Research On Low Voltage Intelligent Switch Based On Power Carrier Technology

Due to the tree-like structure of rural low-voltage distribution network,when there is an abnormal state at a point from the station area to the end of the user,it is easy to cause large-scale power outages of multiple branches.In addition,this structure is easy to cause problems such as unclear information at each node level and difficult fault point location.Therefore,this paper designs a low voltage intelligent switch based on power carrier technology,which can remotely monitor the state of each node and realize the node classification of the station area.Firstly,this paper theoretically analyzes the power carrier communication technology and establishes the multipath fading and noise channel model.By analyzing the applicability of various signal modulation and demodulation schemes in rural power carrier communication,orthogonal frequency division multiplexing（OFDM）technology is adopted as the signal modulation and demodulation scheme,and the transmission of carrier signal on the power line is modeled and simulated in Matlab.The different coding forms and different signal synchronization modes are compared and analyzed.Based on this,the hardware and software of low voltage intelligent switch are designed.In the hardware design of low voltage intelligent switch,ES1667 power carrier module and external circuit are used to realize the basic functions of low voltage intelligent switch.The power supply circuit,main control circuit,relay control circuit,current and voltage acquisition circuit and human-computer interaction circuit of the sub node and the main node are designed respectively,and the node prototype assembly is completed.In the design of low-voltage intelligent switch software,the communication protocol between each node is first determined,and then the system initialization,network application,data transceiver,node classification,overload mode and the functional program flow of the Internet of Things are designed one by one.On this basis,the microcontroller control program and the WEB interactive program are written and tested.Finally,the basic functions of low voltage intelligent switch are tested one by one,and a three-level low voltage intelligent switch network with major node and sub nodes is configured.The test results show that the basic functions of low voltage intelligent switch can be realized,major node can complete the networking and switch classification,and sub nodes can respond to the control instructions of the major node.Each node can react the current state information through the OLED screen and the WEB page in real time.When the current exceeds the limit,it can be switched off.