Maximum power tracking control method of photovoltaic grid-connected inverter with inverse droop characteristic

Abstract

The invention provides a maximum power tracking control method of a photovoltaic grid-connected inverter with inverse droop characteristic. According to the method, a corresponding instruction power is obtained by detecting a power grid frequency and by inverse droop control calculation, and an effect of supporting a system frequency can be achieved by simply changing a normally-used maximum power tracking algorithm. The method is implemented according to the steps of sampling the system frequency in real time; sampling the size of an output power of a DC side, and comparing the size of the output power with the size of an output power of a frequency ring having inverse droop characteristic; and entering an inverse droop working mode when the output power of the frequency ring is relatively low, externally outputting a power by the photovoltaic grid-connected inverter according to the inverse droop characteristic, otherwise externally outputting the power according to maximum power tracking control. The method provided by the invention is simple to implement, the system frequency can be effectively supported, and thus, the method has obvious advantage.

Description

technical field [0001] The invention relates to a maximum power tracking control method of a photovoltaic grid-connected inverter, in particular to a maximum power tracking control method of a photovoltaic grid-connected inverter that has inverted droop characteristics and can limit output active power. Background technique [0002] The active power output by the photovoltaic grid-connected inverter will cause a large disturbance to the system frequency when the grid-connected penetration rate is high, causing the system frequency to change. Therefore, how to make the photovoltaic grid-connected inverter stable The function of system frequency has very important research value. Inverted droop control can effectively maintain the stability of the system frequency. Therefore, the photovoltaic grid-connected inverter with inverted droop characteristics is a new research direction in the field of power electronics. In related research, there are existing literatures "Ji Mingwei...

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Problems solved by technology

[0004] 1) No feasible control strategy was put forward;

[0005] 2) Under the corresponding control strategy proposed, whether the adjustment of photovoltaic output power will cause system instability;

[0006] 2) The design of the control system is complicated, which will change the original relevant parameters of the system and need to be re-tuned and adjusted, and it is impossible to analyze the process of maximum power tracking, and it is impossible to ensure that the photovoltaic modules work in a stable area at all times

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