A Cost-Effective Decentralized Control for AC-Stacked Photovoltaic Inverters

Hua Han,Chao Luo,Mei Su,Zhangjie Liu,Josep Guerrero,Xiaochao Hou,Wenbin Yuan

doi:10.3390/en11092262

Abstract

For an AC-stacked photovoltaic (PV) inverter system with N cascaded inverters, existing control methods require at least N communication links to acquire the grid synchronization signal. In this paper, a novel decentralized control is proposed. For N inverters, only one inverter nearest the point of common coupling (PCC) needs a communication link to acquire the grid voltage phase and all other N − 1 inverters use only local measured information to achieved fully decentralized local control. Specifically, one inverter with a communication link utilizes the grid voltage phase and adopts current control mode to achieve a required power factor (PF). All other inverters need only local information without communication links and adopt voltage control mode to achieve maximum power point tracking (MPPT) and self-synchronization with grid voltage. Compared with existing methods, the communication link and complexity is greatly reduced, thus improved reliability and reduced communication costs are achieved. The effectiveness of the proposed control is verified by simulation tests.

Highlights

Renewable energy generation is drawing more and more attention in the past decades [1,2,3,4,5].AC-stacked photovoltaic (PV) inverter architecture is considered a promising PV generation configuration [6,7,8,9,10,11,12]
low voltage (LV) PV generation units can be connected to the MV/HV grid directly by the AC-stacked PV inverters with no need for a step-up transformer, which leads to improved energy conversion efficiency
In view of the overview above, this paper proposes a min-communication decentralized control method to greatly improve system reliability and lower the communication cost

Summary

Introduction

Renewable energy generation is drawing more and more attention in the past decades [1,2,3,4,5].AC-stacked photovoltaic (PV) inverter architecture is considered a promising PV generation configuration [6,7,8,9,10,11,12]. Compared with the traditional multilevel cascaded H-bridge topology, each AC-stacked PV inverter has an independent output LC filter, which makes it much easier for coordinating all PV inverter units [6,7]. In this way, distributed control methods or even fully decentralized control methods are much easier to implement, which means the communication complexity is much lower and the system’s reliability is higher. In this way, the AC-stacked PV inverter system has great potential for large-scale MV/HV grid-connected distributed PV generation. The motivation of this paper is to propose a min-communication decentralized control for AC-stacked PV inverters

Methods

Results

Conclusion