Status Update: Using NMMS for Building SSWG Cases

Wes WoittCenterPoint Energy2010 SSWG Chair

Current Process

TSP DataPSSE RAW format

ERCOTUsing PSSE

TSP DataPSSE IDEV

Compile Dataand Solve

ERCOT Determines Dispatch Using UPLAN

OutputPSSE Cases

Posted toERCOT Website

Ready for use in planning studies

Case needtuning?

Yes

No

TSP Data• Some have internal databases to compile data • Others take previous case and add projects or corrections as necessary• Incumbent upon each TSP to coordinate and track what is contained in data sent to ERCOT

NMMS Process

TSP DataPSSE RAW format

ERCOTUsing PSSE

TSP DataPMCR

Compile Dataand Solve

ERCOT Determines Dispatch Using UPLAN

OutputPSSE Cases

Posted toERCOT Website

Ready for use in planning studies

Case needtuning?

Yes

No

MOD

PSSE

Topology fromNMMS Topology

ProcessorRAW file to MOD

TSPs ProvideLoads and DeviceControl Profiles

RAW file to MOD

TSPs ProvideFuture Projects

PMCR

Topology Processor (TP)Topology Processor (TP)

• Converts Operations formatConverts Operations formatto Planning format (RAW) filesto Planning format (RAW) files

• MOD produces (.PRJ Project)MOD produces (.PRJ Project)

• Converts “Bus/breaker”Converts “Bus/breaker” to “Bus/branch” model to “Bus/branch” model

Case Builder (CB)Case Builder (CB)

• Builds time-based modelsBuilds time-based models

4

Topology Processor Functionality

What’s been done so far?

• IMM work ERCOT prepopulated much of the planning related data in 2009 TSPs cleaned up over 1000 incorrect Connectivity Node Groups

(CNGs) Moved incorrect Connectivity Nodes into the correct CNGs Worked with ERCOT to correct CNGs and nodes where TSPs did not

have ownership TSPs cleaned up planning related data (Area #s, Zone #s, ckt IDs, etc.)

• Submitted SCR 759• Worked with ERCOT to modify TP• MOD training in July• Currently testing new build process using Topology

Processor (TP) and MOD• Identified issues with TP/IMM

IMM/TP output PSSE v30TSP Combined Issues List #50

• TP is already dated SSWG moved to PSSE v31 in May 2009 New data types and parameters

• PSSE generally puts out a new version annually• For TP to be able to include new data types or new

parameters, IMM will need to be changed not just TP

No Distribution Cap Banks in TP CaseTSP Combined Issues List #38

• TSPs model distribution cap banks at transmission buses in PSSE

Allows cap banks to be switched during planning studies• IMM does not model equipment below transmission

voltage• Hundreds of these cap banks in ERCOT system• Cannot solve through MOD Device Control Profile

Distribution Cap banks

Fall Planning Case Topology Processor Case

Zero Impedance Lines Created by TP Have 9999 MVA Ratings

TSP Combined Issues List #35

• TSPs model about 250 zero impedance lines which have real ratings in SSWG cases• See examples

Zero Impedance Line RatingsPlanning Case

TP Case

Zero impedance branch 46110 – 46111 – 95Rate A = 360 MVARate B = 440 MVARate C = 440 MVA

Non-zero impedance branch 46111 – 46002 – 95Rate A = 455 MVARate B = 478 MVARate C = 580 MVA

North Belt 138 kV

Zero Impedance Line Ratings

Associating Loads and Cap Banks with the Correct CNG

TSP Combined Issues List #33 and #34

• It was somewhat of an art to assign nodes to CNGs to create model that we wanted to see• See example

LEGENDNode Switch AC Line Segment Series Compensator Breaker

• With the current method of modeling, the cap bank and distribution load are associated with Bus 40000. To match the topology of our cases, the cap bank and distribution load should be associated with Buses 40001 & 40002, respectively. With the cap bank and load modeled as part of multi-section lines off of the main bus (40000), we are able to switch the lines, de-energize the cap bank, and “roll” the load to another load bus. This is impossible with the current method, because when the lines are de-energized, the cap bank and load remain on the main bus (40000).• See Figure 2 for the resulting PSSE diagram when the above (current) method of modeling is run through the Topology Processor.• See Figure 3 for the desired PSSE topology of the above substation.

Figure 1: Modeling of Cap Banks and Load Taps in IMMScenario 1

B

D

E

F

A

C

Bus 40000

G

Bus 40002

Bus 40001To Bus 80000

Bus 50000

Ckt. 01

Ckt. 02Bus 60000

To Bus 70000

Figure 2: Resulting PSSE Topology Using Scenario 1 Modeling Method

LEGENDNode Switch AC Line Segment Series Compensator Breaker

• With the current method of modeling, the cap bank and distribution load are associated with Bus 40000. To match the topology of our cases, the cap bank and distribution load should be associated with Buses 40001 & 40002, respectively. With the cap bank and load modeled as part of multi-section lines off of the main bus (40000), we are able to switch the lines, de-energize the cap bank, and “roll” the load to another load bus. This is impossible with the current method, because when the lines are de-energized, the cap bank and load remain on the main bus (40000).• See Figure 2 for the resulting PSSE diagram when the above (current) method of modeling is run through the Topology Processor.• See Figure 3 for the desired PSSE topology of the above substation.

Figure 4: Modeling of Cap Banks and Load Taps in IMMScenario 2

B

D

E

F

A

C

Bus 40000

G

Bus 40002

Bus 40001To Bus 80000

Bus 50000

Ckt. 01

Ckt. 02Bus 60000

To Bus 70000

Figure 5: Resulting PSSE Topology Using Scenario 2 Modeling Method

Figure 3: Desired PSSE Topology

Autotransformer Modeling IssuesTSP Combined Issues List #41, #42, #48, and #52

• #48 and #52: • CNP reported that the TP was incorrectly calculating off-nominal 3-winding

transformer impedances.• Subsequent discussion with ERCOT/Siemens leads us to believe that we are

inputting incorrect Ohmic impedances into IMM – Still testing• Siemens has used this method in other regions and had the same arguments• No documentation about what we are expected to provide in IMM or what

calculation TP is using• #41

• CNP Operations standardizes all autos – SCADA does adjustment automatically• PSSE does not have that same intelligence; therefore, IMM auto models must

be adjusted to reflect real equipment characteristics• Some parameters can be changed in Device Control Profile, but not all• Not talking about ratings and impedances differences

• #42• Allow a phase shift to be applied to transformers and output in the case.

Useful when creating cases for fault duty studies to have this already in case.• This has nothing to do with phase-shifting transformers

Autotransformer Ops Model vs. Planning Model

The device control profile is not robust enough to handle the majority of differences between the Topology Processor output case and the Transmission Planning case. Instead, at least 50 3-winding transformers in CenterPoint Energy’s area will require PRJ files to alter the Topology Processor output case to a typical Transmission Planning case.

Differences Resolved with PRJ

•Moving the LTC from the low winding to the high winding.

•Number of taps

•Specifying a different voltage control bus

•The tap range of the LTC Rmax, Rmin

Differences Resolved with Device Control Profile

•Winding voltage for off-nominal NLTC settings.

•The auto-adjust code for LTC windings

•Voltage control bus regulation values Vmax, Vmin

FACTS Device ModelingTSP Combined Issues List #32

• PSSE allows modeling FACTS devices (STATCOMs, SVCs, TSCs, etc.) in a number of different ways

Generator Switched shunt FACTS Device

• TP only outputs a FACTS device as a generator model• Important to model correctly for dynamic studies

FACTS Devices

Planning Case – CNP’s FACTS Device TP Case model – CNP’s FACTS Device

FACTS Devices

Planning Case – AEN’s FACTS DeviceTP case – AEN’s FACTS Device,

currently on wrong bus

PSSE IDs for Branches

• PSSE allows any two character CKT ID for any branch• IMM has validation rules that series devices PSSE CKT

IDs have to be Sx• TP automatically creates PSSE CKT ID of BC or BO for

any branch that represents and breaker or switch• Would prefer to leave PSSE CKT ID open and left to the

discretion of TSPs

Line IDs with BO/BC ID

RARF Data TSP Combined Issues List #30

• TSPs have seen lots of basic problems with RARF data MBASE Zsorce

• Other RARF data problems Reactive data does not correspond with biennial tests RARFs submitted with erroneous PSSE bus numbers

ERCOT Network Modeling creates NOMCRs Creates problems with TP output as SSWG recently discovered

• Need process to allow TSP review• Even more issues with wind resource RARFs• NPRRs currently being drafted or in process

Equipment Associated with SPS/RAPs Modeled in IMM

TSP Combined Issues List #49

• SPS/RAP models are not real equipment• TSPs see additional data in TP output

Remaining Issues TSP Combined Issues List #26, #27, #28, #29

• #26: Each of the items identified above can be fixed in SSWG base cases through ‘Standard’ PMCRs

Taken as a whole, this represents an enormous amount of corrections to make to the case

SCR being drafted to propose changes to many of these• #27: Changes described in #26 are not implemented by

next spring• #28: SCR 759 is never implemented

Multi-section line creation is not functional• #29: Case building process is still very unclear

Due to these uncertainties Just begun finding issues with MOD

Remaining Issues TSP Combined Issues List #40, #48, #51, #52

• #40: Specific modeling added for contingency analysis, dynamic analysis, short circuit analysis, etc., that is lost by creating cases from IMM data

This punishes TSPs who have made a concerted effort to align their base cases to serve the needs of planning, protection, and stability studies without having to maintain separate cases.

• #48: Topology Processor issues Software is still being changed Radial line reduction still not working properly

• #51: Not all TSPs have PSSE which is creating problems with their ability to create PRJ files

Potential resolution is being discussed, but it is a workaround• #52: Lack of documentation about TP