Real-time Network Analysis sequence ower flo Action Power Optimal Power Flow FIGURE 67 3 Real-time and study network analysis sequences 1. Determine the state of the system based on either current or postulated conditions. 2. Process a list of contingencies to determine the consequences of each contingency on the system in its 3. Determine preventive or corrective action for those contingencies which represent unacceptable risk. eal-time and study network analysis sequences are diagramed in Fig. 67.3 Security control requires topological processing to build network models and uses large-scale ac network typically includes the following functions Topology processor: Processes real-time status measurements to determine an electrical connectivity State estimator: Uses real-time status and analog measurements to determine the "best " estimate of the state of the power system. It uses a redundant set of measurements; calculates voltages, phase angles, and power flows for all components in the system; and reports overload conditions Power flow: Determines the steady-state conditions of the power system network for a specified gener ation and load pattern. Calculates voltages, phase angles, and flows across the entire system Contingency analysis: Assesses the impact of a set of contingencies on the state of the power system and identifies potentially harmful contingencies that cause operating limit violations ptimal power flow: Recommends controller actions to optimize a specified objective function( such as system operating cost or losses) subject to a set of power system operating constraints Security enhancement: Recommends corrective control actions to be taken to alleviate an existing or potential overload in the system while ensuring minimal operational cost. Preventive action: Recommends control actions to be taken in a"preventive "mode before a contingency occurs to preclude an overload situation if the contingency were to occur. Bus load forecasting: Uses real-time measurements to adaptively forecast loads for the electrical connec- ity(bus)model of the power system ne Transmission loss factors: Determines incremental loss sensitivities for generating units; calculates the impact on losses if the output of a unit were to be increased by 1 MW. Short-circuit analysis: Determines fault currents for single-phase and three-phase faults for fault locations across the entire power system network© 2000 by CRC Press LLC 1. Determine the state of the system based on either current or postulated conditions. 2. Process a list of contingencies to determine the consequences of each contingency on the system in its specified state. 3. Determine preventive or corrective action for those contingencies which represent unacceptable risk. Real-time and study network analysis sequences are diagramed in Fig. 67.3. Security control requires topological processing to build network models and uses large-scale ac network analysis to determine system conditions. The required applications are grouped as a network subsystem which typically includes the following functions: • Topology processor: Processes real-time status measurements to determine an electrical connectivity (bus) model of the power system network. • State estimator: Uses real-time status and analog measurements to determine the ‘‘best’’ estimate of the state of the power system. It uses a redundant set of measurements; calculates voltages, phase angles, and power flows for all components in the system; and reports overload conditions. • Power flow: Determines the steady-state conditions of the power system network for a specified gener￾ation and load pattern. Calculates voltages, phase angles, and flows across the entire system. • Contingency analysis: Assesses the impact of a set of contingencies on the state of the power system and identifies potentially harmful contingencies that cause operating limit violations. • Optimal power flow: Recommends controller actions to optimize a specified objective function (such as system operating cost or losses) subject to a set of power system operating constraints. • Security enhancement: Recommends corrective control actions to be taken to alleviate an existing or potential overload in the system while ensuring minimal operational cost. • Preventive action: Recommends control actions to be taken in a “preventive” mode before a contingency occurs to preclude an overload situation if the contingency were to occur. • Bus load forecasting: Uses real-time measurements to adaptively forecast loads for the electrical connec￾tivity (bus) model of the power system network. • Transmission loss factors: Determines incremental loss sensitivities for generating units; calculates the impact on losses if the output of a unit were to be increased by 1 MW. • Short-circuit analysis: Determines fault currents for single-phase and three-phase faults for fault locations across the entire power system network. FIGURE 67.3 Real-time and study network analysis sequences