Estimation method for DC support capability and commutation failure of multi-infeed DC system

Abstract

The invention discloses an estimation method for DC support capability and commutation failure of a multi-infeed DC system. According to an existing estimation method, the change of a DC current is not considered when a critical commutation failure voltage is deduced, and the accuracy is remained to be discussed. The estimation method discloses by the technical scheme comprises the steps of firstly, deducing a critical commutation bus voltage of each DC commutation failure according to a structure parameter and a running state of the system; secondly, determining the support capability of eachdirect current according to self impedance of the commutation bus, electrical distance of a fault point and multi-infeed short-circuit rate; and finally, estimating a commutation failure condition ofeach direct current according to a critical voltage and the support capability. During estimation of the support capability, factors such as multi-infeed short-circuit ratio and the electrical distance of the fault point are simultaneously considered, and the commutation failure critical voltage is comprehensively determined from two aspects of the system structure and the running state; and compared with an existing estimation method, the DC support capability and the commutation failure can be more accurately reflected.

Description

technical field [0001] The invention relates to the field of safety and stability analysis of power systems, in particular to an evaluation method for DC support capability and commutation failure of a multi-infeed DC system. Background technique [0002] In order to effectively solve the increasingly prominent contradiction between the energy structure and power demand, and ensure the economical, reliable and stable operation of the power grid, the interconnection of large-scale regional power grids has emerged as the times require. , National Networking" overall pattern, covering most of the country, becoming one of the largest power grids in the world. However, more than three-quarters of my country's coal reserves are distributed in the northwest region, and four-fifths of the hydropower resources are distributed in the west. The hydropower technologies in Sichuan, Yunnan, and Tibet can develop a capacity of more than 300 million kilowatts, while the central and eastern ...

AI Technical Summary

Problems solved by technology

Based on the short-circuit impedance of the DC converter bus and the grid structure of the AC system, the relevant studies have proposed indicators such as the commutation failure immunity factor and the multi-infeed short-circuit ratio to evaluate the DC support capability, but the focus is single and the two cannot be effectively combined. And the influence of the electrical distance between the fault point and the converter busbar on the DC support capability is ignored

For the evaluation of commutation failure, most of the existing researches use the commutation bus voltage as the judgment index of commutation failure from the AC system level, and derive the critical commutation bus voltage from the limit arc-extinguishing angle. The change of DC current is not considered in the failure voltage, and its accuracy is questionable

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