GRID TIED MULTILEVEL INVERTER WITH POWER QUALITY MONITORING
Advisor:
Dr. Syed Abdul Rahman Kashif
Abstract:
The Project is based on Grid Tied Multilevel Inverter with power quality analysis and monitoring. A
switch ladder multilevel inverter (SLMLI) topology is used to develop a 17-level inverter. Multilevel
inverters can generate the output voltages with very low distortion. Power quality is the most important
parameter that is measured and taken into account by utilities/supply companies to make a guess of the
load demand of a customer. The power quality analyzer developed can measure voltage magnitude
(RMS), current magnitude (RMS), real power, power factor, apparent power, reactive power, total
harmonics distortion (current and voltage), voltage dips-swells and crest factor using NI LabVIEW. Hall
Effect current sensors are used along with the current transformers (CTs) to measures the current of a
particular load for its quality monitoring. For a high current measurement, CTs are used to measure the
current whereas small current measurement can be taken using only current sensors without CTs.
Potential transformers (PTs) are used to acquire the voltage data of the system to calculate the power
quality parameters. Two methods are used to calculate the power quality parameters (voltage, current,
THD, power factor, power, harmonics etc). In the first method, the instantaneous value of all the power
quality parameters are calculated from the real time data that is acquired from a given electrical device.
Those values show the manipulation of live data from an electrical device under test. In the second
implementation method, a running average is computed for all the power quality parameters. That running
average updates every 1.5 seconds on the GUI. Implemented 17-Level inverter for grid connectivity using
LabVIEW and myRIO has THD as low as less than 5%. Its overall efficiency is high meeting the required
international standards for grid connectivity. The 17-level inverter has 10 switches and 6 power supplies
for single phase implementation. The output voltage cycle contains all the possible combinations of
supplies which gives a very high value of output voltage as compared to applied dc voltage of supplies