Composite Load Model Implementation Update Craig Quist, PacifiCorp April 25-27, 2012 TSS Meeting

2 WECC got responses from all but one area coordinator, in some cases default data was submitted hs base case will be used, dyd will initially be released for current load model, dyd with long ID will be available shortly; Will need 2012 ls to be posted before full data is available. Letter with a recommended report format will be sent out. PTI impacts, due to move to RV 32 will be reevaluated next week. Reports due to PacifiCorp (CQ) by May 15, 2012; Report to TSS/RS to distributed in July, about one month ahead of fall meetings. Status at last TSS Meeting (January 25 – 27, 2012)

To date, reports have been received from TID and CAISO… Initial Conclusions & Recommendations… Turlock Irrigation District (TID) –Post-Composite Load Model WCA Results report the newly created bus, not the original bus. This can be confusing. It is recommended that the results being displayed report the original bus, not the new one. –Post Composite Load Model log files suggest there are multiple iterations of the fault being applied. It is recommended to determine if this is true and why it might be happening if it is not the desired results. Composite Load Model – Status Update… 3

Turlock Irrigation District (TID) [cont.] –The Post-Composite Load Model Transient Stability study took almost twice the time as compared to the Pre-Composite Load Model study. This may or may not be due to the suspected iterations mentioned above. This may or may not be a GE PSLF issue. Transient Stability studies take too long currently so it is recommended to work with GE to streamline the process to keep the length of time to a minimum. –The results of the Post-Composite Load Model Study were comparable to the Pre-Composite Load Model Study. Additional buses reported to have a violation. Implementing the load shedding scheme for TID did not change this result. Composite Load Model – Status Update… 4

California ISO (CAISO) –The composite load model works and gives reasonable results –For some contingencies, the system performance in the simulations was the same with the interim load model and with composite load model. –For other contingencies, composite load model showed tripping of some parts of the loads (or reduction in load). –The contingencies that showed load tripping not necessarily were the ones with highest flow on the transmission lines that were out with contingencies. Composite Load Model – Status Update… 5

California ISO (CAISO) [cont.] –Composite load model shows significant difference in the results compared with the interim load model in case of a fault on a bus that has large load connected to it (for example Valley 500 kV). In this case, large amount of load was tripped in the composite load model case both by under-frequency relays and because of motor stalling. How is the PTI PSS/E Revision 32 conversion – composite load model efforts proceeding? Composite Load Model – Status Update… 6

Bill Hall (4/4/12) transmitting composite load model base case to PAC planners: –Attached is a zipped file with the WECC 2012 HS4A1 case containing the dynamic composite load model data. [To get the composite load model to work with the current PSS/E program array dimension limitations.] –I have removed approximately 4/5 of the composite load model data, and all of the under frequency load shedding model data to make room for as much composite load modeling as possible. –The composite load model data was removed for the Alberta, British Columbia, Northwest, California and Nevada areas. –I have also netted out all of the GE wind turbine models (approximately 20 units) so that testing can be done without using a Fortran compiler. –For testing, users must use PSS/E Rev and replace two dynamic modules in their PSS/E software. –I have included the two dynamic modules in the attached zipped file. Please advise me on the status of the testing. Composite Load Model – Status Update… 7

PAC Preliminary Composite Load Model Findings: –Initial analysis was performed to compare two load models for 3 phase fault at Goshen 345kV bus with loss of Goshen - Kinport 345kV line. (Solid black line is with Composite Load Model). –While preliminary study results show that the new Composite Load Model will not limit Bridger and Path C path limits; however, study results did indicate unusual load tripping is now evident using the new load model, which were not evident using the previous model. Bill Hall Inputs: Detailed channels/plots [internal variables] for the composite load models are needed before any conclusions can be drawn. Also, in a 10 second no disturbance simulation, some of the load models (Big Grassy for example) were causing some variations in the network convergence. This should also be explored with detailed channels/plots to determine the behavior of the composite load models. Composite Load Model – Status Update… 8

9 Bonneville 69 kV voltage following a 3 phase fault at Goshen 345kV bus with loss of Goshen - Kinport 345kV line.

Composite Load Model – Status Update… 10 Bonneville 69 kV voltage following a 3 phase fault at Goshen 345kV bus with loss of Goshen - Kinport 345kV line. Load restoration during voltage recovery.

Motor A - Performance 11

Motor B - Performance 12

Motor C - Performance 13

Motor D - Performance 14

Trip – Reclose Factor 15

A single simulation indicates that the new model may increase our transfer capability. [hold applause] We will need lots of studies to make sure if there is an issue for this model. There will be a lots of Modeling Validation kind of work to determine if the data is right. [Issue: cook book approach] Key questions have surfaced: Does the loads tripped this fast? Does the loads restored this quickly? Preliminary - detailed channels/plots analysis for the composite load models 16

Bill Hall composite load model status (4/23/12): –GE PSLF Ver. 18 does not write out the composite load model data correctly in the dyd file. It is critical that the data be written out correctly, without variable names, as the data is modified by the PSLF program. –PSLF to PSS/E data conversion routine is correctly converting the composite load model data when provided with a corrected dyd input file. –PSS/E Rev program array dimensions will only accommodate approximately 1000 of the more than 5000 composite load bus models. A future release of the PSS/E program will be needed to fully test the composite load model on a WECC wide basis. –With a smaller composite load data set, PSS/E dynamics will initialize but some variations in the network convergence can be seen in a 10 second no disturbance simulation. These variations need to be reviewed/resolved before a general review of the model performance can be done with the large variety of data contained in the WECC 2012 HS4A1 operating case. –PacifiCorp Planning is currently performing preliminary analysis. Composite Load Model – Status Update… 17

Composite Load Model Implementation – Going Forward… 18 PSLF Users: –Initial PSLF User study findings submitted to PacifiCorp (CQ) by 6/15/2012. –PSLF User composite load model study findings will be compiled and submitted to M&VWG PSS/E Users: –PacifiCorp initial PSS/E composite load model study findings compiled and submitted to M&VWG. –GE PSLF Ver. 18.x will need be modified to write out the composite load model data correctly in the dyd file. –PSS/E Rev. 32.x program will need to be modified to accommodate 5000 composite load bus models to fully test model. Where do we go from here… M&VWG: –Review initial study findings. –Potential updates to Composite Load Model software and/or data –Rewind process, including analysis by PSS/E users

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