Use of Node-Breaker Model in POM Suite/ROSE Software Presented by Marianna Vaiman, V&R Energy West Wide System Model and Basecase Reconciliation Task Force (WBRTF) WECC WebEx Meeting August 22, 2012 Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

V&R Energy V&R Energy’s services include: Comprehensive software tools for analyzing power system behavior Vendor of POM Suite and ROSE applications Advanced consulting services Cutting edge scientific research V&R is located in Los Angeles, CA I'm convinced you (plural) are the only ones in the industry giving the proper thought and attention to the problems that transmission operators and planners are trying to manage American Transmission Co. V&R Energy’s software allows us to do in 20 minutes what normally takes about seven hours with our present system East Kentucky Power Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

Physical and Operational Margins (POM) Suite Available for real-time and off-line computations Extremely fast: 8 to 10 times faster than similar applications Very reliable and robust solution engine Very flexible scripting Handles extremely large contingency/fault lists: Millions of N-1-1, N-2 contingencies during one simulation run Hundreds of thousands of faults during one simulation run Automates and expedites NERC compliance studies Predicts and prevents cascading outages Offers a boundary-based solution Automatically determines optimal corrective actions to mitigate exceeding operating limits Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

POM Suite - Planning Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

POM Suite Use in Planning NERC-compliance studies: NERC TPL Standards Compliance (TPL-003, TPL-004) Steady State Analysis Transient Stability Analysis NERC FAC-014 Standard Compliance Establishing System Operating Limits NERC PRC-023 Standard Compliance Identification of 100kV- 200kV transmission lines NERC MOD-001, 004, 006, 007, 008, MOD-028, 029, 030 Available transfer capability Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

POM Suite Use in Planning (cont) Voltage stability analysis AC transfer/load pocket and contingency analyses with visualization Determines available transfer capability for each contingency Determines interface flows Automatically builds PV-curves Transmission system expansion analysis Reliability analysis Using results of POM-OPM to compute reliability indices Phase-shifter settings optimization to relieve post-contingency violations Analysis of cascading outages Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

POM Suite – Real Time/ROSE Same algorithms for off-line and real-time analysis Model-based & measurement-based State Estimator Integrated voltage and transient stability analyses Boundary-based solution Automatic analysis of cascading outages Automatic remedial actions to mitigate steady-state & transient stability violations Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

POM Applications in Real-Time Uses of POM Suite in Real-Time include: State Estimation, Voltage stability analysis, Massive AC contingency analysis with remedial actions Use of PMU data to perform voltage stability analysis, predict instability and alarm operators Predicting cascading outages Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

Role of the Node-Breaker Model in POM Suite Bridges real-time and off-line analysis POM Suite/ROSE reads analysis includes: Reading of export file in node-breaker model Performing necessary topology processing Performing steady-state analysis: Voltage stability analysis, AC contingency analysis, RAS implementation, determining remedial actions, etc. Automatic conversion of the node-breaker model to bus-branch model in Siemens PSS/E .raw file format for use in planning analysis Saves the full model Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

POM Suite Integration with Other Applications Easy integration with other applications Reads node-breaker and bus-branch models Node-breaker: Export (“flat”) files from an EMS system, CIM-compatible Bus-branch: Power flow cases in PTI PSS/E rev. 23-32, GE-PSLF version 17 (and earlier), PowerWorld *.aux format Solves and converts cases to POM internal format Modified power flow cases may be saved for future use Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

POM Program Functionalities Main program of the Package Performs power flow computations Performs massive AC contingency analysis for large power system models: Fast AC contingency analysis Automatically generates contingency lists/reads existing lists Analyzes N‑1, N-1-1, and N‑2 contingencies Identifies critical contingencies and associated violations Monitors user-defined constraints: Simultaneously monitors voltage stability, voltage and thermal constraints Computes voltage stability margins Simulates power transfers while monitoring constraints Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

Modes of POM Operation Basic Mode Advanced Mode Automatic Mode Easy, fast computation of a particular contingency, load scaling, simulation of a power transfer Constraints are graphically displayed Advanced Mode Flexibility of analysis using POM commands Constraints are graphically displayed Automatic Mode Massive contingency analysis Script Mode Complete control of computations and output Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

Determining Optimal Remedial Actions (System Adjustments) Fast, powerful and efficient remedial actions tool Automatically alleviates violations during massive AC contingency analysis Increases operating margins RAS is incorporated through scripting Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

Remedial Actions Used in OPM Applies a minimum amount of mitigation measures based on a user-defined priority schedule Available remedial actions include: MW Dispatch MVar Dispatch Capacitor and Reactor Switching Transformer Tap Change Phase Shifter settings Line Switching (In and Out) Switching Not Affected Lines Load Curtailment Optimal Capacitor, Reactor Placement and Size OPM Operating Procedures Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

Analysis of Extreme Events Automated analysis Analysis scenario: Quantify a power system’s ability to withstand cascading outages due to thermal and/or voltage violations Quickly identify initiating events that may lead to cascading events Impractical to apply all N-k contingencies in a bulk power system Automatically identify potential cascading modes Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

A Boundary-Based Solution Automatically identifies the operating region that satisfies N-1/N-1-1/N-2 reliability criteria Finds AC limits for transfer scenarios based on voltage stability, voltage constraints, and thermal constraints Computes dynamic security region Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

Operating Region that Satisfies Reliability Criteria Automatically determines the most limiting contingencies Secure operating region may be formed by several contingencies The area formed by the most limiting contingencies is the area that satisfies N-1 and/or N-2 reliability criteria Power system is secure only when operating within this area Can be used in real-time, on-line and planning environments Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

POM – Transient Stability (POM-TS) Fast and user-friendly dynamic simulation – execution time for a one second simulation is approximately 6 seconds for a 50000 bus case and 17000 dynamic models Fully integrated into POM Supports Library of dynamic models in Siemens PTI’s PSS/E and GE’s PSLF formats Allows for easy inclusion of user-defined models through use of POM scripting Satisfies NERC/WECC criteria Performs fast fault screening in order to determine the most severe three-phase and unbalanced faults in the system Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

ROSE – PMU-based Analysis Region Of Stability Existence - ROSE defines the range of phasor measurements or other system parameters For which the system may securely operate in terms of the accepted N-k security criteria Addresses the problem of utilizing the PMU data to increase the situation awareness of the operators and improve stability and reliability of the electric grid For steady-state analysis: voltage stability, voltage constraint (voltage range and/or pre-to post contingency voltage drop) and thermal overloads may be simultaneously monitored, enforced and visualized on the boundary For steady-state stability has two inputs: node-breaker or bus-branch model Combinatory approach Combines model-based (State Estimator data) and measurement-based (PMU data) computations Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

Use of Node-Breaker Model for Steady-State Stability Analysis POM Suite/ROSE is used for steady-state analysis in real-time and off-line environments, including: Voltage stability analysis: Runs multiple user-defined scenarios; Computations performed for each scenario are: Determining interface limits; Performing PV-curve analysis; Performing VQ-curve analysis. Automatic AC contingency analysis; Reading of existing RAS; Automatically determining optimal remedial actions as an advisory function for operators Never collapses buses during its analysis Always uses FULL NON-CONSOLIDATED MODEL Very strong solution engine Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

Steady-State Voltage Stability Analysis Using Node-Breaker Model PV-Curve and VQ-Curve are most frequently used steady-state techniques for voltage stability assessment At selected buses PV-curve analysis Stresses the system in terms of load increase, power transfer and computes post- contingency voltages Multiple power flow computations to determine the stability margin VQ-curve analysis: Adding a fictitious condenser bus V is independent variable, Q injection is dependent Provides a set of scheduled voltages at a bus Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

Reading Node-Breaker Model in POM Suite/ROSE As export “flat” file is being loaded, its summary is displayed on the interface As POM reads the export file and contingency lists, it performs topology processing Generates a file that lists buses that were split and how they were split as a result of contingencies Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

Displaying Node-Breaker Model in POM Suite/ROSE After export “flat” file is being loaded, it is displayed in the form of: POM Data Tables One-lines that are automatically built Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

Use of Node-Breaker Model for Voltage Stability Analysis Node-breaker representation is used to: Determine import limits on the interfaces Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

Use of Node-Breaker Model for Voltage Stability Analysis Node-breaker representation is used to: Compute and plot PV-Curves Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

Use of Node-Breaker Model for Voltage Stability Analysis Node-breaker representation is used to: Compute and plot VQ-Curves Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

Use of Node-Breaker Model for Analysis of a Particular Contingency A particular contingency may be further analyzed: On the base case While stressing the system in terms of a power transfer, load scaling, etc. Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

Use of Node-Breaker Model for Determining Remedial Actions Remedial actions may be further developed to: Alleviate post-contingency violations Voltage stability, voltage, thermal Increase operating margins Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

Use of Node-Breaker Model for Automatic Contingency Analysis Automatic massive AC contingency analysis may be performed N-1, N-2 contingency analysis RAS enabled/disabled Post-contingency remedial actions may be automatically determined during massive computations Critical contingencies, post-contingency violations and remedial actions reported Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

Challenges of Using Node-Breaker Model Not a formal database: Complex procedures for reading/processing of export “flat” file Utilities/ISOs do not usually use this format internally Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

Advantages of Using Node-Breaker Model in POM Suite Accurate representation of the real-time system: An actual State Estimator snapshot Accurate real-time contingency analysis: Buses may be split, if necessary Breakers are not being collapsed during power flow solution Export file from EMS may be saved as a bus-branch model (in PSS/E .raw format): All breakers are kept in the model as zero-impedance lines Node-breaker model is used in POM Suite for: Voltage stability, contingency analysis, system stressing (power transfer simulation, load scaling), RAS actions, any power flow computation Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.

Thank you! Copyright © 1997-2012 V&R Energy Systems Research, Inc. All rights reserved.