experience with cmld in a practical sol application · experience with cmld in a practical sol...
TRANSCRIPT
Experience with CMLD in a Practical SOL Application
DOE-NERC FIDVR & Dynamic Load Modeling Conference
Alexandria, VAOctober 1, 2015
Robert J. O’KeefeAmerican Electric Power
Load Area Overview
G G
345 kV 345 kV
138 kV138 kV
138 kV
G138-69 kV Network
120 miles to interconnected system
100 miles to another load area
Single-Phase A/C ComponentSensitivity
5% increase in D-component shows following effects on area import limits:
Non-fault initiated generating plant trip150 mw decrease in limit based on avoiding voltage collapse
345 kV transmission line fault and trip200 mw decrease in limit based on avoiding UVLS operations500 mw decrease in limit based on avoiding transient instability
CMLD Issues
1. Question about effect of D-component Tstall value as voltage decreases below Vstall
2. Question about tripping of stalled A, B, and C components as their speed reaches zero
3. Question on representation of D-component stalling and associated FIDVR effect
These issues encountered in attempt to calculatestability import limits for load area
2-Bus Test Case
• Set controllable voltage source on bus 1; CMLD on bus 2
• Ramp voltage source down / up or apply fault
• View CMLD P&Q vs V or T
EPRI CMLD Data, D-Component = 100%Steady-State P,Q vs V Characteristics
Transition to Stall Mode
P
Q
Transition to Stall Mode
P
Q
EPRI CMLD DataSteady-State P,Q vs V Characteristics
Transition to Stall Mode
C-Component 100% Stall/Trip
P
Q
D-component Transition to Stall Mode
C-component 100% Stall/Trip
P
Q
EPRI CMLD Data, D-Component = 0%Steady-State P,Q vs V Characteristics
P
Q
C-component stalls but does not tripC-component stalls
but does not trip
P
Q
EPRI CMLD Data, D-Component = 100%Tstall = .033
P
Q
V infinite bus
V load bus
V infinite bus
P
QV load bus
EPRI CMLD Data, D-Component = 100%Tstall = 999
P
Q
V infinite bus
V load bus
P
Q
V infinite bus
V load bus
EPRI CMLD Data, D-Component = 100%Vstall = 0.10
PSS/E Implementation Questions
What is supposed to be D-component state below Vstall and before Tstall timer times out?
Is this an artificial question arising from the performance (static-empirical) model?
What is supposed to happen to A, B, and C components should their speed reach zero?
Trip or stay energized?
Single-Phase A/C StallingNon-Modeled Factors
• Point-on-wave variability considering three 120-degree displaced phases
• Distance from fault / dependency on rate of voltage drop
Does it make sense to attenuateD-component stall effect somehow?
Interim Remedies Rejected:-Disable stall mode by increasing Tstall or decreasing Vstall-Increase Rstall and Xstall, and perhaps Vstall
EPRI CMLD DataP,Q vs V Trajectories of a Load Bus from Simulation of
Generator trip & Sudden Voltage Collapse
P
Q
P
Q
Other CMLD Advice
Network non-convergence associated with CMLD model may cause simulations to drift
Have found it necessary to decrease the acceleration factors to 0.25 or less to avoid non-convergence in most cases