Method, device and storage medium for evaluating transient stability of grid-connected converter

Abstract

The invention discloses a method, device and storage medium for evaluating the transient stability of a grid-connected converter. The method includes the steps of: obtaining a first curve of VSC current changing with time; judging whether the first curve encounters a point of no return If so, then draw the second curve between the unbalanced power and the current at both ends of the DC capacitor of VSC, and calculate the instability value of VSC according to the second curve; if not, then draw the first curve of the DC voltage error of VSC changing with time Three curves, the fitting curve is obtained according to the third curve, and the attenuation coefficient of the fitting curve is calculated; when the attenuation coefficient is greater than 0, the instability value of the VSC is obtained; Unbalance the fourth curve between power and current, and construct a virtual no-return point, and calculate the stability margin of VSC. The invention can quantitatively evaluate the stability margin of the VSC DC voltage, and makes up for the current technical defect that the transient stability of the VSC DC voltage can only be analyzed through numerical simulation.

Description

technical field [0001] The invention relates to the technical field of transient stability analysis of electrical equipment, in particular to a method, device and storage medium for evaluating the transient stability of a grid-connected converter. Background technique [0002] The rapid development of centralized and distributed renewable energy generation (such as wind power and photovoltaic power generation) has made voltage source converters (Voltage Source Converters, VSCs) widely distributed in modern power systems. The DC voltage of the VSC (the state quantity of the DC bus capacitor) will appear monotonously changing and continuously oscillating due to the accumulation and exchange of energy under the transient condition of the system. [0003] However, the transient stability analysis of inverters in the prior art is generally aimed at inverters using a virtual synchronous generator (VSG) control strategy or a droop control strategy. But at present, the VSC grid-con...

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Problems solved by technology

Moreover, there is a big difference between the equipment characteristics of VSC and conventional synchronous generators. The quantitative evaluation method for transient stability of synchronous generators—EEAC method cannot be directly applied to the quantitative evaluation of VSC DC voltage transient stability; based on VSG and droop The VSC of the control strategy and the VSC based on the vector control strategy have huge differences in dynamic characteristics.

Therefore, the transient stability analysis and judgment method applicable to the VSC based on the VSG and droop control strategy cannot be applied to the VSC based on the vector control strategy, resulting in the VSC under the vector control strategy based on terminal voltage orientation. There is a large gap in the quantitative evaluation technology of the stability margin. At present, it mainly relies on the numerical simulation method, but the pure numerical simulation cannot provide the quantitative information of the stability.

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