Method for evaluating weak voltage area of direct-current receiving end alternative-current system based on dynamic tracking

Abstract

The invention discloses a method for evaluating a weak voltage area of a direct-current receiving end alternative-current system based on dynamic tracking. The method comprises the following steps: 1, based on a WAMS (Wide Area Measurement System), extracting and counting voltage fluctuation waveforms of recent abnormal fluctuation information, confirming a frequent voltage fluctuation area, and calculating a voltage abnormal fluctuation level coefficient C1 of the area; 2, in a normal operation mode, calculating a voltage stability level coefficient C2 of a direct-current receiving end system; 3, calculating a voltage stability level coefficient C3 of the direct-current receiving end under the condition of line fault disconnection; 4, sequencing line faults; 5, integrating C1, C2 and C3 to form a superposition equation, and providing voltage stability grade levels R=C1 / (C2+C3) of different sub-areas, and determining that a sub-area is a dangerous area if R is greater than or equal to 0 and less than or equal to 0.03, and the sub-area is a common dangerous area if R is greater than or equal to 0.03 and less than or equal to 0.5, and the sub-area is an area with relatively small danger if R is greater than or equal to 0.5. By adopting the method, danger grade classification of weak voltage stability level areas can be achieved, voltage unstability risk areas of a direct-current receiving end power grid after faults can be rapidly evaluated, good practicability can be achieved, the workload can be small, and various hidden fault problems can be processed.

Description

technical field [0001] The invention belongs to the technical field of power system security and stability analysis, and in particular relates to a dynamic tracking-based method for assessing voltage weak regions of an AC system at a DC receiving end. Background technique [0002] At present, China's power grid has formed a North China-Central China AC interconnected power grid, and the East China Power Grid operates in an isolated grid, and is connected to the North China-Central China Power Grid through a DC system. According to the plan, China 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. After multiple DC...

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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