Research On Interfering Process And Effects Of Geomagnetic Storm On The Electrical System In High-speed Railway

Geomagnetic storm will threaten the safety operation of railway systems.In this Ph.D dissertation,supported by National Nature and Science Fund(Project No: 41374189,The Circuit Model and Algorithm of Geomagnetic Storm Impacting on High-speed Railway Electrical System),characteristics and effect factors of GIC in high-speed railway is investigated from both actual measurement and modelling calculation.It is necessary and significant to understand the response mechanism of geomagnetic storms against the electrical system of high speed railway,and the experiment to monitor GIC in real-time has been carried out for the traction network of high-speed railway.In addition,GIC calculating model for track circuit is developed,and the characteristics and influence factor of GIC in track circuit are studied in the Ph.D dissertation.GIC evaluation method and GIC level are estimated for traction network,and the impact of geomagnetic storm on the electrical equipment is analyzed.The main work and results are summarized as follows:The cases that geomagnetic storms affect the railway system are analyzed from the previous works,combined with the feature of electrical system of high-speed railway in China.Then,the AT power supply system as an example,GIC flow path were studied for traction network,track circuit and train.The experiment scheme is designed to monitor that geomagnetic storms affect the electrical system of high-speed railway,and the GIC observation experiment have been completed on the traction network at Hebi East substation for the Beijing-Guangzhou Dedicated Passenger Line(DPL),Yanji West subtation for Changchun-Hunchun DPL.Moreover,the GIC monitoring system for high-speed railway has formed based on the GPRS communication technology,and the monitoring data has been sent to the data center for analysis and management,which provides more experimental data for the study of GIC and its influence on electrical system of a high-speed railway.By means of measurement,DC current was captured for the first time in the traction network at Hebi East substation for the Beijing-Guangzhou DPL during geomagnetic storm.After comparison DC current data with magnetic storm data from geomagnetic observatory during geomagnetic storm,it is found that value of the currents and horizontal components of geomagnetic field not only emerge at the same time but also have close relationship,which is affirmative evidence of that the DC current captured in the traction network is related to geomagnetic disturbance.The induced electric field calculated from the geomagnetic field and the Earth conductivity parameters,have been regressed with the DC current captured,which shows the DC current is the results of geomagnetic disturbance.Track circuit equivalent model was developed to calculate GIC and rail potential based on the distributed sources transmission lines theory,coupled with the geoelectric field by an equivalent current source exerted between different earthing points,finally we can calculate the GIC and rail potential on rails.To verify the model,this dissertation established a model of the track circuit to calculate GIC on the rails between Hebi East station and Anyang East station under a uniform electric field,and the GIC curve calculated under actual magnetic storm at Hebi East substation.The calculation results agree the measurement results quite well,and it can be concluded that the proposed model and the calculation method in this dissertation are effective,and can be used for assessing the level of GIC in track circuit.Characteristics of GIC and rail potential in tract circuit were further studied with the influence of rail length,leakage resistance and grounding system.Implementation of calculating GIC also needs to establish the traction network equivalent model.Chain circuit model was established for the traction network based on multi-conductor transmission lines theory.Because GIC has a very low frequency,DC parameters of traction network elements only need to be considered.The dissertation has established the equivalent model of GIC for main traction network elements,such as: serial element,shunt element,etc.Electric field induced at earth surface is coupled to the chain circuit model by equivalent voltage source exerted between shunt element,and the matrix equation is derived to calculate GIC at each node.Yanji West traction network was selected as the object to assess the level of GIC and its potential risks.GIC on the tract lines and the substation were calculated under a uniform electric field,also the GIC and rail potential in tract circuit.In this dissertation,the GIC in traction networks was assessed for the first time,and the calculation results can provide an important reference for evaluating the effects of geomagnetic storm on the equipment in traction networks and risk assessment for the safe operation of high speed railway.