Three Phase Shield Wire Schemes Unbalance and Voltage Fluctuation Reduction Using H-Bridge Cascaded Static Synchronous Compensator (STATCOM)

Alidou Koutou,Mamadou Lamine Doumbia

doi:10.4172/2332-0796.1000187

Abstract

Unbalance and voltage fluctuation are considered as a major problem within the 3-phase Shield Wire Schemes networks (SWS). This paper deals with the methods to reduce the unbalance and voltage fluctuation by using the H-bridge cascaded Static Synchronous Compensator (STATCOM). In unconventional networks without STATCOM, the unbalance factor is generally more than 27%. In this study, we proved that after voltage compensation by the H-bridge cascaded STATCOM, unbalance factor is reduce to 0.15% for ground impedance variation. The ground resistance has been varied between 33 and 8000 Ω, and the ground inductance between 10 and 110 H. Moreover, the voltage fluctuation is reduced. The obtained results correspond to those recommended in power distribution for the proper operation of electrical equipment.

Highlights

IntroductionThe Shield Wire Scheme (SWS) is a technical method to supply power to the villages and communities located along the High Voltage (HV) lines, up to 100 km distant from the HV transforming stations
The Shield Wire Scheme (SWS) is a technical method to supply power to the villages and communities located along the High Voltage (HV) lines, up to 100 km distant from the HV transforming stations.The SWS consists of insulating the shield wires (SWs) from the towers of the HV lines and energizing the SWs with Medium Voltage (MV) (20-34.5 kV) from the HV/MV transformer station at one end of the HV line [1] (Figure 1)
The three-Phase SWS is an unsymmetrical system with voltage fluctuation; because the three-Phase SWS supplying conventional MV/LV distribution transformers operated with one MV terminal permanently grounded [4]

Summary

Introduction

The Shield Wire Scheme (SWS) is a technical method to supply power to the villages and communities located along the High Voltage (HV) lines, up to 100 km distant from the HV transforming stations. The SWS consists of insulating the shield wires (SWs) from the towers of the HV lines and energizing the SWs with Medium Voltage (MV) (20-34.5 kV) from the HV/MV transformer station at one end of the HV line [1] (Figure 1) This technique reduces the cost of investments while adapting to the low power requirements of these communities [2]. Use only passive components, using a series resistorreactor in the earth path and capacitors connected between the two SWs and between each SW and ground [8] While these techniques allow the reduction of voltage unbalance in three-phase Shield wire, these types of passive compensators do not fit when a voltage variation occurs. The SPWM method is based on comparing a sinusoidal modulating signal with a triangular carrier waveform that is arranged according to required switching outputs [11,12] (Figures 4 and 5)

Methodology

Results and analysis of simulation

Conclusion