Mode switching method of direct current microgrid photovoltaic system

Abstract

The invention discloses a mode switching method of a direct current microgrid photovoltaic system, a photovoltaic system controller comprises a photovoltaic battery, a MPPT controller, a direct current bus, a constant voltage controller, a pulse width modulator PWM and a boost converter Boost, and the photovoltaic controller is characterized by being provided with a double integral sliding mode controller DISMC, by comparing the voltage of the direct current bus with direct current upper limit voltage, a voltage excursion signal based on the direct current bus voltage is generated at an outputend of the constant voltage controller, maximum power work voltage of a photovoltaic battery is deviated through the signal, thus, the photovoltaic battery is enabled to exit from a MPPT mode and enters into a constant voltage work region, and a process of switching to a constant voltage mode of the conventional photovoltaic system is substituted, real-time balance of power in the system under aCVC mode can be realized, and the direct current bus voltage is stabilized. The method provided by the invention has no signal switching process, switching of operating modes of the system can be completed through deviating the work voltage of the photovoltaic battery through the constant voltage controller, and thus, seamless switching of modes of the photovoltaic system can be realized.

Description

technical field [0001] The invention relates to a photovoltaic system of a direct current microgrid, in particular to a mode switching method of a photovoltaic system of a direct current microgrid. Background technique [0002] As a micro-grid structure developed in recent years, the DC micro-grid has the advantages of low-carbon environmental protection and high energy utilization. Compared with the AC micro-grid, it has many advantages and is an ideal solution for the future development of micro-grids. As a form of DC microgrid, the photovoltaic storage DC microgrid is mainly composed of solar photovoltaic cells, energy storage units and electrical loads. Among them, photovoltaic cells and DC-DC converters (DC / DC) constitute a photovoltaic power generation system to provide clean energy for the microgrid. [0003] figure 1 It is the structural diagram of the solar-storage DC microgrid, which consists of a photovoltaic system composed of photovoltaic cells and their conve...

AI Technical Summary

Problems solved by technology

For the different control objectives of the two modes, the system adopts two sets of independent control parameters to control respectively. At the moment of switching the working mode, it is impossible to ensure that the output of the two independent closed-loop adjustment loops are consistent before and after the switch, which will inevitably lead to Sudden changes in voltage and current in the front and rear systems, and in severe cases, oscillations will occur, threatening the stable operation of the microgrid

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