Real‐time implementation of transformerless dynamic voltage restorer based on T‐type multilevel inverter with reduced switch count

Abstract

Summary This paper presents T‐type multilevel inverter topology‐based dynamic voltage restorer (DVR) with reduced switch count. In medium voltage and high‐power applications, two‐level voltage source inverters are insufficient because of more voltage stress on switches, large dv/dt, size, and cost of the filter. To overcome these problems, multilevel inverter‐based DVR is suitable, which can be directly connected to the medium voltage distribution system without injection transformer. In addition, the control of the DVR is implemented by abc to dq controller. The voltage compensation capability of the proposed DVR is enhanced by employing the in‐phase compensation technique with reduced carrier pulse width modulation scheme, and also the total harmonic distortion(THD) in the load voltage is reduced. The design and analysis of the proposed system are discussed, and its performance is validated in MATLAB/Simulink and in the OPAL‐RT real time processor.

Voltage Quality Enrichment using Transformerless Dynamic Voltage Compensator based on Asymmetrical Multilevel Inverter

“…However, when switching frequency increases aiming to filter size decrease with respect to switching loss will increase [7][8][9][10]. Hence to reduce filter size along with switching frequency, Multilevel Inverter (MLI)s are used instead of three level bridge inverter for TDVCs [11,12]. Multilevel inverters are used in power systems for its better quality of output waveform.…”

“…Requires more number of switches, more switching loss. MLI with reduced number of switches (SMLI) [11] Reduced filter size and less number of switches.…”

“…are utilized for error signal generation. Sensed three phase PCC voltage as per Equations (8-10) are converted into alpha voltage , and beta voltage, quantities using Clark transformation as per Equations(11)(12)(13) …”

“…These switching pulses operate at fundamental frequency 50Hz. During normal operation when there is no event occurring, no switching pulse supplied for VSI switches.VSI operates in phase with Vpcc during Voltage sag and 180 degree out of phase during voltage swell compensation[8,11]. VSI switching states during conditions such as when there is no disturbance, voltage sag and swell are given in Table3.…”

Comparative analysis of switching angle calculation methods for multilevel inverters

“…The inverters have become an integral part of various systems such as motor drives, renewable energy integration to grid, and power system apparatus like FACT devices, etc. because they impart better control ability to the system 1‐11 . An inverter is used with some control technique to obtain desired output voltage.…”