PLC & SCADA based substation automation

Abstract

lectrical power systems are a technical wonder. Electricity and its accessibility are the greatest engineering achievements of the 20th century. A modern society cannot exist without electricity. Generating stations, transmission lines and distribution systems are the main components of power system. Smaller power systems (called regional grids) are interconnected to form a larger network called national grid, in which power is exchanged between different areas depending upon surplus and deficiency. This requires a knowledge of load flows, which is impossible without meticulous planning and monitoring .Also, the system needs to operate in such a way that the losses and in turn the cost of production are minimum. The major factors that influence the operation of a power system are the changes in load and stability. As is easily understood from the different load curves and load duration curve, the connected load, load varies widely throughout the day. These changes have an impact on the stability of power system. As a severe change in a short span can even lead to loss of synchronism. Stability is also affected by the occurrence of faults, Faults need to be intercepted at an easily stage and corrective measures like isolating the faulty line must be taken. As the power consumption increases globally, unprecedented challenges are being faced, which require modern, sophisticated methods to counter them. This calls for the use of automation in the power system. The Supervisory Control and Data Acquisition (SCADA) and Programmable Logic Controllers (PLC) are an answer to this. SCADA refers to a system that enables on electricity utility to remotely monitor, co-ordinate, control and operate transmission and distribution components, equipment and real-time mode from a remote location with acquisition at date for analysis and planning from one control location. PLC on the other hand is like the brain of the system with the joint operation of the SCADA and the PLC, it is possible to control and operate the power system remotely. Task like Opening of circuit breakers, changing transformer taps and managing the load demand can be carried out efficiently. This type of an automatic network can manage load, maintain quality, detect theft of electricity and tempering of meters. It gives the operator an overall view of the entire network. Also, flow of power can be closely scrutinized and Pilferage points can be located. Human errors leading to tripping can be eliminated. This directly increases the reliability and lowers the operating cost. In short our project is an integration of network monitoring functions with geographical mapping, fault location, load management and intelligent metering.