1. Siemens Power Technologies International
2nd Generation Models for Modeling of Renewable Sources (Wind & PV) in PSS®E Presented by Jay Senthil and Yuriy Kazachkov, Siemens PTI Renewable Energy Modeling task Force (REMTF) Workshop, Salt Lake City, June 17, 2014
September 2002

2. Discussion Outline
Representing wind turbines and Photo Voltaic (PV) in PSS®E Power Flow
PSS®E Dynamic Simulation models of wind turbines and PV systems
2nd Generation Generic wind turbine and PV models in PSS®E
Test results for 2nd Generation wind and PV models
Parameterization of 2nd Generation Generic Model for Siemens 2.3 MW and 3 MW Wind machines
Recent developments- Plant controller for multi-unit application
Issues in Modeling of Wind and PV type devices
Summary

3. Representation of Wind Turbine in PSS®E Power Flow
Wind machine explicitly identified in power flow data
Reactive power boundary conditions :
Limits specified by QT and QB (i.e., same a non-wind machines)
Limits determined from the machine’s active power output and a specified power factor
Fixed reactive power setting determined from the machine’s active power output and a specified power factor (typical for induction machines)

4. Modeling in Power Flow - Real Power
Direct MW dispatch as for conventional machines.
User responsible for aggregation of original wind turbines to equivalent machines.

5. Modeling in Power Flow - Reactive Power
Type 1 and Type 2 WTGs:
If (for example), Qgen consumed is ½ Pgen (i.e. PF  0.9 under-excited):
For example, for WTG rated at 100 MW; Qgen = Qmin = Qmax = 50 Mvar; may want to provide 50 Mvar shunt capacitors at the equivalent WTG terminals.

6. Modeling in Power Flow - Reactive Power
Type 3 and Type 4 WTGs:
For fixed power factor (PFref) control, set Qgen = Qmin = Qmax = Qref = Pgen  tan[arccos (PFref)]
For steady-state voltage control using WTGs with PF range  0.95, set Qmax = Pgen  tan[arccos (0.95)] =  Qmin
For example, for 100 MW WPP using WTGs with +/-0.95 PF range, set Qmax = 33 Mvar and Qmin = 33 Mvar.

7. Collector System Equivalencing Methodology
Computation of equivalent collector system parameters for N wind turbine generators and I branches:
Example
(N=18, I=21)
Source: Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA

8. References
[1] WECC Wind Generator Modeling Group, “WECC Wind Power Plant Power Flow Modeling Guide,” [2] Muljadi, E.; Butterfield C.P.; Ellis, A.; Mechenbier, J.; Hocheimer, J.; Young, R.; Miller, N.; Delmerico, R.; Zavadil, R.; Smith, J. C. “Equivalencing the Collector System of a Large Wind Power Plant.” IEEE Power Engineering Society, General Meeting, June 12-16, 2006, Montreal, Quebec. [3] Wind Modeling IEEE Tutorial. 2008, Pittsburgh, PN; 2009, Seattle, WA 8

9. Representation of Wind Turbine in PSS®E Dynamic Simulation
User prepares dynamic raw data file (“dyr” file) by following example in modeling package documentation
Two distinct groups of Wind Models:
Vendor specific models: are provided as user-written models.
To represent these machines in power flow, designate the machines as ‘Not a Wind Machine’ in the PSS®E power flow generator data record.
Models can be downloaded from:
grid/products/grid-analysis-tools/transmission-system- planning/Pages/transmission-system- planning.aspx?tabcardname=pss%c2%aee%20user%20support
Generic Wind Models: these models are supplied as part of PSS®E library

10. Generic Wind Models in PSS®E
Siemens PTI has been closely involved in efforts of various WECC working groups to develop generic models all 4 types (Types 1 through 4) for wind turbines.
Idea is to create generic models that are parametrically adjustable to represent specific wind turbines available in the market.
All 4 types became standard PSS®E models in Version 32 and above.

11. PSS®E 1st Generation of Generic Wind Models
Above generic model are available as standard library model starting PSS®E 32 11

12. 2nd Generation Generic Wind Turbine Models
PSS®E 2nd Generation Wind Models consistent with WECC REMTF recommendations .
Same set of models to represent different types manufacturers by changing parameters.
PSS®E Model names for 2nd generation models:
REGCAU1: Generator converter model for Types 3, 4 & large scale PV
REECAU1: Electrical control model for Types 3 & 4
REECBU1: Electrical control model for large scale PV
REPCAU1: Plant control model for Types 3 & 4
WTDTAU1: Drive Train model for Types 3 & 4
WTPTAU1: Pitch control model for Type 3
WTARAU1: Aerodynamic model for Type 3
WTTQAU1: Torque control model for Type 3
PSS ®E 33.4 and above for 2nd generation wind, PSS®E 33.5 and above for large scale PV models

13. Testing of 2nd Generation Models
Details of Test Simulation:
Time step (Δt = ¼ cycle)
Run flat (no disturbance) for 1 s
Apply 3-phase fault at bus 41902, run to 1.1 s
Remove fault, trip branch between & 41906, run to 10 s

14. Test results for 2nd Generation models WT4 – plot of vt

15. Test results for 2nd Generation models WT4 – plot of pg

16. Test results for 2nd Generation models WT4 – plot of qg

17. Test results for 2nd Generation models WT3 – plot of vt

18. Test results for 2nd Generation models WT3 – plot of pg

19. Test results for 2nd Generation models WT3 – plot of qg

20. Test results for 2nd Generation models PV – plot of vt

21. Test results for 2nd Generation models PV – plot of pg

22. Test results for 2nd Generation models PV – plot of qg

23. Parameterization of 2nd Generation Generic Model for the 2
Parameterization of 2nd Generation Generic Model for the 2.3 MW & 3 MW Siemens WT
The 2nd generation Renewable Energy Generic Model includes several features that can be successfully used in the course of parameterization of this model for some vendor’s implementation.
Couple of examples:
Low Voltage Power Limit of the generator/converter REGCA module can be used to simulate ramping up active power after fault clearing
The drive train WTDTA module can be used for mimicking the action of the controller responsible for damping of the machine rotor torsional oscillations
Vdl1/Vdl2 look-up tables of the electrical control REECA module can be used for simulating the P-Q capability of the unit under fault conditions.

24. 2.3 MW Siemens WT Terminal Voltage (Close-in fault)

25. 2.3 MW Siemens WT Power (Close-in fault)

26. 2.3 MW Siemens WT Reactive current (Close-in fault)

27. Recent Developments Upgrade of the 2nd Generation RE plant controller
Generic Renewable Plant Control Model REPCAU1 is designed to interact with the local control of the single equivalent (aggregated) unit with control of active and reactive power (Pref and Qref)
Active power path is used for frequency control. The reactive power path may be used to control either the POI voltage or reactive power interchange between the plant and the grid or a power factor at the POI.
Siemens PTI has upgraded the REPCAU1 model to a new REPCMU1 model with the capability to supervise multiple WTGs.
The new REPCMU1 user written model has the same dynamics of the active and reactive power paths as a standard REPCAU1 model and a provision to supervise local controls of up to 150 WTGs.

28. Testing with 4 WTGs supervised by REPCMU1 plant controller
POI Voltage (red), Command from the Plant Controller (blue) as a Response to Step Change in Plant Controller Voltage Reference (black).

29. Issues in Modeling of Wind & PV type devices Issue 1: Fictitious Frequency Spikes
Frequency Spike during and after the fault to prevent fictitious frequency spikes.
Problem is very acute in weak systems.
Causes False Frequency Relay Trips.
Temporary Solution:
Disabling Frequency Relay during fault.
Long-term Solution:
Better frequency calculation – Siemens PTI is investigating this.

30. Issues in Modeling of Wind & PV type devices Issue 2: Network Non Convergence
Problem: Network does not converge at the onset of the fault and after fault clearing
Possible Cause: During the fault,
unlike synchronous machines, no inertia to fix Ө, and hence possibly no voltage angle reference,
WTG control model tries to control P,Q; it needs voltage angle reference to compute the complex current for the given Ө.
PSS®E uses current injection, in the example, voltage is determined by current: YV = I

31. Summary
2nd Generation wind models are available in PSS®E starting Version 33.4.
2nd Generation PV models are available in PSS®E starting Version 33.5.
Models can be parametrically adjusted to represent any specific wind turbines available in the market.

32. Questions? Siemens PTI 400 State Street Schenectady, NY 12305
(518)
(518)