Research On Engineering Application Of Voltage Transformer Ferroresonance Suppression Method

In recent years,the ferroresonance problem caused by the installation of nonlinear ferromagnetic elements in power system has brought great threat to the safety and stability of power grid and equipment.How to effectively and quickly suppress or eliminate resonance has become a major problem to the power sector.Currently the harmonic elimination measures which are used in power systems can reduce the number of resonances in some degree.However,with the economic development,grid structure is becoming more complex.The original suppression measures already can’t meet the system operation requirements.Therefore,the core content of this paper is to explore more effective and reliable resonance suppression measures to mitigate or eliminate the adverse effects of resonance on power system.Through the combination of theoretical analysis and simulation research,the mechanism ferromagnetic resonance caused by voltage transformer is analyzed,which reaveals the followings: accidental factors make the voltage transformer into saturated zone and cause the asymmetry characteristic parameters of three-phase,then cause the neutral point potential rise,further deepening the voltage transformer saturation degree.And then the key elements of the resonance forms is studied.According to the above results,the working principle of various resonant suppression measures applied in engineering is studied,and the resonant suppression effect is compared and analyzed.The performance of the 4PT method for ferroresonance suppression is studied in detail,and the problems and causes in the application of the method are analyzed.In view of the decrease of measuring accuracy of 4PT method in steady-state operation,especially the large error of third harmonic measurement,a 4PT automatic switching strategy was proposed and the realization method of automatic switching was studied.The influence of the switching process on measurement is discussed in detail,and the effectiveness of the proposed improvement measures is verified by PSCAD simulation.It is believed that ferroresonance will greatly threaten the safe and stable operation of power system.With the rapid development of system structure,the form of ferroresonance will be more varied,which is a great challenge for power departments and enterprises.Therefore,it will be more important to study and use more efficient and reliable resonance methods.