Research On The Overvoltage Protection Scheme For High Voltage Electrical System Of Electric Locomotives

Based on HXD21000, HXD1D electric locomotives, electric locomotive in operation process may encounter lightning overvoltage, operation overvoltage, resonance overvoltage generation mechanism are analyzed in theory; combined with field test results describes the operation of the electric locomotive over-voltage environment, over-voltage electric locomotive data collection, when an overvoltage occurs, it will seriously affect the operation of electric locomotive high-voltage electrical equipment, surge arresters and other serious cases may burn high voltage equipments.The composition of high voltage system and arrangement of electric equipment of HXD21000 and HXD1D type electric locomotive are introduced in detail, through the test of lightning arrester, discharge gap and high voltage transformer of electric locomotive, we found that the performance of high voltage protection equipment of electric locomotive is normal, and the over voltage accident of electric locomotive will not happen caused by their own lack of performance. In this paper, the modeling method of arrester and high voltage cable in PSCAD/EMTDC is introduced, using volt-ampere characteristics of exponential function to simulate lightning arrester and the model of the cable is accurately modeled by the frequency dependent modelTesting frequency characteristic arrester, the variation of amplitude frequency, phase frequency and leakage current of lightning arrester in 50Hz-2kHz under different frequency are observed. The equivalent circuit of lightning arrester in high frequency harmonic wave is established; by the measured and equivalent circuit simulation, the conclusion is obtained that the frequency of the action is increased and the loss of the arrester is accelerated. According to the research on the thermal characteristics of the lightning arrester, the limit value of the harmonic voltage in the course of the lightning arrester is pointed out. In the design of the lightning arrester, in order to avoid the thermal damage to the phenomenon occurred in the running process of electric locomotive, we need to enhance arrester’s ability to withstand high frequency harmonic,.Research on the insulation with electric locomotive high voltage system, simulation results show that two surge arresters can protect the electric locomotive more effectively; discharge gap is not suitable for overvoltage protection on the locomotive.Finally, HXD21000 electric locomotives overvoltage protection programs is optimized:use two-stage arrester and remove the discharge gap. Then verify the feasibility of the optimization program in the actual operation. According to HXD21000 locomotive overvoltage protection program optimization experience, HXD1D electric locomotive overvoltage protection program was designed.