Harmonic analysis and practical implementation of a two-phase microgrid system

Abstract

Abstract-This paper analyzes the harmonic contents of a non-linear load connected to a two-phase microgrid system. Although having the same harmonic content as the single-phase power system when supplying a non-linear load under balanced conditions, the two-phase microgrid system presents the following advantages: 1) constant power through the power line at the balanced condition; 2) two voltages i.e., line-to-line and phase voltages, available by using a three wire system; 3) optimized voltage utilization compared to a three-phase system; and 4) a direct connection of both symmetrical two-phase and single-phase electrical machines. This paper presents an approach for analyzing the harmonics of a two-phase non-linear load in a balanced and unbalanced cases. The mathematical model for the symmetrical component of an unbalanced two-phase system has also been presented in this paper. Finally, a practical implementation of the twophase system has been performed, where different types of loads are connected to the two-phase power line to test the voltage control performance.

CPT-Based Control Strategy for a Two-Phase Three-Wire Pv Inverter: a Multifunctional Perspective and a Comprehensive Review

“…However, under unbalanced condition, such 2Φ3w topology cannot be interpreted by conventional three-phase symmetrical components [16], requiring particular analysis of positive and negative sequence components that comprise, for each of them, two phasors of same magnitude but with quadrature angle. Moreover, such existing application requires additional specific understanding of such symmetrical components when harmonic analysis need to be performed [17] under balance and unbalance conditions. In [18], it has also been reassured that off-grid power systems based on 2Φ3w topology (i.e., such as the above-mentioned particular case of microgrids) require particular interpretation and control approaches, as well as that instantaneous power oscillations and magnitude of neutral current are inversely related.…”

Selective Power Conditioning in Two-Phase Three-Wire Systems Based on the Conservative Power Theory

“…The CPT also provides definitions for power terms, leading to the possibility of performing further characterization of the electrical circuit features. The apparent power definition is given by the product between the collective voltage and currents of the circuit as in (11). Note that can be calculated by (12) since the decomposed current terms are orthogonal to each other, as aforementioned.…”

“…Nonetheless, when it comes to two-phase systems with neutral conductor, herein named two-phase three-wire (2Φ3w), there still remains a gap in the literature regarding the employment of methodologies able to accurate mitigate undesired power quality (PQ) issues. Although 2Φ3w systems are not widely encountered, such topology is still present in motor applications [7], railway traction power supplies [8], residential installations around the world [9], [10], as well as on specific topologies of microgrids [11]. Thus, it is of great importance to develop methodologies that can characterize PQ concerns in 2Φ3w circuits, while providing ways of mitigating their related undesired issues.…”

“…However, such approaches do not present novelties focused on the decomposition of currents or power terms, neither characterizing their effects. Thus far, although in [11] circuit analysis based on symmetrical components are proposed for a new topology of two-phase microgrids, which presents two voltages in quadrature, it mainly targets the characterization of powers and harmonics, not directly presenting methods to intervene on power quality issues, nor being directly applied to 2Φ3w systems.…”