Dual Fuzzy-Sugeno Method to Enhance Power Quality Performance using a Single-phase Dual UPQC-Dual PV Without DC-Link Capacitor

Abstract

Unified power quality conditioner (UPQC) is a power electronics device consisting of a series active filter (Se-AF) and a shunt active filter (Sh-AF) connected in parallel through a DC-link circuit to overcome power quality problems, i.e., voltage sag, voltage swell, and non-linear (NL) load. The weakness of the UPQC is that it cannot function normally if the Se-AF and/or Sh-AF fail, and the devices are unable to transfer active power to the load in the event of an interrupt voltage at the source. This paper proposes a novel configuration of a dual UPQC supplied by a dual photovoltaic (PV), hereinafter referred to as 2UPQC-2PV, to improve the power quality performance of a single-phase 220 V/50 Hz distribution system. The 2UPQC-2PV configuration is proposed to anticipate the possible failure of both inverters in one of the UPQC circuits. The PV array replaces the DC-link capacitor to maintain its voltage connected to the DC-link of the UPQC constant while at the same time supplying active power to the load during an interruption voltage. The dual-fuzzy Sugeno (dual-FS) method is used to overcome the weakness of the dual-proportional-integral (dual-PI) control in determining the optimum parameters of proportional and integral constants. There are three disturbances simulated in each-of 2UPQC-2PV and 1UPQC-1PV using dual-FS and dual-PI, i.e., Case 1 (S-Sag-NL), Case 2 (S-Swell-NL), and Case 3 (S -Inter-NL). Each UPQC-PV combination using FS control is compared with PI control resulting in a total of six cases. The 2UPQC-2PV configuration with dual-PI and dual-FS controls, in the three fault cases, is able to produce higher voltage changes than the 1UPQC-1PV configuration. For the 2UPQC-2PV configuration in the three fault cases, Dual-FS control is able to produce lower THDs of load voltage and source current, than the dual-PI control, while meetings the limits of IEEE 519 Standard. In Case 3, the configuration of 2UPQC-2PV using the dual-FS method, is capable of delivering the active power of the load close to that in Case 1.