The Research Of Control And Fault Feeder Detection For New Peterson Coil Based On DSP

More and more distribution networks'neutral point used to connect to the ground through the Peterson coil. But because of the uncertainty of the system running characters and complexity of the fault states with a single-phase short circuit to ground, it is always difficult to carry out the reliability testing of single-phase grounding fault line detection. And there is little effect in real work when some devices of fault feeder detection are used. Some devices of fault feeder detection employ industrial PCs. They are fixed with fans for the need of dispersing heat, which bring to the problem of making ash coming into the PC case. And the long time operation of the fans also causes many faults, and the whole control system needs maintenance at times. In addition, fault feeder detection and control of resonance adopt two systems, which bring to high cost. So, the thesis adopts a type of low loss DSP processor as main controller which composing the control and fault feeder detection system based on DSP in order to deal with the question. Firstly, This thesis analyses the demerit of the current ground-control methods and fault feeder detection methods home and abroad in the distribution system. Then this thesis Analyzes the variation rules of single-phase grounding in steady state and transient state under the circumstance of taking active loss of the new Peterson coil into account in detail, which is different from the rules in existence. And the effects of the current's active component through the new Peterson coil bringing to the earth point are educed. At the same time, the condition of transient current attenuation for Peterson coil is not same when earthed at different time. The phase angle of zero-sequence current through the fault feeder is different from the non-fault feeders', which contributes to the fault feeder detection. The thesis adopts the fault feeder detection method based on the phase angle of zero-sequence current considering the new Peterson coil's active loss. Then theoretical certification has been done. Aiming to detect fast the fault feeder of the Peterson coil's earthed system and control resonance's state, TMS320F2812 DSP of TI Corporation is chosen as the main controller, whose A/D module worked with ADS8364 to complete the zero-sequence current sampling together, in order to control and fault feeder detection of new Peterson coil. The hardware system is presented in detail. The thesis proposed in detail to solve the synchronization of gathering the data and locking up the phase direction of the power net'frequency. At last the device of control and fault feeder detection for new Peterson coil based on DSP is completed. High executing speed of DSP deals with the question of real time process, which minishes the controller loss. And the flowchart of the program is provided at last. At last the new Peterson coil grounding system for simulating is modeled and validated the fault-line-selecting method according to the unique frame of the Peterson coil. The results of the simulations in Saber software prove that the fault feeder detection and the analysis in steady state and transient state are right.