A comparative analysis of placement and control of UPQC in DG integrated grid connected network

Now-a-days, Unified Power Quality Conditioner (UPQC) is introduced in the Distributed Generation (DG) integrated smart grid network to improve the power quality of the network where the bi-directional power flow is a matter of concern. In this paper, a proper placement of a UPQC is identified in an active distribution grid network to synchronize its functionality with the bidirectional power flow without compromising the power quality in the network. In the presence of DG sources and a UPQC in an active distribution network, the following issues are considered; (a) the placement of a UPQC and its sensors in the network, (b) impact of the sensor placement on the UPQC controller, (c) performance of UPQC with bi-directional power flow in the network and (d) the advantages of DG inverter in the presence of UPQC. Extensive simulation studies are performed for all the possible placement of UPQC and its sensors including direct and indirect controlling methods. Based on the simulation results, detailed comparative analyses are also done. It is found that, to harmonize with the bi-directional power flow, the integration of UPQC before the DG system and its sensor before the load (PCC-UPQC-DG-Load) should be the best possible placement in the network. In that case, UPQC with direct control shows the better performance than the indirect control. Finally, in a DG connected network, it is suggested that strategic positioning of UPQC can provide some control flexibility in DG inverters for islanding detection and reconnection techniques.