Research On Technology Principle Of Fault Selection And Network Protection For Full Parallel AT Traction Line

The high-speed or the heavy-haul electrified railway is an important engine to promote the development of national economy and society in the new era.Full parallel AT power supply with strong power supply capacity and flexible operation mode has become the preferred power supply scheme for high-speed and heavy-haul railways,but it is easy to cause more threatening line faults in operation.Since the domestic system has not fully mastered its electrical characteristics,it has caused the current failure of the at traction network relay to expand the power outage.Therefore,the real-time simulation system is urgently needed to build the total parallel at line model,qualitative analysis line fault characteristics,and the network relay protection scheme based on power supply arm.The main research contents are as follows:Firstly,the modeling and experiment of the full parallel at line are carried out,and the composition structure and working principle of the full parallel at power supply network are briefly described.Then,the specific power components of the system modeling are determined Secondly,according to the circuit analysis theory,each power element is equivalent to the encapsulable element model,and the specific simulation parameters are calculated.Thirdly,the completed parallel AT power supply network model is uploaded to the real-time simulation platform RTPlus and compiled.Finally,the short-circuit experiment between different conductors in the upper and lower lines is carried out,and the data are saved.Formulate a new fault selection scheme for fully parallel AT lines.Considering that the full parallel AT power supply system is a strong nonlinear system and a small current grounding system,it is more suitable to adopt the transient protection scheme based on specific frequency components.Firstly,the maximum modulus of the short-circuit current flowing through the autotransformer is obtained by using the wavelet transform to determine the power supply region where the fault occurs.Secondly the empirical mode analysis algorithm is used to calculate the amplitude of the natural mode function of each line in the fault interval,and the fault line is determined by comparing the amplitude.Building a network protection model of fully parallel at line.In order to further improve the intelligence level of fault selection scheme of fully parallel AT line,a network protection model of fully parallel AT line is built according to IEC61850 series standard,and related models are provided with service to undertake the relay protection task of a power supply arm.The experimental results of OPNET network platform prove that the network protection model of fully parallel AT line constructed according to IEC61850 standard has excellent network performance,clear logic and clear structure.The comprehensive simulation experiment and HWIL test show that the fault network selection scheme based on fault current singularity of fully parallel AT line has high sensitivity and selectivity,and the network protection model occupies less bandwidth,so it is very suitable for the construction of relay protection scheme based on network and intelligence.