A Real Time Electrical Load Distribution Monitoring and Controlling System Based on PLCand Webserver

Abstract : As global energy demand is constantly on the rise; power management has been becoming a major issue in the past decades or so due to less energy reserves. Power shutdown is a key crisis at the present time whereas disruption of power can cause a huge production loss for industries which calls for proper power management and monitoring in a systematic way. This paper deals with this issue by developing a prototype system and implementing real time energy monitoring and controlling of the system. In this system, power from main line is distributed and supplied to certain loads. If capacity of distributed load is less than required, then another line will be activated in parallel in order to prevent power shutdown and avoid production losses. More over, this process can ensure safety by tripping the system in case of any fault occurrence. All these are performed in an automated process using PLC and Web server.

 EXISTING SYSTEM :

 Power distribution SCADA system is a computer-based production process control and scheduling automation system. It uses the data acquisition module to monitor and control the operation of field devices so as to achieve data acquisition, device control, measurement, parameter adjustment, and various signal alarms. Electrical load distribution, monitoring & controlling using PLC is comparatively reliable, accurate and more efficient technique than any existing controllers. LAN is used to communicate with PLC and PC with the help of Web server and a Communication board (RS 485) is used also for collecting data from energy meters to execute logical commands using program uploaded in the PLC memory.

 DISADVANTAGE :

 Automatic systems are being favored over manual system since they reduce individual’s effort. Electrical load distribution, monitoring & controlling using PLC is comparatively reliable, accurate and more efficient technique than any existing controllers

 PROPOSED SYSTEM :

 To carry out the load controlling and monitoring ofoverall system, energy meters, PLC and PC are used.Multiple energy meters with a single PLC CPU connectswith a PC to monitor and control required electrical loaddistribution. LAN is used to communicate with PLC and PC with the help of Web server and a Communication board (RS 485) is used also for collecting data from energy meters to execute logical commands using program uploaded in the PLC memory. In the load controlling system, extra load is automatically connected by starting the parallel line when the load consumption is near the expected load. For instance, if the distributed load of one area is 10MW for a day, then normally the line contains 10 MW loads for day long. However, in our system, (As in Figure 2) the first line (bus A) contains 10 MW loads and another line (Bus B) is connected in parallel with 2 MW extra loads. The extra load is used whenever additional load is required in that area. If the voltage or current of system exceeds the rated voltage or current, then fault arises. Moreover, if the load consumption is more than accumulated result of 2 parallel loads or if any fault occurs, then after 20 seconds the system will automatically trip the overall system. This causes automatic power shutdown ensuring safety of the distributed loads and equipment of the system. The system will continue its normal operation only if the fault or excess load is removed within 20 seconds or before starting the system. The time duration for tripping can be reduced or enhanced with the requirements of user of the system. Figure 1illustrates the block diagram of the system. Bus A and Bus B distribute electricity to the loads connected in parallel. Energy Meters communicate with PLC through Modbus. PLC CPU allows the connected loads to be switched on by a relay input and output control. The whole system works under designed logical commands in the PLC.

 ADVANTAGE :

 advantage of using load distribution system is that, it helps us from using many substations, which wastes a huge amount of additional power. For an instance, in AIT Electrical Distribution network (Thailand), 15 substations are being used for academic and residential purpose, in which, the total installation capacity is 13.5 MW whereas the peak load is only 2 MW.