Earth Fault Location System For Non-solidly Earthed Distribution Network

Self-heal is a key function to smart grid. Fast and reliable location is the basis for self-healing distribution network. Distribution network with non-solid grounding have some advantage over solid and low-impedance grounding. In MV system, the faults are mostly single phase to ground faults. A ground fault on system with non-solid grounding draws a small current. Additionally the system is very complex, it is very difficult to locate fault point. At present, earth fault identification has succeeded in projects but fault location is still in the stage of theoretical researches.There is some disadvantages for traditional methods and some methods are not available for non-solidly earthed network. In the field application, some key technique has not been solved. For example, it is difficult to acquire fault signals for overhead lines.The paper proposes transient signals to locate earth fault point. The main research works include:(1) Traditional methods and some difficulty for fault location are analyzed.At present, locating methods can not locating fault point well. The unreliable location principles and difficult measurements for fault signals are the main reasons. There are some other difficulties for field application. For example, time can not be precisely synchronized in different monitoring points and communication network can not transmit large amounts of fault data.(2) Find The fault model and study the localization method based on transient reactive power. The small current grounding fault model and analyses the frequency domain characteristics, study the positioning method based on transient reactive power, to determine the fault section. Use of ATP and matlab simulation model is established, and the effectiveness of the various cases are analyzed in detail on our method.(3) According to the distribution line fault location method, the design includes fault indicator node, GPRS wireless communication network and system of the main fault location system, and the wireless radio frequency module and GPRS module, used for testing point and the center of the communication.(4) According to choice of MCU, the system software part of the main program module, fault location module, communication module three parts, designs the task flow of three parts.