Active damping high-frequency resonance suppression method

Abstract

The invention discloses an active damping high-frequency resonance suppression method. The method comprises the steps of S1, carrying out resonance mechanism analysis on a string photovoltaic grid-connected inverter through a Norton model of the grid-connected inverter; S2, on the basis of conventional double-closed-loop control, introducing a capacitive current high-frequency feedback link; S3, adding a voltage high-frequency feed-forward link at a PCC grid-connected point; and S4, performing equivalent conversion and offset on interactive high-frequency resonance existing in the inverter in the grid-connected cluster system according to the steps S2 and S3, thereby realizing high-frequency resonance suppression of active damping. According to the active damping high-frequency resonance suppression method, capacitive current high-frequency feedback and PCC voltage high-frequency feedforward are combined, and interactive high-frequency resonance existing in an inverter in a grid-connected cluster system is equivalently converted and counteracted, so that self resonance and parallel resonance of the string photovoltaic grid-connected inverter are effectively suppressed, the multi-point high-frequency resonance suppression of the multi-inverter grid-connected system is realized, passive damping control can be replaced, the hardware cost and power consumption are effectively reduced, and the stability of the grid-connected system is remarkably improved.

Description

technical field [0001] The invention relates to the technical field of high-frequency resonance suppression of string-type photovoltaic grid-connected clusters, in particular to an active damping high-frequency resonance suppression method. Background technique [0002] With the popularization and development of large-scale and high-efficiency new energy power generation, the addition of a large number of high-frequency power electronic components has led to multi-point high-frequency resonance in the multi-inverter grid-connected system. In a weak grid environment or when the installed capacity increases, the inverters in the grid-connected cluster system will have the influence of interactive high-frequency resonance. With the increase of the number of grid-connected inverters and the grid impedance, the phase of the grid-connected system gradually tends to be constant, and the reduction of the phase margin will cause high-frequency resonance. At the same time, the reduct...

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Problems solved by technology

In the 41st issue of "Acta Solar Energy Sinica" in 2020, "Controlled Source Equivalent Model and Resonance Mechanism Analysis of Photovoltaic Grid-connected Inverters" establishes an inverter controlled source equivalent model, relying on changes in control parameters and power grid parameters. Discover the change law of grid-connected current resonance, and then give the variation range of the grid-connected resonance point of the inverter, but only consider the resonance of a single inverter grid-connected

In the 40th issue of "Power Technology" in 2020, "LCL Type Photovoltaic Grid-connected Inverter Passive Damping Control Strategy" proposes a passive damping-based LCL grid-connected resonance suppression method, by adding RC branches to the photovoltaic cluster system. Perform resonance suppression, but passive damping requires additional hardware equipment

In the 42nd issue of "Power Grid Technology" in 2018, "Resonance Mechanism and Suppression Technology of Photovoltaic Cluster Inverters" proposed a control strategy combining active damping control and RC-type global resonance suppression to control the photovoltaic cluster system. Multi-point low-frequency resonance suppression, the access of RC passive circuits also increases circuit cost and power consumption

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