Post on 03-Aug-2020
transcript
Joseph Plastino, Process Control Engineer, GE Walid G. Morsi, Assistant Professor, UOIT
EPEC 2011
Problem statement
Describe system using single-line diagram
Machine data input to AVR model
MatLab output: AVR model
Describe features of DVR
MatLab output: DVR model
Three back-up generators running in parallel must limit the voltage dip to 15% and recover to +/-3% of rated volts within 1.5 seconds after start of biggest motor.
Generators are rated for 31500kVA, 0.8 PF, 13.8kV.
Assume generators are initially loaded at 70% by a constant kVA 0.8 PF load.
Large motor rated at 10500kW at 13.8kV with inrush = 3.8 x rated current at 0.15 PF. Efficiency = 0.97 and rated PF = 0.89.
Simplified model from text:
Real model implemented in Matlab:
Exciter Control is a PID controller. Very similar to textbook examples in Chapter 12.
Sensor is an standard IEEE model.
Simplified models show only 1/sƮE .
Model exciter saturation described by open circuit saturation curves.
The air gap line represents the relationship:
1 pu field current = 1 pu stator voltage
For real exciters saturation occurs. Thus, for an x pu increase of field current yields less than x pu increase of stator voltage.
Recall impedance network from SLD.
Find E’ by using phasor diagram for salient pole
synchronous generator.
For salient pole machines IaXs can be shown as the vector sum of IdXd and IqXq.
E’ (here shown as Ef) is the vector sum of VTcos(δ) + IdXd.
VT = IT * Ztotal, where IT = E’/[Ztotal*cos(δ) + X’d*sin(θ+δ)]
Ztotal = Zinitial + Zmotor, where Zinitial is modeled as a constant kVA 0.8 PF load.
Zinitial = VT2 / 0.7, where 0.7 is the per unit power consumed by the load.
Generator voltage VT.
Voltage at load. Line impedance
neglected.
Harmonic filter – passive LC components.
DC-to-AC power conversion.
Rechargeable Battery.
Reference voltage = 1pu.
Voltage Sag from Motor Start.
Load voltage.
Joseph Plastino Process Control Engineer
General Electric (GE), Canada Joseph.plastino@ge.com
Walid G. Morsi Assistant Professor
University of Ontario Institute of Technology (UOIT)
Oshawa, ON, Canada L1H7K4 Walidmorsi.ibrahim@uoit.ca