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Generation & Load Modeling. Lecture #17 EEE 574 Dr. Dan Tylavsky. P,Q. P 1 ,Q 1. |V|. P 2 ,Q 2. L f. - +. V ref. Generator modeling can be very complex. For power flow calculations, what we need is rather simple model.
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Generation & Load Modeling Lecture #17 EEE 574 Dr. Dan Tylavsky
P,Q P1,Q1 |V| P2,Q2 Lf - + Vref • Generator modeling can be very complex. • For power flow calculations, what we need is rather simple model. • Lets look at generator characteristics and develop a model from that.
Under-Excitation Limit Highest permissible stator winding losses. M/c design gives max ohmic stator losses of: PSch Overexcitation limit - exciter current thermal limit. Qmax Qmin PGmin PG Under-Excitation (Small |V|). Recall Pe =EV sin /X; hence PeX/EV Small |V| large small stability margin. QG • PGmin • Water Turbine - low output causes turburlet flow which can cause pitting type damage to blades. • Steam Turbine - don’t have enough steam to keep turbine running smoothly. PSch≡Scheduled Generation Qmax≡Q max limit @ PSch Qmin≡Q min Limit @ PSch
PSch Qmax Qmin PG QG
Model PL + jQL = Constant • Load Models: • Real-time load models are complex. • Voltage regulators. • Switched elements (capacitors). • FACTS (Flexible AC Transmission) devices. • Static load models have: • Voltage dependence. • Frequency dependence. • For power flow we use a simplified model:
IEEE Format • Bus Data • Bus number- 4 digit right justified Cols. 1-4 • Bus Name Cols. 6-17 • Bus Area (Control Area) Cols. 19-20 • Bus Type Col. 26 • 0 Load Bus • 1 Synchronous Capactor: P=Const. & • QG=Const, Vmin<|V|<Vmax • Otherwise |V|=Vlim, Vlim=Vmin,or Vmax • 2 Generator Bus (P-V Bus) P=Const. & • V=Const, Qmin<Q<Qmax ) • Otherwise: QG=Qlim, Qlim=Qmin,or Qmax • 3 Swing Bus (V=Const., =Const.)
IEEE Format • Bus Data • Final Voltage (F6.4) Cols. 28-33 • Final Angle (F7.2) Cols. 34-40 • Load PL (>0 for load) (F9.2) Cols. 41-49 • Load QL (>0 for inductive load) (F9.2) Cols. 50-58 • Load PG (>0 for P flow from generator) (F9.2) Cols. 59-67 • Load QG (>0 for Q flow from generator) (F8.2) Cols. 68-75 • Base kV - Optional (F6.2) Cols. 77-83 • Desired bus voltage (P.U.)(F6.4) Cols. 85-90 • Min. Voltage (PU) or VAR limit(MVAR) Cols. 91-98 • (F8.2 or F8.4, respectively) • Max. Voltage (PU) or VAR limit(MVAR) Cols. 99-106 • (F8.2 or F8.4 , respectively)
IEEE Format • Bus Data • Shunt Conductance (PU) (F8.4) Cols. 107-114 • Shunt Susceptance (PU) (F8.4) Cols. 115-122 • Capacitors are entered a +|B| • Reactor entered as +|G|, -|B| • Remote Control Bus (I4) Cols. 124-127