Research On Ferroresonance Phenomenon Of The Electric Locomotive Passing Phase Insulator

When the electric locomotive passes the electrical phase insulator, PT is a nonlinear ferromagnetic inductor. In the witching process of the circuit structure, the electromagnetic transient may stimulate ferromagnetic resonance. This process will lead to the happening of over-voltage and cause serious influence on safe operation of electric locomotive and the overhead contact system. In this paper, the PSCAD/EMTDC is used to simulate the process of the electric locomotive passing the electrical phase insulator. Combined with the test data of PT excitation characteristics and the test of CRH3A EMU passing electrical phase insulator, this paper analyses the ferromagnetic resonance phenomena and proposes a measure to suppress the ferromagnetic resonance.The paper analyzes the principle of ferromagnetic resonance, to set up the equivalent circuit of the electric locomotive passing electrical phase insulator and build the mathematical expressions of the voltage in the neutral section. The power phase angle and the equivalent capacitance parameters will affect the voltage in the neutral section.In order to simulate the accurate model of the PT, excitation characteristics of PT is measured. Ferromagnetic resonance phenomena of the electric locomotive passing three different types of electrical phase insulators are simulated by PSCAD/EMTDC. The simulation results indicate that if the power phase angle in the range of60°～90°or240°～270°, the voltage in the neutral section is bigger. The maximum voltage in the neutral section is69.75kV and it may stimulate ferromagnetic resonance. In condition of the same power phase angle, if the electrical phase insulator is longer, the equivalent capacitance is bigger, the voltage of the neutral section is smaller and the ferromagnetic resonance phenomena will be controlled. Since the equivalent impedance and capacitance of the system are not reached the chaos value, ferromagnetic resonance phenomena is not happened; the spectrum of the voltage simulated in neutral section is1/3power frequency (16.7Hz) harmonic.The CRH3A EMU test in Hu-kun Passenger Line (from Nanchang South Railway Station to Pingxiang North Railway Station) is described. The waveform of normal working conditions and ferromagnetic resonance when the EMU passes the electrical phase insulator are listed. The spectrum of the voltage in neutral section are1/5power frequency (10Hz) harmonic or1/3power frequency (16.7Hz) harmonic. Theoretical calculation and PSCAD/EMTDC simulation results are compared. It proves the validity and accuracy of the simulation model and theoretical calculations.In the end of the paper, a measure is put forward to control the ferromagnetic resonance phenomena when the electric locomotive passes the electrical phase insulator: RC filters. The parameters of RC filters are designed. And the effectiveness of RC filters is verified by simulation.