Energy management systems (EMS) are automation systems that collect energy measurement data from the field and making it available to users through graphics, online monitoring tools, and energy quality analyzers, thus enabling the management of energy resources. The availability of information to employees in technical areas gives the company a competitive advantage since online and historical data are analyzed and converted into useful information to optimize the use of energy. The first step in implementing an energy management system is the determination of monitoring points. The installation of electric power metering systems allows the utility to monitor its entire network. The monitoring of the electric system operating conditions is therefore primary and essential. This is done by setting a data acquisition system, which uses measuring instruments distributed throughout the electric network, to collect and transmit data to the control center through a communication system.
EMS relies on a SCADA application to perform data monitoring and analysis activities. This application is used to supervise and control the electric power generation and the transmission and distribution systems. Among the benefits brought by SCADA systems are consumer and demand analysis, consumer load analysis, fault checking, topology rearrangement, load analysis on transformers, and intelligent metering. With the evolution and consolidation of smart grids, SCADA will need to incorporate new smart metering elements, such as phasor measurement units (PMUs) and intelligent relays, and consider new renewable sources of power generation and energy storage in electric vehicles (EV). After acquiring the data, a computational tool known as state estimation (SE) is used, which is responsible to process these raw data and make them credible and available to all other EMS applications. State Estimation acts as a filter in smoothing out statistically small errors and suppresses any gross errors caused by the inadequate operation of the data acquisition system.