A Power Control Center is the nerve center of a power system. It monitors frequency, demand and loadings on the transmission lines. It also monitors the protective devices that protect the power system components such as transmission lines, transformers and generators. SCADA(Supervisory Control and Data Acquisition) and EMS (Energy Management System) systems are used in the Control Center to manage the flow of power, meet the daily demand and protect the power system components and monitor any alarms being generated.
One of the key measurement to monitor is the ‘system frequency’. This is the speed at which the generators are spinning (50 cycles per seconds). To keep the frequency at 50cps, the customer power demand must be always equal to the generation supply in a power system. This balance is achieved by keeping the frequency at 50cps at all time. The operator responsible for generation must know the daily demand profile. Generally demand is low at night, but during the day may have two peaks, one in the morning and one in the evening. As the demand increases, the operator can bring on new generators on to the system or require online generator to produce more if they have spare capacity. Sometime the operator has control over some generators, for some he calls the power plants. Generators can automatically make corrections for minor changes in customer demand increases. The power company is required to meet the daily power demand and yet must maintain the the power system frequency at 50cps( also known as 50 hertz or 50Hz).
Real Time data is collected from the power plant through remote devices connected to the control center via communication lines. This data includes power flow, alarms, frequency and voltage levels. Monitoring of alarms are the key to keeping continuity of power to the customers. When alarms are received from transformers, generators or transmission lines corrective action is required to prevent a power black out. The control room operator must take corrective action in a given time to arrest a deteriorating condition such as a fault on a component or excessive loading on a transmission line. Therefore, the operators perform a key function in the entire power system to ensure customers continually receive electricity. They must have the correct tools to do their jobs e.g. 99.99% availability of EMS, SCADA, Alarm Management Application. And must be only burdened with so many alarms in a given time. They must never be flooded with alarms in an emergency situation. If this happens they are bound to loose ‘operation situational awareness’ and take the wrong action. This can result in a major disaster on the power system.