A novel instantaneous power based control method for a four-wire SAPF operating with highly perturbed mains voltages

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.