A solar-storage combined grid-connected system and its control method

Abstract

The invention discloses a light storage combined grid-connected system. The light storage combined grid-connected system comprises a photovoltaic array, a three-phase inverter main circuit, a filter circuit, a power grid, a bidirectional DC / DC converter, an acquisition module, a maximum power point tracking (MPPT) calculation module, a DC voltage / AC current double-loop control module, a bridge arm voltage modulation wave generation module, a battery current / battery voltage acquisition module, a battery DC current calculation module, a battery current closed-loop control module and a DC / DC converter modulation wave generation module which are sequentially connected. With a control method based on the system, the light storage combined grid-connected system can participate in the process of frequency modulation of the power grid like a traditional power generator set, the bidirectional DC / DC converter participates in frequency modulation to transmit or absorb power to or from the power grid when the frequency of the power grid is abnormal, the unfavorable influence of a pure photovoltaic power generation system on the power grid is reduced, and the grid-connection adaptability of a new energy grid-connected system is greatly improved.

Description

technical field [0001] The invention relates to an optical-storage combined grid-connected system and a control method thereof, which can realize the function of simulating the primary frequency regulation of a synchronous generator under the grid-connected working condition of the combined optical-storage system. Background technique [0002] In recent years, with the continuous development of new energy power generation technologies, the penetration rate of distributed power sources based on power electronic interfaces in power systems has continued to increase. In the control strategy of the traditional photovoltaic grid-connected inverter, the photovoltaic inverter always transmits the maximum power obtained from the solar panels to the grid according to the maximum power algorithm (MPPT) during normal operation. When the grid frequency is disturbed, due to Due to the limitation of solar panel output, traditional photovoltaic inverters cannot respond to changes in grid f...

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Problems solved by technology

In the control strategy of the traditional photovoltaic grid-connected inverter, the photovoltaic inverter always transmits the maximum power obtained from the solar panels to the grid according to the maximum power algorithm (MPPT) during normal operation. When the grid frequency is disturbed, due to Due to the limitation of solar panel output, traditional photovoltaic inverters cannot respond to changes in grid frequency and participate in primary frequency regulation of the grid

[0003] Secondly, the photovoltaic power generation system lacks inertia and does not have short-term overload capability. At the same time, the traditional centralized primary energy is gradually reduced, which leads to a gradual decrease in the moment of inertia of the power grid and larger frequency fluctuations, especially for power supplies dominated by photovoltaic power generation. The intermittency and unschedulability of energy in the system further aggravates the frequency fluctuation of the power grid, making the frequency stability of the system more and more serious. In the case of a grid failure, it will not be able to provide short-term power or even go offline, making it difficult for the power system to obtain sufficient power. time to restore the grid, leading to a sharp drop in grid stability

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