

Power Calculation
Algorithm for SinglePhase DroopOperated Inverters Considering
Nonlinear Loads
J. El Mariachet, J. Matas†, Helena Martín,
Abdullah Abusorrah
2018/04/20

Abstract
The average active and reactive powers, Pav
and Qav, are crucial parameters that have to be calculated when sharing
common loads between parallelized droopoperated singlephase inverters.
However, lowpass filters (LPF) with very low cutofffrequency should
be used to minimize the distortion impact in the amplitude and frequency
references provided by the droop equations. This forces the control to
operate at a very low dynamic velocity, degrading the stability of the
parallelized system. For this reason, different solutions had been proposed
to increase the droop operation velocity in literature, but with the consideration
of only sharing linear loads. The issues derived from the sharing of nonlinear
loads had not been properly considered. This paper proposes a method to
calculate Pav and Qav using second order generalized integrators (SOGI)
that increase the velocity of the droop control algorithm considering
nonlinear loads as the design worst case scenario. Then it is employed
a double SOGI (DSOGI) approach to filter the current nonsinusoidal waveform
and provide the fundamental component, which results in a faster transient
response and
improves the system's stability. The proposed calculation method shows
to be faster than other approaches when considering nonlinear loads. Simulations
are provided to validate the proposal.
Published in: Renewable Energy
& Power Quality Journal (RE&PQJ, Nº. 16) 
Pages: 1924 
Date of Publication: 2018/04/20 
ISSN: 2172038X 
Date of Current Version:2018/03/23 
REF: 20018 
Issue Date: April 2018 
DOI:10.24084/repqj16.200 
Publisher: EA4EPQ 
Authors and affiliations
J. El Mariachet*, J. Matas†**, Helena Martín†,
Abdullah Abusorrah**
* Department of Electronic Engineering, Universidad Politécnica
de Cataluña (UPC), Barcelona, Spain.
† Department of Electric Engineering, Universidad Politécnica
de Cataluña (UPC), Barcelona, Spain.
**Renewable Energy Research group, King Abdulaziz University (KAU), Jeddah,
Saudi Arabia.
Key words
Active and reactive power calculation, singlephase inverters,
nonlinear loads, inverter parallelization, droop method, tradeoff speed
and accuracy.
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