The objective of this research work is to develop decoupled modulation control methods for damping inter-area oscillations with low frequencies, so the damping control can be more effective and easier to design with less interference among different oscillation modes in the power system.

A signal-decoupling algorithm was developed that can enable separation of multiple oscillation frequency contents and extraction of a “pure” oscillation frequency mode that are fed into Power System Stabilizers (PSSs) as the modulation input signals. As a result, instead of introducing interferences between different oscillation modes from the traditional approaches, the output of the new PSS modulation control signal mainly affects only one oscillation mode of interest.

The new decoupled modulation damping control algorithm has been successfully developed and tested on the standard IEEE 4-machine 2-area test system and a minniWECC system. The results are compared against traditional modulation controls, which demonstrates the validity and effectiveness of the newly-developed decoupled modulation damping control algorithm.

10aAA15-0021 aWang, Shaobu1 aHuang, Zhenyu1 aHuang, Renke1 aDiao, Ruisheng uhttps://certs.lbl.gov/publications/decoupled-modulation-control02020nas a2200253 4500008003900000022001400039245008400053210006900137260001200206300001400218490000700232520124900239653001301488653000901501653003901510653003601549653001801585100001701603700001501620700002101635700001801656700002001674856007201694 2013 d a0885-895000aMode shape estimation algorithms under ambient conditions: A comparative review0 aMode shape estimation algorithms under ambient conditions A comp c05/2013 a779 - 7870 v283 aThis paper provides a comparative review of five existing ambient electromechanical mode shape estimation algorithms, i.e., the Transfer Function (TF), Spectral, Frequency Domain Decomposition (FDD), Channel Matching, and Subspace Methods. It is also shown that the TF Method is a general approach to estimating mode shape and that the Spectral, FDD, and Channel Matching Methods are actually special cases of it. Additionally, some of the variations of the Subspace Method are reviewed and the Numerical algorithm for Subspace State Space System IDentification (N4SID) is implemented. The five algorithms are then compared using data simulated from a 17-machine model of the Western Electricity Coordinating Council (WECC) under ambient conditions with both low and high damping, as well as during the case where ambient data is disrupted by an oscillatory ringdown. The performance of the algorithms is compared using the statistics from Monte Carlo simulations and results from measured WECC data, and a discussion of the practical issues surrounding their implementation, including cases where power system probing is an option, is provided. The paper concludes with some recommendations as to the appropriate use of the various techniques.10aAA07-00110aAARD10aAutomatic Switchable Network (ASN)10aphasor measurement units (PMUs)10apower systems1 aDosiek, Luke1 aZhou, Ning1 aPierre, John, W.1 aHuang, Zhenyu1 aTrudnowski, Dan uhttps://certs.lbl.gov/publications/mode-shape-estimation-algorithms01820nas a2200277 4500008003900000020002200039245007800061210006900139260003600208300001000244520098900254653001301243653000901256653001701265653001701282653000901299100001901308700001801327700001501345700001601360700002501376700002201401700002201423700002301445856007401468 2011 d a978-1-61284-789-400aDeriving optimal operational rules for mitigating inter-area oscillations0 aDeriving optimal operational rules for mitigating interarea osci aPhoenix, AZ, USAbIEEEc03/2011 a1 - 83 aThis paper introduces a new method for mitigating inter-area oscillations of a large scale interconnected power system by means of generation re-dispatch. The optimal mitigation procedures are derived by searching for the shortest distance from current operating condition to a targeted operating condition with the desired damping ratio of the oscillation mode. A sensitivity-based method is used to select the most effective generators for generation re-dispatch and decision tree is trained to approximate the security boundary in a space characterized by the selected generators. The optimal operational rules can be found by solving an optimization problem where the boundary constraints are provided by the decision tree rules. This method is tested on a Western Electricity Coordinating Council (WECC) 179-bus simplified model and simulation results have demonstrated the validity of the decision-tree-based method and shown promising application in real time operation.

10aAA07-00110aAARD10aoptimization10aoscillations10aWECC1 aDiao, Ruisheng1 aHuang, Zhenyu1 aZhou, Ning1 aChen, Yousu1 aTuffner, Francis, K.1 aFuller, Jason, C.1 aJin, Shuangshuang1 aDagle, Jeffery, E. uhttps://certs.lbl.gov/publications/deriving-optimal-operational-rules02070nas a2200277 4500008003900000020002200039245008600061210006900147260003600216300001000252520120300262653001301465653000901478653003901487653001201526653002601538653002701564653000901591100001601600700002201616700001901638700001501657700001801672700002501690856007701715 2011 d a978-1-4577-1000-100aThe influence of topology changes on inter-area oscillation modes and mode shapes0 ainfluence of topology changes on interarea oscillation modes and aDetroit, MI, USAbIEEEc07/2011 a1 - 73 aThe topology of a power grid network is a piece of critical information for power grid operations. Different power grid topologies can change grid characteristics, inter-area oscillation modes, mode shapes, and even the robustness of the power system. This paper presents some preliminary study results, based on an approved WECC operating case and a modified low damping WECC system, to show the impact of topology changes resulting from N-1 contingencies on power system modes and mode shapes. The results show that topology changes can have very different impact on modal properties in a power system: some result in an unstable situation, while others can improve small signal stability. For the former, the studies show about a 4.5% damping reduction, so a 5% damping margin would be required to ensure the system can sustain the contingencies. For the latter, those topology changes could be used as a control method to improve small signal stability. Mode shapes normally do not change when there is an N-1 topology change. These observations suggest that the inclusion of topological information is useful for improving the accuracy and effectiveness of power system control schemes.

10aAA07-00110aAARD10aAutomatic Switchable Network (ASN)10adamping10apower grid operations10aPower system stability10aWECC1 aChen, Yousu1 aFuller, Jason, C.1 aDiao, Ruisheng1 aZhou, Ning1 aHuang, Zhenyu1 aTuffner, Francis, K. uhttps://certs.lbl.gov/publications/influence-topology-changes-inter-area01571nas a2200241 4500008003900000020002200039245008200061210006900143260003600212300001000248520076300258653001301021653000901034653003901043653003601082653002901118100001501147700001801162700002501180700002001205700002901225856007501254 2011 d a978-1-4577-1000-100aA modified stepwise linear regression method for estimating modal sensitivity0 amodified stepwise linear regression method for estimating modal aDetroit, MI, USAbIEEEc07/2011 a1 - 73 aSmall signal stability problems are one of the major threats to grid stability and reliability. Low damping of inter area modes is usually considered to be a result of heavy power transfer over long distances. This paper proposes a modified stepwise regression method to estimate the modal sensitivity with respect to power flow on the transmission lines based on measurement. This sensitivity is used to identify dominant transmission lines, whose power flow has significant influence on the inter-area modal damping. It is shown through simulation study that the proposed method can effectively estimate the modal sensitivity with respect to line power flow. This, in turn, provides insight on how to improve damping through adjusting tie line flow.

10aAA09-00210aAARD10aAutomatic Switchable Network (ASN)10aphasor measurement units (PMUs)10apower system reliability1 aZhou, Ning1 aHuang, Zhenyu1 aTuffner, Francis, K.1 aTrudnowski, Dan1 aMittelstadt, William, A. uhttps://certs.lbl.gov/publications/modified-stepwise-linear-regression01950nas a2200265 4500008003900000020002200039245009000061210006900151260002900220300001000249520110800259653001301367653000901380653003901389653001201428653001701440653002501457653002601482653002701508100001801535700001501553700002501568700002001593856007101613 2011 d a978-1-4244-9618-100aUse of Modal Sensitivity to Operating Conditions for Damping Control in Power Systems0 aUse of Modal Sensitivity to Operating Conditions for Damping Con aKauai, HIbIEEEc01/2011 a1 - 93 aSmall signal stability is an inherent characteristic of dynamic systems such as power systems. Pole positioning through power system stabilizers (PSS) is often used for improving damping in power systems. A well-designed PSS can be very effective in damping oscillations, especially local oscillations. However, designing PSSs for inter-area oscillations has been a very challenging task due to time-varying operating conditions affecting the oscillations. This paper explores the sensitivity relationship between oscillations and operating conditions, and employs the relationship to derive recommendations for operator's actions to adjust operating conditions for improving damping. Low damping is usually considered to be a result of heavy power transfer in long distance, while specific locations also have significant impact on damping of oscillations. Therefore, it is important to consider locations in deriving recommendations. This paper proposes the concept of relative modal sensitivity and presents its application in deriving recommendations for operator's action in damping control.

10aAA07-00110aAARD10aAutomatic Switchable Network (ASN)10adamping10aoscillations10apower system control10aPower system dynamics10aPower system stability1 aHuang, Zhenyu1 aZhou, Ning1 aTuffner, Francis, K.1 aTrudnowski, Dan uhttps://certs.lbl.gov/publications/use-modal-sensitivity-operating01760nas a2200253 4500008003900000020002200039245011400061210006900175260003500244300001000279520090000289653001301189653000901202653003901211653002101250653003601271653002801307100001501335700001801350700002501368700002101393700002201414856007001436 2010 d a978-1-4244-6549-100aAutomatic implementation of Prony analysis for electromechanical mode identification from phasor measurements0 aAutomatic implementation of Prony analysis for electromechanical aMinneapolis, MNbIEEEc07/2010 a1 - 83 aSmall signal stability problems are one of the major threats to grid stability and reliability. Prony analysis has been successfully applied on ringdown data to monitor electromechanical modes of a power system using phasor measurement unit (PMU) data. To facilitate an on-line application of mode estimation, this paper develops a recursive algorithm for implementing Prony analysis and propose an oscillation detection method to detect ringdown data in real time. By automatically detecting ringdown data, the proposed method helps to guarantee that Prony analysis is properly and timely applied on the ringdown data. Thus, the mode estimation results can be performed reliably and timely. The proposed method is tested using Monte Carlo simulations based on a 17-machine model and is shown to be able to properly identify the oscillation data for on-line application of Prony analysis.

10aAA07-00110aAARD10aAutomatic Switchable Network (ASN)10agrid reliability10aphasor measurement units (PMUs)10apower system monitoring1 aZhou, Ning1 aHuang, Zhenyu1 aTuffner, Francis, K.1 aPierre, John, W.1 aJin, Shuangshuang uhttps://certs.lbl.gov/publications/automatic-implementation-prony02029nas a2200277 4500008003900000020002200039245007200061210006900133260003500202300001000237520114200247653001301389653000901402653003901411653003601450653002701486100001801513700001501531700002501546700001601571700002001587700002901607700002001636700002301656856007201679 2010 d a978-1-4244-6549-100aImproving small signal stability through operating point adjustment0 aImproving small signal stability through operating point adjustm aMinneapolis, MNbIEEEc07/2010 a1 - 83 aModeMeter techniques for real-time small-signal stability monitoring continue to mature, and more and more phasor measurements are available in power systems. It has come to the stage to bring modal information into real-time power system operation. This paper proposes to establish a procedure for Modal Analysis for Grid Operations (MANGO). Complementary to PSS and other traditional modulation-based control, MANGO aims to provide suggestions such as redispatching generation for operators to mitigate low-frequency oscillations. Load would normally not be reduced except as a last resort. Different from modulation-based control, the MANGO procedure proactively maintains adequate damping at all times, rather than reacting to disturbances when they occur. The effect of operating points on small-signal stability is presented in this paper. Implementation with existing operating procedures is discussed. Several approaches for modal sensitivity estimation are investigated to associate modal damping and operating parameters. The effectiveness of the MANGO procedure is confirmed through simulation studies of several test systems.10aAA07-00110aAARD10aAutomatic Switchable Network (ASN)10aphasor measurement units (PMUs)10aPower system stability1 aHuang, Zhenyu1 aZhou, Ning1 aTuffner, Francis, K.1 aChen, Yousu1 aTrudnowski, Dan1 aMittelstadt, William, A.1 aHauer, John, F.1 aDagle, Jeffery, E. uhttps://certs.lbl.gov/publications/improving-small-signal-stability01314nas a2200229 4500008003900000020002200039245011100061210006900172260004000241300001000281520052500291653001300816653000900829653003900838653002600877100002500903700001800928700001500946700002500961700002400986856007401010 2010 d a978-1-4244-6546-000aInitial studies on actionable control for improving small signal stability in interconnected power systems0 aInitial studies on actionable control for improving small signal aNew Orleans, LA, USAbIEEEc04/2010 a1 - 63 aPower consumption and demand continues to grow around the world. As the electric power grid continues to be put under more stress, the conditions of instability are more likely to occur. One cause of such instabilities is intearea oscillations, such as the oscillation that resulted in the August 10, 1996 blackout of the WECC. This paper explores different potential operations of different devices on the power system to improve the damping of these interarea oscillations using two different simulation models.

10aAA07-00110aAARD10aAutomatic Switchable Network (ASN)10aPower system modeling1 aTuffner, Francis, K.1 aHuang, Zhenyu1 aZhou, Ning1 aGuttromson, Ross, T.1 aJayantilal, Avnaesh uhttps://certs.lbl.gov/publications/initial-studies-actionable-control01698nas a2200277 4500008003900000245011600039210006900155260001200224300000700236520082500243653001301068653000901081653003801090653001001128100001801138700001901156700001501175700002201190700002501212700002901237700001601266700002001282700002001302700002301322856007501345 2010 d00aMANGO - Modal Analysis for Grid Operation: A Method for Damping Improvements through Operating Point Adjustment0 aMANGO Modal Analysis for Grid Operation A Method for Damping Imp c10/2010 a923 aWith more and more phasor measurements available and ModeMeter techniques maturing, there is yet a need for methods to bring modal analysis from monitoring to actions. The methods should be able to associate low damping with grid operating conditions, so operators or automated operation schemes can respond when low damping is observed. The work presented in this report aims to develop such a method and establish a Modal Analysis for Grid Operation (MANGO) procedure to provide recommended actions (such as generation re-dispatch or load reduction), and aid grid operation decision making for mitigating inter-area oscillations. This project directly contributes to the Department of Energy Transmission Reliability Program's goal of "improving reliability of the nation's electricity delivery infrastructure."

10aAA07-00110aAARD10aadvanced measurements and control10aCERTS1 aHuang, Zhenyu1 aDiao, Ruisheng1 aZhou, Ning1 aFuller, Jason, C.1 aTuffner, Francis, K.1 aMittelstadt, William, A.1 aChen, Yousu1 aHauer, John, F.1 aTrudnowski, Dan1 aDagle, Jeffery, E. uhttps://certs.lbl.gov/publications/mango-modal-analysis-grid-operation01776nas a2200241 4500008003900000020002200039245010900061210006900170260003500239300001000274520096800284653001301252653000901265653003901274653003601313653002601349100001501375700001801390700001701408700002001425700002101445856006801466 2009 d a978-1-4244-4241-600aElectromechanical mode shape estimation based on transfer function identification using PMU measurements0 aElectromechanical mode shape estimation based on transfer functi aCalgary, CanadabIEEEc07/2009 a1 - 73 aPower system mode shapes are a key indication of how dynamic components participate in low-frequency oscillations. Traditionally, mode shapes are calculated from a linearized dynamic model. For large-scale power systems, obtaining accurate dynamic models is very difficult. Therefore, measurement-based mode shape estimation methods have certain advantages, especially for the application of real-time small signal stability monitoring. In this paper, a measurement-based mode shape identification method is proposed. The general relationship between transfer function (TF) and mode shape is derived. As an example, a least square (LS) method is implemented to estimate mode shape using an autoregressive exogenous (ARX) model. The performance of the proposed method is evaluated by Monte-Carlo studies using simulation data from a 17-machine model. The results indicate the validity of the proposed method in estimating mode shapes with reasonably good accuracy.10aAA07-00110aAARD10aAutomatic Switchable Network (ASN)10aphasor measurement units (PMUs)10aPower system modeling1 aZhou, Ning1 aHuang, Zhenyu1 aDosiek, Luke1 aTrudnowski, Dan1 aPierre, John, W. uhttps://certs.lbl.gov/publications/electromechanical-mode-shape01776nas a2200205 4500008004100000020002200041245007400063210006900137260001800206300000800224520114800232653001001380653003101390653001001421100001101431700001301442700001801455700002301473856007401496 2009 eng d a978-1-4244-3810-500aThe system impact of air conditioner under-voltage protection schemes0 asystem impact of air conditioner undervoltage protection schemes bIEEEc03/2009 a1-83 aThis paper presents the results of simulating and evaluating an under-voltage protection scheme, which takes stalled air-conditioner (a/c) units offline so that the slow voltage recovery phenomena can be prevented in areas heavily loaded with AC motors during summer peak periods. First, a three-feeder test-bed was used to quantify the effectiveness of the protection scheme and the sensitivity of the under-voltage relay settings. Then, two real system events from the Western US power grid were simulated to evaluate the area-level impact of the protection scheme proposed by Southern California Edison. The study demonstrates that after 75% or more of the stalled a/c units are disconnected, the feeder voltage recovers in a few seconds, much quicker than the tens of seconds that standard thermal relays need to trip the stalled motor offline. The drawback is that after the voltage recovered, it settles at a higher value than prior to the faults because a large proportion of load is shed. Therefore, the coordination among the capacitor bank operation is recommended to suppress the overvoltage caused by tripping of the AC motor load.10aFIDVR10aFIDVR Composite Load Model10aRTINA1 aLu, N.1 aYang, B.1 aHuang, Zhenyu1 aBravo, Richard, J. uhttp://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=484005303048nas a2200181 4500008004100000020001500041245004900056210004900105260006500154520248900219653001002708653001402718653001002732100001102742700001202753700001802765856008302783 2008 eng d aPNNL-1779600aAir Conditioner Compressor Performance Model0 aAir Conditioner Compressor Performance Model aRichland, WAbPacific Northwest National Laboratoryc08/20083 aIn recent years, phasor measurement units (PMUs) have recorded more and more slow voltage recovery (SVR) events in the electrical grid, especially in areas supplying heavy air-conditioning loads. The sustained low voltages have caused power quality issues and raised concerns about system voltage collapse. Meanwhile, the significant reduction in voltage stability margin may lead to a similar chain of events. For these reasons, it is critical that SVR events be modeled and prevented to assure that the system voltage recovers to its nominal value in a few seconds. Fundamentally, SVR events are caused by stalled compressors inside single-phase air-conditioning (SPAC) units, which can not be simulated satisfactorily by either three-phase motor models or ZIP models. Therefore, a new modeling approach is needed. During the past years, the Western Electricity Coordinating Council (WECC) Load Modeling Task Force (LMTF) has led the effort to develop the new modeling approach. As part of this effort, the Bonneville Power Administration (BPA), Southern California Edison (SCE), and Electric Power Research Institute (EPRI) Solutions tested 27 residential air-conditioning units to assess their response to delayed voltage recovery transients. After completing these tests, different modeling approaches were proposed, among them a performance modeling approach that proved to be one of the three favored for its simplicity and ability to recreate different SVR events satisfactorily. Funded by the California Energy Commission (CEC) via Lawrence Berkeley National Laboratory under its load modeling project, researchers at Pacific Northwest National Laboratory (PNNL) led the follow-on task to analyze the motor testing data to derive the parameters needed to develop a performance model for the SPAC unit. To derive the performance model, PNNL researchers first used the motor voltage and frequency ramping test data to obtain the real (P) and reactive (Q) power versus voltage (V) and frequency (f) curves. Then, curve fitting was used to develop the P-V, Q-V, P-f, and Q-f relationships for motor running and stalling states. The resulting performance model ignores the dynamic response of the air-conditioning motor. Because the inertia of the air-conditioning motor is very small (H<0.05), the motor reaches from one steady state to another in a few cycles, so, the performance model is a fair representation of the motor behaviors in both running and stalling states.10aFIDVR10aFIDVR-00710aRTINA1 aLu, N.1 aXie, YL1 aHuang, Zhenyu uhttp://www.pnl.gov/main/publications/external/technical_reports/pnnl-17796.pdf03638nas a2200181 4500008004100000245005200041210005000093260005100143520306600194653001003260653001403270653001803284653001003302100001803312700002703330700001603357856008303373 2007 eng d00aLoad Monitoring: CEC/LMTF Load Research Program0 aLoad Monitoring CECLMTF Load Research Program bPacific Northwest National Laboratoryc11/20073 aThis report is intended to serve as a reference for future load monitoring projects. The identification of specific vendor's equipment/software, etc. in this document is for research documentation only and does not constitute an endorsement of these items. Load monitoring provides an important means to understand load behavior in the actual system. This understanding helps to develop load models to represent the load behavior in simulation studies. Load monitoring provides measured data needed for load model validation, load composition studies, and load uncertainty analysis. Depending on various needs, load monitoring may be implemented differently with different monitoring hardware, different measured quantities, and different requirements for sampling rates, signal types, record length and availability, with different costs. Potential load monitoring options include traditional supervisory control and data acquisition (SCADA), phasor measurement units (PMUs), portable power system monitors (PPSMs), digital fault recorders (DFRs), protective relays, power quality monitors, and a low-cost monitoring device being developed by Western Electricity Coordinating Council (WECC) Disturbance Monitoring Working Group (DMWG). Characteristics of these options are summarized in this report. Current load monitoring practices at several utility companies are presented as examples of load monitoring. Each example consists of the following aspects of load monitoring: objective of load monitoring, monitoring location selection, description of monitoring equipment, communication for load monitoring, cost, and use of the data. The purpose of load monitoring is to provide better load characterization and better load management, i.e., the core element of load monitoring is focused on applications. Five load monitoring applications are proposed in this report, with some preliminary case studies: • Load monitoring for top-down load composition: The total load profile obtained from load monitoring data can be decomposed to derive fractions of individual load types if load profiles of individual load types are known. • Load monitoring for load composition validation: Load profiles generated by the load composition model can be validated against load profiles derived from load monitoring data. • Load monitoring for load model validation: The general approach of model validation is to compare model simulation against measurements, as was applied to WECC generator model validation. Load monitoring provides the basis for load model validation. • Load monitoring for uncertainty analysis: Statistical analysis can be performed on load monitoring data to quantify load variations over selected time periods. • Load monitoring for load control performance evaluation: This is the trend that loads will play a more and more active role in managing the power system. Similar to generator performance monitoring, load monitoring can be used to ensure the load behaves as designed for correct credits and control enforcement. 10aFIDVR10aFIDVR-00710aload modeling10aRTINA1 aHuang, Zhenyu1 aLesieutre, Bernard, C.1 aYang, Steve uhttp://www.pnl.gov/main/publications/external/technical_reports/PNNl-17110.pdf01271nas a2200169 4500008003900000245008000039210006900119260003500188300001400223520070900237653001300946100001800959700001500977700002100992700001901013856006901032 2006 d00aModel Validation of Power System Components Using Hybrid Dynamic Simulation0 aModel Validation of Power System Components Using Hybrid Dynamic aDallas, TX, USAbIEEEc05/2006 a153 - 1603 aHybrid dynamic simulation, with its capability of injecting external signals into dynamic simulation, opens the traditional dynamic simulation loop for interaction with actual field measurements. This simulation technique enables rigorous comparison between simulation results and actual measurements and model validation of individual power system components within a small subsystem. This paper uses a real example of generator model validation to illustrate the procedure and validity of the component model validation methodology using hybrid dynamic simulation. Initial model calibration has also been carried out to show how model validation results would be used to improve component models

10aAA07-0011 aHuang, Zhenyu1 aNguyen, T.1 aKosterev, Dmitry1 aGuttromson, R. uhttps://certs.lbl.gov/publications/model-validation-power-system01631nas a2200181 4500008003900000245009700039210006900136260001200205300000700217520103000224653000901254653003801263653001001301100002501311700001801336700002501354856007001379 2005 d00aArchiving and Management of Power Systems Data for Real-Time Performance Monitoring Platform0 aArchiving and Management of Power Systems Data for RealTime Perf c01/2005 a403 aOver the past century, power systems have advanced from single generating plants to highly interconnected grids spanning thousands of miles. These modern power systems play an essential role in our society by providing a highly reliable energy source. However, they occasionally experience massive breakups affecting large residential and industrial areas. The lessons learned from such breakups are instructive but costly.

Assuring power system reliability has been a major objective since the beginning of the industry. Today's power engineers are especially concerned about power system reliability for a number of reasons. Economy growth demands more power from the electric infrastructure, and increases the stress upon aging facilities. Deregulation encourages operating the system in ways for which it was not originally designed, and that operation becomes increasingly variable and difficult to predict. Grid managers find it increasingly difficult to determine and observe the limits of safe operation.

10aAARD10aadvanced measurements and control10aRTGRM1 aMartinez, Carlos, A.1 aHuang, Zhenyu1 aGuttromson, Ross, T. uhttps://certs.lbl.gov/publications/archiving-and-management-power