Control method for preventing serious grid frequency deviation under serious failure

Abstract

The invention provides a control method for preventing serious grid frequency deviation under serious failure. The method is applied to an AC-DC hybrid power grid; and through additional control functions of a direct current system, when serious failure causing serious system frequency deviation occurs, by changing the power of direct current, serious frequency deviation of the AC-DC hybrid power grid after serious failure is prevented, action of a third defense line of the system is prevented, or generator trip and load shedding amount of the action of the third defense line is reduced. Compared with the prior art, the control method has the advantages of preventing serious system frequency deviation, and enhancing system stability and operating economy and the like.

Description

technical field [0001] The invention relates to the field of electric power technology, in particular to a control method for preventing severe deviation of power grid frequency under serious fault. Background technique [0002] With the rapid development of the economy, the demand for electricity in the national economy is getting higher and higher, and there is a serious imbalance in the supply and demand of power resources in our country. For example, areas with relatively rich hydropower and thermal power resources are mostly concentrated in the west and southwestern regions of our country. However, the available power resources in the eastern and southeastern regions with high power demand are very limited, forcing the long-distance, large-capacity DC transmission system to develop rapidly with its own advantages. my country's ultra-high voltage and ultra-high voltage DC transmission systems The rapid development enables power resources to be efficiently and safely sent ...

AI Technical Summary

Problems solved by technology

However, load areas such as Jiangsu and Guangdong are connected through the DC transmission system and the AC line. In this mode of operation, once the AC line connected to the external network fails and refuses to operate stably, it may cause the out-of-step decoupling device to operate, resulting in AC The DC hybrid power grid becomes a pure DC connection with the external network. When all the networking lines are disconnected, it may cause a deviation of the system frequency, resulting in high-frequency cut-off or low-frequency load shedding. If a blocking fault occurs in the DC system, the frequency deviation will be more serious

The frequency deviation directly leads to the action of the third line of defense of the system, the action of the high frequency cutting machine or the low frequency load shedding device

The action of the third line of defense will cause the system to lose a large amount of load or power, which is not conducive to the safety and economy of system operation.

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