Status Update: Using NMMS for Building SSWG Cases Wes Woitt CenterPoint Energy 2010 SSWG Chair

Current Process TSP Data PSSE RAW format ERCOT Using PSSE TSP Data PSSE IDEV Compile Data and Solve ERCOT Determines Dispatch Using UPLAN Output PSSE Cases Posted to ERCOT Website Ready for use in planning studies Case need tuning? 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 Data PSSE RAW format ERCOT Using PSSE TSP Data PMCR Compile Data and Solve ERCOT Determines Dispatch Using UPLAN Output PSSE Cases Posted to ERCOT Website Ready for use in planning studies Case need tuning? Yes No MOD PSSE Topology from NMMS Topology Processor RAW file to MOD TSPs Provide Loads and Device Control Profiles RAW file to MOD TSPs Provide Future Projects PMCR

Topology Processor (TP) Topology Processor (TP) Converts Operations format to Planning format (RAW) files Converts Operations format to Planning format (RAW) files MOD produces (.PRJ Project) MOD produces (.PRJ Project) Converts “Bus/breaker” to “Bus/branch” model Converts “Bus/breaker” to “Bus/branch” model Case Builder (CB) Case Builder (CB) Builds time-based models Builds 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 v30 TSP 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 Case TSP 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 CaseTopology 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 Ratings Planning Case TP Case

Zero impedance branch – – 95 Rate A = 360 MVA Rate B = 440 MVA Rate C = 440 MVA Non-zero impedance branch – – 95 Rate A = 455 MVA Rate B = 478 MVA Rate 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

LEGEND Node Switch AC Line Segment Series Compensator Breaker With the current method of modeling, the cap bank and distribution load are associated with Bus To match the topology of our cases, the cap bank and distribution load should be associated with Buses & 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 IMM Scenario 1 B D E F A C Bus G Bus Bus To Bus Bus Ckt. 01 Ckt. 02 Bus To Bus 70000

Figure 2: Resulting PSSE Topology Using Scenario 1 Modeling Method

LEGEND Node Switch AC Line Segment Series Compensator Breaker With the current method of modeling, the cap bank and distribution load are associated with Bus To match the topology of our cases, the cap bank and distribution load should be associated with Buses & 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 IMM Scenario 2 B D E F A C Bus G Bus Bus To Bus Bus Ckt. 01 Ckt. 02 Bus To Bus 70000

Figure 5: Resulting PSSE Topology Using Scenario 2 Modeling Method

Figure 3: Desired PSSE Topology

Autotransformer Modeling Issues TSP 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 Modeling TSP 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 Device TP 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