| The operation of the power system is greatly affected by natural disasters.When there are snow,storms,etc,it is easy to cause the power system to operate in isolated networks.It is urgent to analyze the high-frequency characteristics of the regional power grid after the fault is solved.Corresponding frequency control scheme to ensure safe and stable operation of the power grid.This article first studies the faults of the small hydropower collection type transmission network,and proposes the configuration principle of high frequency control measures.Chain generator tripping and high-frequency generator tripping schemes are provided for the power grid of delivery region in a hydropower station of Qinhuangdao.The effectiveness of the allocation scheme is verified through simulation of the splitting fault under typical operation mode.Secondly,study on the transient frequency characteristics and control strategy of hydropower unit isolated network in the case of large hydropower and small power grid-type regional power grids.The configuration of over-speed protection and overvoltage protection of hydroelectric unit were summarized.With the measurement of transfer power from regional network to main network,the original control target is substituted by appropriate and new value and the feed-forward signal showing attenuation characteristic is added to the valve command position.The effectiveness of the improved method is confirmed by digital simulation.Finally,this paper makes a study about impacts caused by important parameters of the speed control system for thermal power units under the splitting failure of power grids at the sending end on the frequency dynamic process of the power grids after its splitting.And taken a power grid at the receiving end in Tangshan as the research object,this paper studies low-frequency characteristics of regional grids after its splitting and puts forward proposals on improving the ability of unit’s frequency modulation. |
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