A novel control scheme to reduce the reactive power processed by a Multifunctional Voltage-Quality Regulator

•Elimination of PCC voltage harmonics without extra current measurements.•Reduction of reactive power circulation between the MVQR and the grid.•Detailed mathematic analysis of the proposed scheme. Solving voltage regulation in underrated grid networks can be very time consuming and costly for operators and unpleasant for customer, who constantly experience equipment malfunctions due poor voltage quality. Active solutions such as Multifunctional Voltage-Quality Regulator (MVQR) work well as a quick fix in these cases, bringing voltages to the right levels as soon as installed, feeding active or reactive power into their point of connection. Unfortunately, current solutions can be fastidious, adjusting voltage levels that are already adequate for customer services to a specific fixed setpoint, unnecessarily spending energy, overusing distribution networks, wearing out energy-storage components and eventually not optimizing the equipment’s regulation capacity. To address the aforementioned problems, this manuscript proposes a control scheme to reduce the reactive power processed in an existing MVQR. The MVQR was based in a distribution static compensator (DSTATCOM) with active harmonic filtering feature. Where voltage-magnitude regulation is achieved by reactive power injection only, while harmonic mitigation is performed by harmonic injection based on PCC-voltage-detection-method (PCC-VDM). The proposed MVQR control scheme reduces the reactive energy injection when the voltage level at PCC is within limits of relevant standards. The main contribution of this paper is the detailed mathematic analysis of the scheme for reducting the reactive energy injection, which had not been found in literature. This analysis shows how to design this scheme to obtain better regulation, guarantee dynamic decoupling from other control loops, as well as ensure closed-loop system stability. Simulation and experimental results were carried out for validation of the proposed control method. The proposed MVQR had shown itself an efficient and effective addition, reducing significant processed reactive power using wisely resources, likely available in similar MVQR topologies.