Variable Speed Drive DC-Bus Voltage Dip Proofing

Freeman Chiranga,Lesedi Masisi

doi:10.3390/en14248257

Abstract

This paper proposes a power electronic module that uses a switched capacitor for retaining the integrity of the dc-link voltage of a variable speed drive (VSD) during a 0.2 s short-term power interruption (STPI). Ride-through was achieved through switched capacitor onto the dc bus. However, this technique presents a challenge of the high inrush currents during a ride through compensation. In this work both analytical and experimental investigations were conducted in order to reduce the in-rush currents and its impact on the performance of the VSD during the STPI. Inrush peak currents were reduced by approximately 90%. Experimental results showed torque pulsations of 12.8% and 14.3% at the start and end of dc-link voltage compensation, respectively. A method for sizing the switched capacitor and the inrush limiting resistors is proposed. This methodology is based on the use of readily available nameplate information of the VSD and the electric motor. The proposed module can be retrofitted to existing VSDs that are based on v/f control.

Highlights

Electricity supply in developing economies is characterized by low generation and dominated by frequent faults and outages owing to lack of financial resources, old infrastructure and poor maintenance [1,2,3]
When a 0.2 s short-term power interruption (STPI) was simulated on the variable speed drives (VSD) supply, the dc-link voltage started deThis will mean that the chosen standard capacitor will satisfy the conditions to not drop caying a constant rate from an initial valueaofSTPI
This paper investigated and developed inrush current mitigation schemes for a proposed dc bus voltage ride through a power electronic module

Summary

Introduction

Electricity supply in developing economies is characterized by low generation and dominated by frequent faults and outages owing to lack of financial resources, old infrastructure and poor maintenance [1,2,3]. Voltage dip sensitive equipment including variable speed drives (VSD) are negatively affected by such frequent faults and outages leading to voltage dip-related trips. This results in disruptions of critical processes, loss of production and revenue [4]. Most modifications to existing topologies would require close collaboration with different manufacturers to access design base technical information Such arrangements present challenges due to intellectual property which is closely guarded by manufacturers and not readily available for access by users of VSDs. Modifications to the drives must be limited to an electrical connection only between the existing VSDs and ride-through enhancing module. This results in limited options available for enhancing ride-through capability for existing VSDs

Methods

Results

Conclusion