Research On A New Fault Indicator For Distribution Network

With the society develops, power grid becomes more and more important to the economy, its intelligence and quick response to events is not only the symbol of the power system modernization, but also the presentation of our overall national strengthen.As Distribution network covers a wide range and has complicated structure, it is difficult to find the fault location when line failure happens especially when single phase earthing happens, in order to help shortening the time for fault location so that the crews can restore the fault quickly, the fault indicators have been widely used in distribution network. However, most fault indicators on sell now face two problem:some fault indicators have to be installed with FTU and DTU, so that they can make use of their high-precision PT and CT to realize the fault detection, apparently, this kind of installation is restricted and of high cost; some fault indicators are able to operate in lines by themselves, but they can only obtain the current information of the line via CT, these fault indicators are not able to detect the single phase earthing fault accurately. What is more, the way to install fault indicators in our country is to install them superfluously, which costs much and get low efficiency. How to obtain the balance between economy and shortening the fault interruption time has not been discussed in domestic.This paper would design a completely new fault indicator, including innovation both in hardware and software. On the hardware, the paper design the electric field sense circuit, power supply circuit and current information obtaining circuit; On the software, the paper combines the first half wave current and electric field induced voltage to improve the detection accuracy for single phase earthing fault; On the remote communication, the paper put forward the method combining the PLC(Power line communication) and RF(Radio frequency) to conquer the shortage of traditional communication method for fault indicator which makes use of GPRS. On the other hand, the paper also discuss the problem of optimal configuration of fault indicator, puts comprehensive analysis both on its cost and its efficiency, and comes up with the objective function for the optimal configuration, and solves the function with immune algorithm. In the last chapter, the paper makes use of the Simulmk and Proteus to verify the validity of the software and hardware.