A parameter adjustment method of grid-connected inverter system based on sensitivity analysis

Abstract

The invention relates to a grid-connected inverter system parameter adjusting method based on sensitivity analysis. The grid-connected inverter system parameter adjusting method comprises the following steps of S1, setting an outer loop adjusting parameter and an inner loop adjusting parameter of a grid-connected inverter system, and obtaining a closed-loop transfer function of the grid-connected inverter system; S2, obtaining a sensitivity function of each parameter and a sensitivity functional relation in the grid-connected inverter system based on a definition of system sensitivity; S3, obtaining a parameter adjusting formula according to the sensitivity functional relation; and S4, adjusting the value of a parameter according to the parameter adjusting formula for eliminating an influence which is generated by power grid impedance change, and evaluating parameter adjusting precision according to sensitivity deviation of the sensitivity functional relation. Compared with the prior art, the grid-connected inverter system parameter adjusting method is advantageous in that a relatively good stability margin and a relatively good bandwidth control strategy of the system are realized through adjusting the parameter when a power grid impedance changes through sensitivity analysis design. The grid-connected inverter system parameter adjusting method has advantages of effective system complexity reduction, high control precision, low realization cost, high practicability, etc.

Description

technical field [0001] The invention relates to the field of power grid operation control, in particular to a method for adjusting parameters of a grid-connected inverter system based on sensitivity analysis. Background technique [0002] Due to the characteristics of the distribution of solar energy resources in my country, many photovoltaic inverters are installed in remote areas. Long cables and low-power transformers make the impedance at the public coupling point of the power grid relatively large, and generally present inductive in the lower frequency range. The impact on the stability of the device cannot be ignored. A large change in grid impedance, that is, under a weak grid, will lead to impedance mismatch, which will generate harmonic currents and even lead to system instability. Traditional grid-connected current control of inverters does not take into account the influence of grid impedance, and some scholars have conducted related research on this. For example...

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Problems solved by technology

[0004] 1. Research shows that the changing high grid impedance has a non-negligible impact on the grid-connected inverter control system, but the traditional grid-connected inverter control strategy does not take this factor into account (ie weak grid)

[0005] 2. The existing impedance analysis method and stability margin analysis did not involve the specific impact of changing high grid impedance on the system, and did not establish a functional relationship between them, so the precise relationship between system parameters could not be obtained

[0006] 3. Some existing control strategies to eliminate the influence of grid impedance are often very complicated, which greatly increases the complexity of the system

[0007] 4. A control system with better robustness is often more adaptable to weak power grids. The selection of controller parameters has a great impact on the robustness of the system. Existing research has not specifically involved this aspect

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