Simulation Study On The Producing Mechanism And Suppression Measures For Distribution System Overvoltage Of Gudong Oilfield

Power system is one of the most important infrastructures in oil field.With the development of oil field,the distribution network scale of Gudong Oil Plant has been increasing.And the topology structure and load style has become more and more complicated.Therefore,the influence factor is very complex in the modern distribution system.In recent years,various over voltage as well as unknown reason tripping sometimes occurs,and there are lots of apparatus damaged.Although many measures have been carried out,the result is not obvious.The direct and indirect loss caused by outage is very high.This dissertation analyzes the statistic fault data and influence by fault,and the key factors influencing the supply reliability is discussed,based on the distribution system structure and its parameters.The mechanism of inner and outer overvoltage in the oil field distribution network is studied.And the method to cope with over voltage is presented and the simulation model is built.Based on the neutral point unearthed mode of the oil field distribution network,the intermittent arch-earth fault overvoltage and the ferromagnetic resonance overvoltage is analyzed as well as their cause.The overvoltage producing process with intermittent arch-earth fault is interpreted and the situation of ferromagnetic resonance overvoltage is analyzed combining the field parameters of oil plant distribution network.The unified solution for intermittent arch-earth fault overvoltage and ferromagnetic resonance overvoltage is to make the neutral point earthed by the arc suppression coils.Based on the existing earthed mode of the transformer and its arresters,the mode of three spot earthed together and the mode of three spot earthed independently is analyzed.Then their lightning protection performance is compared.And the former is better to protect the transformers.In theory,the influence of the grounded lead parameter to the lightning protection performance is analyzed.And the conclusion is drawn that the grounded lead must be cut as short as possible,which can improve the lightning protection performance.Based on PSCAD software,the simulation model about the inner and outer overvoltage in the oil field distribution network is built.The simulating results prove its validity.The conclusion of this dissertation is the theory base and technical support to cope with the over voltage in the Gudong oil plant.It lays the foundation for plan and maintenance the distribution system to improve the supply reliability in the future.