Design Of Wireless Monitoring And Control System For Large Industrial Users Based On PLC And Power Sensor

The source of this subject is a sub-project of Shanxi Coal Transportation and Marketing Group Co.,Ltd.’s school-enterprise cooperation project "Design and Energy Saving Analysis of Coal Mine Substation Monitoring System Based on Demand Side Management Platform".In recent years,with the deepening electricity market reform in China,a two-part electricity price has been set for large industrial users.This electricity price policy limits the maximum value of an enterprise’s average load every fifteen minutes in a month.When the threshold is exceeded,an additional electricity fee will be charged.Every year when a large industrial user signs an electricity purchase contract with the grid,the greater the maximum demand,the more basic electricity prices will be charged;even the smaller the maximum demand,if the electricity consumption exceeds the maximum demand,the additional electricity charges will be higher.Therefore,this article helps large industrial users to propose solutionslarge industrial users wireless monitoring and control system.The essence of this system is to increase the backup power supply in the factory.When the power consumption of the electrical equipment is about to reach the maximum demand,switch to the backup power supply to reduce the main power supply of large industrial users and make the actual power supply of the main power supply.Do not exceed the maximum demand at the time of signing the contract(if you exceed it,you will need to pay a fine),save the factory’s electricity bills and establish a ZigBee network-based power Internet of Things.This article is designed as a wireless monitoring and control system for large industrial users based on PLC and power sensors.This system uses Siemens S7-1200 SMART PLC as the control core of the lower computer,and the upper computer is Siemens KTP700 Basic PN simplified screen,which realizes the s Table action of the relay in the system.,A power sensor is installed on the side of the electrical equipment to obtain power information.The specific work of this paper includes the following aspects:(1)Build a wireless monitoring and control system,which mainly introduces the system design principles and overall architecture,and at the same time explains the relevant technical theories involved in the system.(2)The hardware system of the monitoring and control system for large industrial users was built using WB electronic power sensor,Ebyte ZigBee module and Siemens S7-1200 SMART PLC.Carried out ZigBee module selection and communication configuration,respectively configured ZigBee coordinator and terminal,completed the wireless transmission of data;selected the hardware of the power sensor,and designed the communication circuit of RS-485 wiring;through the power sensor The serial port debugging realizes the communication between the sensor and the PLC;the relay control circuit is designed to realize the timely switching of the standby power supply.(3)The software design of the monitoring and control system for large industrial users is realized by using Portal software.The communication program between the PLC and the power sensor was written to realize the real-time transmission and recording of power data;the wiring ports of the PLC were allocated and the wiring of the PLC was designed;the working flow chart of the PLC was drawn according to the action requirements specified by the working principle of the system,And completed the PLC control main program design according to the flowchart;wrote the PLC operation detection program,real-time monitoring of whether the PLC is operating normally.(4)The man-machine interface of the monitoring and control system for large industrial users was designed by using the built-in Win CC software of Portal.The interface includes manual control screen,automatic operation screen and data monitoring screen.The manual control interface realizes the manual switching of the backup power supply to prevent emergencies;the automatic operation interface is designed for the system operation time,relay switching status and PLC operation status The display window realizes the real-time monitoring of the system operation status;the data monitoring screen includes data such as power,voltage,current waveform,power factor,frequency,1st harmonic content,and 3rd harmonic content.(5)In order to determine the maximum demand and standby power capacity of the system,double-layer optimization is carried out.The outer layer uses the quantum genetic algorithm(GQA),and the inner layer uses the YALMIP toolbox with CPLEX as an auxiliary solution tool to calculate the relevant index parameters of the inner and outer layers of the energy storage configuration.Two-layer optimization is used to calculate the system parameters when photovoltaic panels and lead-acid batteries are used as backup power sources.Through the analysis of calculation examples,it can be known that the system can produce economic benefits in a short time and achieve the expected effects of system design.(6)A feasibility experiment was carried out on the system to verify the law of action of the system and prove that the system can be put into actual use in the factory.