Grid Grounding Fault Line Selection Device Based On DSP

In recent years,with the rapid development of Chinese economy,businesses have a growing demand for electricity,the distribution network is increasing scale,the security and reliable operation of the power system relate to all aspects of the national economy.In my country,the distribution network which is less than the voltage level of 66KV adopted Neutral indirect grounded system,that the small current grounding system;when the system was running under this way,a single-phase ground fault accounted for more than 80%of the small current grounding system ground faults.Even though the relevant rules provided that small current grounding system can run with fault 1 to 2 hours after occurring a single-phase ground fault,single-phase ground fault of small current system usually did not cause circuit protection device automatically remove the fault,so it is easy to induce intermittent arc overvoltage of long duration and affecting wide range;More serious is that it can breakdown the equipment of insulation weak,thereby developped into a phase short circuit,which caused the accident of power failure or equipment damage and leaded to the expanded accident.So when single-phase ground fault occurs in the system,we must be promptly and accurately determine the faulty line and remove it or isolate from the system.Due to the electric characteristic of a single-phase ground fault of the small current grounding system is not obvious,fault situation is complex,and therefore the selection of fault line is still a problem;At present a lot of good line selection algorithm only stopped at the simulation theory,and which did not specifically apply to line selection device,but the line selection device of the small current grounding fault on the market adopted nmostly steady-state algorithm based on SCM or uniprocessor,thereby which made the dvice itself limited performance,so far in practical application,it did not compeletely solve the problem of line selection of small current single-phase ground.This project deeply studied the development status of the line selection device and line selection technology of small current grounding,selected the line selection algorithm of transient value that had complex calculation but the better effect of line selection,and designed a set of line selection device of small current grounding fault based on DSP + CPLD + ARM + 51 SCM,which was according to features of the line selection algorithm of transient value,that large amount of computation and sampling datas having a high requirement in real-time.The device ensured performance to fully meet the requirements of the device itself,but also provided a high performance hardware platform for the follow-up studies of the line selection algorithm,which had more complex and greater amount of computation.