Method for setting parameters of speed governor of direct current delivering-out system of hydroelectric generating unit

Abstract

The invention discloses a method for setting parameters of a speed governor of a direct current delivering-out system of a hydroelectric generating unit. The method comprises the following steps of establishing a model for analyzing stability of the speed governor of a water turbine; obtaining a transfer function of a power generator and an external system thereof, a transfer function of a linearized model of the water turbine, and a transfer function of a linearized model of the speed governor; solving a closed-loop transfer function corresponding to the model for analyzing the stability of the speed governor of the water turbine, and a closed-loop characteristic equation of the speed governor, and utilizing Routh stability criterion to obtain a transient descending rate value range and a buffer time constant value range for stabilizing a speed governing system; performing time domain simulation in the transient descending rate valve range and the buffer time constant value range for stabilizing the speed governing system, so as to obtain optimum parameters of the speed governor of the water turbine. The method has the advantages that by adopting the model for analyzing the stability of the speed governor of the water turbine, and combining the Routh stability criterion and the time domain simulation, the optimum parameters of the speed governor of the water turbine are finally obtained, and the robustness is stronger; the method is widely applied to the field of power.

Description

technical field [0001] The invention relates to the field of electric power, in particular to a parameter setting method of a speed governor of a hydroelectric unit sending out a system through a direct current. Background technique [0002] In an island system, the water hammer effect of the turbine may cause the governor to become unstable, and then cause low-frequency oscillations. The negative damping characteristic of the hydroelectric unit is the main cause of the low frequency oscillation. Generally speaking, the water turbine and governor will produce negative damping in the low frequency band, and the phase lag of the steam turbine itself is small. When the phase lag of the governor is also small, positive damping will be produced in the low frequency band. These are all related to the parameter setting of the turbine governor. [0003] After the asynchronous interconnection between Yunnan Power Grid and the main grid of China Southern Power Grid, the characterist...

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Problems solved by technology

[0003] After the asynchronous interconnection between Yunnan Power Grid and the main grid of China Southern Power Grid, the characteristics of Yunnan Power Grid’s high proportion of hydropower and high proportion of DC external load are very similar to the transmission system of large-scale hydropower plants through DC islands. The reduction of external damping and the water hammer effect of turbines will Produces a large phase lag in the low frequency band, causing ultra-low frequency oscillation problems

The characteristic experiment of asynchronous networking also proves that if Yunnan hydropower units still adopt the parameters of synchronous networking, it will cause continuous ultra-low frequency oscillation with an oscillation frequency of 0.05Hz and a fluctuation range between 49.9Hz and 50.1Hz, and the robustness is weak

[0004] In the island system, when dealing with the low-frequency oscillation caused by the negative damping characteristics of the turbine governor, the general solution is to set the dead zone of the primary frequency modulation of the generator to be greater than the dead zone of the DC frequency limiter (Frequency Limit Controller, FLC), but this The method is not suitable for the asynchronous interconnection system realized by the regional grid through DC

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