Research On Single Phase To Ground Automatic Fault Section Location In Non-solidy Earthed Network

To solve the small current grounding fault of the Power Distribution Network timely is always the problems of the power department has been exploring. There is a series of advantages for small current neutral grounding system, however, when a single phase-to-earth fault occurs, they are rather difficult to identify the fault feeder because the fault currents are much too small, especially under disturbance and detecting error. How to detect the fault correctly and location the fault position has been an important research task of small current grounding system.This paper analyzes the fault feature of small current neutral grounding system detailedly, summarizes the present fault location methods and analyzes the factor which affects the precision of the fault location, based on this, the fault diagnosis mainly according to zero sequence current colony amplitude and phase comparison for neutral ungrounded system and zero-sequence current active components and amplitude comparison of fifth harmonics for neutral grounded system through an arc suppression coil, both of which integrate the fault feature of each line in an area to diagnose faults with applying fuzzy comprehensive decision. This paper has designed the fault indicator based on Ultralow-power Microcontroller Unit MSP430F1610 of Texas Instruments corp. The fault indicator is a dual battery-powered and the powering circuit of GPRS is controlled by software that makes sure the fault indicator can work for a long time of outdoor. Also, a radio transceiver module based on nRF905 has been designed to share the fault parameter of each line of an area, such as amplitude, phase of zero sequence current and so on. It has supplied the hardware foundation for the implementation of fault diagnosis arithmetic. This paper designs to transmits the fault information to the supervise centre by Q2403 GPRS module to complete the fault location. As for the software design, this paper has implemented the saftware control of the GPRS model and RFID model by MCU, and completed the software design of data acquisition and processing.Through a lot of ATP simulation and laboratory grounding fault experiments show that the fault diagnosis method in this paper can judge the ground faults of small current grounding system of power distribution accurately and reliably. It is practical to locate the fault position by using the GPRS technology, so the method has broad application prospects and a high practical value...