Parallel operation of photovoltaic power conditioning system modules for large-scale photovoltaic power generation

In this study, parallel operation of photovoltaic (PV) power conditioning system (PCS) modules for large-scale PV power generation is proposed. This system consists of PCS modules that are connected in parallel and share the dc-link voltage. PCS modules can be easily connected in parallel for high-power extension and independent control of the PCS module is achieved. Since this system does not use communication lines among the PCS modules, sensing signal noise and the mutual interference can be neglected. In addition, the number of PCS modules operating simultaneously can be controlled in accordance with the irradiance. Thus, system efficiency can be maximised and PCS module life time is extended. Further, the system has high availability since it has N + 1 redundancy that is achieved by increasing the power capacity of PCS modules through the use of an additional PCS module. A prototype of the proposed system is implemented at a rated power of 500 kW. Experimental results for parallel operation of PCS modules show the feasibility of the proposed control.