Presented By:ARUN KUMAR N.K1OX11EPE01

In this Presentation, a new Active Power Filter (APF) control scheme has proposed to improve the performance of the APF. This presentation presents a new technique with instantaneous power theory (P-Q theory) in order to control of APF under non- ideal mains voltage conditions. Performance of the proposed scheme has been found feasible and excellent to that of the instantaneous reactive power algorithms under various non-ideal mains test scenarios. MATLAB/SIMULINK power system toolbox is used to simulate the proposed system. The proposed methods performance is compared with conventional instantaneous power (P-Q) theory. The simulation results are presented and discussed showing the effectiveness of the control algorithm.

INTRODUCTIONPOWER QUALTITY IN POWER DISTRIBUTION SYSTEMSSOLUTIONS TO POWER QUALITY PROBLEMSBASIC PRINCIPLE OF ACTIVE POWER FILTERSTYPES OF THE ACTIVE POWER FILTERSINSTANTANEOUS POWER THEORYTHE PROPOSED METHODSHUNT ACITVE POWER FILTER3-PHASE 4-WIRE SHUNT ACIVE POWER FILTER WITH RENEWABLE ENERGY INTERFACESIMULATION RESULTSCONCLUSIONREFERENCE

In a modern power system, increasing of loads and non-linear equipment's have been demanding the compensation of the disturbances caused for them. These nonlinear loads may cause poor power factor and high degree of harmonics.Active Power Filter (APF) can solve problems of harmonic and reactive power simultaneously.APF have the ability to adjust the amplitude of the synthesized ac voltage of the inverters by means of pulse width modulation or by control of the dc-link voltage, thus drawing either leading or lagging reactive power from the supply.Shunt APFs allow the compensation of current harmonics and unbalance, together with power factor correction

Power Quality can be defined as the physical physical characteristics of the electrical supply provided under normal operating conditions that do not disturb the customers process.Power Quality problem exists due to change in voltage, current or frequency deviation results in a failure or in a bad operation of the equipment.Power Quality problems are due to Natural PhenomenaSwitching PhenomenaConnection of high power non linear loadsVoltage Sags

There are two approaches to the mitigation of power quality problems.Load ConditioningLine ConditioningA flexible and versatile solution to voltage quality problems is offered by Active Power Filters.Shunt active power filters operate as a controllable current sourceseries active power filters operates as a controllable voltage source

Active Filter ConnectionLoad on AC SupplyAC Supply On LoadShuntCurrent Harmonic Filtering.Reactive current compensation.Current unbalance.Voltage FlickerSeriesCurrent Harmonic Filtering.Reactive current compensation.Current unbalance.Voltage FlickerVoltage Unbalance Voltage Sag/Swell.Voltage Unbalance.Voltage Distortion.Voltage Interruption.Voltage Flicker and notching.

3phase uncontrolled diode bridge rectifier with resistive loadingUsing the switching mode power converter to perform the harmonic current elimination. The power converter is controlled to generate a compensation current, which is equal but opposite the harmonic and reactive currents generated from the nonlinear load.A voltage source inverter having IGBT switches and an energy storage capacitor on DC bus is implemented as a shunt APF.

Fig. Block Diagram of APF

Shunt Active Power Filters:It compensate current harmonics by injecting equal-but-opposite harmonic compensating current.It operates as a current source injecting the harmonic components generated by the load but phase shifted by 180deg.

Fig. Compensation characteristics of a shunt active power filter

2. Series Active Power Filters:Fig. Series active power filter topology It compensate current system distortion caused by non-linear loads.The high impedance imposed by the series APF is created by generating a voltage of the same frequency that the current harmonic component that needs to be eliminated.Voltage unbalance is corrected by compensating the fundamental frequency negative and zero sequence voltage components of the system.

Hybrid Active Power Filters:Fig. Hybrid Active power filterBy controlling the amplitude of the voltage fundamental component across the coupling transformer, the PF of the power distribution system can be adjusted.The control of the load power factor imposed a higher voltage across the filter capacitor.This type of configuration is very convenient for compensation of high power medium voltage non linear loads

In three-phase circuits, instantaneous currents and voltages are converted to instantaneous space vectors.Three-phase currents and voltages are calculated as following equations

In three-phase conventional instantaneous power is calculated as follows:P=e.i +e.iIn fact, active power (p) is equal to following equation:P=ea.ia +eb.ib +ec.ic

and are orthogonal coordinates.

Instantaneous real and imaginer powers are calculated as equation

The above equation can be written as

From above instantaneous compensating current as and Co ordinates are given below

It must be used when the voltages are distorted or unbalanced and sinusoidal currents are desired.In proposed method, instantaneous voltages are firs tconverted to - coordinates and then to stationary d-q coordinates. The produced d-q components of voltages are filtered and reverse converted - coordinates. These filtered - components of voltages are used in conventional instantaneous power theory.

A new APF control scheme has been proposed to improve the performance of APF under non-ideal mains voltage scenarios. Experimental results in a scaled-down laboratory prototype will be done and reported in future paper. APF, based on the proposed theory, give satisfactory operation even when the system phase voltages are unsymmetrical and distorted, because no distortion appears in the line currents. The APF is found effective to meet IEEE 519 standard recommendations on harmonics levels in all of the non-ideal voltage conditions. The switching frequency and also switching losses are reduced %23 in proposed method

Engin zdemir, Member, IEEE, Murat Kale, Sule zdemir., Active Power Filter for Power Compensation Under Non-Ideal Mains VoltagesLuis A. Morn, Juan W. Dixon.,- Using active power filters to improve power qualityAkagi,H., Kanazawa,Y., and Nabae,A., Instantaneous reactive power compensators comprising switching devices without energy storage components. IEEE Transactions on Industrial Applications, Vol.20, pp. 625- 630, 1984.Singh, B., Haddad K., Chandra, A., A New Control Approach to Three- Phase Active Filter for Harmonics and Reactive Power Compensation, IEEE Trans. on Power Systems, Vol.13, No.1, pp. 133-138, 1998.

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