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In order to correct the power factor and limit the flow of harmonics in the source, the effectiveness of active power filters associated to control law is no longer to be demonstrated. Almost all of these methods are designed for a perfect sinusoidal source and do not produce sinusoidal current when the voltages are disturbed. The work developed here concerns active filtering on a perturbed network, that is to say the presence of voltage harmonics at the connection point in addition to a system of unbalanced voltages. A proposed method called DCAP (Direct Control for Active Power) is based on new definition of the sinusoidal active currents desired on the source and assuming a unity power factor under perturbed and polluted system voltages that leads to the DCAP control strategy for active filter. This method considers the active power and the effective value of the fundamental of the voltage is described and its results are compared with those obtained by the p-q theory, the modified p-q theory and the p-q-r method for application on a three-wire disturbed and non-linear load distribution network. The comparison concerns the harmonic distortion rate (THD) of the desired currents obtained on the source as well as Unbalance Factor (UF) of the system of these currents.

There are today many techniques for controlling active filters on single-phase networks in order to correct the power factor and limit the harmonics consumed at the source. Almost all of these methods are determined for a perfect sinusoidal source. The work developed here concerns the taking into account of a perturbed network, that is to say the presence of voltage harmonics at the connection point. The results are validated by experiment on a low power system.

In this paper, two current reference extraction methods for harmonic compensation in single-phase active power filters are presented and evaluated. The first method known as the ip-iq technique is based on the fundamental extraction from the load current, whereas the second strategy which is the Direct Control for Active Power (DCAP) method employs power calculation leading to a new definition for active current in case of perturbed source voltages. The comparison is carried on in terms of DC voltage regulation in case of disturbed source voltage. First, both control schemes are analyzed based on the obtained reference currents using simulation results. It is shown that the DCAP is more accurate on the reference current extraction than the ip-iq method. Next, the performance of the DCAP method in terms of current distortion and power factor in presence of a highly perturbed source voltage is demonstrated.

New definition for active current in case of perturbed source voltages is developed and employed as reference compensation currents for an active power filter. In this paper, different control methods using the instantaneous power theory approach are applied to the 3-phase 4-wire split-capacitor Shunt Active Power Filter (SAPF). The control techniques that have been considered for comparison are: the original p-q method, the modified p-q, the pseudo-mapping matrix, the p-q-r theory, the NF p-q method, and the proposed Direct Control for Active Power (DCAP) novel method issued from the novel definition of active current. All these control schemes are compared in two aspects. First, a qualitative comparison, based on simulation results, is performed on the source and neutral currents in all cases of sine-wave/distorted and balanced/unbalanced source voltages. Then, a quantitative comparison is carried out to evaluate the performance of each method in different operating conditions. Three indexes are used for this assessment: 1) the current Unbalance Factor (UFi) in accordance with IEEE 1195-1995, 2) the Total Harmonic Distortion (THD), and 3) the rate of neutral current compensation. It will be proven that the DCAP method ensures sinusoidal and balanced source currents with a THD and an UF that meet the standard requirements in all cases of operation, as well as a compensated neutral current on the source side.

A four leg static compensator for harmonic mitigation and reactive power compensation is proposed for an unbalanced load consisting of CFL and R-L linear loads. The converter is controlled in order to insure high power factor and neutral current compensation at the source level. In order to verify the performance of the power conversion system a digital model of the CFL is developed and implemented into the SimPower simulation platform. The obtained results show high quality performance of the converter in terms of total harmonic distortion, power factor and transient characteristics. In addition, the system response towards load variation and unbalance is tested and analyzed.

The non-sinusoidal current absorbed by non-linear loads induces current harmonic distortion in the power grid and affect severely its power quality. More specifically, Compact Fluorescent Lamps (CFL) with no power factor correction cause low power factor and high harmonic distortion. In this paper, and after an experimental measurement, a mathematical model of a 23W compact fluorescent lamp is proposed. This model is established on the basis of experimental data and using a spectral decomposition up to 31st harmonic. After model verification through numerical simulations using Matlab, the effect of increasing the number of CFL lamps, mixed to a load consisting of televisions and refrigerators, on the power factor, total harmonic distortion, the active, reactive and distorting power is evaluated. It is demonstrated that, by increasing the nonlinear part of the load given by the CFLs, the power factor reaches its maximum for a specific combination of CFLs and the given load, and then decreases for an increasing number of CFLs, whereas the total current harmonic distortion always increases. On the contrary, by using incandescent lamps instead of CFLs, it is shown that the power factor grows continuously whereas the total harmonic distortion decreases for an increasing number of lamps.