Power quality improvement in distribution networks containing distributed energy resources using unified power quality conditioner

Distributed energy resources (DERs) are necessary due to the increasing demand of electrical energy and depletion of fossil fuels. When DERs are placed in the distribution system, various power quality problems arise including voltage unbalances and current harmonics. These problems arise due to the excess power which is fed back to the network when generation in a particular phase exceeds load demand owing to the presence of DERs. The paper proposes the use of shunt active power filter (SAPF) and unified power quality conditioner (UPQC) to reduce the power quality problems. SAPF performs as expected during normal conditions but when an unbalance is present in the system, undesirable effects are seen. These problems can be mitigated using UPQC. The system with DER and SAPF/UPQC has been modeled using MATLAB and the performance analysis of SAPF and UPQC has been studied and compared.