Selected Papers on the use of POM Suite of Applications

 Calculation and Visualization of a Power System Stability Margin Based on the PMU Measurements (381.12 kB) This paper introduces the concept of the Region Of Stability Existence (ROSE) and describes the framework for utilizing PMU data for computing of this region and  operational margins. The approach presented in this paper is an automated process to continuously monitoring the transmission system in real-time environment by accurately calculating power system stability margins. Voltage constraints, thermal limits and steady-state stability are simultaneously monitored during the analysis. The region is shown on the planes of two phase angles and real powers. The paper also demonstrates the effect of remedial actions on the region. The approach is illustrated by using  the ISO New England’s real-time model, SCADA data and PMU measurements. The study results show that this approach is effective in improving the reliability of the ISO New England's transmission network and may be used for preventing major blackouts.

 Fast Fault Screening for Real-Time Transient Stability Assessment (2.47 MB)

As a deregulated system is being operated closer to the system limits, system operators require a fast screening tool that will assess the system’s stability and identify the most severe fault locations in the system. Some of these locations might be already known to planners and operators while other new locations emerge as the system conditions dynamically change in a real-time operating environment. The proposed capability will allow planners and operators to assess transient (angular) stability very fast. The Fast Fault Screening (FFS) technique is a very fast approach to identify and rank the most severe three-phase and unbalanced fault locations. Testing showed that it took less than one minute to determine and rank the most severe faults using the proposed Fast Fault Screening (FFS) approach. FFS has been shown as a practical tool to perform transient stability studies required under the existing and forthcoming NERC standard TPL-001-1. During this project, FFS was also demonstrated as an effective tool for transient stability assessment in on-line and near real-time environments.

 Implementation of the Optimal Mitigation Measures for Transmission Planning Assessment (409.57 kB) 

 Assessing Vulnerability to Cascading Outages (793.53 kB)

This paper addresses the testing and implementation of a fast process for sequential contingency simulation in order to identify the potential cascading modes due to thermal overloads. It also presents computation of the vulnerability index of cascading, based on an estimated likelihood and consequences of cascading outages. The approach described in this paper offers a unique capability to automatically identify initiating events that may lead to cascading outages. 

 Prevention of Cascading Outages at Con Edison (142.76 kB)

This paper describes the framework for assessment and prevention of cascading outages caused by the thermal overloads.The described approach helps to prevent the cascading outages by optimizing the existing available controls in the transmission network. Optimal remedial actions are applied first after the occurrence of an initiating event, and then at each cascading Tier, until the cascading event is mitigated. The paper also presents the ranking of cascading outages that is based on a minimum amount of load curtailment which is needed to alleviate the steady-state stability violations caused by cascading events.

 N-1-1 AC Contingency Analysis as a Part of NERC Compliance Studies at Midwest ISO (190.07 kB)

This paper addresses the development, testing and implementation of a fast automated process for assessing power system performance following the loss of two bulk transmission elements consecutively (N-1-1 contingency analysis) and simultaneously (N-2 contingency analysis). The approach described in this paper offers the flexibility to utilize various sets of system adjustments depending on types and values of post-contingency limit violations. It also incorporates a sequential contingency simulation in order to identify the potential cascading modes due to thermal overloads. Massive AC contingency analysis, automatically identifying various sets of system adjustments and prediction of cascades are performed within one computational run.

 Real-Time Evaluation of System Reliability Using a Boundary-Based Concept for EKPC System (486.03 kB)

This paper addresses a comprehensive approach to evaluate reliability in a large transmission system for on-line and real-time environments. The paper also addresses the growing need for broader coordination between planning and operations. The paper describes how the boundary-based AC approach was utilized to evaluate the reliability of the EKPC network. The approach described in this paper offers a unique capability to automatically identify the boundary of the secure operating region for each contingency and rank contingencies in on-line and off-line environments. The study also shows how to optimize a transmission system using existing resources without building new transmission lines.

 Fast Fault Screening Approach to Assessing Transient Stability in Entergy’s Power System (383.14 kB)

This paper addresses a fast process for performing transient stability studies in a large transmission system. The paper describes how the most severe three-phase fault locations were identified in Entergy’s power system network. The approach described in this paper offers a unique capability to automatically identify the most severe fault locations and perform ranking of these most severe faults in on-line and off-line environments. The study was performed using the Entergy loadflow and dynamic data to validate the proof of concept. It took approximately one minute to determine and rank 23 most severe fault locations in Entergy’s power system.

 Identifying Optimal Remedial Actions for Mitigating Violations & Increasing Transfer Capability (427.13 kB)

This paper describes the utility experience in identifying and optimizing mitigation measures based on a user-defined priority schedule to alleviate voltage, thermal and voltage stability violations.

 Utility Experience Computing Physical and Operational Margins: Part I – Basic Concept and Evaluation (297.15 kB)

This paper deals with the application of the concept of Physical and Operational Margins to analysis of the power system behavior. The approach offers a fast and accurate determination of the bottlenecks in the transmission network and the optimal mitigation measures needed to alleviate the identified violations. The technical foundation of the approach and its practical benefits are described.

 Utility Experience Computing Physical and Operational Margins: Part II – Power System Studies (246.03 kB)

This paper deals with the application of the concept of Physical and Operational Margins to the analysis of the power system behavior. This approach has been evaluated by the EPRI Probabilistic Reliability Assessment (PRA)

 New Approach to Constructing Seasonal Nomograms in Planning and Operations at Idaho Power Company (265.63 kB)

This paper addresses a novel approach to constructing the seasonal nomograms for both Planning and Operations environments. The paper describes how the nomograms were automatically constructed for the Idaho Power Co. (IPC) power system network. The approach presented in this paper offers a unique capability to automatically determine the effect of various stressing factors on the studied interfaces (paths) in Planning and Operations environments. This approach also allows the operator to determine and visualize the secure operating region.

Probabalistic Reliability Evaluation Study at Korea Power System By Using PRA (742.1 kB)

Reliability and power quality have been increasingly important in recent years due to a number of black-out events occurring throughout the world. This paper presents a practical method of probabilistic reliability evaluation of Korea Power system by using the Probabilistic Reliability Assessment (PRA) and Physical and Operational Margins (POM).

 Reliability Management of Korea Power System Operation with POM/OPM/BOR (244.42 kB)

This paper illustrates the potential applications of POM/OPM/BOR, which are used for deterministic reliability evaluation in the operation mode (Operational Planning and Operations) in Korea Power System. Deterministic reliability evaluation in this paper is based on the philosophy of the marginality and the limitation of physical quantities such as voltage and line flow under contingency analysis.

 Determining the Secure Region at Operation for Idaho Power Company (812.48 kB)

This paper deals with quick security calculations that provide a quantitative impact of every contingency on system conditions in Idaho Power Co. while simulating two simultaneous power transfers. The secure region of power system operation is determined and plotted for each contingency. Contingencies are ranked based on the size of the secure operating region, and the most limiting contingencies are identified. Optimal mitigation measures that increase the size of the secure operating region are then determined for each contingency. The effect of remedial actions on the size of the secure operating region is analyzed.

 Novel, Non-Linear Security Based Approach to Assess Transfer Capability at Idaho Power Company (501.45 kB)

This paper presents a novel non-linear security-based approach for the transfer capability assessment at Idaho Power Co. The objective of the study is to maximize a specific power transfer without any violation of the monitored constraints. Contingency analysis is performed. Contingencies that have the most limiting effect on the transfers are determined and the most limiting facilities are identified. The smallest Secure Operating Region is determined. The effect of mitigation measures on the transfer capability limit is analyzed. The study was performed using full AC analysis methodology for contingency screening and transfer studies. AC limits for transfer scenarios are computed based on thermal, voltage and voltage stability constraints.

Additional Resources

 NYPA Innovators with POM (2.35 MB)

 Applying Fast Fault Screening at Entergy (481.79 kB)

 General POM Applications Overview (1.19 MB)

 POM Benefits at EKPC (4.02 MB)