J. Giri

University of Liège, Luik, Walloon Region, Belgium

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Publications (9)3.16 Total impact

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    ABSTRACT: PMU devices are expected to grow in number from a few to several hundreds in the next five years. Some relays are already global positioning system-capable and could provide the same type of data as any PMU. This introduces a new paradigm of very fast accurate synchrophasor measurements from across the grid in real-time that augment and parallel existing slower SCADA measurements. Control center applications will benefit from this PMU data; for example, use of PMU data in state estimation is expected to improve accuracy and robustness, which in turn will result in more timely and accurate N-1 security analysis, resulting in an overall improvement of grid system reliability and security. This paper describes results from a recent implementation of this technology, the benefits and future work.
    Power & Energy Society General Meeting, 2009. PES '09. IEEE; 08/2009
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    ABSTRACT: This paper presents keys in avoiding total system collapse though enhancing grid reliability and stability with a better, smarter, faster SCADA system.
    IEEE Power and Energy Magazine 05/2009; · 1.58 Impact Factor
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    ABSTRACT: The recent world-wide rash of power systems blackouts has provided an added impetus to wide-scale deployment of phasor measurement units (PMUs). Initial applications of PMUs in the late 1980s and 1990s were isolated due to the limited infrastructure availability and lack of computational support for extensive processing of the networked information. Today, networks of hundreds of PMUs are in place and more are planned.The recognition that networks of PMUs can provide greater power system reliability is based on their ability to give direct access to the state of the power system at any given instant.
    IEEE Power and Energy Magazine 10/2008; · 1.58 Impact Factor
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    ABSTRACT: This paper describes the integration of stability assessment tools in the EMS. The main functions are the transient security and voltage security tools. They are invoked under several modes of operation to address the current state of the system as well as the immediate short-term planning horizons. Data exchange, preparation and output visualization are described in the context of distributed architectures and the latest user interface technology. The operators will be able to analyze transactions under various conditions and contingences that could potentially lead to insecure behavior. The dynamic tools are triggered as part of the on-line network and study network sequences. The architecture and system configuration is the key to ensuring fast, robust and accurate dynamic solutions. Several CPUs are used to reduce the execution time for day and week-ahead analysis. The user friendly data exchange setup prevents conflict between several instances of DSA users and models.
    Power Systems Conference and Exposition, 2004. IEEE PES; 11/2004
  • J. Giri, R. Avila-Rosales
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    ABSTRACT: Summary form only given as follows. Security assessment has always played an important role in system operation, and has always been one of the most computationally expensive calculations in the control center. The new RTO models require the solution of very large systems of unprecedented size. Simulating systems of these sizes impose additional computational challenges and are affected by model accuracy, solution techniques and system architecture. The concept of "n-1" security is a requirement in the context of the uncertain electricity market environment. So several contingencies and monitored facilities must be included as part of the optimization techniques to guarantee "n-1" security, and to relieve constraints during the congestion management process. Model accuracy and validity becomes a major issue when dealing with very large databases. Since these databases are created by merging databases of various transmission companies, the overall model needs to be checked and validated to a greater degree than in the past. One of the basic functions of the spot/balancing and congestion management markets, is a bid-based security constrained economic dispatch, which considers real-time system balancing and re-dispatch to avoid congestion and maintain flows and constraints under several contingencies and limits. Given an operating condition, a single contingency could determine the limits on the transmission network, and branch power flows may be bound by its impact in the event the contingency takes place. Post-contingency analysis is used to identify the set of binding constraints for the optimization loop, therefore anticipated contingencies can limit the system at all times. Security assessment gets more complicated if the market deals with day-ahead hourly schedules, where participants will buy and sell energy and transmission, settle and reconfigure financial transmission rights via locational marginal prices. In general the electricity market applications are b- ased on a combination of optimization methods and efficient load flow solutions for realtime as well as day-ahead calculations. This will demand considerable computational time, paving the way to distributed and parallel processing. On-line and day-ahead voltage security has been implemented considering the use of more than one processor, but the voltage security constraints have not been implemented yet as part of the security constrained dispatch. Validity of the network models, faster algorithmic solutions, efficient data exchange and client/server distributed architecture are keys to providing security assessment in the electricity market environment.
    Power Engineering Society Summer Meeting, 2002 IEEE; 08/2002
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    ABSTRACT: Transient stability assessment, preventive control measures and dynamic ATC calculations are addressed for a new deregulated EMS system. The combination of time domain analysis, SIME and optimal power flow provide a reliable solution for future transaction requirements and the current operating point
    Power Engineering Society Summer Meeting, 2000. IEEE; 02/2000
  • J. Giri
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    ABSTRACT: The author describes how traditional energy management system (EMS) power system applications are undergoing changes, in order to adapt to the users needs of the deregulated energy markets environment
    Power Engineering Society Winter Meeting, 2000. IEEE; 02/2000
  • J. Giri, R.A. Rosales
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    ABSTRACT: Electric utility companies around the world are experiencing new security challenges as they move towards deregulation of power system operation. Independent power producers, distribution companies, competitive economic transactions between buyers and sellers, open access requirements and free energy routing through the transmission system are putting a greater emphasis on online transient stability assessment (TSA). Most companies with stability concerns are willing to consider online implementation of TSA and the determination of remedial and preventive control actions for the operation of their power system. This paper describes the requirements for online TSA integration from an EMS control center user's point of view. DTS and study modes of operation are also presented for planning and current operation analysis. Functional and implementation requirements are described that will enable a successful online deployment of TSA in an EMS. Voltage security assessment (VSA) is included in all figures to complete the EMS and control center picture
    Power Engineering Society Winter Meeting, 2000. IEEE; 02/2000
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    ABSTRACT: An integrated scheme is proposed for computing on-line power system available transfer capability (ATC) while meeting static and transient stability constraints. The approach is based on the coupling of an OPF program with a method, called MAT (maximum allowable transfer), which relies on SIME (single machine equivalent) and its variants. The way in which this combined approach proceeds is outlined. Basically, the approach takes care of the stability constraints by (generally) decreasing active power on critical machines, then reallocating power generation on noncritical machines so as to ensure maximum allowable power transfer on the considered tie-lines. Stated otherwise, the combined use of the MAT method with the OPF program succeeds in reaching the multifold objective: to guarantee maximum power transfer on the defined tie-lines, and to meet transient stability constraints vis-a-vis all plausible contingencies, together with static constraints. The whole procedure is robust, in the sense that it converges consistently and readily to the solution. It is also compatible with real-time requirements
    Power Engineering Society Summer Meeting, 1999. IEEE; 08/1999