Three-Phase PV CHB Inverter for a Distributed Power Generation System

Abstract

This work deals with the design of a three-phase grid-tied photovoltaic (PV) cascade H-bridge inverter for distributed power conversion. The power balancing among the phases must be properly addressed. In fact, an intra-phase power imbalance-arising from uneven irradiance and temperature conditions-generates a per-phase power imbalance. This latter can be compensated by the injection of a proper zero-sequence voltage, while the intra-phase balance is ensured by means of a hybrid modulation method which is able to guarantee the handling of unequal DC (Direct Current) sources, stable circuit operation, and maximization of PV power production. The digital controller is developed and tested in Matlab/Simulink environment integrated with XSG (Xilinx System Generator), thus allowing an easy transfer on a field-programmable gate array (FPGA) platform and accurately describing the behavior of a real hardware implementation. Thus, numerical results have been considered to prove the effectiveness of the proposed approach.

Special Issue on Advancing Grid-Connected Renewable Generation Systems

“…The second paper, authored by G. Brando, A. Dannier, A. Del Pizzo, and I. Spina, discusses the control and modulation techniques for a centralized PV system using interleaved inverters [7]. The third paper, authored by P. Guerriero, M. Coppola, F. Di Napoli, G. Brando, A. Dannier, D. Iannuzzi, and S. Daliento, presents the design of a three-phase grid-connected PV cascaded H-bridge inverter [8]. The fourth one introduces a detailed probabilistic reliability model for a PV system [9], authored by A. Alferidi and R. Karki.…”

PV Module-Level CHB Inverter with Integrated Battery Energy Storage System

“…A feasible way to realize a distributed photovoltaic (PV) converter architecture is represented by the multilevel topology, which typically exploits a single dc/ac power conversion stage for each PVG, also in the case of transformerless grid-tie application. Among the different possible implementations, the Cascaded H-Bridge (CHB) has found a crucial place in recent research activities devoted to PV application [3][4][5][6][7][8][9][10][11][12][13][14][15][16]. In fact, in addition to the well-known advantages (e.g., modularity, scalability, redundancy, etc .…”

“…The main drawback of PV CHB topology is the possibility to operate the system under deep mismatch conditions when overmodulation occurs [10,18,19] theoretically up to square-wave operation, which represents the maximum allowable power capacity of a cell. In such a case, the modulation strategy should be able to ensure CHB inverter operation also in overmodulation region, but conventional modulation techniques (also in their properly modified versions) cannot exploit an extended modulation index range [10,11], while hybrid modulation method [10,15,16] can reach overmodulation with no detrimental effect on the harmonic content of the output current (i.e., grid current) and ensuring optimal performance in terms of MPPT efficiency (also if the operating voltage of PVG will keep away from its MPP). In addition, the transfer of the overall active power from PVGs to the grid can be firstly reached by assuring that the total dc-link voltage is higher than the grid peak voltage.…”

“…As previously discussed, the double-stage configuration of the single power cell can solve the issues related to the MPPT performance, while also assuring a total dc-link voltage higher than the grid peak voltage with a reduced number of cells, but the main drawback of system operation under deep mismatch conditions, when overmodulation occurs, is unfortunately still present. In fact, it can be partially solved only by means of suitable modulation strategy [10,15,16,18,19], which allows system operation in the overmodulation region, otherwise, the high-power cells, which reach the overmodulation region, generate more harmonics at their output terminals. As a consequence, due to the series connection of CHB cells at the ac side, the total ac voltage (or rather its fundamental component) results to be highly distorted, thus affecting the current injected to the grid [11].…”

A Single-Stage Buck-Boost Three-Level Neutral-Point-Clamped Inverter with Two Input Sources for the Grid-Tied Photovoltaic Power Generation

“…To date, most of the applied PV converter is two-level inverter, whose main shortcomings are the high operational current and in consequence the low operational efficiency [1][2]. For the purpose of increasing power conversion efficiency, the multilevel converters are preferably assumed as the interfacing converter between the PV array and the distribution grid due to its inherent operational characteristics [3][4][5][6][7], such as the reduced voltage stress, low harmonic distortion, low EMI and reduced current rating. Moreover, the mature 1500V PV panel in commercial allows the PV systems integrated into the high voltage grid (e.g.…”