Control method of independent direct-current bus open-winding double-inverter photovoltaic power generation system

Abstract

The invention discloses a control method of an independent direct-current bus open-winding double-inverter photovoltaic power generation system. Aiming at an open-winding double-inverter photovoltaicpower generation system of which the direct current sides of two inverters are connected with photovoltaic arrays respectively, the method comprises the following steps of: obtaining active and reactive current given values of the system by adjusting the direct current side voltages of the two inverters, and obtaining modulated waves to drive the two inverters through current closed-loop control and a 120-degree mutual difference decoupling modulation strategy. According to the control method, independent control of the direct-current side voltages of the two inverters can be realized, so thattwo paths of maximum power tracking can be realized, the power generation capacity is improved, and meanwhile, leakage current generated due to the existence of distributed capacitance of the photovoltaic array to the ground can be suppressed. Compared with an existing method, the electric energy quality of the grid-connected current is not affected while the control target is achieved, the control method is simple, and engineering implementation is easy.

Description

technical field [0001] The invention belongs to the control technology of open-winding double inverters in the field of electrical engineering, and in particular relates to a control method for an independent DC bus open-winding double-inverter photovoltaic power generation system. Background technique [0002] Compared with the traditional flying capacitor type and mid-point clamped multi-level inverter topology, the open-winding dual-inverter topology requires fewer devices to generate the same number of levels, and has higher DC voltage utilization High efficiency and strong redundancy, so it has been widely concerned in the fields of motor drive and new energy grid-connected power generation. When open-winding dual inverters are used in the field of photovoltaic grid-connected power generation, two inverters connected to one photovoltaic array can realize two-way maximum power tracking, which is obviously better than two inverters connected to the same photovoltaic array...

AI Technical Summary

Problems solved by technology

[0007] 1. The existing control methods based on the average voltage controller and the balanced voltage controller cannot realize the independent control of the DC side voltage of the two inverters, and the suppression of the zero-sequence current in the system is not considered;

[0008] 2. The existing control method based on active current command distribution modulation wave can realize independent control of the DC side voltage of the two inverters, but does not consider the suppression of zero-sequence current in the system;

[0009] 3. The existing control method based on decoupling modulation with a mutual difference of 120 degrees and the modulation waves of the two inverters are switched to each other at a certain frequency can realize independent control of the DC side voltage of the two inverters, and the zero-sequence circulating current in the system is also suppressed. However, the implementation process of this control method is complicated, and it will cause the harmonics of the grid-connected current to increase

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