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Prepared By
Dr. R ASHOK KUMAR,
ASP / EEE, GRTIET
 Determining the state of power system is crucial
and requirements for the real time decision
making in power system security.
 The main purpose of both of these that is
operating states and the state transition
diagram is for the power system security.
 The power system needs to be secured.
 We need to protect it from the black out or any
internal or external damage.
 Dyliacco’s Classification:
 In 1968, Dyliacco was the first one to introduce
the classification of states in power system
security.
 The operating states were classified into:
 Preventive State
 Emergency State
 Restorative State
 In 1978, the next type of state classification was
suggested by Fink and Carlsen.
 In their classification the operating states are of
5 types:
 Preventive
 Alert
 Emergency
 Extreme
 Restorative
 There are five main blocks in state transition
diagram
 a) Normal State
 b) Alert State
 c) Emergency State
 d) Extreme State
 e) Restorative State
 In the normal operating state, the system is said
to be secure and all constrains like voltages at
nodes, real and active power generation, real
and active power flows are satisfied.
 The aim of power system is to keep the
operating state of power system to lie in
normal state.
 Even though this is a stable operating state, any
slight disturbance will take it to the abnormal state.
 The system should also continue to operate
‘normally’ even in the case of credible contingencies.
 The operator should ‘foresee’ such contingencies
(disturbance) and take primitive control actions (as
economically as possible) such that the system
integrity and quality of power supply is maintained.
 A normal state of the system said to be in alert
state if one or more of the postulated
contingency states, consists of the constraint
limits violated.
 When the system security level falls below a
certain level or the probability of disturbance
increases, the system may be in alert state .
 The power balanced between generation and
load is still satisfied.
 However, either overvoltage or voltage
violations happens in emergency state.
 If suitable control action is taken, the state can
still be restored to normal state or at least alert
state.
 In the event of disturbance, like generator
outage or line outage, the operating
conditions changes and the variables like
node voltages and powers (real and
reactive); real and reactive power flows
violate the operating limits or constrains.
 The abnormal state or insecure state is further classified
into the following states:
 a. Alert
 b. Emergency
 c. In-extremis (or islanding).
 The control objective in the emergency state is to relieve
system stress by appropriate actions.
 Economic considerations become secondary at this stage
 When the system is in emergency, if no proper
corrective action is taken in time, then it goes
to either emergency state or extremis state.
 In this regard neither the load or nor the
operating constraint is satisfied, this result is
islanding.
 The power system disturbance, based on its nature, can
lead the power system to a blackout or brownout state.
 In the blackout state, the entire load is separated from
the generators, through either the tripping of generators
or the transmission lines.
 No load is supplied.
 In the brownout state, partial load is supplied through
the transmission network.
 The blackout state is more severe than
brownout state and required several stages for
restoring in back to normal operating state.
 The control objective in this state is to steer the
system to a normal state again by taking
appropriate actions.
 E stands for equality constraint and I stand for
inequality constraint.
 Equality constraint are related to active power
flow and reactive power flow.
 Inequality constraint are monitoring the limits
on the various factors such as voltage,
frequency and current.
 For normal operation conditions the E and I
constraint are within the limits.
 If it goes beyond the dotted line then the
system goes to alert state.
 If the preventive action is not taken then the
system goes into emergency state, in which
inequality constraint limits are violated,
 if proper emergency control is taken then the
system goes back to alert state and then the
normal state.
 In case of extreme condition, the equality and
inequality constraint both are violated.
STATE TRANSITION DIAGRAM in psoc subject

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STATE TRANSITION DIAGRAM in psoc subject

  • 1. Prepared By Dr. R ASHOK KUMAR, ASP / EEE, GRTIET
  • 2.  Determining the state of power system is crucial and requirements for the real time decision making in power system security.  The main purpose of both of these that is operating states and the state transition diagram is for the power system security.  The power system needs to be secured.  We need to protect it from the black out or any internal or external damage.
  • 3.  Dyliacco’s Classification:  In 1968, Dyliacco was the first one to introduce the classification of states in power system security.  The operating states were classified into:  Preventive State  Emergency State  Restorative State
  • 4.
  • 5.  In 1978, the next type of state classification was suggested by Fink and Carlsen.  In their classification the operating states are of 5 types:  Preventive  Alert  Emergency  Extreme  Restorative
  • 6.  There are five main blocks in state transition diagram  a) Normal State  b) Alert State  c) Emergency State  d) Extreme State  e) Restorative State
  • 7.
  • 8.  In the normal operating state, the system is said to be secure and all constrains like voltages at nodes, real and active power generation, real and active power flows are satisfied.  The aim of power system is to keep the operating state of power system to lie in normal state.
  • 9.  Even though this is a stable operating state, any slight disturbance will take it to the abnormal state.  The system should also continue to operate ‘normally’ even in the case of credible contingencies.  The operator should ‘foresee’ such contingencies (disturbance) and take primitive control actions (as economically as possible) such that the system integrity and quality of power supply is maintained.
  • 10.  A normal state of the system said to be in alert state if one or more of the postulated contingency states, consists of the constraint limits violated.  When the system security level falls below a certain level or the probability of disturbance increases, the system may be in alert state .
  • 11.  The power balanced between generation and load is still satisfied.  However, either overvoltage or voltage violations happens in emergency state.  If suitable control action is taken, the state can still be restored to normal state or at least alert state.
  • 12.  In the event of disturbance, like generator outage or line outage, the operating conditions changes and the variables like node voltages and powers (real and reactive); real and reactive power flows violate the operating limits or constrains.
  • 13.  The abnormal state or insecure state is further classified into the following states:  a. Alert  b. Emergency  c. In-extremis (or islanding).  The control objective in the emergency state is to relieve system stress by appropriate actions.  Economic considerations become secondary at this stage
  • 14.  When the system is in emergency, if no proper corrective action is taken in time, then it goes to either emergency state or extremis state.  In this regard neither the load or nor the operating constraint is satisfied, this result is islanding.
  • 15.  The power system disturbance, based on its nature, can lead the power system to a blackout or brownout state.  In the blackout state, the entire load is separated from the generators, through either the tripping of generators or the transmission lines.  No load is supplied.  In the brownout state, partial load is supplied through the transmission network.
  • 16.  The blackout state is more severe than brownout state and required several stages for restoring in back to normal operating state.  The control objective in this state is to steer the system to a normal state again by taking appropriate actions.
  • 17.
  • 18.  E stands for equality constraint and I stand for inequality constraint.  Equality constraint are related to active power flow and reactive power flow.  Inequality constraint are monitoring the limits on the various factors such as voltage, frequency and current.
  • 19.  For normal operation conditions the E and I constraint are within the limits.  If it goes beyond the dotted line then the system goes to alert state.
  • 20.  If the preventive action is not taken then the system goes into emergency state, in which inequality constraint limits are violated,  if proper emergency control is taken then the system goes back to alert state and then the normal state.  In case of extreme condition, the equality and inequality constraint both are violated.