International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395 -0056
Volume: 04 Issue: 03 | Mar -2017
p-ISSN: 2395-0072
www.irjet.net
Two-Feeder Converter Based Interline Unified Power Quality Conditioner Vijeth K.M. Software Engineer at Loginware Softtec Pvt Ltd.., Karnataka, India. ---------------------------------------------------------------------***--------------------------------------------------------------------2. SYSTEM DESCRIPTION Abstract - Electronic equipment in commercial and industrial process has resulted in increasingly sensitive electrical loads to be fed from power distribution system which introduces contamination to voltage and current waveforms at the point of common coupling of industrial loads. The unified power quality conditioner (UPQC) is connected between two different feeders(lines), hence this UPQC connection is called Interline UPQC (IUPQC). Keywords: Distribution system, power quality, voltage sag/swell, voltage source converter, sensitive load.
1.INTRODUCTION To improve the power quality in the power distribution system, the custom power device like voltage source converter (VSC) is used extensively in custom power applications. Due to the increasing of sensitive loads, the power quality issues are gaining more attention. Disturbance in the distribution network creates almost all the power quality problems. A DSTATCOM is a voltage source inverter (VSI) based power electronic device. It is supported by a DC capacitor where the short term energy is stored. A DSTATCOM can compensate for unbalanced and distortion in the load such that the balanced sinusoidal current flows through the load [2]. DSTATCOM can regulate the voltage of distribution bus [3]-[4]. A DVR can compensate the distortion and voltage sag/swell in the supply side voltage so that the voltage across the critical/sensitive load is perfectly regulated [5]-[6]. AUPQC can perform both the functions of DVR and DSTATCOM [7]-[8]. Two VSCs are present in UPQC, one of the VSC is connected in series and other is connected in shunt with the same distribution feeder. Supply is provided to the VSCs by a common DC bus. Two VSCs can also be connected to two different feeders in the distribution system. The VSC performs the operation of DVR. In [9], two separate the adjacent feeders , a configuration called IDVR has been discussed in which two DVRs are connected in series with two different feeders. In IDVR a number of voltage restorers are connected in such a way that they share a common DC link. For the selected line of distribution system the common DC link provides the series compensation.
Š 2017, IRJET
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Impact Factor value: 5.181
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In this paper IUPQC is used to regulate the voltage of feeder-1 and protects the sensitive load from disturbances occurring upstream in feeder-2. In order to maintain the voltage constant in two different feeder lines we are using UPQC configuration. UPQC is connected between two independent feeders. It consists of two VSCs, one is connected in series and the other is connected in parallel with the distribution system. VSC performs both the operation of DVR and DSTATCOM. The two links of the VSCs are supplied by a common DC capacitor. Here we are taking the various bus voltages and the analysis is carried out. The best suited IUPQC configuration is suggested for the better compensation of distribution system. Finally the transient analysis of the system with IUPQC is analyzed for different faults such as voltage sag in feeder-1, upstream faults in feeder-2 such as L, LG, LLG and LLLG and load change. The structure control and capability of the IUPQC are discussed. The efficiency of the proposed configuration has been verified through simulation studies using SIMULINK/MATLAB.
2.1 Proposed System The fig-1 shows the single line diagram of IUPQC connected in the distribution system. It consists of two feeders, Feeder-1 and Feeder-2. Each feeders are connected to different substations. The system supplies the loads L-1 and L-2. Vs1 and Vs2 are the supply voltages . From the fig-1 we can observe that the IUPQC is connected between the two buses B-1 and B-2. The voltages of the buses B-1 and B-2 are denoted by Vt1 and Vt2. The currents flowing through the Feeder-1 and Feeder-2 are represented by is1 and is2 while the load currents are denoted by il1 and il2. Vl2 is the load L2 voltage. The main aim of the IUPQC is to maintain the bus voltages Vt1 and Vt2 constant against voltage sag/swell and other interruptions in the two feeder lines. From this model the IUPQC can absorb the power from one feeder to maintain the voltage of the other feeder constant. This can be obtained by supplying the two VSCs by a common DC capacitor. The main objective of the proposed configuration is to: 1. To protect the sensitive load L-2 from the disturbances occurring in the system by regulating the voltage Vt2. 2. To regulate the bus B-1 voltage Vt1 against sag/swell and or disturbances in the system. ISO 9001:2008 Certified Journal
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