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Note to Shawn, Donald, Dmitry and John • My intent is not to go offbase with anything you guys are saying. So check for that. • Generator Testing and Validation folks, Transmission Planners and WECC have important roles and we “all” need to work together • Validation is difficult,,,,, WECC and Transmission Planners need accurate ONLINE data. • The Models are simple compared to the complexity of the plants. SO….. • Generator test and validation folks need to meet the requirements, use WECC approved models and do the best they can and help explain the differences to the Transmission Planner • Transmission Planner: Don’t expect perfection • Thus my theme is : “what is reasonable for adequately validated models”
The Role of Transmission Planner • Collect reports from the generator owners • Verify that the WECC-approved model parameters provided by the Generator Owner are adequately validated by comparing the simulated response of the unit against either the recorded baseline tests or a disturbance response • Work with the Generator Owner on resolving the differences between simulated and actual responses • Submit the accepted validated models to WECC and shall notify the Generator Owner that the models are accepted. • If a model data validation report is rejected, the Transmission Planner shall inform the Generator Owner of the reason(s) for the rejection.
The WECC Approved Models • Transmission planner must submit the models to WECC using one of the approved models • A transmission planner can use any models they wish for their own use • The WECC approved models list will be updated from time to time. • Generator owner should use the best model available when the validate their test. • This may not be the best model available when they submit there test report and that is okay. • The generator owner may not have the latest and greatest updates to PSLF or PSSE and have access to the newer models when they do their validation and reports. • This is okay…The next re-validation will catch up. • Wind Power Facilities (check with ABE) • WECC has approved a type 1 and type 3 generic model • WECC does not have a requirement yet for submission of: • wind turbine dynamic models • validated report wind turbine dynamic models • Submission of dynamic data is voluntary at this time
Testing and Validation Requirements • Be Clear on “What is Required” and “What is Acceptable” • Option 1. Validation using Recordings taken at the Point of Interconnection of the Generating Facility. • The validation shall be done for events of voltage and frequency deviations and oscillations at the point of interconnection. • The acceptable validation methods are listed in the Model Validation Requirements • there may be others methods that may come forth for consideration, if you are unsure, contact the MVWG for clarification. • Option 2. Validation using Recordings taken at the Generating Unit. • Validation shall be done for the following events: • a) disturbances or tests that result in generator stator voltage and reactive power changes. • b) disturbances that result in generator frequency changes or tests that result in generator real power changes. • The acceptable validation methods are listed in the Model Validation Requirements • there may be others methods that may come forth for consideration, if you are unsure, contact the MVWG for clarification.
What is a Reasonably Accurate Models cont. • The Transmission Planner wants a good on-line model which is accurate representation of the generating unit to system events. \ • Accurate data may not be easy to get • Validation using off-line tests are often done as they model parameters are often easier to identify parameters and often easier to simulate. • On-line validation at typical operating levels will provide more confidence in the parameters for system studies. • If the test and validation engineer is attempting to get more accurate on-line data and compromising off-line accuracy, that is okay.
What is a Reasonably Accurate Models • Not all Simulations will be a good fit to the Measurement • Some generation facilities will have very accurate validation and some will not. • Some of the Challenging Validation • Governor systems at industrial or co-gens can be difficult. • WECC has no governor models that represent co-gens very well (where the output of a gas unit effects the output of a steam unit) • Some older excitation systems can be difficult to get a “perfect” match • (such as older static excitation system use field current feedback on the rectifiers and these control loops are often not represented in the standard models) • Retrofitted excitation (static AVR into a rotating exciter)
What is a Reasonably Accurate Models cont. • Not every test needs to be validated • A generator may require several tests that will help a validation engineer develop the appropriate parameters. However not every test needs to be validated or simulated. • For example a 10% AVR step maybe helpful to assess non-linearities in the AVR, or limits etc, but a 1 to 2% step “may” is better to validate the dynamics of the excitation system. • A load rejection test is useful to determine inertia, but it “may not” be useful to assess the governor. The behavior of older mechanical governors may not be well represented for a load rejection • Not that most governor models also represent the prime mover. A typical thermal governor model will not have a boiler control representations, and sometimes the affect of the boiler controls may show up in the tests.
What is a Reasonably Accurate Models cont. • Simulation does not represent all the behavior of an on-line measurement does not make the model inaccurate. • Generator that are on-line and being tested are also subject to the conditions of the power grid. Thus the measurements will reflect the behavior of the generating unit to the test and the system. • The validation will not reflect or simulate the conditions caused by the power grid. • Power oscillations for example can be caused by perturbations on system voltage, water hammer in penstocks etc Measured generator MW under normal non-test conditions.
Some Simple Guides to those who Test and Validate and to Transmission Planners • To Generator Testing and Validation Personnel • You need to follow the WECC policy and requirements and you may need to follow local requirements. Check with your Transmission Planner. • If the simulation and measurements seem out, but it is the best than can be done. Then: • You need to provide sufficient information in the report to allow the transmission planner to assess if the model is adequately validated. • If you are making tradeoffs where the off-line accuracy is compromised to obtain better on-line accuracy, say so. • If you are unsure of anything, discuss it with your transmission planner and the WECC MVWG. (It is easier to resolve issues before the testing and reporting has been done)
Some Simple Guides to those who Test and Validate and to Transmission Planners • To Transmission Planners • As great as the models are, they are in many cases much simpler than the field equipment • The validation engineer may choose not to match the measurement. Look for their explanation. • If you cannot simulate the test the way it was performed, it is likely that the results will be different. the model performance. • Some validation can play back measured data and this can have a different result that relying on the simulation data. • If you are unsure of anything, discuss it with the WECC MVWG. (It is easier to resolve issues before the testing and reporting has been done)