Time Synchronization Algorithm Research For Detection Of Power Grid Transmission Line Fault In Coal Mine Based On WSN

Coal mine power grid transmission line provides motivational guarantee for coal mine safety production. Compared with traditional cable detection technology, WSN technology has advantages in fault detection for coal mine power grid transmission line, such as self-organization, low power consumption, high flexibility, low transmission delay etc. But the premise is that WSN nodes must keep synchronization to process data information collaboratively which makes the coal mine power grid transmission line fault point location rapid, accurate and reliable. This article focuses on research of WSN time synchronization problem of coal mine power grid transmission line fault detection, the main research include:(1) Combined with the typical network topology structure of the WSN and the strip coal mine power grid transmission line topology, a treelike stratification time synchronization algorithm based on WSN called RBTP is proposed. The algorithm is divided into two stages: levels discovery and child nodes collection, and time synchronization. The whole WSN nodes are divided into reference node, response node and nonresponsive node. The algorithm uses two-way message exchange mechanism to exchange the synchronous data packets between reference node and response node, and use the least square method to deal with the synchronization timestamp information to realize the synchronization between response node and other nonresponsive node. MATLAB simulation shows that energy consumption of RBTP reduced two orders of magnitude compared with TPSN and one order of magnitude compared with RBS algorithm. Furthermore, the synchronization precision within the range of synchronous times displayed by simulation can satisfy coal mine power grid transmission line fault detection for requirements of time synchronization precision.(2) Combined with the topology of the transmission line of coal mine and the basis of the simulation analysis of RBTP algorithm, clustering stratification time synchronization algorithm based on WSN called CLLTP is proposed. Algorithm is divided into two stages: hierarchical cluster and time synchronization. Synchronous phase is divided into cluster head nodes synchronization and the cluster nodes synchronization. The cluster head nodes and benchmark node adopt bi-directional multicast synchronization mechanism, and the maximum likelihood estimation is used to calculate the clock skew. Within the cluster nodes use two-way radio synchronization mechanism, and the maximum likelihood estimation is used to calculate clock skew between the cluster head nodes and secondary cluster head nodes, and the minimum variance unbiased estimation is used to calculate phase offset and frequency offset of clock between within the cluster of other nodes and cluster head nodes. The simulation shows that while the algorithm improves energy consumption slightly compared with RBTP algorithm, it obtains the higher synchronization precision. Therefore, it can satisfy requirements for time synchronization precision which coal mine power grid transmission line fault detection needs in the longer period.Compared with the traditional time synchronization algorithm, these synchronization algorithms which this paper researches can reduce energy consumption greatly, and they can satisfy the demands for time synchronization precision in the coal mine power grid transmission line fault detection.