Ee1401 Power System Operation And Control Energy Control Center Safety,

EE1401 POWER SYSTEM OPERATION AND CONTROL ENERGY CONTROL CENTER Safety, Quality, Reliability, Economy are the criteria governing the operation of an electric power system. To operate the system with minimum generation cost and low losses and to meet the criteria following tasks are performed: • Maintain the balance between load and generation. • Maintain the reactive power balance in order to control the voltage profile. • Maintain an optimum generation schedule to control the cost and environmental impact of the power generation. • Ensure the security of the network against credible contingencies. This requires protecting the network against reasonable failure of equipment or outages. The state of the power network is ever changing because loads and networks configuration change, making it difficult to operate the system. Moreover, the response of many power network apparatus is not instantaneous. Changing trends and growth have increased the need for computer-based operator support in interconnected power systems. For automation the electric utilities depend on a sophisticated integrated system for monitoring and control, having a multi tier structure with many levels of elements such as switchgear, which includes facilities for remote monitoring and control, protective relays and automatic transformer tap-changers (Level - 0), telecontrol cabinets providing facilities for actuator control, interlocking, and voltage and current measurement (Level - 1), data concentrators/master remote terminal unit including a man/machine interface (Level - 2), supervisory control and data acquisition (SCADA) system (Level 3). The SCADA system accepts telemetered data and displays them to operators has an alarm management subsystem that monitors informs the operators of abnormal conditions. Two control centers that are normally implemented in an electric utility are EMS for the operation of the generation-transmission system, and DMS for the operation of the distribution system, which are intended to help the dispatchers in monitoring and control of the system. The simplest of such systems perform the function of SCADA and others may have other sophisticated power application functions. Energy Management System (EMS) Energy Management System (EMS) assists the operator in monitoring and control of the electrical network with power application software and contains all the features of SCADA systems in data acquisition, control and monitoring. Load management, loss minimization, peak shaving and load shifting are some important activities of EMS implemented. EMS and SCADA systems consist of a networked architecture of computers performing online computations with backup support. EMS functions can be classified as: • Base functions • Generation functions • Network functions

MEENAKSHI COLLEGE OF ENGINEERING, CHENNAI 78

EE1401 POWER SYSTEM OPERATION AND CONTROL

EMS Functions 1. Base functions Data Acquisition: The data acquisition function collects, manages, and processes information from the RTUs. Supervisory Control: Supervisory control enables the operator to remotely control all circuit breakers on the system together with some line isolators. Alarm Processor: Notifies the operator of changes in the power system or the computer control system. Logical Alarming: Predetermine a typical set of alarm operations, which would result from a single cause and prioritize for display. Sequence of Events Function: Extremely useful for post-mortem analysis of protection and circuit breaker operations. Historical Database: Take any data obtained by the system and store in a historical database.

MEENAKSHI COLLEGE OF ENGINEERING, CHENNAI 78

EE1401 POWER SYSTEM OPERATION AND CONTROL Automatic Data Collection: Process taken when there is a major system disturbance. A disturbance archive is created with pre-disturbance and post-disturbance snapshots. Load Shedding Function: To identify that particular load block and instruct the system to automatically open the correct circuit breakers involved. Safety Management: Safety management provided by an EMS is specific to each utility. 2. Generation Functions The main functions that are related to operational scheduling are • Load forecasting • Unit commitment • Economic dispatch and automatic generation control (AGC) • Interchange transaction scheduling (to define power transfer schedules on tie-lines with neighboring utilities.) 3. Network Analysis Functions They can be subdivided into real-time applications and study functions. The real time functions are for a particular function or functions to be executed periodically or by a defined event manually. The network study functions are used to study any number of “what if” situations. The functions that can be executed are: • Topology Processing (Model Update) Function. • State Estimation Function. • Network Parameter Adaptation Function • Dispatcher Power Flow (DPF) • Network Sensitivity Function. • Security Analysis Function. • Security Dispatch Function • Voltage Control Function • Optimal Power Flow Function

MEENAKSHI COLLEGE OF ENGINEERING, CHENNAI 78