Fault Set Formation Method for Voltage Stability Assessment of AC System with Multiple DC Feeds and Receiving Terminals

Abstract

The invention discloses a method for forming a voltage stability assessment fault set of an AC system with multiple direct current feed-in receiving terminals, which is characterized in that it includes: collecting recent fluctuation data of multiple direct-current feed-in direct current receiving-end systems and the corresponding transmission curve of the maximum power direct current transmission system , and the regional load and start-up mode at that time to form a relationship table, and perform rule reduction on the relationship table according to the reduction rules to determine the typical operation mode for a period of time in the future; calculate the voltage stability level coefficient of the receiving end system under the typical operation mode; Calculate the voltage stability level coefficient S of the DC receiving end system under various line fault disconnection conditions n ; The line faults are sorted according to the voltage stability level coefficient of the DC receiving end system; combined with the power flow transfer after the fault, the low voltage point and the risk coefficient of the electrical distance of the fault point, the worst cascading fault set is combined. The present invention can quickly evaluate the voltage instability risk of the receiving end power grid of the DC system after a fault by analyzing the characteristics of the transient voltage instability accidents that may exist in the current AC-DC hybrid power grid.

Description

technical field [0001] The invention relates to a method for forming a fault set for voltage stability evaluation of an AC system with multiple DC feed-in and receiving terminals, and belongs to the technical field of power system safety and stability analysis. Background technique [0002] At present, my country's power grid has formed a North China-Central China AC interconnected power grid, and the East China Power Grid operates in isolation, and is connected to the North China-Central China Power Grid through a DC system. According to the plan, my country will build dozens of UHV DC projects in the next 10-20 years, and gradually form a UHV AC-DC hybrid power grid to supply power to the central and eastern load centers through UHV DC and AC systems. Conventional HVDC transmission systems require sufficient commutation voltage from the AC system at the receiving end, and will absorb a large amount of reactive power from the AC system after commutation failure occurs. Afte...

AI Technical Summary

Problems solved by technology

[0004] For the AC / DC hybrid fed into the receiving end grid, the more serious safety and stability problem is the possible cascading failure of the AC / DC system, that is, the failure of the AC system may cause the continuous commutation failure of the DC system, which in turn leads to DC blocking and greater power transfer to the AC channel, triggering a cascading power grid collapse accident

The current research methods for this problem are still single. In engineering, the time domain simulation method is mainly used. Through the transient stability simulation of various AC and DC system fault combinations, it is evaluated whether it will cause the continuous commutation failure of the DC system, and then cause more damage. It is a serious cascading failure; however, this method faces problems such as heavy workload and difficulty in enumerating potential failures

In addition, some studies have been carried out at home and abroad on the formation mechanism and evolution process of cascading faults, and analysis methods such as power flow transfer evaluation after faults and small-world characteristics of power grids have been proposed, which have promoted the development of cascading fault set construction technology; but the current Research methods mostly focus on theoretical analysis or summary of operating experience. How to propose an effective and practical method of cascading fault set construction in combination with the actual situation of the power grid still needs further research

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