A new approach to design digital controller for three phase active power line conditioner for harmonic compensation using 8051 microcontroller

Various electronic circuits such as inverters, choppers, cyclo-converters, SMPS used by industrial and domestic purposes are non-linear in nature, which makes the load current to be distorted, causing undesirable effects like heating, equipment damages, EMI related problems in power system. The active power filter (APF) is the best solution for eliminating the harmonics caused by the non-linear loads. This paper presents about a three-phase four-wire active power filter for power line conditioning to improve power quality in the distribution network and implementation of a digitally controlled APF. The active power filter is implemented with PWM based current controlled voltage source inverter (VSI).The switching signals for APF are generated through proposed three-level hysteresis current controller (HCC). The shunt APF system is modeled and investigated under different unbalanced non-linear load conditions using MATLAB program. The Controller Design using Hardware Description Language (VHDL or VERILOG) becomes independent of process technology. Synchronous reference frame (SRF) is used for generation of reference current. Both PI current algorithm and HCC are written in VHDL code and implemented using FPGA platform.

This paper present three-phase four-wire active filter for power line conditioning (PLC) to improve power quality in the distribution network. The active power filter (APF) is implemented with PWM based current controlled voltage source inverter (VSI). This VSI switching signals are generated through proposed three-level hysteresis current controller (HCC) that achieves significant reduction in the magnitude and variation of the switching frequency; it is indicating improved performance compared to 2-level HCC. The shunt APLC system is modeled and investigated under different unbalanced non-linear load conditions using Matlab programs. The simulation results reveal that the active power filter is effectively compensating the current harmonics and reactive power at point of common coupling. The active power line conditioner system is in compliance with IEEE 519 and IEC 61000-3 recommended harmonic standards.

Fryze Current Controller Based Active Power Filter

Current Control of the Isolated Self-Excited Induction Generator using Shunt Active Filter

41 - Active Filters

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 400 V L–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.

The current paper presents a role of Unified Power Quality Conditioner (UPQC) in 3 phase 4 wire distribution system to improve the power quality. The UPQC is realized by the integration of series and shunt active power filters (APF) sharing a common dc bus capacitor. The realization of shunt APF is carried out using a three-phase, four-leg Voltage Source Inverter (VSI), and the series APF is realized using a three-phase, three-leg VSI. To extract the fundamental source voltages as reference signals for series APF, d-q-0 theory is used. For the control of shunt APF, Clark transformation concept is applied. The performance of the applied control algorithm is evaluated in terms of source neutral current mitigation, mitigation of voltage and current harmonics in a three-phase, four-wire distribution system for different combinations of linear and non-linear loads. The reference signals and sensed signals are used in a hysteresis controller to generate switching signals for shunt and series APFs. MATLAB/Simulink-based simulations that support the functionality of the UPQC are obtained.

This paper presents a novel control scheme for unified power quality conditioner (UPQC) based on three-level neutral point clamped (NPC) inverter using fuzzy logic and Ann's for controlling respectively series and shunt APFs. The proposed UPQC is able to mitigate source current harmonics and compensate all voltage disturbances. It is designed by the integration of series and shunt active filters (AFs) sharing a common DC bus capacitor. The DC voltage is maintained constant using proportional integral voltage controller. The synchronous reference frame (SRF) theory is used to get the reference signals for the shunt APF and the power reactive theory (P-Q theory) for the series APF. The shunt and series active power filter (APF) reference signals derived from the control algorithm and sensed signals are injected in two intelligent controllers to generate switching signals. The performances of the proposed UPQC system are evaluated using Matlab-Simulink software and SimPowerSystem Toolbox. The simulation results show the performance of the proposed UPQC at the common connection point of the non-linear load to improve the power energy quality.

The fitting of an active power filter (APF) to mitigate the effects of a diode or thyristor bridge-rectifier is predicated on the assumption that the rating of the filter is reasonable (i.e. small) compared with the rating of the existing bridge rectifier or of a replacement active rectifier. The ratings of both shunt and series APFs are analysed in a variety of operating conditions. Ratings are assessed through peak voltage and mean current as appropriate for junction semiconductor devices. Rms ratings are also given because of their familiarity. The series APF, appropriate for the compensation of harmonic voltage sources, is of a generally higher rating than the shunt APF, appropriate for harmonic current sources. The use of a shunt APF where a series APF is appropriate results in poor device utilisation. The semiconductor ratings of an APF can be reduced by using hybrid schemes. Removing large-amplitude, low-order current harmonics with harmonic traps is effective for the shunt APF. Reducing peak voltages by attenuating high-frequency components is effective with the series APF. Arranging rectifiers into multipulse arrangements is seen to be effective for both shunt and series APFs. The ratings are approximately halved for the 12-pulse case.

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

In this paper, the principle, structure of the Active Power Filter (APF) system and PWM control are all discussed, and based on the improved instantaneous reactive power theory, a kind of fast feasible algorithm for distortion currents detection, harmonic current suppression and reactive power compensation in shunt active power filter is put forward, meanwhile, considering the problem of power devices active power loss in the main circuit, compensating current feedback and DC bus link voltage control are added, finally, a shunt active power filter for typical current harmonic source with thyristor rectifier load is simulated based on MATLAB/Simulink toolbox, by the detailed simulation experiments, in-depth research and analysis of the simulation results, the correctness and feasibility of the compensation scheme for harmonic current detection and APF system are all verified. The proposed scheme of the harmonic current suppression and reactive power compensation is achieved, which can provide a good reference to the research and design of APF.

Shunt Active Power Filters (APFs) are the up-to-date solution to power quality problems. Harmonic reference detection is the key word for the proper operation of shunt APF. One of the most famous detection control schemes for shunt APFs is the Synchronous Reference Frame (SRF). In this paper, two new modifications of (SRF) detection control scheme are presented. The first modification is done by introducing a new scheme for the dc bus control loop. The second modification is accomplished by implementing the SRF without load current sensors and using only the supply current sensors. These improvements, compared to the conventional (SRF), simplify the control system, minimize the system delay time, improve the APF performance, and reduce the cost of the system. The simulation results, using MATLAB/SIMULINK, demonstrate the viability and simplicity of the modified control scheme, its success in meeting power quality standards limits, and increasing the accuracy of generated reference signal.

A medium power Current Source Converter (CSC) based 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. For this purpose, four CSC based APF units 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 natural 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 (SHAM) 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.

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.

The unified power quality conditioner (UPQC) is a power conditioning device, which is a integration of back to back connected shunt active power filter (APF) and series APF to a common DC link voltage. For improvement of power quality (PQ) problems in a three-phase four-wire distribution system, two topologies are proposed in this paper. A comparative analysis of these topologies along with the most common four-leg voltage source inverter (VSI) based topology of four-wire UPQC is discussed in this work. The performance of each topology of UPQC is evaluated for different PQ problems like power-factor correction, load balancing, current harmonic mitigation, voltage harmonic mitigation and source neutral current mitigation. The synchronous reference frame (SRF) theory is used as a control strategy of series and shunt APFs. The simulation results using MATLAB/Simulink enviournment are obtained, which support the effectiveness of these topologies of UPQC for power quality improvement.