A method for frequency control of island power grid with multiple DC outputs

Abstract

The invention relates to a frequency control strategy for a multiple DC (Direct Current) send-out island power grid. The frequency control strategy comprises the following steps of: 1, for the multiple DC send-out island power grid of which the system frequency is risen or reduced due to a fault, firstly, starting a first defense line and utilizing a DC system frequency limiting function to control the system frequency; 2, when the frequency exceeds a frequency operated dead zone of a dynamo governor, starting another measure in the first defense line, i.e. carrying out primary frequency modulation control by the dynamo governor; 3, when the frequency exceeds a range of 49.0 to 50.6Hz, starting a second defense line, i.e. cutting off a generator or a load according to a control strategy; 4, when the frequency exceeds 50.6Hz, starting a third defense line and carrying out high-frequency cut-off protection to cut off a generating set; 5, when the frequency exceeds 51.5Hz, enabling the generator to execute the overspeed protection action and cutting off the generating set. The frequency control strategy can be used as an actual control strategy for stabilizing the frequency of a large-scale multiple DC send-out island system to be applied to production and operation of the power grid and also can be applied to emulation calculation of related research.

Description

technical field [0001] The invention relates to a method for controlling the frequency of an island power grid with multiple direct current transmissions, and belongs to the technical field of power system security and stability analysis. technical background [0002] The characteristics of resource endowment and unbalanced economic development in the region of China Southern Power Grid determine that China Southern Power Grid needs to carry out west-to-east power transmission and cross-regional resource optimization for a long period of time. Yunnan is rich in hydropower resources. As a large-scale hydropower transmission base of China Southern Power Grid, two direct current circuits of Xiluodu and Nuozhadu will be built and put into operation in the "Twelfth Five-Year Plan". Yunnan will also plan to send 14 million kilowatts of hydropower, and eventually send DC to 8 times. In order to reduce the interaction between AC and DC in Yunnan Power Grid, especially the power ang...

AI Technical Summary

Problems solved by technology

On the one hand, due to the "12th Five-Year Plan" coming to the vision, the scale of DC in Yunnan power grid is gradually increasing, and the scale of single-circuit DC is about 5 million kilowatts. If there is excess power, the system frequency will increase; on the other hand, there are many large-scale hydropower plants in Yunnan. If the transmission line of the power station fails in the isolated grid operation mode, the power station and the system will be disassembled, and the power shortage in the network will cause the system frequency to decrease.

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