Research On Prevention And Control Of Electrical Fire In The Special Places

VWith the advancing of the new era in China,the modern national economy is increasingly dependent on the power supply.As a result of the increasing number of electrical fire accidents,many peoples' livelihood issues are triggered.In order to achieve timely and effective "pre-fire prevention and control",new types of electrical fire prevention and control technologies have attracted much attention of a large number of scholars and experts.According to the defection that serial electric arc faults cannot be identified accurately in the three small places---small stalls,small workshops,small entertainments,this thesis presents a new type of serial arc fault identification method,namely high-frequency harmonic component method,which can effectively identify serial arc faults.The main work and conclusions are as follows.Firstly,the causes of the formation of electrical fires in the three small places were studied.In the meantime,the methods that how to prevent the occurrence of electrical fires as well as current management and control measures were pointed out.Combined with the weaknesses of electrical fire prevention and control technology in the three small places as well as government's electrical fires prevention and control technical standard,the future development trend of electrical fire prevention and control technology in the three small places was predicted.Then the deep theory explorations of fault are,including the formation mechanism of fault are,the mathematical model constructing of series arc,the simulation of the optimal model and so on,were conducted.The power system simulation was done and found that the electrical arc current within the circuit displayed very high distortion characteristic when the series arc occurs,which provides theory foundation for detecting serial electrical faults.Therefore,the fault arc simulation test platform was built in this thesis,and the structure of the fault test platform was designed,as well as the design and selection of data acquisition equipment were finished.By introducing collection process of the test data,multiple waveforms for various loads could be obtained.Through the series arc fault test of resistive loads and nonlinear loads,the current waveform and arc current waveform under normal operation of various types of household common loads were got respectively,then the two were compared in the time domain and the significant changes were identified from the waveforms.Because time domain waveforms could not be clearly distinguished,hence,the fast Fourier transform was proposed as the fault arc signal analysis method.From the perspective of frequency domain,the test data was subjected to fast Fourier transform,and the linear load and non-linear load spectrum analysis were performed respectively to get a spectrum analysis diagram.In the end,the two methods for identifying the eigenvalues of fault arc signals,namely the third harmonic amplitude method and the high frequency harmonic component method were introduced.Finally,a comprehensive test analysis and verification of the proposed fault arc identification method were conducted.First of all,the triple harmonic amplitude method was verified using other resistive loads and nonlinear loads in laboratory.The data displayed that this method is only applicable to the case of resistive loads with series arcs,while non-linear loads are not suitable for this method.Secondly,the second new method proposed in this thesis was verified,so-called the high-frequency harmonic component method,which can be applicable to both resistive loads and nonlinear loads.The data showed that this method can effectively identify series arc faults and has a highly universality.