Research On The Strategy Of TCSC To Inhibit The Subsynchronous Resonance Of Power System

High-voltage long-distance sending systems of large pit power plants often use series capacitance compensation to increase the transmission capacity of transmission lines,and to increase the voltage level of the lines and enhance the transient stability of the system.It is a very cost-effective method to use the series complement to achieve the above functions.However,the application of series capacitance compensation may lead to Sub Synchronous Resonance(SSR)of the power system,which may cause shaft system torsional vibration in the turbine generator set,which will cause fatigue in the shaft system and reduce the service life of the unit.In severe cases,it may cause shaft Department of fracture and seriously affect the safe and stable operation of the power system.Therefore,it is of urgent practicality and very important engineering application significance to study the sub-synchronous resonance of TCSC for suppressing power system.This paper first introduces the basic concept of subsynchronous resonance,and studies the mechanism of subsynchronous resonance caused by the series capacitance compensation device.The characteristics of each electrical parameter under the occurrence mechanism were analyzed,and the main factors affecting the oscillation characteristics of the generator were studied.The effects of induction generators,electromechanical torsional vibration interactions and the amplification of transient moments,and the interaction of three forms are analyzed in detail.Four commonly used subsynchronous resonance analysis methods are described and the five suppression devices used in domestic engineering are compared and compared.Finally,TCSC was selected as a device for suppressing subsynchronous resonance.Secondly,the basic operating mode of TCSC is studied,and the fundamental frequency characteristics,sub-frequency characteristics and harmonic characteristics of TCSC are studied.The simulation model of single-phase TCSC circuit is established in MATLAB simulation software,and the selection of the K value of the main characteristic parameter of TCSC is analyzed through simulation.The mechanism of TCSC in inhibiting SSR and the operating conditions of TCSC were studied.The control strategies of TCSC in suppressing SSR were analyzed and compared.Finally,the open loop impedance control strategy was used to achieve the suppression function.Finally,in the PSCAD/EMTDC simulation software,the first standard model of IEEEsubsynchronous resonance is taken as the research foundation,and a subsynchronous resonance simulation model containing TCSC is established.When the three-phase short-circuit fault is added to the system,torsional vibration occurs between the masses in the shafting system.The simulation data in the PSCAD is imported into MATLAB and analyzed in the frequency domain using the FFT program to analyze the occurrence of subsynchronous resonance.The mechanical torsional frequency.By designing TCSC module parameters,the open-loop impedance control strategy is adopted to achieve TCSC suppression of sub-synchronous resonance,and simulations compare the suppression effect of TCSC in the total compensation capacity under different proportions.Simulation results show that TCSC cannot suppress SSR when it accounts for 20% of the total compensation capacity.TCSC can suppress SSR when the total compensation capacity is 40%,and TCSC is better than 40% when the total compensation capacity is 60%.