13-03-2014, 03:52 PM
Contingency Analysis using PowerWorld Simulator
Contingency Analysis.pdf (Size: 337.75 KB / Downloads: 127)
Background and Objective
NERC Standard TPL-001-1 (Transmission System Planning Performance Requirements)1
proposes several requirements for demonstrating reliable operation of the power system over the
planning horizon. Category P3 and P6 planning events described in TPL-001-1 involve an initial
loss of a generator or transmission component, possibly followed by system adjustments,
followed by another loss of a generator or transmission component. The approach for conducting
analysis with PowerWorld Simulator will depend on if and when system adjustments may be
applied to mitigate post-contingent violations, and the degree to which effective system
adjustments are understood.
Contingencies and system adjustments may be modeled with Simulator's Contingency Analysis
tool. System adjustments are modeled explicitly as part of each contingency. Model Criteria may
be assigned to actions which only occur under certain system conditions. Analysis using
Simulator's optimal power flow (OPF) or security-constrained optimal power flow (SCOPF) may
help the system planner identify appropriate actions for system adjustments to mitigate
transmission line or interface overloads. (Voltage violations cannot be analyzed with the
methods described here.) Contingency Analysis may be performed to evaluate the effectiveness
of such system adjustments.
System Adjustments:
A set of corrective actions executed by automatically by a control system
or manually by a system operator to mitigate the effects of a contingency or strengthen the
system to withstand a possible future contingency. System adjustments may include the opening
or closing of a transmission element; the opening, closing, or redispatch of a generator; the
changing of a phase shifting transformer angle; the opening, closing, or changing of the a
switched shunt setpoint; or the curtailment of load. System adjustments are sometimes referred to
as Remedial Action Schemes (RAS) or Special Protection Schemes (SPS). System adjustments
may include actions that occur every time a certain contingency occurs or actions that occur only
when certain system conditions are met.
System Adjustments after a Primary Contingency
In this situation, it is assumed that the system must be able to withstand a Secondary
Contingency subsequent to the Primary Contingency, with no violations. Here, the SCOPF is
applied to the post-Primary Contingency system state, considering the entire set of Secondary
Contingencies, to determine if any system adjustments are needed following the Primary
Contingency, such that all Secondary Contingencies can occur without overloads. It is assumed
that system adjustments will not occur following the Secondary Contingency. Figure 9 illustrates
a possible procedure for this analysis.