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Chiang H.-D.,Cornell University | Li H.,Bigwood Systems Inc. | Tada Y.,Tokyo Electric Power Company | Tong J.,PJM Interconnection LLC
17th Power Systems Computation Conference, PSCC 2011 | Year: 2011

In this paper, the concept of a group of coherent contingencies is formulated and demonstrated. These group properties include static and dynamic group properties. A scheme for identifying groups of coherent contingencies from a large contingency list is also developed. Numerical examples are presented to illustrate groups of coherent contingencies and the associated group properties. These group properties can have a variety of practical applications; in particular, they can be explored and incorporated into the development of power system analysis, computation and control.


Chiang H.-D.,Cornell University | Li H.,Bigwood Systems Inc. | Tong J.,PJM Interconnection LLC | Causgrove P.,Bigwood Systems Inc.
IEEE Power and Energy Society General Meeting | Year: 2011

An on-line tool developed for voltage stability analysis and enhancement (VSA&E) of large-scale power systems is presented in this paper. The tool has several major functions related to voltage security assessment, load margin calculations, contingency analysis, fast identification of insecure contingencies and critical contingencies, development of preventive control against insecure contingencies and development of enhancement control for increasing load margins for critical contingencies. The parallel version of this tool currently handles on-line models of 20-000 buses with the contingency list in the order of thousand. Some analytical results behind this tool are described. © 2011 IEEE.


Chiang H.-D.,Cornell University | Li H.,Bigwood Systems Inc. | Tong J.,PJM Interconnection LLC | Tada Y.,Tokyo Electric Power Company
Power Systems | Year: 2013

This paper describes an effective methodology for on-line screening and ranking of a large set of contingencies. An evaluation study of the on-line methodology in a real-time environment as a transient stability analysis (TSA) screening tool is presented. Requirements for an on-line screening and ranking tools are presented. The methodology of BCU classifiers implemented in the TEPCO-BCU package was evaluated on the PJM system as a fast screening tool to improve on-line performance of the PJM TSA system. This evaluation study is the largest in terms of system size, 14,500-bus, 3000 generators, for a practical application of direct methods for on-line TSA. The total number of contingencies involved in this evaluation is about 5.3 million. The evaluation results were very promising and confirm the practicality of the methodology based on direct methods, in particular the BCU method for on-line TSA of large-scale systems with a large set of contingencies. © Springer-Verlag Berlin Heidelberg 2013.


Tanabe R.,Tokyo Electric Power Company | Tanaka T.,Toshiba Corporation | Serizawa Y.,Japan Central Research Institute of Electric Power Industry | Li H.,Bigwood Systems Inc.
International Transactions on Electrical Energy Systems | Year: 2014

This paper presents a platform for integrating a voltage stability assessment and enhancement (VSA&E) application into wide-area situational awareness (WASA) based on international standards. VSA&E is a key tool for maintaining and enhancing voltage security of bulk power systems. As power systems become more complicated and the penetration of renewable energies increases, system operators require powerful tools to analyze voltage security of the system based on actual online system operating conditions. We have proposed a concept of the international standard-based WASA that can provide such a next generation VSA&E application platform with no vendor lock-in. The effectiveness and practicability of the international standard-based WASA are demonstrated with VSA&E application integrated into a WASA evaluation system. Copyright © 2013 John Wiley & Sons, Ltd. Copyright © 2013 John Wiley & Sons, Ltd.


Li H.,Bigwood Systems Inc. | Haq E.,California Independent System Operator | Abdul-Rahman K.,California Independent System Operator | Wu J.,California Independent System Operator | Causgrove P.,Bigwood Systems Inc.
International Transactions on Electrical Energy Systems | Year: 2014

Voltage stability analysis and control are key applications for maintaining and enhancing the voltage security of bulk power systems. In today's control center, as power systems become more stressed and the penetration of renewable energies increases, system operators need to analyze voltage security of the systems based on actual operating conditions, contingency and power transactions of the system. In this paper, the model used to represent a power system losing stability is described. It is shown that the voltage collapse point is reached at saddle-node bifurcation or a structure-induced bifurcation. Computation of P-V curves showing system load margin to voltage collapse, system load margin to voltage-limit violation and system load margin to thermal-limit violation is presented. The architecture and example results of the Voltage Stability Analysis and Enhancement system at the California Independent System Operator implementing this research are shown. The continuation power flow engine at the core of this work is presented in detail, and study results are shown. Other key functions, contingency selection (insecure or critical) and ranking, preventive control to increase the load margin of insecure contingencies such that it is secure and enhancement control to increase the load margin of critical contingencies, are presented. Finally, a novel method to enhance the continuation power flow in handling uncertainty of renewable energy is shown. Copyright © 2014 John Wiley & Sons, Ltd. Copyright © 2014 John Wiley & Sons, Ltd.

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