AC-DC hybrid power grid DC blocking frequency safety and stability evaluation method and system

Abstract

The invention provides an AC-DC (alternating-current and direct-current) hybrid power grid DC blocking frequency safety and stability evaluation method and system, belongs to the technical field of power system frequency stability evaluation. The method comprises the steps of constructing a training sample set based on historical power flow data; taking the expected dynamic simulation output vector of the training sample set as a frequency safety and stability index, and constructing a direct-current blocking frequency safety and stability rapid evaluation model; training the direct-current locking frequency safety and stability rapid evaluation model, and identifying a high-risk operation scene influencing the safety and stability of the direct-current locking frequency of an alternating-current and direct-current hybrid power grid on line; and updating a to-be-evaluated scene in real time according to the predicted load change and the scheduling plan, and refreshing the online identified high-risk evaluation scene. According to the method and the system, the rationality of the frequency safety and stability evaluation result of the system is improved, the frequency safety and stability evaluation results under different operation modes can be rapidly calculated due to the fact that time domain simulation is avoided, the adaptability to a large-scale power grid is improved, the evaluation accuracy is improved, and the method is more suitable for engineering practice.

Description

technical field [0001] The invention relates to the technical field of power system frequency stability evaluation, in particular to a safety and stability evaluation method and system for DC blocking frequency of an AC / DC hybrid power grid. Background technique [0002] With the intensive operation of UHV DC projects and the changes in load composition and characteristics, the characteristics of step-wise increase in the feed-in and DC power receiving scale of UHV DC clusters are presented. The structural contradiction of "strong DC and weak AC" is becoming more and more prominent, the coupling relationship between the AC power grid and the DC transmission channel is getting closer, the safety of the receiving end power grid is facing new challenges, and the integrated operation characteristics and overall stability of the power grid are becoming more and more obvious. The connection of large-capacity UHV DC transmission in the receiving end grid of AC-DC hybrid connection ...

AI Technical Summary

Problems solved by technology

[0007] In short, the existing frequency security and stability assessment methods have at least the following deficiencies: (1) The interaction between the DC system and the AC system is not fully considered: the high-voltage DC transmission system accounts for an increasing proportion of the transmission network, and the DC system through commutation If the inverter is connected with the AC system, the DC blocking will cause power impact on the AC system, and the failure of the AC system will lead to the work of the converter of the DC system. In serious cases, it will affect the normal operation of the DC system and further lead to cascading failures.

(2) With the expansion of the scale of the power grid, the calculation time of the existing time-domain simulation method is long, and it is difficult to apply and online real-time evaluation

(3) The evaluation accuracy of traditional equivalent model methods and shallow machine learning methods is relatively low, and cannot be applied to large-scale power grids

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