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Grounding fault and injecting AC into DC control system in substation may lead to many protector problems, such as maloperation and miss trip, Based on the traditional unbalanced bridge and blocking condenser principle, the IUB(Improved Unbalanced Bridge) is put forward to detect ground resistance and alternating voltage occurred in substation DC system. The circuit of IUB models in MATLAB/Simulink...
The advantages of low-voltage direct current (LVDC) distribution power systems are emerging with the proliferation of distributed generators and power electronic devices. In comparison with the existing LVDC application in telecommunication, vehicle, ship and traction systems, LVDC distribution power systems concern more protection for safety, especially protection against electric shock caused by...
In this paper we show that the HVDC converter transformer valve side has the diversity and space-time discrete. Considering the influence of failure time on the fault feature, this paper proposes a method of fault feature stage dividing. The basis of fault feature stage dividing is given, and simulation result is showed for comparison. The protection test and BPP strategy research is also discussed...
As the finish of national distribution network updating, the national distribution network situation is going to be better. There are more single phase grounding faults than interphase short circuit faults. But the general used current protection equipment, which only reflects the interphase short circuit, cannot reflect grounding fault. And the distribution network is getting more complex. So the...
This paper introduces the design principle of a new insulation monitoring device on DC system based on AT89S52. The method of measuring insulation resistance between ground and DC power supply using switch-controlled is proposed, by which the state of combination switch can be changed though programming, a variety of effective circuit structure can be produced, linear equations of voltage sampling...
On the basis of comparison and analysis of the present grounding fault monitoring methods such as method of AC injection, method of DC leakage and so on, this paper points out their shortcomings in practical applications. A novel method named method of different frequency signals for detecting grounding fault of DC system is advanced, which can overcome the bad influence of distributed capacitor between...
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