Power quality is a subject of intense study over recent years, given that it affects the economic impact and costs of utilities, supply and manufacturing. Modern powered electronic equipment is usually nonlinear in nature and causes propagation of harmonic current. This disruptive current can be countered by various solutions, but active power filtering is the most captivating solution. In this paper, a Shunt Active Power Filter (SAPF) system is considered with a new corrector design for both the DC and AC sides. The new design is based on an association between double fuzzy logic and single PI correctors resulting in two 'DFPI' correctors devoted to regulating the DC voltage and the AC current of the SAPF. The DFPI corrector is more advantageous than the classic PI or fuzzy controllers implemented alone for regulation purposes of the SAPF control variables (DC voltage and the AC current). This is demonstrated, in this paper, through the addressed theoretical analysis of the proposed DFPI corrector and the studies shown in the simulation section comparing the proposed DFPI, single fuzzy, double fuzzy and PI controllers. Performances in terms of the filtering quality of the AC feeder side and the SAPF DC-bus voltage regulation quality (THDis%/THDVs%) are noted. The obtained numerical results prove the effectiveness of the DFPI corrector which also described a faster response time, a reduced overshoot and a lessened static error.

A comparative analysis of DFPI correctors and different techniques to regulate a shunt active power filter

Power quality is a subject of intense study over recent years, given that it affects the economic impact and costs of utilities, supply and manufacturing. Modern powered electronic equipment is usually nonlinear in nature and causes propagation of harmonic current. This disruptive current can be countered by various solutions, but active power filtering is the most captivating solution. In this paper, a Shunt Active Power Filter (SAPF) system is considered with a new corrector design for both the DC and AC sides. The new design is based on an association between double fuzzy logic and single PI correctors resulting in two 'DFPI' correctors devoted to regulating the DC voltage and the AC current of the SAPF. The DFPI corrector is more advantageous than the classic PI or fuzzy controllers implemented alone for regulation purposes of the SAPF control variables (DC voltage and the AC current). This is demonstrated, in this paper, through the addressed theoretical analysis of the proposed DFPI corrector and the studies shown in the simulation section comparing the proposed DFPI, single fuzzy, double fuzzy and PI controllers. Performances in terms of the filtering quality of the AC feeder side and the SAPF DC-bus voltage regulation quality (THDis%/THDVs%) are noted. The obtained numerical results prove the effectiveness of the DFPI corrector which also described a faster response time, a reduced overshoot and a lessened static error.

Concert and Analysis of Auto-Tuning Dual-Feedback Biological Harmonic Controller for Industrial Claims

Abstract A reference current estimation method for control of shunt active power filter using a digital filter based synchronous reference frame theory is presented. To extort the fundamental component of source current, the synchronous reference frame theory is suitable because of its easy mathematical calculation compared to other control algorithms. For industrial applications, the load will be continuously varying, so continuous parameter tracking is most essential for controlling the total harmonic distortion (THD) for various conditions. Artificial intelligent controller based on mammalian limbic system and an emotional process is presented in dc link voltage control for a three-phase shunt active power filter. A novel approach of the intelligent techniques for control and decision-making processes was introduced, which is based on the emotion-processing mechanism in the brain, and is essentially an active selection that is based on emotional cues and sensory inputs. A model of shunt active power filter system for improving power quality by using the artificial intelligent control system is presented, which controls the dc link voltage spike through the transient period precisely and maintains speedy settling time during sudden changing of load. This generation of artificial intelligent controllers that has high auto learning speed with a simple arrangement shows an outstanding error-free environment for industrial applications. All of the parameters were analyzed and compared with proportional–integral (PI) and fuzzy gain scheduling controllers.

Predictive model approach based direct power control for power quality conditioning

This paper has presented improved control structure based direct power control (DPC) applied for shunt active power filtering. Basically, DPC control strategy employs instantaneous active and reactive power terms as controlled variables. This work introduces an integration concept of predictive control algorithm for shunt active power filter system application. Process of this latter adopts discrete model of PWM converter in the aim to predict future behaviour of the system. Switching vector selection principles for predictive control is very different compared to conventional method. For conventional DPC the selection is performed via heuristic switching table while predictive DPC algorithm takes on an optimized way based on cost function minimization depending to power errors, this latter evaluate the effects of each active voltage vector and the one reducing the cost function is chosen to be applied in the next sampling period. The application of optimal switching state leads to regulate the input active and reactive power which resulted in the cancellation of harmonic power component contained in the network. Simulation results are presented to verify the validity and effectiveness of the proposed predictive DPC in terms of dynamic and steady state performance for shunt active power filtering application.

Neural Network Based ILST Control Strategy for a DSTATCOM with Solar Photovoltaic System for Power Quality Improvement

The power quality compensator chosen in this paper is a DSTATCOM which integrates a three phase four leg Voltage Source Converter (VSC) with a DC capacitor (Cdc). A single stage Solar Photovoltaic (SPV) system is implemented for maintaining the DC link voltage (Vdc) of the Shunt Active Power Filter (SAPF). The system proposed, improves the Power Quality (PQ) of the utility system as well as feeds the solar energy extracted into the system. Maximum Power Point Tracking (MPPT) is implemented to excerpt solar energy. The purpose of the proposed system is to mitigate harmonics and neutral current (Isn),to compensate reactive power and to maintain power factor near unity. The SAPF improves the PQ of the proposed system. The control algorithm proposed for SAPF is Neural Network (NN) based Improved Linear Sinusoidal Tracer (ILST) algorithm. An instantaneous compensation technique controls the variations in PV power of the SPV system with fast dynamic response. The proposed system is also compared with battery operated Boost Converter (BC) SPV fed SAPF system. The battery operated SPV system boost the DC link voltage and thus improves PQ throughout the day. The NN based control strategy and the SPV system are modeled, developed and validated in MATLAB SIMULINK. The simulation results justify the effectiveness of the propounded system.

PENURAS KUASA AKTIF PIRAU SATU FASA MENGGUNAKAN STRATEGI KAWALAN RINGKAS

This paper describes a single phase shunt active power filter system used in compensating current harmonics and improving electrical line’s power factor via simplified control strategy based on estimation of nonlinear load’s equivalent resistance. By employing MATLAB Simulink simulation tool, the proposed control strategy successfully compensated source current harmonics and corrected line power factor to near unity. Moreover, analysis on the system performance indicated that the system’s achieved fast time response, stabilized system and near zero steady state error. To verify the proposed system, experimental results also presented.

Performance Enhancement of Shunt Active Power Filter Using a Kalman Filter-Based ${{{\rm H}}_\infty }$ Control Strategy

This paper proposes a Kalman filter (KF)-based H ∞ control scheme for a three-phase shunt active power filter (SAPF) system. For the current control loop, a H ∞ controller is designed with a mixed sensitivity approach for achieving stability and high-disturbance rejection in the SAPF system. A new current reference scheme is also proposed that employs KF to avoid synchronization circuit and proportional integral (PI) controller loop resulting in a reliable and cost-effective SAPF system. This reference scheme can self-regulate the dc-link voltage by a fast and adaptive estimation of the source reference current with power system perturbations raised in source or load sides. The efficacy of the proposed KF-H ∞ control algorithm is evaluated through comparison with an existing PI and PI plus vector PI (PI-PIVPI) algorithm and then validated with experimental studies pursued using a dSPACE1104. From the obtained experimental results, it is observed that the proposed SAPF significantly outperforms the existing PI-PIVPI in terms of exhibiting robustness to modeling uncertainties and insensitivity to grid perturbations such as harmonics, measurement noise, and phase angle jump. Thus, the power quality improvement is achieved in terms of perfect current harmonics cancellation as well as power factor improvement.

Backstepping control of three-phase three-level four-leg shunt active power filter

In this paper, backstepping control for three-level four-leg shunt active power filter (SAPF) system is proposed. The adopted filtering topology requires both a three-dimensional space vector modulation (3DSVM) for controlling the three-level four-leg inverter as well as DC voltage and filter currents control. The regulation of the DC voltage and filter currents is accomplished by backstepping controllers. The voltage-balancing control of two split DC capacitors of the three-level four-leg SAPF is achieved using three-level three-dimensional space vector modulation equipped by a balancing strategy based on the effective use of the redundant switching states of the inverter voltage vectors. The simulation results show the effectiveness of the proposed filtering system in terms of the compensation of the harmonics and the zero sequence current and the operation at unity power factor.

A Robust LQG Servo Control Strategy of Shunt-Active Power Filter for Power Quality Enhancement

This paper proposes a linear quadratic Gaussian (LQG) servo controller for the current control of shunt-active power filter (SAPF) operating under balanced and unbalanced supply voltages. This LQG controller is comprised of a LQ regulator and a Kalman filter (KF) that minimizes the error between the output currents and their variations. A feedback compensator is used in LQG servo controller that benefits an SAPF system by increasing tracking error reduction, gain stability, reducing amplitude distortion and sensitivity to external disturbances. A KF-based new reference current generation scheme is developed here to resolve the difficulty of tuning gains of a proportional integral controller and for avoiding the use of voltage sensors making it cost effective. Consequently, this reference scheme has self-capability of dc-link voltage regulation by adaptively estimating the peak value of source reference current with changing load conditions. The control algorithm is embedded in SAPF using a MATLAB/Simulink software environment. The effectiveness of the proposed LQG ServoKF algorithm is evaluated through comparison with an existing LQR <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">KF</sub> algorithm and then validated with experimental studies pursued using a dSPACE1104 computing platform. From the obtained experimental and simulation results, it is observed that the proposed control strategy exhibits superior performance in terms of robustness improvement and current harmonics mitigation under steady-state and dynamic load conditions, thus making it more effective for practical applications.

Experimental investigations on Ant Colony Optimized PI control algorithm for Shunt Active Power Filter to improve Power Quality

Active Power Filters (APFs) have become a potential option in mitigating the harmonics and reactive power compensation in single-phase and three-phase AC power networks with Non-Linear Loads (NLLs). Conventionally, the assessment of gain values for Proportional plus Integral (PI) controllers used in APF employs model based controllers. The gain values obtained using traditional method may not give better results under various operating conditions. This paper presents Ant Colony Optimization (ACO) technique to optimize the gain values of PI controller used in Shunt Active Power Filter (SAPF) to improve its dynamic performance. The minimization of Integral Square Error (ISE), Integral Time Square Error (ITSE), Integral Absolute Error (IAE) and Integral Time Absolute Error (ITAE) are considered as cost functions for the proposed system. The proposed SAPF is modeled and simulated using MATLAB software with Simulink and SimPowerSystem Blockset Toolboxes. The simulation results of the SAPF using the proposed methodology demonstrates improved settling time (Ts) with ISE as cost function. For instance, the Ts for ISE 4.781 is found to be 28.5 ms. Finally, hardware implementation of the proposed SAPF system is done using Xilinx XCS500E Spartan 3E FPGA board.

Simplified multi‐modular shunt active power filter system and its modelling

To meet the requirement of large capacity for harmonic suppression and reactive power compensation, modular shunt active power filter (SAPF) system is attractive for its high-reliability and flexibility. However, a unique physical address is needed for each module in traditional SAPFs. If a module fails, the faulted module should be substituted by another one with the same physical address. Therefore it is hard to realise modularisation, and the cost of the system is high. In addition, in such a system, a single SAPF generally adopts the topology with LCL filter and are coupled because of grid impedance. Generally, this coupling is not taken into account when designing the control laws. In consequence, depending on the number of paralleled SAPFs and the grid impedance, the paralleled SAPFs do not behave as expected. In this study, a simplified N + 1 redundant SAPF system and its control strategy are presented. The SAPFs are modelled as a multivariable system. The analysis carried out enables to obtain an equivalent SAPF that describes the totality of paralleled SAPFs. The coupling effect is described and the control law design of paralleled SAPFs with LCL filters is clarified. The validity of the simplified N + 1 SAPF system and the efficiency of the control strategies are demonstrated by prototype experiments.

Model predictive‐based shunt active power filter with a new reference current estimation strategy

This study presents a new reference current estimation method using proposed robust extended complex Kalman filter (RECKF) together with model predictive current (MPC) control strategy in the development of a three-phase shunt active power filter (SAPF). A new exponential function embedded into the RECKF algorithm helps in the estimation of in phase fundamental component of voltage ( v h ) at the point of common coupling considering grid perturbations such as distorted voltage, measurement noise and phase angle jump and also for the estimation of fundamental amplitude of the load current ( i h ). The estimation of these two variables ( v h , i h ) is used to generate reference signals for MPC. The proposed RECKF-MPC needs less number of voltage sensors and resolves the difficulty of gain tuning of proportional-integral (PI) controller. The proposed RECKF-MPC approach is implemented using MATLAB/SIMULINK and also Opal-RT was used to obtain the real-time results. The results obtained using the proposed RECKF together with different variants of Kalman filters (Kalman filter (KF), extended KF (EKF) and extended complex KF (ECKF)) and PI controller are analysed both in the steady state as well as transient state conditions. From the above experimentation, it was observed that the proposed RECKF-MPC control strategy outperforms over PI controller and other variants of Kalman filtering approaches in terms of reference tracking error, power factor distortion and percentage total harmonic distortion in the SAPF system.

SAPF for the Inter-harmonics on Grid Network Compensation

Using SAPF (shunt active power filter) has been proved as an effective way for harmonic compensation. In practical applications, the performance of SAPF will be impacted by interharmonics and non-periodic disturbances. This paper analyzed the CPT (conservative power theory) definition of power theory and the application method for SAPF. Repetitive controller and PI controller were used as a combination way for the harmonic and inter-harmonic compensation. By the EID (equivalent input-disturbance) controller, the performance for non-periodic interference suppression of SAPF can be improved. By simulation with MATLAB, the models of SAPF system, repetitive controller and EID controller were built. Through the computer simulation method, we can verify the designed system performance.

A Robust Extended Complex Kalman Filter and Sliding-mode Control Based Shunt Active Power Filter

—This article presents the design of a new shunt active power filter that employs a modified robust extended complex Kalman filter approach with an exponential robust term embedded for reference current estimation together with a current controller based on the sliding-mode control concept. The robust extended complex Kalman filter exploits a new weighted exponential function to handle these grid perturbations to estimate the reference signal in shunt active power filter system. The current controller in the proposed shunt active power filter has been designed using a sliding-mode control strategy because of its ability to handle parameter uncertainties and ease in implementation. To test the effectiveness of the proposed shunt active power filter, extensive simulations were performed using MATLAB/Simulink (The MathWorks, Natick, Massachusetts, USA), and real-time studies were made using OPAL-RT (Montreal, Quebec, Canada). Results obtained from the above studies using the proposed shunt active power filter together with the different variants of Kalman filter (Kalman filter, extended Kalman filter, extended complex Kalman filter) are analyzed, and it is observed that the proposed robust extended complex Kalman filter-sliding-mode control based shunt active power filter provides accurate and improved harmonics mitigation and reactive power compensation.

Harmonic power compensation capacity of shunt active power filter and its relationship with design parameters

In this study, the equation for the reactive and harmonic power compensation of a shunt active power filter (APF) system has been derived by studying the power exchange mechanism and power tetrahedron phasor diagram. The switching dynamics of a voltage source inverter (VSI)-based three-phase, three-wire (three-leg /half-bridge) shunt APF system with hysteresis band current control has been studied and verified by simulation. The relation between the design parameters and their effects on the active losses has also been identified. Detailed calculation and extensive simulation have been performed for a three-phase, three-wire shunt APF implemented in a 400VL-L distribution system, as an example, to study the effects of design parameter selection and their role in active power loss calculation. Simulated and calculated results are presented for the important design parameters for different switching frequencies together with their associated losses and kVA ratings. The procedure can be followed to design the parameters for other topologies, such as three-phase, four-wire or single-phase systems.

Fryze Current Controller Based Active Power Filter

Harmonics in a power system can result in communication interference, transformer heating, or solid-state device malfunctions. Active power line conditioners (APLC) or Active power filter (APF) are one important way to achieve harmonic reduction. The purpose of this work is to present shunt active power filter which mitigates harmonic contents in source current due to non linear load present in the system. The novel active power filter is based on Fryze current controller with a positive sequence detector, an approach different from conventional method; the aim is to guarantee the reduction in harmonic from source current. The shunt APF system is implemented with current controlled Voltage Source Inverter (VSI) and is connected to the distribution network for canceling current harmonics. The reference currents are generated using Fryze current minimization (FCM) algorithm and switching signals for VSI are generated from hysteresis current controller (HCC). The shunt APLC system is tested and the performance parameters are obtained under various non-linear and unbalanced load conditions. This is a time domain approach, easy to understand and implement.

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

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

Research on Harmonic Suppression in Power System Based on Improved Adaptive Filter

This paper described the structure of a Shunt Active Power Filter system and compared various methods of active power filter harmonic detection, then the improved adaptive algorithm was used in active power filter harmonic detection; as regards the control strategy, the control method that based on optimal voltage space vector hysteresis current was presented in this paper for tracking control, And by using Matlab/Simulink simulation software, the Adaptive filter detection system and control model of Three-phase three-wire Shunt Active Power Filter were established. Simulation results showed that the selected detection method and control strategy of harmonic current played a fairly good compensation role on the harmonics which was generated by nonlinear loads and had a good dynamic compensation performance.

PI and fuzzy logic controllers for shunt active power filter — A report

This paper presents a shunt Active Power Filter (APF) for power quality improvements in terms of harmonics and reactive power compensation in the distribution network. The compensation process is based only on source current extraction that reduces the number of sensors as well as its complexity. A Proportional Integral (PI) or Fuzzy Logic Controller (FLC) is used to extract the required reference current from the distorted line-current, and this controls the DC-side capacitor voltage of the inverter. The shunt APF is implemented with PWM-current controlled Voltage Source Inverter (VSI) and the switching patterns are generated through a novel Adaptive-Fuzzy Hysteresis Current Controller (A-F-HCC). The proposed adaptive-fuzzy-HCC is compared with fixed-HCC and adaptive-HCC techniques and the superior features of this novel approach are established. The FLC based shunt APF system is validated through extensive simulation for diode-rectifier/R–L loads.