Power Calculation Algorithm for Single-Phase Droop-Operated Inverters Considering Nonlinear Loads and unsing n-Order SOGI Filtering

Abstract

The average active and reactive powers, P and Q, are crucial parameters that have to be calculated when sharing common loads between parallelized droop-operated single-phase inverters. However, the droop method algorithm should employ low-pass filters (LPF) with very low cutoff frequency to minimize the distortion impact in the provide droop amplitude and frequency references. This situation forces the droop control to operate at a very low dynamic velocity, degrading the stability of the parallelized system. For this reason, different solutions had been proposed in literature to increase the droop velocity, but the issues derived from the sharing of nonlinear loads had not been properly considered. This work proposes a novel method to calculate P and Q based on the fundamental components of the inverter's output voltage and current and using the measured phase angle between the output voltage and current. The method is used under normal and highly distorting conditions due to the sharing non-linear loads. The fundamental components are obtained by means of the highly filtering capability provided by norder cascaded second order generalized integrators (nSOGI). The proposed method leads to faster and more accurate P and Q calculations that enhances the droop-method dynamic performance. Simulations are provided to validate the proposal.

Advanced control scheme and dynamic phasor modelling of grid‐tied droop‐controlled inverters

“…Note that we use the computation of powers in a three-phase balanced system (based on the product of harmonic-free voltage and current), because it provides constant instantaneous powers, unlike in the case of a single phase, where it produces oscillating instantaneous real and reactive powers [30].…”

HIL-Assessed Fast and Accurate Single-Phase Power Calculation Algorithm for Voltage Source Inverters Supplying to High Total Demand Distortion Nonlinear Loads

“…When functioning in islanded mode, single-phase MGs are weaker in terms of stability, as compared with three-phase VSI-based systems, especially when sharing NLLs. In these conditions, accurate and fast calculations of P-Q become crucial [34,35]. Different solutions for the calculation of single-phase P-Q can be found in the literature.…”

“…Then, in Reference [35], it was proposed a method that introduced a pre-filtering of the measured current before the calculation of the instantaneous powers that resulted in being faster in front of NLL. This pre-filtering was achieved by the band-pass filter (BPF) capability of a double SOGI approach (DSOGI), followed by the remotion of the double frequency power components like Reference [34], but without the LPF final stage. The fastest solution from those benchmarked was [35], but at the cost of increased complexity in the calculation scheme and a worsening of the reactive averaged power calculation.…”

Inter-connected AC/DC HMGS power management with 3-phase and 1-phase ILC

“…Decentralized control scheme for MG performs without communication link, as several control schemes like through droop control or reverse droop control, line impedance droop control, angle droop control, virtual impedance, adaptive voltage droop control [2]. A conventional method to control and operate single phase inverters connected in parallel to MG with reducing the harmonic distortion [3]. Interlinking converter (ILC) performance is always discussed for stability, excessive power losses the issues are highlighted and analyzed by controlling the voltage and current [4].…”