DYNAMIC SECURITY ANALYSIS

DYNAMIC SECURITY ANALYSIS The North American Electric Reliability Council (NERC) definessecurity as “the prevention of cascading outages when the bulk power supply issubjected to severe disturbances.” To assure that cascading outages will nottake place, the power system is planned and operated such that the followingconditions are met at all times in the bulk power supply:• No equipment or transmission circuits are overloaded;• No buses are outside the permissible voltage limits (usually within+5 percent of nominal); and• When any of a specified...

Read More

OPTIMAL PREVENTIVE AND CORRECTIVE ACTIONS

OPTIMAL PREVENTIVE AND CORRECTIVE ACTIONS stability problems, preventive actions are required. If a feasible solution existsto a given security control problem, then it is highly likely that other feasiblesolutions exist as well. In this instance, one solution must be chosen fromamong the feasible candidates. If a feasible solution does not exist (which isalso common), a solution must be chosen from the infeasible candidates.Security optimization is a broad term to describe the process of selecting apreferred solution from a set of (feasible...

Read More

CONTINGENCY ANALYSIS

CONTINGENCY ANALYSIS Contingency analysis indicates to the operator what might happen tothe system in the event of unplanned equipment outage. It essentially offersanswers to questions such as “What will be the state of the system if an outageon part of the major transmission system takes place?” The answer might bethat power flows and voltages will readjust and remain within acceptable limits,or that severe overloads and under-voltages will occur with potentially severeconsequences should the outage take place.A severe overload, persisting...

Read More

POWER SYSTEM SECURITY

POWER SYSTEM SECURITY By power system security, we understand a qualified absence of risk ofdisruption of continued system operation. Security may be defined from acontrol point of view as the probability of the system's operating point remainingin a viable state space, given the probabilities of changes in the system(contingencies) and its environment (weather, customer demands, etc.).Security can be defined in terms of how it is monitored or measured, as theability of a system to withstand without serious consequences any one of a preselectedlist...

Read More

POWER FLOW CONTROL

POWER FLOW CONTROL power flows:1. Prime mover and excitation control of generators.2. Switching of shunt capacitor banks, shunt reactors, and static varsystems.3. Control of tap-changing and regulating transformers.4. FACTS based technology.A simple model of a generator operating under balanced steady-stateconditions is given by the Thévenin equivalent of a round rotor synchronousmachine connected to an infinite bus as discussed in Chapter 3. V is thegenerator terminal voltage, E is the excitation voltage, δ is the power angle, andX is the positive-sequence...

Read More

EMS FUNCTIONS (energy management system)

EMS FUNCTIONS System dispatchers at the EMS are required to make short-term (nextday) and long-term (prolonged) decisions on operational and outage schedulingon a daily basis. Moreover, they have to be always alert and prepared to dealwith contingencies that may arise occasionally. Many software and hardwarefunctions are required as operational support tools for the operator. Broadlyspeaking, we can classify these functions in the following manner:• Base functions• Generation functions• Network functionsEach of these functions is discussed briefly...

Read More

ENERGY CONTROL CENTER

ENERGY CONTROL CENTER The following criteria govern the operation of an electric powersystem:• Safety• Quality• Reliability• EconomyThe first criterion is the most important consideration and aims toensure the safety of personnel, environment, and property in every aspect ofsystem operations. Quality is defined in terms of variables, such as frequencyand voltage, that must conform to certain standards to accommodate therequirements for proper operation of all loads connected to the system.Reliability of supply does not have to mean a constant...

Read More