Design And Research On A New Type Insulation Monitoring Device With The Function Of Detecting AC Into DC

DC power supply is an important part of power system,on the one hand,for the battery charging,at the same time for the relay protection and automation control device to provide stable and reliable power supply.AC power transforms into direct current power supply mainly through the high frequency power supply module.The reliability of the DC power supply for the safe running of the transformer substation plays an important role.So must constantly monitor the DC system online,and to realize the rapid diagnosis of DC system of fault and the real-time assessment of the operation of DC system.To avoid when DC system grounding fault happens,lead to incorrect action of signal circuit,control circuit,relay protection,etc,must be in one point of ground fault,the system can timely discover and send the alarm signal.And for this manufacturers and users to develop different types of microcomputer insulation monitoring device.Microcomputer insulation monitoring device as the guarantee of normal operation of DC system can meet the requirements of DC grounding fault detection.But with the application of DC system,the system is more and more complex.AC interlarding DC system appeared,and the diversity of alternating current into direct current system,the harm and influence of DC system is diversity.So the research about new insulation monitoring device with the function of detecting AC interlarding DC system has great significance.The paper the composition of the DC power supply system,the function and working principle of each module,and the connection mode of DC bus.Then the work principle of the microcomputer insulation monitoring device are expounded.Three of DC system grounding fault detection method,bridge method,AC test and DC test for narrative analysis respectively,and compared the advantages and disadvantages of different detection principle are detailed separately.Then the insulation monitoring device with the function of detecting AC interlarding DC is designed.First the principle of detecting AC interlarding DC and DC interconnection which are newly added are analyzed.Then parts of hardware circuit of the new insulation monitoring device are designed,including the ADC modulus conversion circuit,electric bridge circuit,display circuit,communication circuit,input and output circuit and power circuit.And the software implementation of the microcomputer insulation monitor is developed,including AC detection software implementation,DC insulation detection software implementation and interconnected detection software implementation.At last through Positive and negative to ground DC voltage test,Dc system insulation reducing test,AC into the DC system signal test,DC system interconnection test,verify the function of the new insulation monitoring device with the function of detecting AC interlarding DC,and Prove that the new insulation monitoring device can realize scheduled functions.